Journal of Dairy Science

Interpretive Summaries, February 2012

2012-02-01

Invited review: Genomic analysis of data from physiological studies. By Garrick et al., page 499. Physiology is concerned with elucidating the functions of living organisms and their organs or tissues. Early studies determined the functions of particular organs, such as the mammary gland. Later studies identified physiological differences between animals in different stages of life or in different environmental circumstances, sometimes to the level of individual genes. Genomics addresses the entire genome, and has empowered a new phase in physiology research that focuses on identifying and studying the genes that account for variation in performance by causing physiological differences to develop. This knowledge will improve our understanding of biology and may lead to novel strategies to manipulate animal performance.

ADSA Member News

2012-02-01

The 2012 ADSA-AMPA-ASAS-CSAS-WSASAS Joint Annual Meeting will be held July 15–19, 2012, in Phoenix, Arizona. From the Phoenix CVB (http://www.visitphoenix.com/about-phoenix/index.aspx):“America's sixth-largest city still has real cowboys and rugged mountains and the kind of cactus most people see only in cartoons. Phoenix is the gateway to the Grand Canyon, and its history is a testament to the spirit of puebloans, ranchers, miners and visionaries. Projected against this rich backdrop is a panorama of urban sophistication: Resorts and spas that drop jaws and soothe souls. Stadiums and arenas worthy of the world's biggest sports spectacles. Restaurants with inspired cuisine and inspiring patio views. Golf courses that beckon players the year round. Shopping centers as stylish and eclectic as the fashions they house.”

Invited review: Genomic analysis of data from physiological studies

D.J. Garrick, L.H. Baumgard, H.L. Neibergs — 2012-02-01

Abstract: Physiology deals with the functions of living organisms and their systems, and its scientific endeavors can be viewed as having temporally occurred in 3 phases. The first phase of physiology studies focused on determining the functions of particular organs and tissues and their functional differences according to physiological status. The second phase of studies focused on characterizing differences in these functions according to the environment, or productivity. The third phase of studies focuses on determining the physiological causes of differences in productivity. Distinguishing cause from effect in physiological systems of inter-related processes is problematic, such that science has struggled to identify the root physiological mechanisms and their role in the network of genes leading to differences in productivity. Genomics is the study of the entire genome and provides powerful new tools that will accelerate third-phase discoveries of causal physiological processes. That research exploits information on DNA polymorphisms known as markers, complete DNA sequence, RNA sequence, and RNA expression in particular tissues at specific life stages. Physiologists can determine the genetic cause of mutant animals, identify genetic differences between cases and controls, and identify genes responsible for differences in performance between average and above-average animals. In some species, physiologists can leverage genomic data being used to predict genetic merit in elite seedstock populations, as a starting point to identify genes that will then motivate detailed physiological studies in the organs or tissues and stages of life in which those genes are expressed. Such work will increase our knowledge of biology and may lead to novel approaches to manipulate animal performance.

Manufacture of Fior di Latte cheese by incorporation of probiotic lactobacilli

F. Minervini, S. Siragusa, M. Faccia, F. Dal Bello, M. Gobbetti, M. De Angelis — 2012-02-01

Abstract: This work aimed to select heat-resistant probiotic lactobacilli to be added to Fior di Latte (high-moisture cow milk Mozzarella) cheese. First, 18 probiotic strains belonging to Lactobacillus casei, Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus paracasei, Lactobacillus plantarum, Lactobacillus rhamnosus, and Lactobacillus reuteri were screened. Resistance to heating (65 or 55°C for 10min) varied markedly between strains. Adaptation at 42°C for 10min increased the heat resistance at 55°C for 10min of all probiotic lactobacilli. Heat-adapted L. delbrueckii ssp. bulgaricus SP5 (decimal reduction time at 55°C of 227.4min) and L. paracasei BGP1 (decimal reduction time at 55°C of 40.8min) showed the highest survival under heat conditions that mimicked the stretching of the curd and were used for the manufacture of Fior di Latte cheese. Two technology options were chosen: chemical (addition of lactic acid to milk) or biological (Streptococcus thermophilus as starter culture) acidification with or without addition of probiotics. As determined by random amplified polymorphic DNA-PCR and 16S rRNA gene analyses, the cell density of L. delbrueckii ssp. bulgaricus SP5 and L. paracasei BGP1 in chemically or biologically acidified Fior di Latte cheese was approximately 8.0 log10cfu/g. Microbiological, compositional, biochemical, and sensory analyses (panel test by 30 untrained judges) showed that the use of L. delbrueckii ssp. bulgaricus SP5 and L. paracasei BGP1 enhanced flavor formation and shelf-life of Fior di Latte cheeses.

Preference mapping of commercial Labneh (strained yogurt) products in the Lebanese market

D. Kaaki, O. Kebbe Baghdadi, N.E. Najm, A. Olabi — 2012-02-01

Abstract: Labneh or strained yogurt is a fermented milk product popular in Lebanon, the Middle East, and in the Balkan regions. With increased consumer awareness about the health benefits of consuming diets low in fat, reduced-fat Labneh products have emerged on the Lebanese market. The objectives of this study were to assess the physicochemical and sensory properties of commercial bovine Labneh products differing in fat content. Seven commercial bovine Labneh brands were chosen. Three brands were available in full-fat, reduced-fat, and zero-fat versions, 3 in full-fat and zero-fat versions, and 1 in full-fat and reduced-fat versions, resulting in a total of 17 tested samples. The moisture, fat, protein, ash, pH, and nitrogen-free extract contents were determined and instrumental texture characteristics measured using a texture analyzer. Nine trained panelists used quantitative descriptive analysis to profile the sensory attributes of the samples and an acceptability test was carried out with 73 panelists. Brand type had a significant effect on all chemical parameters, as did fat level, except for nitrogen-free extract. Instrumental texture analysis showed a significant effect of brand and fat levels, as well as their interaction, on all attributes, except for adhesiveness and fat level. Sensory analysis suggested that significant differences existed between brands for most attributes. Full-fat samples were significantly more yellow, less sweet, and possessed a stronger acidic aftertaste than did their reduced-fat and zero-fat counterparts. Acceptability clearly decreased as fat level decreased from full fat to zero fat, with full-fat Labneh samples rating highest on the acceptability of appearance, flavor, texture, and overall acceptability.

Comparison of the metabolic profiles of noncoagulating and coagulating bovine milk

H. Harzia, K. Kilk, I. Jõudu, M. Henno, O. Kärt, U. Soomets — 2012-02-01

Abstract: We hypothesize that, through milk composition and different milk metabolites, it is possible to characterize the technological properties (e.g., coagulation) of milk. In this research, liquid chromatography mass spectrometry was used to obtain profiles of low molecular weight organic compounds in 143 milk samples. The metabolic profiles of milk from cows were correlated with their coagulation properties. Using multivariate data analysis methods, we demonstrated that the metabolic profiles of the milk were correlated with coagulation ability. Several marker ions responsible for differential coagulation were found. Although not all affected metabolites could be identified, the most significant differences were found for carnitine and oligosaccharides. Exploitation of these results may increase the use of biomarkers to assess the coagulation ability of milk. This study represents the first large-scale metabolomic profiling of noncoagulating and coagulating bovine milk samples in Estonia.

In vivo methods for testing allergenicity show that high hydrostatic pressure hydrolysates of β-lactoglobulin are immunologically inert

I. López-Expósito, R. Chicón, J. Belloque, R. López-Fandiño, M.C. Berin — 2012-02-01

Abstract: The major milk allergen β-lactoglobulin (β-LG) exhibits an enhanced susceptibility to proteolysis under high hydrostatic pressure and this may be an efficient method to produce hypoallergenic hydrolysates. The aim of this work was to evaluate the in vivo allergenicity of 3 β-LG hydrolysates produced under atmospheric pressure or high-pressure conditions. Hydrolysates were chosen based on previous experiments that showed that they provide a complete removal of intact β-LG but differed in vitro IgE-binding properties that could be traced to the peptide pattern. The ability to trigger systemic anaphylaxis was assessed using C3H/HeJ mice orally sensitized to β-LG. Outcome measures included symptom score, body temperature, serum mouse mast cell protease 1 (mMCP-1), and quantification of circulating basophils. Mast cell degranulation in vivo was assessed by passive cutaneous anaphylaxis. The 3 tested hydrolysates showed an abrogated allergenicity as revealed by the absence of anaphylactic symptoms and a decrease in body temperature. We demonstrated that the peptides present in the hydrolysates had lost their ability to cross-link 2 human IgE antibodies to induce mast cell degranulation, thus indicating that most of the peptides formed retain just one relevant IgE-binding epitope. The orally sensitized mouse model is a useful tool to address the in vivo allergenicity of novel milk formulas and demonstrates the safety of hydrolysates produced under high-pressure conditions.

Effect of high-pressure treatment on denaturation of bovine lactoferrin and lactoperoxidase

C. Mazri, L. Sánchez, S.J. Ramos, M. Calvo, M.D. Pérez — 2012-02-01

Abstract: Lactoferrin and lactoperoxidase are whey proteins with biological properties that may provide health benefits to consumers. These properties are vulnerable to potentially denaturing conditions during processing. High-pressure treatment is an appealing alternative to the traditional heat processing of foods because it exerts an antimicrobial effect without changing the sensory and nutritional quality of foods. In this work, the effect of high-pressure treatment on the denaturation of lactoferrin and lactoperoxidase present in skim milk and whey, and as isolated proteins in buffer, was studied over a pressure range of 450 to 700MPa at 20°C. Denaturation of lactoferrin was measured by the loss of reactivity with their specific antibodies using a sandwich ELISA. Denaturation of lactoperoxidase was determined by measuring the loss of enzymatic activity using a spectrophotometric technique. No substantial inactivation of lactoperoxidase was observed in any treatment assayed. The concentration of the residual immunoreactive lactoferrin after each pressure treatment was determined, and the data were subjected to kinetic analysis to obtain D and Z values. Denaturation of lactoferrin increased with pressure and holding time, and D values were lower when lactoferrin was treated in whey than in milk, and lower in both whey and milk than in phosphate buffer. Thus, protein is denatured more slowly in buffer and in milk than in whey. Denaturation of lactoferrin in the 3 media was found to follow a reaction order of n=1.5. Volumes of activation of about −34.77, −24.35, and −24.09mL/mol were obtained for lactoferrin treated in skim milk, whey, and buffer, respectively, indicating a decrease in protein volume under pressure.

Survival of lactic acid bacteria from fermented milks in an in vitro digestion model exploiting sequential incubation in human gastric and duodenum juice

T. Faye, A. Tamburello, G.E. Vegarud, S. Skeie — 2012-02-01

Abstract: In the present study, the survival of 9 lactic acid bacteria (5 Lactococcus strains, 3 Lactobacillus strains, and 1 strain of Enterococcus hirae), was investigated in vitro under conditions similar to human digestion using human gastric and duodenal juices. The tolerance of the bacteria was also tested with traditional methods using acidic conditions and bile salts. The strains were subjected to a model digestive system comprising sequential incubation in human gastric and duodenal juices, in a 2-step digestion assay at 37°C, simulating the human upper gastrointestinal tract with human gastric juices at pH 2.5 and human duodenal juices at pH 7. The bacterial strains were tested either as washed cells from culture media or in fermented milk. The initial in vitro testing in acid and bile salts showed that Lactobacillus strains and the E. hirae strain displayed a significantly higher acid tolerance than the lactococci. The lactobacilli and the Enterococcus numbers increased, whereas the lactococci decreased at least 1 log during the bile salt treatment. The Lactobacillus strains showed the highest survival rate in the model digestive system when washed bacterial cultures were used with a minor log reduction, whereas the lactococci numbers were reduced by at least log 4. However, when using fermented milks in the model digestion system it was demonstrated that the Enterococcus strain and 2 strains of Lactococcus lactis ssp. cremoris benefited significantly from the presence of the fermented milk as food matrix, with log numbers >log 7 and 5, respectively, after digestion of the fermented milk. The analyses reported comprise a comprehensive in vitro testing regimen suitable for evaluation of the survival of candidate probiotic bacteria in human digestion as an initial prescreen to clinical trials.

