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Maintenance of breast milk immunoglobulin A after high-pressure processing. By Permanyer et al., page 877. In exceptional circumstances, human milk banks provide a good alternative. This study compares the thermal pasteurization system commonly used to preserve breast milk with a new system using high pressure. The results show that high-pressure treatment eliminates microorganisms as well as thermal treatment while preserving essential defense molecules, some of which are lost with the thermal technique.

Short communication: Separation and quantification of caseins and casein macropeptide using ion exchange chromatography. By Holland et al., page 893. This work developed and improved a published method to separate and quantify the four major caseins from milk samples (i.e., containing whey proteins). The process is carried out with a mini-preparative cation exchange column (1 or 5 mL of column volume) using urea and sodium acetate as elution buffer at pH 3.5 with a NaCl gradient. All four major caseins were separated and the purity of each peak was assessed. This method can also be employed to determine the decrease in κ-casein and the release of the casein-macropeptide during enzymatic hydrolysis using rennet.

Interrelationships between herd-level reproductive performance measures based on intervals from initiation of the breeding program in year-round and seasonal calving dairy herds. By Morton, page 901. In year-round calving herds, reproductive performance has traditionally been described relative to each cow's calving date. In these herds, managers do not allow insemination for specified periods following calving; insemination is permitted only from the cow's initiation of breeding program date. This research assesses reproductive performance in year-round and seasonal calving dairy herds using measures based on interval from each cow's initiation of breeding program date and reports interrelationships between these measures. This research highlights those measures that must be improved to increase herd reproductive performance and will help advisors assess this alternative approach to measuring herd reproductive performance in year-round calving herds.

Naturally occurring mastitis effects on timing of ovulation, steroid and gonadotrophic hormone concentrations, and follicular and luteal growth in cows. By Lavon et al., page 911. The present study examined the effect of subclinical chronic mastitis, and short-term clinical mastitis that ended 20 ± 7 d before the study, on the timing of ovulation and plasma concentrations of hormones. About 30% of cows with mastitis, mainly subclinical, exhibited delayed ovulation that was associated, in a subset of cows, with low plasma estradiol concentrations. Delayed ovulation was associated with delayed or low and delayed luteinizing hormone surge. These findings partially explain the negative effect of mastitis before insemination on low conception rates of dairy cows.

Supplementation of progesterone via controlled internal drug release inserts during ovulation synchronization protocols in lactating dairy cows. By Chebel et al., page 922. Cows not detected in estrus after presynchronization with prostaglandins are more likely to be anovular. Treatment of cows not detected in estrus and submitted to timed artificial insemination (AI) protocols with intravaginal controlled internal drug release (CIDR) inserts containing progesterone improved pregnancies per AI regardless of cyclic status and herd. Improvements in pregnancies per AI of cows treated with CIDR likely resulted from improved synchrony of ovulation after the timed AI protocol.

Assessment of lameness prevalence and associated risk factors in dairy herds in England and Wales. By Barker et al., page 932. The mean prevalence of lameness on 205 dairy farms in the United Kingdom was 36.8%, with a range of 0 to 79.2%. This is a welfare concern given the pain associated with lameness. Risk factors associated with lameness were the presence of damaged concrete, cows pushing or turning sharply near the parlor, cattle grazing pasture also grazed by sheep, the use of automatic scrapers, and not treating lame cows within 48 h of detection. Having no digital dermatitis on the farms and having a herd with breed or breeds other than Holstein-Friesian was associated with reduced lameness.

Increasing the revenues from automatic milking by using individual variation in milking characteristics. By André et al., page 942. Automatic milking systems are currently being used more and more by dairy farms worldwide. These milking systems allow cows to freely determine the time of milking; nevertheless, the farmer may regulate the milking interval. There is variation in milk yield and milking duration between cows, which is influenced by frequency of milking. This paper assesses the variation in milking characteristics and the economic potential of using this individual variation for determining the optimal milking interval for each cow. Results indicate that accounting for individual milking characteristics improves revenues from automatic milking.

Measures of weight distribution of dairy cows to detect lameness and the presence of hoof lesions. By Pastell et al., page 954. Automated measures of how cows distribute their weight between their legs can help identify lame cows and cows suffering from sole ulcers. Measures of asymmetry in the weight applied within a pair of legs can help identify cows that are moderately or severely lame or that suffer from sole ulcers, but are only moderately successful in identifying cows that are mildly lame.

