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Addition of straw to the early-lactation diet: Effects on feed intake, milk yield, and subclinical ketosis in Holstein cows

  • Hesam A. Seifi
    Affiliations
    Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, V6T 1Z4, Canada

    Department of Clinical Sciences, School of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad 91775-48974, Iran
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  • Julianna M. Huzzey
    Affiliations
    Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, V6T 1Z4, Canada

    Animal Science Department, College of Agriculture, Food and Environmental Sciences, California Polytechnic State University, San Luis Obispo 93407
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  • M.A. Khan
    Affiliations
    Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, V6T 1Z4, Canada

    Animal Nutrition and Physiology Team, Grasslands Research Centre, AgResearch Ltd., Private Bag 11008, Palmerston North 4474, New Zealand
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  • Daniel M. Weary
    Affiliations
    Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, V6T 1Z4, Canada
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  • Marina A.G. von Keyserlingk
    Correspondence
    Corresponding author
    Affiliations
    Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, V6T 1Z4, Canada
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Open ArchivePublished:January 14, 2021DOI:https://doi.org/10.3168/jds.2020-18549

      ABSTRACT

      This study evaluated feed intake, milk yield, and subclinical ketosis in dairy cows in early lactation fed 2 different diets postpartum. Cows are typically offered a high-energy ration immediately after calving. We compared a conventional high-energy total mixed ration (TMR) with a transition ration that contained chopped straw. We predicted that adding chopped straw would increase dry matter intake, milk production, and indicators of energy metabolism during the first 3 wk of lactation compared to cows fed a conventional high-energy TMR. We also predicted that carryover effects would be likely for at least 2 wk after treatment ended. A total of 68 mixed-age Holstein cows were enrolled in the study 3 wk before their expected calving. All cows were managed on a single high-forage diet during the dry period. At calving, cows were allocated to 1 of the 2 diets: half to the conventional high-energy TMR (CTMR; n = 34; net energy for lactation = 1.61 Mcal/kg; neutral detergent fiber = 31.7%), and the other half to a high-forage TMR containing chopped wheat straw, equivalent to 4.27% dry matter (STMR; n = 34; net energy for lactation = 1.59 Mcal/kg; neutral detergent fiber = 33.7%) for 3 wk after calving. Cows on STMR were then shifted to CTMR for the next 2 wk to study short-term residual effects on the performance of cows. Treatments were balanced for parity, body condition score, and body weight. Feed intake was measured daily from 2 wk before to 5 wk after calving using automatic feed bins. Blood was sampled twice weekly from 2 wk before to 5 wk after calving, and β-hydroxybutyrate and glucose were measured in serum samples. Subclinical ketosis was identified using a threshold of β-hydroxybutyrate ≥1.0 mmol/L in wk 1 after calving and ≥1.2 mmol/L in wk 2 to 5 after calving. Cows were milked twice daily, and weekly samples (composite samples of morning and afternoon milkings) were analyzed to determine total solids, fat, protein, lactose, and somatic cell count. Data were analyzed in 2 separate periods: the treatment phase (wk +1, +2, and +3) and the post-treatment phase (wk +4 and +5). The addition of straw to the TMR negatively affected the dry matter intake of STMR cows during wk 2 and 3 of lactation. Daily milk yield during the first 5 wk of lactation was lower in STMR cows than in CTMR cows. Concentrations of β-hydroxybutyrate were higher in CTMR cows than in STMR cows during wk 1, but this effect was reversed during wk 2 and 3 of lactation. By 21 d in milk, STMR cows had a greater risk of developing subclinical ketosis than CTMR cows. Adding chopped wheat straw to the TMR during the first 21 d after calving lowered dry matter intake and provided no metabolic or production benefits to lactating dairy cattle.