Proteomic analysis and immunodetection of the bovine milk osteopontin isoforms

N. Bissonnette, P.L. Dudemaine, C. Thibault, G. Robitaille — 2012-02-01

Abstract: The aim of this study was to characterize the osteopontin (OPN) secreted in bovine milk and to determine whether the different forms are the product of spliced variants. Spliced variants of the human gene and secreted osteopontin isoforms have been reported in human tumor tissue. In bovine milk, we identified 2 major forms: one corresponding to the full-length coding transcript and a truncated version of this form. No alternative spliced transcripts were detected in the lactating mammary gland tissue, in milk somatic cells, or in peripheral blood immune cells. The 60-kDa bovine osteopontin (bOPN) and a truncated 40-kDa protein isoform were confirmed by mass spectrometry and further characterized by immunoblotting using a panel of 6 antibodies targeting different domains of the protein. Of the 3 human anti-OPN antibodies targeting the N-terminal segment of the protein, only one detected all forms on sodium dodecyl sulfate-PAGE; one human anti-OPN antibody failed to detect bOPN, whereas the other detected only the 60-kDa protein, albeit barely in its phosphorylated form. Detection was generally more sensitive when the 60-kDa protein was dephosphorylated. Two polyclonal antibodies raised against bOPN were tested: one targeting the milk-purified bOPN (bOPN-121) and one targeting a bovine epitope (synthetic peptide) corresponding to a carboxy-terminal domain of the protein (bOPN-117). The bOPN-121 antibody detected all forms irrespective of the phosphorylation status of bOPN. The bOPN-117 and the mouse anti-human OPN (hOPN-4) antibodies, which recognized different domains of the carboxy-terminal segment of the protein, also preferentially detected the dephosphorylated 60-kDa protein. Whereas phosphorylation had a major effect on detection for several antibodies, deglycosylation slightly decreased immunodetection for the tested antibodies. In particular, phosphorylation is the major posttranslational modification that influenced the weak detection capacity of several antibodies. This fact needs to be taken into account for immunodetection of milk content. In conclusion, the OPN forms secreted in bovine milk are not the product of alternative splicing. The 40-kDa protein appears to be a truncated hypophosphorylated variant of the full-length 60-kDa form, which is highly phosphorylated. Together, the proteomic and immunoblotting analyses used to characterize bovine milk OPN revealed the complex nature of the bovine milk OPN forms.

Proteomic profiling of microbial transglutaminase-induced polymerization of milk proteins

J.F. Hsieh, P.H. Pan — 2012-02-01

Abstract: Microbial transglutaminase (MTGase)-induced polymerization of individual milk proteins during incubation was investigated using a proteomics-based approach. The addition of MTGase (0.25–2.0 units/mL) caused the milk proteins to polymerize after a 3-h incubation period. Sodium dodecyl sulfate-PAGE analysis showed that the total intensities of the protein bands that corresponded to αS-casein, β-casein, and κ-casein decreased from 8,245.6, 6,677.2, and 586.6 arbitrary units to 1,911.7, 0.0, and 66.2 arbitrary units, respectively. Components with higher molecular weights were observed, and the intensity of these proteins increased after 3h of incubation. These results support that inter- or intramolecular crosslinking occurred in the casein proteins of MTGase-treated milk. Two-dimensional electrophoresis analysis indicated that isomers of β-casein, κ-casein, a fraction of serum albumin, αS1-casein, αS2-casein, β-lactoglobulin, and α-lactalbumin in the milk were polymerized following incubation with MTGase. In addition, MTGase-induced polymerization occurred earlier for β-casein and κ-casein isomers than for other milk proteins.

Changes in the initial stages of a glucose-proline Maillard reaction model system influences dairy product quality during thermal processing

Y.-G. Guan, S.-L. Wang, S.-J. Yu, S.-M. Yu, Z.-G. Zhao — 2012-02-01

Abstract: The Maillard reaction always occurs during the thermal processing of dairy products, which significantly influences their quality. In the present study, the initial stages of a glucose-proline model system were investigated in water and different types of buffer solutions. Results showed that phosphate buffer accelerated the reversible degradation of the initial stages of the reaction. The proposed catalysis mechanism was that hydrogenous and dihydric phosphate radical anions simultaneously accepted and donated protons for the conversion of the intermediates into N-glycosylamine. The catalysis mechanism was confirmed via testing and no reducing of hydrogenous and dihydric phosphate radical anions was observed during the reaction. Moreover, both N-(1-deoxy-d-fructos-1-yl)proline and its degradation compounds were analyzed. Results showed that degradation of N-(1-deoxy-d-fructos-1-yl)proline to form 5-hydroxymethyl-2-furaldehyde and formic acid was also accelerated by phosphate buffer. An interesting phenomenon was that citrate decreased 5-hydroxymethyl-2-furaldehyde formation, which might be because Strecker-type degradation occurred more easily than 1,2-enolization reaction in citrate buffer solution. However, this hypothesis has not been confirmed, and element label experiments should be carried out in the future.

Determination of melamine in milk and dairy products by high performance liquid chromatography

A. Filazi, U.T. Sireli, H. Ekici, H.Y. Can, A. Karagoz — 2012-02-01

Abstract: A simple, precise, accurate, and validated reverse-phase HPLC method was developed for the determination of melamine in milk (pasteurized and UHT milk) and dairy products (powdered infant formula, fruit yogurt, soft cheese, and milk powder). Following extraction with acetonitrile:water (50:50, vol/vol), samples were purified by filter (0.45μm), separated on a Nucleosil C8 column (4.6mm × 250mm, 3μm) with acetonitrile:10mmol/L sodium l-octane sulfonate (pH 3.1; 15:85, vol/vol) as mobile phase at a flow rate of 1mL/min, and determined by a photodiode array detector. A linear calibration curve was obtained in the concentration range from 0.05 to 5mg/kg. Milk and dairy products were fortified with melamine at 4 levels producing average recovery yields of 95 to 109%. The limits of detection and quantification of melamine were 35 to 110 and 105 to 340μg/kg, respectively. The method was then used to analyze 300 samples of milk and dairy products purchased from major retailers in Turkey. Melamine was not found in infant formulas and pasteurized UHT milk, whereas 2% of cheese, 8% of milk powder, and 44% of yogurt samples contained melamine at the 121, 694±146, and 294±98μg/kg levels, respectively. These findings were below the limits set by the Codex Alimentarius Commission and European Union legislation. This is the first study to confirm the existence of melamine in milk and dairy products in Turkey. Consumption of foods containing these low levels of melamine does not constitute a health risk for consumers.

Short communication: A comparative analysis of recombinant chymosins

J.A. Vallejo, J.M. Ageitos, M. Poza, T.G. Villa — 2012-02-01

Abstract: The first step in cheesemaking is the milk clotting process, in which κ-caseinolytic enzymes contribute to micelle precipitation. The best enzyme for this purpose is chymosin because of its high degree of specificity toward κ-casein. Although recombinant bovine chymosin is the most frequently used chymosin in the industry, new sources of recombinant chymosin, such as goat, camel, or buffalo, are now available. The present work represents a comparative study of 4 different recombinant chymosins (goat and buffalo chymosins expressed in Pichia pastoris, and bovine and camel chymosin expressed in Aspergillus niger). Recombinant goat chymosin exhibited the best catalytic efficiency compared with the buffalo, bovine, or camel recombinant enzymes. Moreover, recombinant goat chymosin exhibited the best specific proteolytic activity, a wider pH range of action, and a lower glycosylation degree than the other 3 enzymes. In conclusion, we propose that recombinant goat chymosin represents a serious alternative to recombinant bovine chymosin for use in the cheesemaking industry.

Short communication: Annatto in Cheddar cheese-derived whey protein concentrate is primarily associated with milk fat globule membrane

D. Zhu, S. Damodaran — 2012-02-01

Abstract: The yellow color of Cheddar cheese whey arises from a residual amount of annatto that partitions into the whey during Cheddar cheese manufacture. Bleaching of the color using hydrogen peroxide or benzoyl peroxide is often a prerequisite to produce an acceptable neutral-colored whey protein concentrate and isolate. However, the use of these strong oxidizing agents often generates off-flavors as a result of lipid oxidation and results in loss of nutritive value due to protein oxidation. The objective of this study was to determine the extent of partitioning of annatto between protein, milk fat globule membrane (MFGM), and aqueous (serum) phases of cheese whey so that a simple method can be developed to remove annatto from cheese whey. The MFGM was separated from Cheddar cheese whey using a recently developed novel method. Quantitative analysis of the distribution of annatto in the fat-free whey protein isolate (WPI), the MFGM fractions, and the serum phase revealed that annatto was not bound to the protein fraction but was mostly distributed between the serum phase and the MFGM fraction. The results showed that a colorless WPI or whey protein concentrate could be produced from Cheddar cheese whey by separation of MFGM from the whey, followed by diafiltration. This approach will negate the need for using bleaching agents.

Immunization of adult dairy cattle with a new heat-killed vaccine is associated with longer productive life prior to cows being sent to slaughter with suspected paratuberculosis

2012-02-01

Abstract: The objective of this study was to evaluate the efficacy of a new heat-killed Mycobacterium avium ssp. paratuberculosis (MAP) vaccine for control of premature culling in tuberculosis-free dairy cattle. Feces and gastrointestinal tissues were collected from 50 vaccinated cows and 38 nonvaccinated cows at slaughter and analyzed by bacteriological culture and histopathology. Vaccination was associated with a significant reduction of the frequency of vaccinated animals with MAP in feces and gut tissues compared with the nonvaccinated animals. In addition, the frequency of vaccinated animals with heavy bacterial load in gut tissues was 40% lower than the frequency of the nonvaccinated animals with the same MAP load. The peak age of paratuberculosis-associated culling was from 4.5 to 5 yr old (21%) in the vaccinated animals and from 3 to 4.5 yr old (60%) in the nonvaccinated animals. The vaccinated and nonvaccinated animals with suspected paratuberculosis were culled at an average age of 4.7 and 3.7 yr old, respectively. Therefore, a significant increase in the productive life of the vaccinated animals sent to slaughter with suspected paratuberculosis was observed. In addition, our analysis revealed a positive effect of the vaccine on the carcass weights of the animals with severe histopathological lesions at slaughter compared with the nonvaccinated animals. In summary, our findings suggest a therapeutic effect of the vaccine and a significant attenuation of pre-existing infection in cows naturally infected with paratuberculosis that were adults at the time of vaccination.

Sickness behavior in dairy cows during Escherichia coli mastitis

K.K. Fogsgaard, C.M. Røntved, P. Sørensen, M.S. Herskin — 2012-02-01

Abstract: The consequences of mastitis in terms of dairy cow behavior are relatively unknown. Future assessment of dairy cow welfare during mastitis will be facilitated by knowledge about the potential of mastitis to induce sickness behavior. Our aim was to examine behavior of dairy cows in the period from 2 d before (d −2 and −1) to 3 d (d 0, 1, and 2) after experimental intramammary challenge with Escherichia coli. Effects of experimentally induced mastitis on behavior were examined in 20 primiparous Danish Holstein-Friesian cows, all 3 to 6 wk after calving and kept in tie stalls. After evening milking on d 0, each cow received an intramammary infusion with 20 to 40 cfu of E. coli in 1 healthy front quarter. Paraclinical and bacteriological examinations were conducted to confirm infection. Half of the cows were subjected to liver and udder biopsies twice during the trial. Behavior was video-recorded on 5 consecutive days, d −2 to +2 after challenge when the cows were not disturbed by humans. The behavior of the animals was compared among all days. Infection with E. coli altered the behavior of the dairy cows. Time spent feeding was lower in the initial 24h after infection compared with that on the other days (16.6±1.1, 16.5±1.0, 13.2±1.2, 18.1±1.1, and 16.0±0.8% of time for d −2, −1, 0, 1, and 2, respectively). The duration of standing idle increased on d 0 compared with that on the control days and d 1 and 2 (29.4±2.6, 28.0±2.3, 39.1±2.6, 31.4±3.8, and 25.9±2.6% of time for d −2, −1, 0, 1 and 2, respectively). The frequency of self-grooming behavior per hour decreased in the initial 24h compared with that on d −2, −1, and 2 (4.1±0.8, 5.4±1.9, 3.2±0.6, 3.6±0.6, and 4.8±1.0 for d −2, −1, 0, 1, and 2, respectively). Likewise, duration of rumination and frequency of turning the head against the udder decreased in the first days after infection (rumination: 32.2±1.6, 34.8±1.8, 27.9±1.7, 30.0±2.6, and 34.8±1.7% of time; and frequency of turning head: 0.6±0.1, 0.6±0.1, 0.3±0.1, 0.3±0.1, and 0.6±0.1 per hour for d −2, −1, 0, 1 and 2, respectively). The cows subjected to biopsies showed an overall decreased lying time during the entire observation period (36.3±1.5 vs. 46.1±2.2% of time) but not directly related to the period after the biopsies. Dairy cows show classic signs of illness behavior in the hours after intramammary challenge with E. coli. This knowledge can be useful for the development of welfare assessment protocols, early disease detection, and for future work aimed at understanding the behavioral needs of dairy cows suffering from mastitis.