Effect of heat treatment of bovine colostrum on bacterial counts, viscosity, and immunoglobulin G concentration. By Elizondo-Salazar et al., page 961. A study was conducted to identify the optimal temperature and time at which heat treatment of bovine colostrum would least change viscosity and immunoglobulin G concentrations yet reduce bacterial count. First milking colostrum was used and heated at a variety of times and temperatures often used for pasteurization systems. Heating bovine colostrum at 60̊C for 30 or 60 min reduced bacterial count, slightly reduced immunoglobulin G concentration, and did not affect viscosity.

Effect of days to conception in the previous lactation on the risk of death and live culling around calving. By Pinedo and De Vries, page 968. The objective was to quantify the effect of days to conception in the previous parity on the risk of death and live culling in the proximity of a subsequent calving in Holstein cows enrolled in the Dairy Herd Improvement program. Results indicated a doubling of the risk of death or live culling when number of days to conception increased from 90 to greater than 300 d. Increased risk of death and live culling is costly and this association should be included in the economic evaluation of reproductive programs.

Pharmacokinetics of progesterone in lactating dairy cows: Gaining some insights into the metabolism from kinetic modeling. By Turino et al., page 988. Kinetic modeling indicated an enzyme-catalyzed metabolism of progesterone involving cooperative substrate-binding sites, resulting from allosteric effects that yield a sigmoidal saturation rate curve. Kinetic parameters were estimated for two groups of lactating Holstein cows with different daily milk yields. The study found, for the first time, a remarkable quantitative agreement of the Hill coefficient value with that reported in pharmacokinetic studies involving cytochrome P450, family 3, subfamily A-mediated reactions in other mammals, humans included.

Up-regulation of expression of interferonstimulated gene 15 in the bovine corpus luteum during early pregnancy. By Yang et al., page 1000. Interferon-τ (IFNT), the pregnancy recognition signal in ruminant species, is secreted by conceptus trophectoderm cells and induces expression of interferonstimulated gene 15 (ISG15) in the uterus, peripheral blood cells, and corpus luteum in ewes. In this study, the results indicate that expression of ISG15 is upregulated in the bovine corpus luteum rather than the mammary gland during early pregnancy. However, cultured luteal cells do not respond to IFNT, suggesting that the pregnancy-dependent stimulation in ISG15 expression is controlled by something other than IFNT in the bloodstream.

Effect of a high cornstarch diet on hepatic cytochrome P450 2C and 3A activity and progesterone half-life in dairy cows. By Lemley et al., page 1012. Poor reproductive performance is a problem in the dairy industry, and current pregnancy rates for lactating dairy cows are approximately 35 to 40%. Part of the problem can be attributed to high energy demands, which can lead to excessive steroid inactivation in the liver. In the present study, we found that a high cornstarch diet tended to improve energy balance, increased secretion of insulin, reduced cytochrome P450 activity, and tended to increase the half-life of progesterone. Therefore, a high cornstarch diet may be beneficial during early pregnancy by decreasing the high rate of progesterone disappearance without affecting cow performance during lactation.

Contribution of the female reproductive tract to low fertility in postpartum lactating dairy cows. By Rizos et al., page 1022. Infertility in dairy cattle is a multifactorial problem that may be linked to follicle development and the quality of the ovulated oocyte, to sperm transport and fertilization, to the reproductive tract environment, or to a combination of these factors. Here, using a state-of-the-art endoscopic technique for embryo transfer, we provide evidence that the reproductive tract of the postpartum lactating dairy cow may be less capable of supporting early embryo development than that of the nonlactating heifer; this may contribute to the lower conception rates observed in such animals.

Association between Mycobacterium avium subspecies paratuberculosis infection and milk production in two California dairies. By Aly et al., page 1030. The association between Mycobacterium avium ssp. paratuberculosis and fat-corrected milk (FCM) was estimated using longitudinal data from 5,926 cows on 2 California dairies. Cows that were seropositive produced 2.5 kg less 4% FCM/d than their seronegative herdmates. In addition, cows that were positive by fecal culture in liquid medium produced 2.2 kg less 4% FCM/d than their fecal culture-negative herdmates. There was no evidence that mastitis, increased somatic cell counts, or uterine or metabolic conditions confounded the association between Mycobacterium avium ssp. paratuberculosis test results and milk production.

Modulation of the bovine innate immune response by production of 1α,25-dihydroxyvitamin D3 in bovine monocytes. By Nelson et al., page 1041. When bovine monocytes (a subpopulation of immune cells) recognize a pathogen, they produce the enzyme that converts the inactive form of vitamin D to the active form. Activation of vitamin D in monocytes increased the potential of monocytes to kill invasive pathogens and recruit other immune cells to the site of infection. Future studies are needed to determine the amount of dietary vitamin D necessary to support optimum immune function in cattle.