Increased fertility in lactating dairy cows resynchronized with Double-Ovsynch compared with Ovsynch initiated 32 d after timed artificial insemination

2012-02-01

Abstract: The objective was to determine if using a Double-Ovsynch protocol [DO; Pre-Resynch: GnRH–7 d–PGF2α–3 d–GnRH, 7 d later Breeding-Resynch: GnRH–7 d–PGF2α–56 h–GnRH–16 h–timed artificial insemination (TAI)] to resynchronize ovulation after a previous TAI would increase synchrony and pregnancies per AI (P/AI) compared with an Ovsynch protocol initiated 32 d after TAI (D32; GnRH–7 d–PGF2α–56 h–GnRH–16 h–TAI). Lactating Holstein cows at various days in milk and prior AI services were blocked by parity and randomly assigned to resynchronization treatments. All DO cows received the first GnRH injection of Pre-Resynch 22 d after TAI, and cows (n=981) diagnosed not pregnant using transrectal ultrasonography 29 d after TAI continued the protocol. Pregnancy status for all D32 cows was evaluated 29 d after TAI so fertility and pregnancy loss could be compared with that of DO cows. All D32 cows received the first GnRH injection of Ovsynch 32 d after TAI, and cows (n=956) diagnosed not pregnant using transrectal palpation 39 d after TAI continued the protocol. In a subgroup of cows from each treatment, ultrasonography (n=751) and serum progesterone (P4) concentrations (n=743) were used to determine the presence of a functional corpus luteum (CL) and ovulation to the first GnRH injection of D32 and Breeding-Resynch of DO (GnRH1), luteal regression after PGF before TAI, and ovulation to the GnRH injection before TAI (GnRH2). Overall, P/AI 29 d after TAI was not affected by parity and was greater for DO compared with D32 cows (39 vs. 30%). Pregnancy loss from 29 to 74 d after TAI was not affected by parity or treatment. The percentage of cows with a functional CL (P4 ≥1.0ng/mL) at GnRH1 was greater for DO than D32 cows (81 vs. 58%), with most DO cows having medium P4 (60%; 1.0 to 3.49ng/ml), whereas most D32 cows had either low (42%; <1.0ng/mL) or high (36%; ≥3.5ng/mL) P4 at GnRH1. Ovulation to GnRH1 was similar between treatments but was affected by serum P4 at GnRH. Cows with low P4 (<1.0ng/mL) had the greatest ovulatory response (59%), followed by cows with medium (≥1.0 to 3.49ng/mL; 38%) and then high (≥3.50ng/mL; 16%) P4 at GnRH1. A greater percentage of DO cows were synchronized compared with D32 cows (72 vs. 51%) primarily due to a greater percentage of D32 than DO cows without a functional CL at the PGF injection before TAI (35 vs. 17%) or without complete CL regression before GnRH2 (17 vs. 7%). We conclude that DO increased fertility of lactating dairy cows during a resynchronization program primarily by increasing synchronization of cows during the Ovsynch protocol before TAI.

Effect of dietary copper source on response to coliform mastitis in dairy cows

R.W. Scaletti, R.J. Harmon — 2012-02-01

Abstract: The effect of organic or inorganic dietary Cu on Escherichia coli mastitis was investigated in first-lactation heifers. Twenty-eight primigravid Holstein heifers were assigned to 3 treatments in a completely randomized block design with 10 blocks of 3 animals grouped by expected calving date. Treatments were as follows: basal diet [7.1mg Cu/kg of dry matter (DM); CON] and diets supplemented with Cu (10mg/kg of DM) as Cu sulfate (CUS) or as Cu proteinate (CUP). Treatments were fed individually from 60 d prepartum through 49 d of lactation. All heifers were marginally deficient at the onset of the experiment (liver Cu of 60mg/kg) and did not differ between groups. Mean liver Cu concentrations were about 3-fold greater in CUS and CUP compared with CON at d 0, 21, and 42 of lactation. At d 34 postpartum, one pathogen-free quarter per cow was infused with Escherichia coli strain 727. Copper supplementation did not lower peak responses to challenge; however, CUP tended to offer some benefits: milk bacterial count with CUP was lower compared with CON at 24, 48, and 72h and lower than CUS at 24 and 96h, and postchallenge milk production tended to be greater for CUP. Clinical udder score was lower at 12h for CUP and CUS compared with CON, and at 144h CUP had lower clinical scores compared with CUS or CON. Somatic cell count, dry matter intake, plasma Cu, and plasma ceruloplasmin did not differ between treatments. Compared with the control diet or Cu sulfate supplement, supplementation with Cu proteinate tended to improve the clinical status of cows after live E. coli intramammary challenge.

The effect of clinical lameness on liveweight in a seasonally calving, pasture-fed dairy herd

J.I. Alawneh, M.A. Stevenson, N.B. Williamson, N. Lopez-Villalobos, T. Otley — 2012-02-01

Abstract: This study investigated the effect of lameness on liveweight (LW) in pasture-fed dairy cattle. The data comprised 222,446 averaged daily LW measurements from 828 lactations of 542 mixed-age cows in a seasonally calving, pasture-fed New Zealand dairy herd. The LW measurements for individual cows were aggregated into weekly averages and analyses conducted to evaluate the effect of a diagnosis of lameness on LW change after controlling for the effect of week in milk, parity, LW at calving, breed, calendar month, and season. In lame cows, LW decreased for up to 3wk before lameness was diagnosed and for up to 4wk after treatment. Total LW loss arising from a single lameness episode was, on average, 61kg (95% confidence interval: 47 to 74kg). The results from this study demonstrate how LW records for individual animals can be used to enhance a herd manager's ability to detect lame cows and present them for treatment. The methods presented here show how daily LW monitoring might be used as a tool for early detection of lameness in dairy cattle.

Effects of plane of nutrition and feed deprivation on insulin responses in dairy cattle during late gestation

K.M. Schoenberg, R.M. Ehrhardt, T.R. Overton — 2012-02-01

Abstract: Nonlactating Holstein cows (n=12) in late pregnancy were used to determine effects of plane of nutrition followed by feed deprivation on metabolic responses to insulin. Beginning 48 d before expected parturition, cows were fed to either a high plane (HP) or a low plane (LP) of nutrition (162 and 90% of calculated energy requirements, respectively). Cows were subjected to an intravenous glucose tolerance test [GTT; 0.25g of dextrose/kg of body weight (BW)] on d 14 of treatment and a hyperinsulinemic-euglycemic clamp (HEC; 1μg/kg of BW/h) on d 15. Following 24h of feed removal, cows were subjected to a second GTT on d 17 and a second HEC on d 18 after 48h of feed removal. During the feeding period, plasma nonesterified fatty acid (NEFA) concentrations were higher for cows fed the LP diet compared with those fed the HP diet (163.6 vs. 73.1μEq/L), whereas plasma insulin was higher for cows fed the HP diet during the feeding period (11.1 vs. 5.2μIU/mL). Glucose areas under the curve during both GTT were higher for cows fed the LP diet than for those fed the HP diet (4,213 vs. 3,750mg/dL × 60min) and was higher during the GTT in the feed-deprived state (4,878 vs. 3,085mg/dL × 60min) than in the GTT during the fed state, suggesting slower clearance of glucose during negative energy balance either pre-or post-feed deprivation. This corresponded with a higher dextrose infusion rate during the fed-state HEC than during the feed-deprived-state HEC (203.3 vs. 90.1 mL/h). Plasma NEFA decreased at a faster rate following GTT during feed deprivation compared with that during the fed state (8.7 vs. 2.9%/min). Suppression of NEFA was highest for cows fed the HP diet during the GTT conducted during feed deprivation, and lowest for cows fed the HP diet during the fed-state GTT (68.6 vs. 50.3% decrease from basal). Plasma insulin responses to GTT were affected by feed deprivation such that cows had a much lower insulin response to GTT by 24h after feed removal (995 vs. 3,957μIU/mL × 60min). During the fed-state HEC, circulating concentrations of NEFA were 21% below basal for cows fed the HP diet and 62% below basal for cows fed the LP diet; during feed deprivation, NEFA were 79 and 59% below basal for the HP and LP diets, respectively (diet × HEC). Cows that are fed below energy requirements or are feed deprived have slower clearance of glucose and greater NEFA responses to glucose challenge. Additionally, feed deprivation had a large effect on insulin secretion. Overall, effects of feed deprivation were larger than effects of plane of nutrition.

Changes in serum pregnancy-associated glycoprotein, pregnancy-specific protein B, and progesterone concentrations before and after induction of pregnancy loss in lactating dairy cows

J.O. Giordano, J.N. Guenther, G. Lopes, P.M. Fricke — 2012-02-01

Abstract: Lactating crossbred dairy cows were synchronized to receive a timed artificial insemination (TAI), and blood samples were collected from all cows from TAI until pregnancy diagnosis 39 d after TAI (period 1), and from pregnant cows from onset of treatment until the end of the experiment (period 2). Cows diagnosed pregnant 39 d after TAI were randomly assigned to 1 of 3 treatments to receive (1) an i.m. injection of saline (CON, n=10); (2) an i.m. injection of PGF2α (PGF, n=10); or (3) an intrauterine infusion of 120mL of hypertonic saline (INF, n=9). During period 1, serum pregnancy-associated glycoprotein (PAG) concentrations began to increase in pregnant cows by 25 d after TAI and differed from those in nonpregnant cows by 27 d after TAI, whereas serum pregnancy-specific protein B (PSPB) concentrations in pregnant cows differed from those in nonpregnant cows by 22 d after TAI. During period 2, time from treatment to cessation of the embryonic heartbeat was greater for PGF than for INF cows (36.0±5.7 vs. 0.2±0.1h, respectively), and time from treatment to conceptus disappearance was greater for INF than for PGF cows (7.1±3.3 vs. 1.9±0.3 d, respectively). Overall, progesterone concentration was greater for CON and INF than for PGF cows (8.7±2.8, 8.2±3.1, and 1.0±2.3ng/mL, respectively) due to luteal regression for PGF cows and corpus luteum maintenance for CON and INF cows. Serum PAG and PSPB concentrations differed among CON cows and PGF and INF cows beginning 1 and 2.5 d after treatment for PAG and PSPB, respectively. By 9.5 d after treatment, PAG and PSPB concentrations were similar to those of nonpregnant cows. We conclude that although timing of conceptus expulsion occurred 5.2 d later for INF than for PGF cows, serum PAG and PSPB concentrations decreased at a similar rate from the onset of treatment for both models of pregnancy loss evaluated.