Application of one injection of prostaglandin F2α in the five-day Co-Synch + CIDR protocol for estrous synchronization and resynchronization of dairy heifers. By Rabaglino et al., page 1050. The ovulation-synchronization protocol, 5-d Co-Synch + CIDR, allows for timed artificial insemination (TAI) of dairy heifers, avoiding the need for estrus detection. Four experiments were conducted to determine reproductive responses in dairy heifers receiving 1 injection of prostaglandin F2α (PGF2α) in the 5-d Co-Synch + CIDR protocol. No differences in pregnancy per TAI were found between 1 versus 2 injections of PGF2α. The 5-d Co-Synch + CIDR protocol with 1 injection of PGF2α is an efficient management program to achieve acceptable pregnancy per TAI in dairy heifers.

Acidification of calf bedding reduces fly development and bacterial abundance. By Calvo et al., page 1059. The production of house flies at commercial dairies affects both animal welfare and neighbor relations. Calf bedding mixed with excreta, spilled milk and grain, and water promotes optimal conditions for bacterial and immature fly (larval) development, often resulting in high adult fly abundance near calf-rearing facilities. The present study demonstrated that an antimicrobial acidifier, sodium bisulfate, was an effective tool in decreasing the survival of fly larvae and the bacteria they feed on when applied to calf bedding. Application of sodium bisulfate to calf bedding in the field should reduce adult fly populations originating from calf hutch environments.

Short communication: Survey of fresh cow management practices of dairy cattle on small and large commercial farms. By Heuwieser et al., page 1065. The objective was to survey fresh cow management practices considering calving, health, and postpartum diseases. Only 18.5% of farm managers documented fresh cow exams. Most of the dairy managers used subjective criteria such as general appearance (97.0%) and appetite (69.7%) to identify sick cows. Only a minority of the responding dairy managers monitored their fresh cows using objective (fever, 33.6%) or semiquantitative (subclinical ketosis, 2.8%; body condition score, 36.4%) measures. On most farms, the veterinarian visited the herd only if needed (72.6%), with significant differences between small or medium and large farms.

Technical note: Variation in daily milk yield calculations for dairy cows milked in an automatic milking system. By Nielsen et al., page 1069. A correct daily milk yield for dairy cows milked in an automatic milking system is hard to estimate because of irregular milking intervals. Three different calculation methods were tested and the most advanced method, calculating the milk yield from midnight to midnight, significantly reduced the variation between days and can therefore be used as a management tool.

Variability in in situ ruminal degradation parameters causes imprecision in estimated ruminal digestibility. By Hackmann et al., page 1074. Many feed evaluation systems use mean degradation parameter values to estimate in vivo ruminal digestibility. We demonstrated large variability around these mean parameter values (values of coefficient of variation around 20%) for grass and legume forages. Owing to this large variability, as we showed using propagation of uncertainty, digestibility estimated using mean parameter values had large 95% confidence limits (80.5% of digestibility means). These findings suggest that digestibility estimated from mean parameter values has little biological and practical significance.

Replacement of starch from corn with nonforage fiber from distillers grains and soyhulls in diets of lactating dairy cows. By Ranathunga et al., page 1086. Ground corn as a source of starch was replaced with dried distillers grains and soyhulls as a source of nonforage fiber in lactating dairy cow diets. Results suggest that nonforage fiber can substitute for starch without affecting milk production and composition. Dry matter intake was reduced as starch was removed from the diets, resulting in increased feed efficiency. This research demonstrated that distillers grains and soyhulls can replace starch from corn in lactating dairy cow diets.

Control of Escherichia coli O157:H7 in corn silage with or without various inoculants: Efficacy and mode of action. By Pedroso et al., page 1098. Escherichia coli O157:H7 is an important cause of food-borne diseases. This project evaluated whether and how different bacterial inoculants can eliminate E. coli O157:H7 from contaminated corn silage during storage and feedout phases. The pathogen was eliminated from all silages within 3 d because of the low pH (<4) achieved early in the ensiling process. During the feedout phase, only Lactobacillus buchneri inoculants increased aerobic stability, maintained a low pH, and eliminated or greatly reduced the E. coli O157:H7 population. Antibacterial activity against E. coli O157:H7 was evident in all inoculants but not in inoculated silages, suggesting that E. coli elimination or reduction was mediated by pH reduction.