Hormones, metabolites, and reproduction in Holsteins, Jerseys, and their crosses

K.L. Brown, B.G. Cassell, M.L. McGilliard, M.D. Hanigan, F.C. Gwazdauskas — 2012-02-01

Abstract: Holsteins (HH), Jerseys (JJ), and their crosses in first (n=157) and second (n=107) lactation were used to determine if reproduction, progesterone (P4), insulin-like growth factor 1 (IGF-1), insulin, nonesterified fatty acids (NEFA), and milk production differed between genetic groups. Thirty-four cows were Holstein-Jersey (HJ) crosses, 46 were Jersey-Holstein (JH) crosses, 48 were purebred Holsteins (HH), and 29 were purebred Jerseys (JJ) in first lactation, whereas the second-lactation animals included 23 HJ, 35 JH, 35 HH, and 14 JJ. Blood samples were collected weekly for the first 10 wk postpartum. Analyses were conducted using the MIXED, chi-square, and GLIMMIX procedures (SAS Institute Inc., Cary, NC). Seasons of calving were cold (November to May) and hot (June to October) and were combined with year to form 8 year-seasons. Days open and number of services were affected by genetic group. The HH were open 169±8 d, which was greater than HJ (143±9 d), JJ (132±10 d), and JH (127±8 d). The HH had 2.4±0.1 services per pregnancy, which was greater than JH (1.9±0.1), but not different from HJ (2.1±0.2) or JJ (2.1±0.2). Concentrations of NEFA were greater in lactation 2 (0.52±0.02mEq/L) than in lactation 1 (0.45±0.02mEq/L) and decreased over the 10-wk period. Concentrations of NEFA were greater in the cold season except in yr 3. Insulin in lactation 1 (0.81±0.03ng/mL) was greater than in lactation 2 (0.72±0.03ng/mL); insulin decreased to wk 2 then gradually increased. The HJ had the greatest insulin concentrations (0.87±0.04ng/mL) and the JJ had the lowest (0.66±0.04ng/mL), and IGF-1 gradually increased over the 10-wk period. Milk production (actual yield in the first 305 d, not adjusted for fat and protein) was affected by genetic group, lactation number, year-season, and wk 1 insulin. The HH produced 10,348±207kg of milk, which was greater than the HJ (9,129±230kg), the JH (9,384±190kg), and the JJ (7,080±240kg). Milk production in lactation 2 (9,676±163kg) was greater than that in lactation 1 (8,294±160kg). The JJ (10.3±4.7%) had the highest frequency of mastitis. The chance of getting mastitis for HH (1.1±0.9%) differed from that for HJ (9.4±4.1%), JH (8.1±3.4%), and JJ (10.3±4.7%). Genetic group affected hormones and metabolites, which may partially explain differences in reproductive measures and milk yield.

Effect of postcalving serum nonesterified fatty acids concentration on the functionality of bovine immune cells

C. Ster, M.-C. Loiselle, P. Lacasse — 2012-02-01

Abstract: The periparturient period is marked by metabolic, hormonal, and immunological changes, which have an effect on the incidence of infectious and metabolic diseases. In a previous study, a slower increase in milk production was induced by milking cows once daily during the first week of lactation, leading to an improvement in levels of several metabolites, including nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA). The aim was to determine the influence of serum collected on d 2, 5, and 61 postpartum from cows milked once or twice daily on immune cell functions and to determine which of the constituents were responsible for these effects. Peripheral blood mononuclear cells (PBMC) and polymorphonuclear leukocytes were collected from healthy midlactation cows and their immune functions (i.e., proliferation and interferon-γ production and chemotaxis, phagocytosis, and oxidative burst, respectively), were evaluated in presence of serum, NEFA, and BHBA. Proliferation of PBMC was greater with d-61 (65.1±1.6%) serum than with d-2 (37.3±2.4%) or d-5 (48.4±1.6%) serum and greater with d-2 and -5 serum from cows milked once (42.2±3.7 and 54.0±2.5) compared with cows milked twice daily (32.4±3.0 and 42.9±2.1). Proliferation was inversely correlated with the concentration of NEFA and BHBA in the serum (r=−0.86). Adding NEFA to d-61 serum to reach the level present in d-5 serum decreased proliferation to the level observed with d-5 serum. No effect of BHBA addition was observed. The release of interferon-γ by PBMC was lower in d-5 serum (766±63 pg/mL) than in d-61 serum (1,187±90 pg/mL) and by NEFA. Milking frequency did not affect chemotaxis, phagocytosis, or oxidative burst of polymorphonuclear leukocytes. Phagocytosis decreased over time in serum from d 2 to 61. Similarly, oxidative burst was greater with d-5 serum (12.7×108 ± 1.6×108 relative light units) than with d-61 serum (9.0×108 ± 1.6×108 relative light units). The NEFA had a negative effect on oxidative burst, but BHBA did not. In conclusion, several immune cell functions appear affected by the NEFA concentration. Therefore, strategies that prevent increases in blood NEFA during the transition period may limit postpartum immunosuppression.

Effect of intramammary infection on milk electrical conductivity in Murciano-Granadina goats

J.R. Díaz, G. Romero, R. Muelas, M. Alejandro, C. Peris — 2012-02-01

Abstract: Measurements of electrical conductivity (EC) of milk are used in mastitis detection in cows due to the low cost, possibility of automation, and rapid diagnosis, but the literature about EC measurement in goats is scarce. In this study, we studied the effect of the establishment of intramammary infection (IMI) on EC of goat milk by gland using daily measurements. Additionally, the effects on milk yield, somatic cell count (SCC), and mineral content were analyzed. Eight primiparous and 10 multiparous Murciano-Granadina goats free from IMI were included in the study. Health conditions of the participating animals were monitored for 16 d and then various unfavorable health situations that may arise on commercial farms were simulated to increase the chances of IMI. Once the IMI was confirmed, the experiment continued for another 16 d. Statistical analysis was conducted using a linear mixed model considering several periods regarding the establishment of the infection and whether it affected one or both glands in the animal. The establishment of IMI caused a significant increase of EC, SCC, and chlorides in the infected glands, whereas the sodium:potassium ratio and the ratio of EC between collateral glands showed significant increases only in bilaterally infected animals. The microorganisms that caused greater increases of EC were Staphylococcus aureus and a gram-negative bacterium. Changes due to other isolated microorganisms (coagulase-negative staphylococci and streptococci) were small. No significant differences in milk yield were determined. The significant effect of infection on EC in the affected glands suggests that the use of a system based on daily readings of EC could be useful in IMI detection of goats.

Association between bovine leukemia virus, production, and population age in Michigan dairy herds

R.J. Erskine, P.C. Bartlett, T.M. Byrem, C.L. Render, C. Febvay, J.T. Houseman — 2012-02-01

Abstract: The objective of this study was to determine the herd-level effect of bovine leukemia virus (BLV) infection on dairy production, culling, and cow longevity. During routine herd testing, Dairy Herd Improvement Association technicians collected milk samples from about 40 cows from each of 104 randomly selected Michigan dairy herds averaging ≥120 milking cows and 11,686kg of milk/yr. Milk samples were analyzed for the presence of anti-BLV antibodies by ELISA, and herd- and lactation-specific estimates of BLV prevalence were computed to determine which were the most predictive of herd milk production, culling rate, and cow longevity (proportion of cows in their third or greater lactation). On this basis, the herd BLV index (an unweighted mean BLV prevalence rate for lactation number 1, 2, 3, and ≥4) was selected as the measure of BLV prevalence that was the most highly associated with BLV economic impact. Step-down multivariate analysis was used to determine the extent to which any of 19 herd-level management variables may have confounded the association of BLV index and measures of herd economic impact (milk production and cow longevity). The BLV index was not associated with the 12-mo culling rate, but was negatively associated in the final multivariable model with the proportion of cows that were ≥third lactation, and was negatively associated with herd milk production. In summary, increased prevalence of BLV within Michigan dairy herds was found to be associated with decreased herd milk production and decreased cow longevity. Our results provide evidence that BLV infection is associated with herd-level economic impacts in high-performing dairy herds.

Detection of hoof lesions using digital infrared thermography in dairy cows

M. Alsaaod, W. Büscher — 2012-02-01

Abstract: The objective was to investigate infrared thermography (IRT) as a noninvasive diagnostic tool for early detection of foot pathologies in dairy cows. This was achieved by measuring changes in coronary band temperature before and after claw trimming in response to visual detection of abnormalities of the hooves. We hypothesized that by focusing on the coronary band region, IRT is able to detect lesions of the hind limbs of dairy cows associated with lameness. In this study, 626 individual observations were collected from 24 cows before and after claw trimming. Infrared thermography was used to assess the surface temperature of the coronary band (CB) region and skin (S), and the temperature difference (ΔT) between CB and S of the hind limbs. The average, minimum, and maximum surface temperatures were recorded in both regions. Temperatures of CB and S and ΔT were significantly higher in cows ≤200 d in milk than in cows >200 d in milk for all healthy hooves: 31.8±2.7 versus 29.8±3.6; 28.5±2.5 versus 27.2±3.3°C, and 3.31±1.7 versus 2.51±1.3°C, respectively. Temperatures of CB and S regions were positively correlated with ambient temperature. This association was best described by a linear model (R2=0.92 and 0.99, respectively). The temperatures of CB and S regions were 30.3±3.2°C and 27.3±2.9°C; 32.1±1.7°C and 28.6±2.1°C; and 33.8±1.3°C and 29.9±1.8°C for parlor temperatures of 12.2, 15.7, and 20.3°C, respectively. In the pre- and post-trimming data analysis, a significant difference was found in temperature of the coronary band between cows with lesions and cows without lesions. A threshold value was established to determine the temperature difference between lesion and nonlesion hind claws on CB at 0.64 and 1.09°C before and after claw trimming (sensitivity=85.7%, specificity=55.9%; and sensitivity=80.0%, specificity=82.9%, respectively) with the aim of detecting hoof lesions. In conclusion, the results demonstrate an increase in surface temperature of the lame limb when a hoof has a lesion.

Effects of synchronization treatments on ovarian follicular dynamics, corpus luteum growth, and circulating steroid hormone concentrations in lactating dairy cows

M.M. Herlihy, M.A. Crowe, M.G. Diskin, S.T. Butler — 2012-02-01

Abstract: Lactating dairy cows (n=57) ≥45 d postpartum at first service were enrolled in a randomized complete block design study to evaluate treatments to synchronize estrus and ovulation. At 10 d before artificial insemination (AI), animals were randomly assigned to 1 of 3 treatments: (1) d −10 GnRH (GnRH1; 10μg of buserelin, i.m.) and controlled internal drug release insert [CIDR, 1.38g of progesterone (P4)]; d −3 PGF2α (PGF; 25mg of dinoprost, i.m.); d −2 CIDR out; and AI at observed estrus (CIDR_OBS); (2) same as CIDR_OBS, but GnRH (GnRH2) 36h after CIDR out and timed AI (TAI) 18h later (CIDR_TAI); or (3) same as CIDR_TAI, but no CIDR (Ovsynch). Transrectal ultrasound was used to assess follicle size before ovulation and on d 4, 8, and 15 after the presumptive day of estrus (d 0) to measure the corpus luteum (CL). Blood samples were collected to determine concentrations of estradiol (E2; d −10, −9, −3, −2, −1, and 0) and P4 (d −10, −9, −2, −1, 0, 1, 4, 6, 8, 11, and 15). No treatment differences were observed in either circulating concentrations of P4 or the ovulatory response to GnRH1 at the onset of synchronization treatments. Circulating concentrations of P4 were greater for CIDR_OBS and CIDR_TAI compared with Ovsynch at 24h after CIDR insertion (5.34 and 4.98 vs. 1.75 ng/mL) and immediately before CIDR removal (1.65 and 1.48 vs. 0.40 ng/mL). Peak circulating concentrations of E2 were greater for CIDR_OBS compared with Ovsynch (3.85 vs. 2.39pg/mL), but CIDR_TAI (2.82pg/mL) did not differ from either CIDR_OBS or Ovsynch. The interval from PGF injection to peak circulating E2 did not differ between CIDR_TAI and Ovsynch (52.1 vs. 49.8h). Both CIDR_TAI and Ovsynch, however, had shorter intervals from PGF injection to peak circulating E2 concentrations compared with CIDR_OBS (67.8h). The diameter of the dominant follicle before ovulation was greater for CIDR_OBS compared with Ovsynch (18.5 vs. 16.0mm) but CIDR_TAI (17.1mm) did not differ from either of the other treatments. The mean interval from PGF to ovulation was longer for CIDR_OBS (100.0h) compared with CIDR_TAI and Ovsynch (84.4 and 83.2h, respectively). Use of CIDR_OBS resulted in increased preovulatory follicle size and greater circulating concentrations of E2 due to a longer period of preovulatory follicle growth. Progesterone supplementation during synchronization and GnRH on the day before TAI affected ovulatory follicle size, and periovulatory circulating concentrations of P4 and E2. No differences, however, in postovulatory P4 or luteal volume profiles were observed.