Effect of milk replacer program on digestion of nutrients in dairy calves. By Hill et al., page 1105. Calves fed up to 1.09 kg daily of 27 to 29% protein milk replacer powders and weaned at 42 or 49 d had low starter intakes, concentrations of serum amylase, and digestion of starter postweaning compared to calves fed 21% protein, 21% fat powders at 0.44 kg daily. Calves fed 0.66 kg of a 27% protein, 17% fat powder and weaned at 28 or 42 d had no reductions in intake or digestion compared with calves fed 0.44 kg of powder and gained as much body weight from 0 to 84 d as calves fed 1.09 kg of powder.

Effects of an acute feed restriction at the onset of the seasonal breeding period on reproductive performance and milk production in pasturegrazed dairy cows. By Burke et al., page 1116. A severe restriction in pasture intake for 14 d from the commencement of the seasonal breeding period reduced milk yield by 22% and the 6-wk pregnancy rate by 6.6%. These outcomes support the importance of astute feeding management, including forecasting feed deficits and preemptive actions to minimize the severity of feed shortages, within pasture-based dairy systems that are markedly influenced by climatic conditions.

Estimation of rumen outflow in dairy cows fed grass silage-based diets by use of reticular sampling as an alternative to sampling from the omasal canal. By Krizsan et al., page 1138. Compared with sampling from the duodenum, there is less interference from endogenous N flow and abomasal digestive processes when determining ruminal nutrient outflow by sampling digesta at the omasal canal. However, sampling from the omasum can reduce feed intake. The results from this study indicate that nutrient and microbial protein outflow from the rumen can be measured using a reticular sampling technique. The reticular sampling technique provides a promising alternative to sampling from the omasal canal because there is less interference with the animal and also no advanced sampling equipment is required.

Effects of spontaneous heating on forage protein fractions and in situ disappearance kinetics of crude protein for alfalfa-orchardgrass hays packaged in large round bales. By Coblentz et al., page 1148. In a series of 3 hay harvests from the same research site, 96 large-round bales were made at preset bale diameters of 0.9, 1.2, or 1.5 m and at moisture concentrations ranging from 9.3 to 46.6%. Bale moisture and diameter both affected postharvest storage temperature, which subsequently resulted in increased concentrations of fiber-bound crude protein components that could be related to heating degree days >30̊C or maximum internal bale temperatures by various curvilinear regression models. Within ranges of heating encountered most commonly under field conditions, estimates of rumen-degradable protein for heated hays declined in primarily linear patterns that exhibited close association with measures of spontaneous heating.

Preliminary investigation on reliability of genomic estimated breeding values in the Danish Holstein population. By Su et al., page 1175. Genomic prediction is a new technology for genetic evaluation by which accurate estimated breeding values (EBV) can be obtained using genome-wide dense markers. This study investigated the reliability of direct genomic EBV for 18 traits in the Danish Holstein population. Squared correlations between genomic EBV and published EBV ranged from 0.252 to 0.700, with an average of 0.418. These results indicate that genomic selection can greatly improve the accuracy of selection for young bulls and bull dams compared with traditional selection based on parent average (0.289 in average).

The genetic relationship of body weight and early-lactation health disorders in two experimental herds. By Frigo et al., page 1184. When cows consume less energy in feed than needed for production and maintenance, especially in early lactation, they may experience health problems. The pattern of genetic associations between body weight and diseases was evaluated in this study. Cows that were genetically inclined to have greater body weight and less body weight loss in the early stages of lactation tended to have fewer diseases.

A model for the genetic evaluation of number of clinical mastitis cases per lactation in Czech Holstein cows. By Wolf et al., page 1193. From data collected on 5 farms in the Czech Republic between 1996 and 2008, including 9,550 lactations of 6,242 cows, a heritability of 0.11 was estimated for the number of clinical mastitis cases per 305-d lactation. The genetic correlations of mastitis with 305-d milk yield and somatic cell score were 0.34 and 0.80, respectively. A 3-trait animal repeatability model with somatic cell score and milk yield as the additional traits is recommended for the genetic evaluation of clinical mastitis of Czech Holsteins.

Quantitative trait loci mapping of calving and conformation traits on Bos taurus autosome 18 in the German Holstein population. By Brand et al., page 1205. Functional herd life in dairy cattle is substantially affected by udder health and calving performance. In an attempt to reveal the functional background of previously reported quantitative trait loci for calving traits and udder health on bovine chromosome 18, we performed linkage, linkage disequilibrium, and combined linkage and linkage disequilibrium analyses. We identified quantitative trait loci affecting calving performance and conformation traits. Further analyses indicated that variation in conformation traits might be a functional background for quantitative trait loci affecting calving traits and udder health traits on chromosome 18 in the German Holstein population.