Short communication: Supplementing grape marc to cows fed a pasture-based diet as a method to alter nitrogen partitioning and excretion

S.L. Greenwood, G.R. Edwards, R. Harrison — 2012-02-01

Abstract: The inclusion of the grape marc into livestock rations provides an opportunity not only to use a waste byproduct resourcefully, but also to induce beneficial metabolic changes in animals. Grape marc contains condensed tannins that could alter N metabolism, which would be beneficial from an environmental perspective. The objective was to determine if dietary grape marc could decrease urinary N excretion from nonlactating dairy cattle. Eighteen multiparous cows were randomly divided into 2 equal groups, receiving either (1) pasture+2kg of dry matter (DM)/d energy pellet per cow (control group) or (2) pasture+2kg of DM/d energy pellet per cow+3kg of DM/d grape marc per cow. Urine, fecal, and blood samples were collected at baseline (d 0) and at d 9. Cows receiving grape marc excreted 22% more N in feces compared with the control group. Cows offered grape marc had lower plasma urea nitrogen concentrations (2.42 and 2.97±0.1mmol/L from treatment and control cows, respectively), but had no significant difference in urine urea concentration compared with control animals (84.24 and 114.1±17.62mmol/L from treatment and control cows, respectively). Overall, the potential exists to alter N metabolism in dairy cows using dietary grape marc. The exact mechanisms causing this shift in N metabolism require further investigation.

Short communication: Pheromonicin-SA affects mRNA expression of toll-like receptors, cytokines, and lactoferrin by Staphylococcus aureus-infected bovine mammary epithelial cells

2012-02-01

Abstract: Pheromonicin-SA (Ph-SA) is a newly developed, engineered multidomain peptide that has a bactericidal effect against Staphylococcus aureus. The objective of this study was to characterize innate immune responses by Staph. aureus-stimulated bovine mammary epithelial cells (BMEC) following treatment with Ph-SA. Primary BMEC from one lactating Holstein cow were isolated and exposed to Staph. aureus for 2h, and then treated with rifampicin or Ph-SA. Total RNA was isolated from BMEC at 0, 2, 6, 12, and 24h postinfection, and the mRNA expression of selected genes, including toll-like receptor (TLR)2 and TLR4, IL-1β, IL-6, IL-8, tumor necrosis factor α (TNF-α), and lactoferrin, was quantified by real-time PCR. In the rifampicin group, increases in the expression of mRNA for TNF-α, IL-1β, IL-6, IL-8, and lactoferrin were observed at 6h postinfection and in the expression of mRNA for TLR2 but not for TLR4 at 12h postinfection. In the Ph-SA group, increases in the mRNA expression of TLR2, TNF-α, IL-1β, IL-6, IL-8, and lactoferrin were observed at 6h postinfection, and an increase in TLR4 mRNA expression was observed at 24h postinfection. At 24h postinfection, the mRNA expression of TLR4, TNF-α, IL-1β, IL-6, IL-8, and lactoferrin was higher in the Ph-SA group than in the rifampicin group. In conclusion, Ph-SA might promote the expression of mRNA for TLR2, TLR4, the pro-inﬂammatory cytokines IL-1, IL-6, and TNF-α, the chemotactic factor IL-8, and lactoferrin in Staph. aureus-infected BMEC. Moreover, Ph-SA may be of value as an antibiotic in promoting innate immune responses by Staph. aureus-infected bovine mammary epithelial cells.

Defining ruminal and total-tract starch degradation for adult dairy cattle using in vivo data

R.A. Patton, J.R. Patton, S.E. Boucher — 2012-02-01

Abstract: Literature was searched for studies performed in adult dairy cattle that simultaneously measured starch degradability in the rumen (RSDeg) and starch digestion in the total tract to compute postruminal starch digestion (PRSDig). Forty-one studies with 161 dietary treatments were used to form the data set. Of these diets, the major starch source was corn for 83 diets, small grain for 58 diets, and sorghum for 8 diets. Corn RSDeg was more variable than other sources. As measured in vivo across all starch sources, the percent RSDeg was influenced only by the amount of starch consumed, with the amount of degradation being approximately 75% at low starch intakes and decreasing to about 60% when 4kg or more of starch were consumed. Small grain starch had greater RSDeg than corn or sorghum starch, which were approximately equal. The PRSDig of corn and small grain starches were approximately equal, but sorghum was about 15% less. Across all diets, models derived from the Cornell Net Carbohydrate Protein System predicted percentage of total-tract digestibility of starch very accurately, but overpredicted RSDeg and, as a result, underpredicted percent PRSDig. Calculation of RSDeg using a French model predicted the mean RSDeg with greater accuracy but less precisely. The relative differences in RSDeg percent among starch sources was correctly predicted by these models. A model using a revised rate of digestion as a way of combining effects of starch type and processing was developed, which predicted corn starch RSDeg and PRSDig with greater accuracy than nutrition models but only slightly better than using the mean observed degradation or the French calculation. Inaccuracies in prediction of RSDeg may be due mainly to processing effects and particle sizes, but these were not well reported in literature studies and were difficult to estimate. More accurate assessment of RSDeg and PRSDig will require better and more consistent reporting of grain processing. Based on this study, the French calculation is the most accurate of the models examined, although adjustments will be required to improve accuracy.

Preweaning milk replacer intake and effects on long-term productivity of dairy calves

F. Soberon, E. Raffrenato, R.W. Everett, M.E. Van Amburgh — 2012-02-01

Abstract: The preweaning management of dairy calves over the last 30 yr has focused on mortality, early weaning, and rumen development. Recent studies suggest that nutrient intake from milk or milk replacer during the preweaning period alters the phenotypic expression for milk yield. The objective of this study was to investigate the relationship between nutrient intake from milk replacer and pre- and postweaning growth rate with lactation performance in the Cornell dairy herd and a commercial dairy farm. The analysis was conducted using traditional 305-d first-lactation milk yield and residual lactation yield estimates from a test-day model (TDM) to analyze the lactation records over multiple lactations. The overall objective of the calf nutrition program in both herds was to double the birth weight of calves by weaning through increased milk replacer and starter intake. First-lactation 305-d milk yield and residuals from the TDM were generated from 1,244 and 624 heifers from the Cornell herd and from the commercial farm, respectively. The TDM was used to generate lactation residuals after accounting for the effects of test day, calving season, days in milk, days pregnant, lactation number, and year. In addition, lactation residuals were generated for cattle with multiple lactations to determine if the effect of preweaning nutrition could be associated with lifetime milk yield. Factors such as preweaning average daily gain (ADG), energy intake from milk replacer as a multiple of maintenance, and other growth outcomes and management variables were regressed on TDM milk yield data. In the Cornell herd, preweaning ADG, ranged from 0.10 to 1.58kg, and was significantly correlated with first-lactation yield; for every 1kg of preweaning ADG, heifers, on average, produced 850kg more milk during their first lactation and 235kg more milk for every Mcal of metabolizable energy intake above maintenance. In the commercial herd, for every 1kg of preweaning ADG, milk yield increased by 1,113kg in the first lactation and further, every 1kg of prepubertal ADG was associated with a 3,281kg increase in first-lactation milk yield. Among the 2 herds, preweaning ADG accounted for 22% of the variation in first-lactation milk yield as analyzed with the TDM. These results indicate that increased growth rate before weaning results in some form of epigenetic programming that is yet to be understood, but has positive effects on lactation milk yield. This analysis identifies nutrition and management of the preweaned calf as major environmental factors influencing the expression of the genetic capacity of the animal for milk yield.

Fatty acid composition and bacterial community changes in the rumen fluid of lactating sheep fed sunflower oil plus incremental levels of marine algae

P.G. Toral, A. Belenguer, K.J. Shingfield, G. Hervás, V. Toivonen, P. Frutos — 2012-02-01

Abstract: Supplementation of ruminant diets with plant oils and marine lipids is an effective strategy for lowering saturated fatty acid (FA) content and increasing the concentration of cis-9,trans-11 conjugated linoleic acid and long-chain n-3 FA in ruminant milk. However, changes in populations of ruminal microorganisms associated with altered biohydrogenation of dietary unsaturated FA are not well characterized. Twenty-five lactating Assaf ewes were allocated at random to 1 of 5 treatments composed of dehydrated alfalfa hay and concentrates containing no additional lipid (control), or supplemented with 25g of sunflower oil and 0 (SO), 8 (SOMA1), 16 (SOMA2), or 24 (SOMA3) g of marine algae/kg of diet dry matter. On d 28 on diet, samples of rumen fluid were collected for lipid analysis and microbial DNA extraction. Appearance and identification of biohydrogenation intermediates was determined based on complementary gas chromatography and Ag+-HPLC analysis of FA methyl esters. Total bacteria and the Butyrivibrio group were studied in microbial DNA by terminal RFLP analysis, and real-time PCR was used to quantify the known Butyrivibrio bacteria that produce trans-11 18:1 or 18:0. Dietary supplements of sunflower oil alone or in combination with marine algae altered the FA profile of rumen fluid, which was associated with changes in populations of specific bacteria. Inclusion of marine algae in diets containing sunflower oil resulted in the accumulation of trans 18:1 and 10-O-18:0 and a marked decrease in 18:0 concentrations in rumen fluid. At the highest levels of supplementation (SOMA2 and SOMA3), marine algae also promoted a shift in ruminal biohydrogenation pathways toward the formation of trans-10 18:1 at the expense of trans-11 18:1. Changes in the concentration of biohydrogenation intermediates were not accompanied by significant variations in the abundance of known cultivated ruminal bacteria capable of hydrogenating unsaturated FA. However, certain bacterial groups detected by terminal RFLP (such as potentially uncultured Lachnospiraceae strains or Quinella-related bacteria) exhibited variations in their relative frequency consistent with a potential role in one or more metabolic pathways of biohydrogenation in the rumen.

Nutrient demand interacts with grass particle length to affect digestion responses and chewing activity in dairy cows

K.L. Kammes, M.S. Allen — 2012-02-01

Abstract: Effects of grass particle length on dry matter intake (DMI), milk production, ruminal fermentation and pool sizes, digestion and passage kinetics, and chewing activity and the relationship of these effects with preliminary DMI (pDMI) were evaluated using 15 ruminally and duodenally cannulated Holstein cows in a crossover design with a 14-d preliminary period and two 18-d treatment periods. During the preliminary period, pDMI of individual cows ranged from 22.6 to 29.8kg/d (mean=25.8kg/d) and 3.5% fat-corrected milk yield ranged from 29.2 to 56.9kg/d (mean=41.9kg/d). Experimental treatments were diets containing orchardgrass silage chopped to either (a) 19-mm (long) or (b) 10-mm (short) theoretical length of cut as the sole forage. Grass silages contained approximately 46% neutral detergent fiber (NDF); diets contained 50% forage, 23% forage NDF, and 28% total NDF. Preliminary DMI, an index of nutrient demand, was determined during the last 4 d of the preliminary period when cows were fed a common diet and used as a covariate. Main effects of grass particle length and their interaction with pDMI were tested by ANOVA. Grass particle length and its interaction with pDMI did not affect milk yield, milk composition, or rumen pH. Long particle length tended to decrease DMI compared with short particle length, which might have been limited by rumen fill or chewing time, or both. Passage rates of feed fractions did not differ between long and short particle lengths and were not related to level of intake. As pDMI increased, long particles decreased ruminal digestion rate of potentially digestible NDF at a faster rate than short particles. As a result, long particles decreased or tended to decrease rates of ruminal turnover for NDF, organic matter, and dry matter and increased their rumen pools compared with short particles for cows with high pDMI. Long particles increased eating time, which affected cows with high intake to the greatest extent, and total chewing time compared with short particles. As intake increased, ruminal digestion (kg/d) and digestibility (%) of starch decreased, rumen pool size of starch increased, and postruminal digestion and digestibility of starch increased quadratically. When grass silage was the only source of forage in the diet, increasing chop length from 10 to 19mm tended to decrease DMI but did not negatively affect productivity of cows, which were fed adequate fiber.