Relationships between milk yield and somatic cell score in Canadian Holsteins from simultaneous and recursive random regression models. By Jamrozik et al., page 1216. Milk yield and somatic cell score in the first 3 lactations of Canadian Holsteins exhibited heterogeneous (across and within lactation) simultaneous and recursive relationships. In the most plausible model, somatic cell score affected milk yield adversely whereas milk yield had a positive effect on the concentration of somatic cells. Estimates of covariances and genetic parameters did not differ largely between multiple-trait model and models with different links for phenotypes. Similarly, rankings of animals with respect to genetic merit for milk yield, somatic cell score, and lactation persistency did not differ among models.

Evidence of genetic resistance of cattle to infection with Mycobacterium bovis. By Brotherstone et al., page 1234. Bovine tuberculosis is widespread and is increasing in incidence in many countries. In the United Kingdom alone, the cost of the disease is currently around $150 million per year. In this paper we show that there is heritable variation in individual cow susceptibility to bovine tuberculosis and that selection for milk yield is unlikely to have contributed to the current epidemic. It is therefore possible for farmers and breeding companies to select breeding stock that will produce offspring with maximum resistance to bovine tuberculosis.

Polymorphisms in the bovine lactoferrin promoter are associated with reproductive performance and somatic cell count. By O’Halloran et al., page 1253. Lactoferrin is an important innate immune protein that has well-recognized antibacterial and antiviral properties. In this study, variants in the bovine lactoferrin gene were found to associate with reproductive performance and somatic cell count. Finding variants that associate with fertility in dairy herds is important to provide opportunities to fast-track improvements in bovine reproductive performance. The lack of an effect of these variants on milk production traits strengthens the potential importance of these variants, or at least lactoferrin, in selection for improved fertility.

Short communication: Milk protein genetic variation and casein haplotype structure in the Original Pinzgauer cattle. By Caroli et al., page 1260. The aim of this work was to analyze milk protein genetic variation in the Original Pinzgauer, a dual-purpose (dairy and beef) cattle breed of European origin. The survival of an ancestral casein allele combination (namely, the C-A2-B-A haplotype) was found. The maintenance of ancestral haplotypes could have provided the Original Pinzgauer with an enhanced fitness, also affecting the productivity of this local breed.

The carbon footprint of dairy production systems through partial life cycle assessment. By Rotz et al., page 1266. Relationships for predicting all important sources and sinks of greenhouse gas exchange from dairy farms were integrated in a comprehensive model that predicts the net emission and carbon footprint of production systems. This footprint varies with animal characteristics and the feeding and manure-handling strategies used. To illustrate the model, carbon footprints of 0.37 to 0.69 kg of CO2 equivalent/kg of energy-corrected milk were found for common production practices in Pennsylvania and southern California. This software provides a unique tool for comprehensive assessment of management effects on greenhouse gas emissions in milk production.

Extended lactations in a seasonal-calving pastoral system of production to modulate the effects of reproductive failure. By Butler et al., page 1283. Extended lactations in seasonal-calving, pasture-based systems could be a useful strategy to circumvent the costs of culling and replacing nonpregnant cows. The performance of cows that had failed to conceive during the preceding breeding season was measured in a 24-mo calving interval system, and effects on farm profitability were modeled. Profitability in 24-mo calving interval systems was lower than in systems with a 12-mo calving interval regardless of cow milk production potential. The farm profit was increased when high-producing cows that had failed to become pregnant were maintained in a 24-mo calving interval system instead of culling and replacing.

Debunking the myth of the hard-to-reach farmer: Effective communication on udder health. By Jansen et al., page 1296. This study explores farmers who are assumed to be unreachable with mastitis information and aims to define ways to disseminate knowledge to them. Results of 24 interviews with socalled hard-to-reach farmers showed that this group is not homogeneous and can be divided into 4 categories based on their trust in external information sources and their orientation toward the outside world: proactivists, do-it-yourselfers, wait-and-see-ers, and reclusive traditionalists. Communication strategies to reach farmers need to be tailored to the different types of farmers, their needs, and their preferred information sources.

A survey of dairy calf management practices in Canada that affect animal welfare. By Vasseur et al., page 1307. Despite increasing concerns about welfare and the significant cost of rearing heifers, calf mortality and morbidity remain high in North America. Following a survey of 115 farms in Quebec via a 1-h interview, 7 areas of calf management were identified as needing improvement: calving management and care of the newborn, colostrum management, calf–dam separation, painful procedures, calf feeding, weaning, and calf housing. This risk factor assessment was the first step in an intervention strategy to improve calf welfare on dairy farms.