Effects of replacing canola meal as the major protein source with wheat dried distillers grains with solubles on ruminal function, microbial protein synthesis, omasal flow, and milk production in cows

G.E. Chibisa, D.A. Christensen, T. Mutsvangwa — 2012-02-01

Abstract: A study was conducted to determine the effects of replacing canola meal (CM) as the major protein source with wheat-based dried distillers grains with solubles (W-DDGS) on ruminal fermentation, microbial protein production, omasal nutrient flow and animal performance. Eight lactating dairy cows were fed in a replicated 4 × 4 Latin square design with 28-d periods (20 d of dietary adaptation and 8 d of measurements). Four cows in one Latin square were ruminally cannulated for measurements of ruminal fermentation characteristics and flow of nutrients at the omasal canal. Cows were fed either a standard barley silage-based total mixed ration containing CM as the major protein supplement (0% W-DDGS, control) or diets formulated to contain 10, 15, and 20% W-DDGS (dry matter basis), with W-DDGS replacing primarily CM. Diets were isonitrogenous (18.9% crude protein) and contained 3.0, 3.2, 3.5, and 3.7% ether extract for 0, 10, 15, and 20% W-DDGS, respectively. Diets contained 50% forage and 50% concentrate. Inclusion of W-DDGS linearly increased dry matter intake (29.5, 31.2, 30.2, and 31.9kg/d for 0, 10, 15, and 20% W-DDGS, respectively). The addition of W-DDGS in place of CM resulted in a 1.2- to 1.8-kg increase in milk yield (42.9, 44.7, 44.1, and 44.5kg/d for 0, 10, 15, and 20% W-DDGS); however, a quadratic change in feed efficiency (i.e., milk yield/DM intake) occurred as the dietary level of W-DDGS increased. Treatments did not differ for milk fat, protein, and lactose concentrations; however, quadratic changes were observed in milk yields of fat (1.48, 1.56, 1.62, and 1.55kg/d for 0, 10, 15, and 20% W-DDGS, respectively), protein (1.44, 1.46, 1.49, and 1.42kg/d) and lactose (1.96, 2.02, 2.09, and 1.93kg/d). Ruminal fermentation characteristics did not change except that the inclusion of 20% W-DDGS resulted in a decrease and a tendency for a decrease in molar concentrations of isobutyrate and total volatile fatty acids, respectively. Omasal flow of total bacterial nonammonia N (NAN) and bacterial efficiency (g of total bacterial NAN flow/kg of organic matter truly digested in the rumen) were not different among diets; however, feeding W-DDGS resulted in a quadratic increase in nonammonia nonbacterial N flow at the omasal canal (271, 318, 336, and 311g/d for 0, 10, 15, and 20% W-DDGS, respectively). These data indicate that W-DDGS can substitute for CM as the major protein source in dairy cow diets without negatively affecting ruminal fermentation, microbial protein production, and omasal nutrient flow, and can potentially increase dry matter intake and milk yield.

Effects of varying rates of tallgrass prairie hay and wet corn gluten feed on productivity of lactating dairy cows

D.J. Rezac, K.N. Grigsby, N.M. Bello, B.J. Bradford — 2012-02-01

Abstract: Productivity of lactating dairy cows fed diets with wet corn gluten feed (WCGF, Sweet Bran, Cargill Inc., Blair, NE) as the primary energy substrate and prairie hay as the primary source of physically effective neutral detergent fiber (peNDF) was assessed relative to a control diet. Forty-eight Holstein cows, 100 to 250 d in milk, were randomly assigned to 1 of 6 pens and pens were randomly assigned to treatment sequence in a replicated 3×3 Latin square. Treatments were a control diet with 18% alfalfa, 18% corn silage, 33% WCGF, and 15% forage NDF (CON); a diet with 20% tallgrass prairie hay, 46% WCGF, and 13% forage NDF (TPH20); and a diet with 14% tallgrass prairie hay, 56% WCGF, and 9% forage NDF (TPH14). Midway through period 2, TPH14 was discontinued due to the high prevalence of diarrhea among cows on that treatment. Data from period 2 for TPH14 pens were discarded, and the pens that had been assigned to TPH14 for period 3 were randomly assigned to the other 2 treatments. Pen-level data were analyzed using linear mixed models, including the random effects of period and pen and the fixed effect of treatment. For animal-level data, additional random effects were introduced to account for subsampling. No evidence for treatment effects was apparent on dry matter intake. Least squares mean milk yields were 36.2, 34.6, and 35.2kg/d for CON, TPH20, and TPH14, respectively, and were not significantly different. Milk fat concentration was higher for CON and TPH20 than for TPH14, with means of 3.48, 3.41, and 2.82%, respectively. Fat yield was significantly greater for CON compared with TPH20 and TPH14. Milk urea nitrogen was greatest for TPH20 and TPH14 and least for CON, consistent with differences in dietary protein content. Efficiencies, expressed as energy-corrected milk divided by dry matter intake, were 1.47, 1.42, and 1.24 for CON, TPH20, and TPH14, respectively, and were not significantly different. These data indicate that TPH14 did not provide adequate peNDF to support normal rumen function in mid lactation dairy cows; instead, TPH20 may be a feasible diet for use on dairies where high-NDF grass hay and WCGF are available.

Short communication: Varying dietary dry matter concentration through water addition: Effect on nutrient intake and sorting of dairy cows in late lactation

J.A. Fish, T.J. DeVries — 2012-02-01

Abstract: The objective of this study was to determine if feed sorting can be reduced and if nutrient consumption can be limited in late-lactation cows through water addition to a nutrient-dense total mixed ration (TMR) with a dry matter (DM) content greater than 60%. Twelve lactating Holstein cows (214.8±28.5 d in milk) were exposed to 2 diets in a crossover design with 28-d periods. Diets had the same ingredient composition and differed only in DM percentage, which was reduced by the addition of water. Treatment diets were (1) dry TMR (61.7% DM) and (2) wet TMR (51.9% DM). Dry matter intake and milk production (4% fat-corrected milk; FCM) were recorded for the last 14 d of each treatment period. For the final 4 d of each period, fresh feed and orts were sampled for particle size analysis and subsequent calculation of sorting activity (expressed as a percentage of predicted intake). Adding water to the diet tended to decrease the amount of DM in the fine particle fraction, increase starch concentration in the longer ration particles, and reduce starch concentration in the shortest ration particles. All cows sorted against long ration particles; the extent of this sorting did not differ between the dry and wet treatments (72.9 vs. 77.6%). There tended to be more sorting for fine ration particles on the dry diet compared with the wet (106.3 vs. 104.0%). Water addition had no effect on production, with similar DMI (27.9 vs. 26.5 kg/d), 4% FCM (28.7 vs. 27.6 kg/d), and efficiency of production (0.98 vs. 1.00kg of 4% FCM/kg of DMI) between the dry and wet treatments. Adding water to a TMR with greater than 60% DM containing primarily haylage and corn silage forage sources may change ration particle DM distribution and particle starch content, possibly contributing to less sorting for the smallest ration particles. This research does not provide evidence that water addition to such a TMR can effectively limit DMI in late-lactation cows and, thus, improve efficiency of milk production.

Short communication: Kelp taste preferences by dairy calves1

2012-02-01

Abstract: Kelp is a common feed additive used on many dairy farms in the United States. However, few data are available supporting the efficacy of its addition to cattle feed. The purpose of this study was to evaluate the taste preferences of calves provided with 0, 30, or 60g of kelp daily in a sequential elimination experiment. Calves in this study always ranked the control treatment first when given a choice and consumed 34.5% more dry matter from the control treatment in the first 3-d segment of the experiment. During the second feeding segment (d 4 and 5), when the control treatment was removed, daily dry matter consumption was reduced in 4 out of 6 calves compared with control calves when this treatment was available (first feeding segment). However, calves did not differentiate between the 2 amounts of kelp. Results indicated that calves preferred calf starter grains without kelp.

Short communication: Effects of feeding sweet sorghum silage on milk production of lactating dairy cows

S. Amer, P. Seguin, A.F. Mustafa — 2012-02-01

Abstract: The objective of this study was to determine the feeding value of sweet sorghum silage (SS) for dairy cows compared with alfalfa silage (AS). Two diets were formulated with a 50:50 forage:concentrate ratio. Sweet sorghum silage and AS constituted 70% of the forage in each diet (dry matter basis). Twelve lactating Holstein cows in early lactation were used in a crossover experiment. Relative to AS, SS contained 58% more neutral detergent fiber and 36.6 and 72.7% less acid detergent lignin and crude protein, respectively. Milk yield (33.0 vs. 36.7kg/d) was lower for cows fed SS than for those fed AS. However, dry matter intake, energy-corrected milk, and feed efficiency were similar for both dietary treatments. Replacing AS with SS increased concentrations of milk fat (4.44 vs. 3.80%) and total solids (13.31 vs. 12.88%) and reduced concentrations of milk lactose (4.55 vs. 4.61%), milk solids-not-fat (8.88 vs. 9.08%), and milk urea nitrogen (10.0 vs. 14.0mg/dL). We concluded that replacing AS with SS had negative effects on milk yield, whereas dry matter intake, energy-corrected milk, and milk efficiency were similar.

Validation of single nucleotide polymorphisms associated with milk production traits in dairy cattle

2012-02-01

Abstract: Single nucleotide polymorphism (SNP) associations with milk production traits found to be significant in different screening experiments, including SNP in genes hypothesized to be in gene pathways affecting milk production, were tested in a validation population to confirm their association. In total, 423 SNP were genotyped across 411 Holstein bulls, and their association with 6 milk production traits—Australian Selection Index (indicating the profitability of an animal's milk production), protein, fat, and milk yields, and protein and fat composition—were tested using single SNP regressions. Seventy-two SNP were significantly associated with one or more of the traits; their effects were in the same direction as in the screening experiment and therefore their association was considered validated. An over-representation of SNP (43 of the 423) on chromosome 20 was observed, including a SNP in the growth hormone receptor gene previously published as having an association with protein composition and protein and milk yields. The association with protein composition was confirmed in this experiment, but not the association with protein and milk yields. A multiple SNP regression analysis for all SNP on chromosome 20 was performed for all 6 traits, which revealed that this mutation was not significantly associated with any of the milk production traits and that at least 2 other quantitative trait loci were present on chromosome 20.

Imputation of genotypes with low-density chips and its effect on reliability of direct genomic values in Dutch Holstein cattle

H.A. Mulder, M.P.L. Calus, T. Druet, C. Schrooten — 2012-02-01

Abstract: Genomic selection using 50,000 single nucleotide polymorphism (50k SNP) chips has been implemented in many dairy cattle breeding programs. Cheap, low-density chips make genotyping of a larger number of animals cost effective. A commonly proposed strategy is to impute low-density genotypes up to 50,000 genotypes before predicting direct genomic values (DGV). The objectives of this study were to investigate the accuracy of imputation for animals genotyped with a low-density chip and to investigate the effect of imputation on reliability of DGV. Low-density chips contained 384, 3,000, or 6,000 SNP. The SNP were selected based either on the highest minor allele frequency in a bin or the middle SNP in a bin, and DAGPHASE, CHROMIBD, and multivariate BLUP were used for imputation. Genotypes of 9,378 animals were used, from which approximately 2,350 animals had deregressed proofs. Bayesian stochastic search variable selection was used for estimating SNP effects of the 50k chip. Imputation accuracies and imputation error rates were poor for low-density chips with 384 SNP. Imputation accuracies were higher with 3,000 and 6,000 SNP. Performance of DAGPHASE and CHROMIBD was very similar and much better than that of multivariate BLUP for both imputation accuracy and reliability of DGV. With 3,000 SNP and using CHROMIBD or DAGPHASE for imputation, 84 to 90% of the increase in DGV reliability using the 50k chip, compared with a pedigree index, was obtained. With multivariate BLUP, the increase in reliability was only 40%. With 384 SNP, the reliability of DGV was lower than for a pedigree index, whereas with 6,000 SNP, about 93% of the increase in reliability of DGV based on the 50k chip was obtained when using DAGPHASE for imputation. Using genotype probabilities to predict gene content increased imputation accuracy and the reliability of DGV and is therefore recommended for applications of imputation for genomic prediction. A deterministic equation was derived to predict accuracy of DGV based on imputation accuracy, which fitted closely with the observed relationship. The deterministic equation can be used to evaluate the effect of differences in imputation accuracy on accuracy and reliability of DGV.

Accuracy of noninvasive breath methane measurements using Fourier transform infrared methods on individual cows

J. Lassen, P. Løvendahl, J. Madsen — 2012-02-01

Abstract: Individual methane (CH4) production was recorded repeatedly on 93 dairy cows during milking in an automatic milking system (AMS), with the aim of estimating individual cow differences in CH4 production. Methane and CO2 were measured with a portable air sampler and analyzer unit based on Fourier transform infrared (FTIR) detection. The cows were 50 Holsteins and 43 Jerseys from mixed parities and at all stages of lactation (mean=156 d in milk). Breath was captured by the FTIR unit inlet nozzle, which was placed in front of the cow's head in each of the 2 AMS as an admixture to normal barn air. The FTIR unit was running continuously for 3 d in each of 2 AMS units, 1 with Holstein and another with Jersey cows. Air was analyzed every 20s. From each visit of a cow to the AMS, CH4 and CO2 records were summarized into the mean, median, 75, and 90% quantiles. Furthermore, the ratio between CH4 and CO2 was used as a derived measure with the idea of using CO2 in breath as a tracer gas to quantify the production of methane. Methane production records were analyzed with a mixed model, containing cow as random effect. Fixed effects of milk yield and daily intake of the total mixed ration and concentrates were also estimated. The repeatability of the CH4-to-CO2 ratio was 0.39 for Holsteins and 0.34 for Jerseys. Both concentrate intake and total mixed ration intake were positively related to CH4 production, whereas milk production level was not correlated with CH4 production. In conclusion, the results from this study suggest that the CH4-to-CO2 ratio measured using the noninvasive method is an asset of the individual cow and may be useful in both management and genetic evaluations.

Genomic associations with somatic cell score in first-lactation Holstein cows

2012-02-01

Abstract: This genome-wide association study aimed to identify loci associated with lactation-average somatic cell score (LASCS) and the standard deviation of test-day somatic cell score (SCS-SD). It is one of the first studies to combine detailed phenotypic and genotypic cow data from research dairy herds located in different countries. The combined data set contained up to 52 individual test-days per lactation and thereby aimed to capture temporary increases in somatic cell score associated with infection. Phenotypic data for analysis consisted of 46,882 test-day records on 1,484 cows, and genotypic data consisted of 37,590 single nucleotide polymorphisms (SNP). Using an animal model, the associations between each individual SNP and the phenotypic data were estimated. To account for the risk of false positives, a false discovery rate threshold of 0.20 was set. The analyses showed that LASCS was significantly associated with a SNP on Bos taurus autosome (BTA) 4 and a SNP on BTA18. Likewise, SCS-SD was associated with this SNP on BTA18. In addition, SCS-SD significantly associated with a SNP on BTA6. Relatively few associations were found, suggesting that LASCS and SCS-SD are controlled by multiple loci distributed across the genome, each with a relatively small effect. Increased knowledge on genetic regulation of LASCS and SCS-SD may aid in identification of genes that play a role in mastitis resistance. Such knowledge helps us understand the genetic mechanisms leading to mastitis and in discovery of targets for mastitis therapeutics.

Genomic prediction for Nordic Red Cattle using one-step and selection index blending

2012-02-01

Abstract: This study investigated the accuracy of direct genomic breeding values (DGV) using a genomic BLUP model, genomic enhanced breeding values (GEBV) using a one-step blending approach, and GEBV using a selection index blending approach for 15 traits of Nordic Red Cattle. The data comprised 6,631 bulls of which 4,408 bulls were genotyped using Illumina Bovine SNP50 BeadChip (Illumina, San Diego, CA). To validate reliability of genomic predictions, about 20% of the youngest genotyped bulls were taken as test data set. Deregressed proofs (DRP) were used as response variables for genomic predictions. Reliabilities of genomic predictions in the validation analyses were measured as squared correlations between DRP and genomic predictions corrected for reliability of DRP, based on the bulls in the test data sets. A set of weighting (scaling) factors was used to construct the combined relationship matrix among genotyped and nongenotyped bulls for one-step blending, and to scale DGV and its expected reliability in the selection index blending. Weighting (scaling) factors had a small influence on reliabilities of GEBV, but a large influence on the variation of GEBV. Based on the validation analyses, averaged over the 15 traits, the reliability of DGV for bulls without daughter records was 11.0 percentage points higher than the reliability of conventional pedigree index. Further gain of 0.9 percentage points was achieved by combining information from conventional pedigree index using the selection index blending, and gain of 1.3 percentage points was achieved by combining information of genotyped and nongenotyped bulls simultaneously applying the one-step blending. These results indicate that genomic selection can greatly improve the accuracy of preselection for young bulls in Nordic Red population, and the one-step blending approach is a good alternative to predict GEBV in practical genetic evaluation program.

Short communication: Fertility, somatic cell score, and production of Normande×Holstein, Montbéliarde×Holstein, and Scandinavian Red × Holstein crossbreds versus pure Holsteins during their first 5 lactations

B.J. Heins, L.B. Hansen — 2012-02-01

Abstract: Normande (NO)×Holstein (HO) crossbred cows (n=251), Montbéliarde (MO)×HO crossbred cows (n=503), and Scandinavian Red (SR)×HO crossbred cows (n=321) were compared with pure HO cows (n=416) for fertility, somatic cell score (SCS), and 305-d projected milk, fat, and protein production during their first 5 lactations. The SR was a combination of Swedish Red and Norwegian Red. Cows were housed in 6 commercial herds in California and calved from June 2002 to January 2009. The NO, MO, and SR sires of crossbred cows were artificial insemination bulls via imported semen. The NO×HO, MO×HO, and SR×HO cows had fewer days to first breeding, enhanced first-service conception rates, higher pregnancy rates, and 12 to 26 fewer days open than did pure HO cows during their first 5 lactations. Mean SCS across lactations was similar for NO×HO (3.25) and pure HO (3.27) cows; however, MO×HO (2.98) and SR×HO (3.12) cows were significantly lower for SCS than were pure HO cows. The MO×HO cows and SR×HO cows were only 3 and 4% lower, respectively, than pure HO cows for 305-d projected production of fat (kg) plus protein (kg); however, NO×HO cows were 10% lower than pure HO cows for fat plus protein production. Therefore, the MO and SR are candidate breeds for crossbreeding with HO to improve the fertility and udder health of herds with high mean production.

Short communication: Is crossbreeding only beneficial in herds with low management level?

M. Kargo, P. Madsen, E. Norberg — 2012-02-01

Abstract: The economic benefit of crossbreeding has been well known for many years within dairy production. However, in most countries with an intensive dairy production, an extended use of systematic crossbreeding has not occurred. This may be due to the myth that heterosis is expressed mainly in low-producing herds. The aim of the study was to investigate the effect of heterosis with different management levels in Danish Jersey herds. More than 300,000 records of 305-d milk, fat, and protein yield from first-lactation Danish Jersey cows with different contributions from original Danish and US Jersey were analyzed using an animal model. The herds were distributed in 5 management groups based on production level. First, the results showed a large increase in additive genetic variance from the herds with lowest production level to the high-producing ones, and second, heterosis for all 3 production traits were lowest within the low-intensity management group and tended to be highest in the intermediate management groups. The results, therefore, support that crossbreeding is a breeding system that should be considered valuable for all management levels.

Estimating efficiency in automatic milking systems

A. Castro, J.M. Pereira, C. Amiama, J. Bueno — 2012-02-01

Abstract: Milking data of 34 single automatic milking system (AMS) units on 29 Galician dairy farms were analyzed to determine the system capacity in each farm under actual working conditions. Number of cows, milk yield, milkings per cow per day, actual milking time, rejected milking time, cleaning time, and machine downtime were used to determine the number of cows milked per AMS unit to obtain the optimal values of milkings per cow and milk production. Multiple linear regression data analysis was used to model the linear relationship between the dependent variable, milk yield per AMS per year, and the predictor variables: number of cows per AMS, milkings per cow per day, milk flow rate, and rejections per AMS per year. An AMS unit milked 52.7±9.0 cows daily at 2.69±0.28 milkings per cow, with a total milking downtime of 1,947±978h/yr and a milk yield of 549,734±126,432kg/yr. The predictor variables cow and milk flow rate had a greater level of influence on the milk yield per AMS than milkings per cow and rejections, and explained the 87% of the variation. The AMS in Galician dairy farms could facilitate an increase of 16±8.5 cows per AMS without impairing milking performance; in this way, the quantity of milk obtained per robot annually could be increased (185,460±137,460kg). This would make it possible to recoup the cost of the system earlier. In the present situation, the daily milking throughput could be maximized at 2.4 to 2.6 milkings per cow.

Ability of commercially available dairy ration programs to predict duodenal flows of protein and essential amino acids in dairy cows

D. Pacheco, R.A. Patton, C. Parys, H. Lapierre — 2012-02-01

Abstract: The objective of this analysis was to compare the rumen submodel predictions of 4 commonly used dairy ration programs to observed values of duodenal flows of crude protein (CP), protein fractions, and essential AA (EAA). The literature was searched and 40 studies, including 154 diets, were used to compare observed values with those predicted by AminoCow (AC), Agricultural Modeling and Training Systems (AMTS), Cornell-Penn-Miner (CPM), and National Research Council 2001 (NRC) models. The models were evaluated based on their ability to predict the mean, their root mean square prediction error (RMSPE), error bias, and adequacy of regression equations for each protein fraction. The models predicted the mean duodenal CP flow within 5%, with more than 90% of the variation due to random disturbance. The models also predicted within 5% the mean microbial CP flow except CPM, which overestimated it by 27%. Only NRC, however, predicted mean rumen-undegraded protein (RUP) flows within 5%, whereas AC and AMTS underpredicted it by 8 to 9% and CPM by 24%. Regarding duodenal flows of individual AA, across all diets, CPM predicted substantially greater (>10%) mean flows of Arg, His, Ile, Met, and Lys; AMTS predicted greater flow for Arg and Met, whereas AC and NRC estimations were, on average, within 10% of observed values. Overpredictions by the CPM model were mainly related to mean bias, whereas the NRC model had the highest proportion of bias in random disturbance for flows of EAA. Models tended to predict mean flows of EAA more accurately on corn silage and alfalfa diets than on grass-based diets, more accurately on corn grain-based diets than on non-corn-based diets, and finally more accurately in the mid range of diet types. The 4 models were accurate at predicting mean dry matter intake. The AC, AMTS, and NRC models were all sufficiently accurate to be used for balancing EAA in dairy rations under field conditions.

Stay-green ranking and maturity of corn hybrids: 1. Effects on dry matter yield, nutritional value, fermentation characteristics, and aerobic stability of silage hybrids in Florida

K.G. Arriola, S.C. Kim, C.M. Huisden, A.T. Adesogan — 2012-02-01

Abstract: This study determined effects of maturity, stay-green (SG) ranking, and hybrid source on dry matter (DM) yield, nutritive value, fermentation, and aerobic stability of corn hybrids. One high stay-green (HSG) hybrid and one average stay-green (ASG) hybrid with similar relative maturity (117 d) from each of 2 seed companies (Croplan Genetics, St. Paul, MN; Pioneer Hi-Bred International, Des Moines, IA) were grown on 1-× 6-m plots at random locations within each of 4 blocks. The hybrids were harvested at 25, 32, and 37% DM from each plot and separated into thirds for botanical fractionation and analysis, whole-plant chemical analysis, and ensiling. Chopped, whole plants were ensiled (8kg) in quadruplicate in 20-L mini-silos for 107 d. A split-plot design was used for the study. Yields of whole-plant and digestible DM and concentrations of starch and DM increased with maturity, whereas concentrations of crude protein, water-soluble carbohydrates, and neutral detergent fiber decreased. High SG hybrids had greater DM yield than ASG hybrids when harvested at 25 and 37%, but not 32% DM. Unlike those from Croplan Genetics, the Pioneer HSG hybrid had greater ear and whole-plant DM concentration than their ASG hybrids. Stover moisture and CP concentration were greater among HSG versus ASG hybrids, particularly among Croplan Genetics hybrids. Croplan Genetics HSG hybrids had greater neutral and acid detergent fiber concentrations and lower in vitro DM digestibility in the unensiled whole-plant, the stover, and the silage than their ASG hybrids, whereas contrasting trends were evident for Pioneer hybrids. Silage fermentation indices were largely unaffected by hybrid SG ranking, maturity, or source. Yeast counts increased with maturity and exceeded 105cfu/g; therefore, all silages deteriorated with 26h, irrespective of treatment. Among the hybrids examined, the optimal maturity for optimizing DM yield and nutritive value of the ASG and HSG hybrids was 37% DM. Stay-green ranking had maturity-dependent effects on the yield of hybrids but had varying effects on nutritional value depending on the source of the hybrid.

Stay-green ranking and maturity of corn hybrids: 2. Effects on the performance of lactating dairy cows

K.G. Arriola, S.C. Kim, C.R. Staples, A.T. Adesogan — 2012-02-01

Abstract: To address producer concerns that feeding high stay-green (SG) corn hybrids is associated with decreased performance and health problems in dairy cows, this study examined how the performance of cows was affected by feeding hybrids with contrasting SG rankings and maturities. Two near-isogenic corn hybrids with high (HSG; Croplan Genetics 691, Croplan Genetics, St. Paul, MN) and low (LSG; Croplan Genetics 737) SG rankings were grown on separate halves of a 10-ha field, harvested at 27% (maturity 1) or 35% (maturity 2) dry matter (DM) and ensiled in bag silos for 84 and 77d, respectively. A further treatment involved addition of water (15L/t) to the HSG maturity 1 hybrid during packing to compound the potential negative effects of excess water in the HSG hybrid. Each of the resulting silages was included in a total mixed ration consisting of 35, 55, and 10% (DM basis) of corn silage, concentrate, and alfalfa hay, respectively. In experiment 1, the total mixed ration was fed for ad libitum consumption twice daily to 30 Holstein cows (92±18d in milk). This experiment had a completely randomized design and consisted of two 28-d periods, each with 14d for adaptation and 14d for sample collection. In experiment 2, the ruminal fermentation of the diets was measured using 5 ruminally cannulated cows on the last day of three 15-d periods. Ruminal contraction rate (2.28±0.14 contractions/min), milk yield (36.7±1.3kg/d), yield of milk protein (1.1±0.03kg/d), and concentration of milk protein (2.9±0.03%) were not affected by treatment. Feeding diets containing HSG instead of LSG reduced intake of crude protein (CP) and neutral detergent fiber, digestibility of neutral detergent fiber, and concentrations of ruminal total volatile fatty acids (VFA) and milk fat when the hybrids were harvested at 27% DM but not 35% DM. Across maturity stages, feeding diets containing HSG instead of LSG decreased DM and CP digestibility, increased rectal temperature and plasma ceruloplasmin concentration, and increased the efficiency of milk production. Except for increasing yeast and mold counts, adding water to the HSG hybrid harvested at 27% DM did not have adverse effects but was associated with greater starch intake, CP digestibility, and ruminal total VFA concentration, and decreased acetate to propionate ratio in dairy cows.

The relationship between weight, age, and average daily gain to show performance of Georgia 4-H and Future Farmers of America (FFA) commercial dairy heifers

M.L. London, J.K. Bernard, M.A. Froetschel, J.K. Bertrand, W.M. Graves — 2012-02-01

Abstract: Three studies were conducted to determine the relationship between dairy heifer growth and placing in the show ring. In the first study, 1,744 commercial dairy heifers (all breeds and crossbred animals) were evaluated to determine effects of growth on placing within Georgia Commercial Dairy Heifer Shows from 2007 to 2010. Birth weights were determined using breed birth weight averages, with crossbreeds being the average of 2 parent breeds. Average daily gains (ADG) were calculated and heifers were given rankings based on placing in show and for age and weight. Data was analyzed using the Spearman correlation calculations in the SAS software (SAS Institute Inc., Cary, NC). Age and ADG were inversely correlated (r=−0.89). Mean ADG for all heifers was determined to be 0.65kg, below National Research Council recommendations of 0.7 to 0.8kg. No strong relationship (r=−0.07) was observed between ADG and placing. Heavier heifers within a class showed a small positive relationship (r=0.10) with placing. For study 2, 238 heifers shown at the 2010 Georgia Junior National Livestock Show (Perry, GA) were measured and evaluated for ADG, placing, body weight, age, withers height, hip height, hip width, and jaw width. Height at withers had a moderate relationship (r=0.42) with placing, followed by hip height (r=0.32). A positive relationship (r=0.65) was observed between withers height and hip height. The correlation between weight and placing was determined (r=0.11). Age and ADG had a strong inverse relationship (r=−0.87). Study 3 evaluated 1,489 Holstein heifers shown from 2007 to 2010. Data was analyzed using the Penn State Growth Monitor Spreadsheet Curves. In total, 63.75% did not meet Penn State recommendations for body weight gain. Performance and physical features associated with age indicates that commercial dairy heifers are underfed. The effects of heat stress and high feed costs also play a role. This has economic implications because these animals will likely require more time before they enter the milk herd. The Commercial Dairy Heifer Program is vital for youth development in Georgia. However, those involved need to be encouraged to improve nutritional management practices.

Effects of feeding strategy on milk production, reproduction, pasture utilization, and economics of autumn-calving dairy cows in eastern North Carolina

2012-02-01

Abstract: A balance among stocking rate (SR), pasture management, and supplementary feeding is required to optimize overall farm performance and profitability in pasture-based dairying. Beginning in September 2003, a seasonal, autumn-calving, pasture-based farming system was established to address the effects of feeding strategy (FS; i.e., a unique combination of stocking and supplementation rate) on productive, reproductive, and economic performance of lactating herds over 3 yr. Eighty lactating cows (1/3 Holsteins, 1/3 Jerseys, and 1/3 crosses of those breeds) were randomly assigned to either a lesser stocking, lesser supplementation group [LSR; 2.2 cows/ha, 6.3kg of dry matter (DM) of a corn-based concentrate consumed daily, n=40] or a greater stocking, greater supplementation group (HSR; 3.3 cows/ha, 9.2kg of DM of a corn-based concentrate consumed daily, n=40). Pasture/forage crop rotations included annual ryegrass and sorghum-Sudan (50%), annual ryegrass and bermudagrass (20%), and a tall fescue–white clover pasture (30%). Pre- and postgrazing herbage mass values and grazing intervals (3,347±255.8kg of DM/ha, 1,861±160.6kg of DM/ha, 23.6±1.9 d) did not differ between FS. The nutritive value of fresh and conserved forages was similar between feeding strategies, except for acid detergent fiber in freshly grazed bermudagrass (29.6 vs. 26.3% of DM for LSR and HSR, respectively). Cows on HSR tended to spend more time on an adjacent feeding area where conserved forages were offered (85 vs. 61 d/yr) as opposed to grazing paddocks (204 vs. 228 d/yr). Lactation performance was greater for HSR; cows on HSR produced 10.8% more milk fat and 6.3% more milk protein than cows on LSR. Holstein cows produced the greatest amounts of mature-equivalent milk, but did not differ from crossbred cows in terms of energy-corrected milk, and mature-equivalent fat and protein yields. Reproductive efficiency did not differ among feeding strategy, but breed differences were observed; conception rates at first and all services, as well as pregnancy rates, were greater for Jersey and crossbred cows compared with Holsteins. The greater stocking rate required additional supplemental concentrate and time away from grazing paddocks, but reproductive efficiency was similar and overall lactation performance was greater. The greater stocking rate resulted in increased productivity and greater income over feed costs per unit of land.

Survival, lifetime production, and profitability of Normande × Holstein, Montbéliarde × Holstein, and Scandinavian Red × Holstein crossbreds versus pure Holsteins

B.J. Heins, L.B. Hansen, A. De Vries — 2012-02-01

Abstract: Pure Holstein (HO) cows (n=416) were compared with Normande (NO) × HO (n=251), Montbéliarde (MO) × HO (n=503), and Scandinavian Red (SR) × HO (n=321) crossbred cows for survival, lifetime production, and profitability in 6 commercial herds in California. The SR crossbred cows were sired by both Swedish Red and Norwegian Red bulls. Cows calved from June 2002 to January 2009. For analysis of survival to subsequent calvings, lifetime production, and profitability, data were restricted to 3 of 6 herds because they had at least 20 cows in each of the breed groups. All cows had the opportunity to calve at least 4 times. Best prediction, which is used by USDA for national genetic evaluations in the United States, was used to determine lifetime production to 4 yr (1,461 d) in the herd after first calving from test-day observations. Production and survival were estimated after 4 yr to calculate lifetime profit. A profit function was defined to include revenues and expenses for milk, fat, protein, and other solids production; somatic cell count; reproduction; feed intake; calf value; salvage value; dead cow disposal; and fixed cost. The NO × HO (1.2%), MO × HO (2.0%), and SR × HO cows (1.6%) had significantly fewer deaths than did pure HO cows (5.3%) during the first 305 d of first lactation. All crossbred groups had significantly more cows that calved a second, third, and fourth time, and had mean survival that was 300 to 400 d longer than did pure HO cows. The NO × HO, MO × HO, and SR × HO cows had significantly higher lifetime fat plus protein production than did pure HO cows up to 1,461 d after first calving. For profitability (ignoring possible differences in health costs), NO × HO cows had 26% greater projected lifetime profit per cow, but 6.7% less profit per cow-day, than did pure HO cows. On the other hand, MO × HO and SR × HO cows had 50 to 44%, respectively, more projected lifetime profit per cow and 5.3 to 3.6%, respectively, more projected profit per cow-day than did pure HO cows.

Erratum to “Short communication: Effects of β-lactoglobulin, stearoyl-coenzyme A desaturase 1, and sterol regulatory element binding protein gene allelic variants on milk production, composition, acidity, and coagulation properties of Brown Swiss cows” (J. Dairy Sci. 95:450–454)

2012-02-01

The following paragraph was omitted from page 451: Calculations of allele frequencies and tests of Hardy-Weinberg equilibrium were carried out using Genepop software (Raymond and Rousset, 1995). An association study for the LGB, SCD, and SREBP-1 gene variants was performed using Bayesian methodology. Milk production, quality, and MCP were analyzed from 294 records. The model included effects of DIM class (6 levels), parity (first, second, third, and greater than third), and the effect of LGB, SCD, and SREBP-1 genotypes (with 3 levels each: CC, CT, TT for LGB; CC, CT, TT for SCD; and LL, LS, SS for SREBP-1). The model also included the effects of additive sire (u), herd (h), and residual (e). Note that test-day effects were confounded with herd effects, because all cows in a given herd were sampled on the same day, with sampling days differing among herds. Prior distributions for the additive genetic effects in u and herd effects in h were normal densities: where A was the numerator relationship matrix among sires, I was the identity matrix, and and were additive genetic and herd variances, respectively. Flat priors were used for systematic effects and dispersion parameters. Marginal posterior distributions of all parameters were obtained using the Gibbs sampler (Gelfand and Smith, 1990). In the present work, the Gibbs sampler ran with a single chain of 100,000 points, and the first 10,000 were discarded as burn-in, previously tested by the Raftery and Lewis (1992) methodology. Our Bayesian approach considered the marginal posterior distribution of half of the difference between the estimated effects of homozygous genotypes (i.e., the additive effect). The posterior median was used as point estimate of parameters of concern. Lower and upper bounds of the 95% highest posterior probability density regions for additive and dominance effects were estimated from the Gibbs samples. In this case, the posterior probability (P) was the probability of a difference being greater than zero for positive effects or lower than zero for negative effects; from here, we considered an effect as relevant when the posterior probability over (or below) zero was >0.90.

Erratum to “A field trial on the effect of propylene glycol on milk yield and resolution of ketosis in fresh cows diagnosed with subclinical ketosis” (J. Dairy Sci. 94:6011–6020)

J.A.A. McArt, D.V. Nydam, P.A. Ospina, G.R. Oetzel — 2012-02-01

Throughout this paper, the unit for β-hydroxybutyrate (BHBA) should be mmol/L (not mM/L). The journal regrets the error.