      Key words

      INTRODUCTION

      Early lactation is marked by a sudden increase in nutrient demands to support lactation, accompanied by low feed intake around calving (
      • Drackley J.K.
      ADSA Foundation Scholar Award: Biology of dairy cows during the transition period: the final frontier?.
      ); this combination results in almost all cows entering a period of negative energy balance that is most pronounced during the first few weeks of lactation (
      • Grummer R.R.
      • Mashek D.G.
      • Hayirli A.
      Dry matter intake and energy balance in the transition period.
      ). The weeks following calving are characterized by increased lipolysis (
      • Allen M.S.
      • Bradford B.J.
      • Oba M.
      The hepatic oxidation theory of the control of feed intake and its application to ruminants.
      ), high circulating concentrations of nonesterified fatty acids (NEFA), and increased the risk of subclinical ketosis and ketosis (
      • Bradford B.J.
      • Yuan K.
      • Farney J.K.
      • Mamedova L.K.
      • Carpenter A.J.
      Invited review: Inflammation during the transition to lactation: New adventures with an old flame.
      ).
      Increasing the concentrate content of the diet immediately postpartum has been associated with greater DMI and milk production (
      • Rabelo E.
      • Rezende R.L.
      • Bertics S.J.
      • Grummer R.R.
      Effects of transition diets varying in dietary energy density on lactation performance and ruminal parameters of dairy cows.
      ). However, increasing concentrate inclusion relative to forage in the TMR can lead to an accumulation of volatile fatty acids in the rumen, reducing its buffering capacity (
      • McCann J.C.
      • Luan S.
      • Cardoso F.C.
      • Derakhshani H.
      • Khafipour E.
      • Loor J.J.
      Induction of subacute ruminal acidosis affects the ruminal microbiome and epithelium.
      ) and increasing the risk of subacute ruminal acidosis (
      • Gozho G.N.
      • Plaizier J.C.
      • Krause D.O.
      • Kennedy A.D.
      • Wittenberg K.M.
      Subacute ruminal acidosis induces ruminal lipopolysaccharide endotoxin release and triggers an inflammatory response.
      ), displaced abomasum, ruminal ulcer, and liver abscess (
      • Allen M.S.
      • Bradford B.J.
      • Oba M.
      The hepatic oxidation theory of the control of feed intake and its application to ruminants.
      ;
      • Bradford B.J.
      • Yuan K.
      • Farney J.K.
      • Mamedova L.K.
      • Carpenter A.J.
      Invited review: Inflammation during the transition to lactation: New adventures with an old flame.
      ;
      • Lacasse P.
      • Vanacker N.
      • Ollier S.
      • Ster C.
      Innovative dairy cow management to improve resistance to metabolic and infectious diseases during the transition period.
      ).
      Interest has been increasing in the use of straw in dry-cow diets (
      • Vickers L.A.
      • Weary D.M.
      • Veira D.M.
      • von Keyserlingk M.A.G.
      Feeding a higher forage diet prepartum decreases incidences of subclinical ketosis in transition dairy cows.
      ;
      • Mann S.
      • Yepes F.A.
      • Overton T.R.
      • Wakshlag J.J.
      • Lock A.L.
      • Ryan C.M.
      • Nydam D.V.
      Dry period plane of energy: Effects on feed intake, energy balance, milk production, and com-position in transition dairy cows.
      ), but to our knowledge no study has addressed whether there are benefits to continuing to feed a less energy-dense diet during the first weeks postpartum. Including limited amounts of straw in milking rations has been advocated by some (
      • Ferris C.P.
      • Patterson D.C.
      • Gordon F.J.
      • Kilpatrick D.J.
      The effects of incorporating small quantities of straw in grass/grass silage-based diets for dairy cows.
      ;
      • Oba M.
      • Allen M.S.
      Dose-response effects of intra-ruminal infusion of propionate on feeding behavior of lactating cows in early or mid-lactation.
      ). Furthermore, the inclusion of straw in the diet of early-lactation dairy cows as a source of physically effective fiber may improve digestion and the absorption of nutrients by promoting a stable rumen environment (e.g., less fluctuation in rumen pH), achieved by increasing chewing and salivary buffer secretion (
      • Nandra K.S.
      • Hendry A.
      • Dobos R.C.
      A study of voluntary intake and digestibility of roughages in relation to their degradation characteristics and retention time in the rumen.
      ;
      • Mertens D.R.
      Creating a system for meeting the fiber requirements of dairy cows.
      ;
      • Beauchemin K.A.
      • Eriksen L.
      • Nørgaard P.
      • Rode L.M.
      Short communication: Salivary secretion during meals in lactating dairy cattle.
      ).
      We hypothesized that the addition of chopped straw would reduce the energy density and increase the physically effective fiber of the TMR. We predicted that cows given this ration during the first 3 wk of lactation would show improved DMI, milk production, and indicators of energy metabolism during the first 3 wk of lactation compared to cows fed a conventional high-energy TMR. We also predicted that carryover effects would be likely once treatment had ended, so we followed the cows for an additional 2 wk.

      MATERIALS AND METHODS

      Experimental Animals

      This study was conducted at The University of British Columbia's Dairy Education and Research Centre (Agassiz, British Columbia) from January to July 2012. The study was approved by The University of British Columbia Animal Care Committee (Application A10–0162) and performed in accordance with the guidelines outlined by the
      • Canadian Council on Animal Care
      The CCAC guidelines on: the care and use of farm animals in research, teaching and testing.
      . A total of 68 Holstein dairy cows (21 primiparous and 47 multiparous) were enrolled in this study. At enrollment, cows were randomly assigned to 1 of 2 treatments: a high-energy lactation TMR [CTMR; n = 34; 10 primiparous and 24 multiparous cows (average parity ± standard deviation: 3.2 ± 1.7)]; or a high-forage TMR containing chopped wheat straw [STMR; n = 34; 11 primiparous and 23 multiparous cows (average parity ± standard deviation: 3.4 ± 1.9)].

      Housing, Management, Dietary Treatments, and Feed Monitoring System

      Cows were moved into an experimental prepartum pen at approximately 3 wk before their expected calving date. The prepartum pen consisted of 24 freestalls fitted with a mattress (Pasture Mat, Promat Inc., Woodstock, ON, Canada) covered with 5 cm of sand bedding, 12 feed bins (Insentec, Marknesse, Netherlands), and 2 water troughs (Insentec). The Insentec feeding system used in the present study has been described in previous studies (
      • Chapinal N.
      • Veira D.M.
      • Weary D.M.
      • von Keyserlingk M.A.G.
      Technical note: Validation of a system for monitoring individual feeding and drinking behavior and intake in group-housed cattle.
      ;
      • Neave H.W.
      • Weary D.M.
      • LeBlanc S.J.
      • Huzzy J.M.
      • von Keyserlingk M.A.G.
      Behavioral changes before metritis diagnosis in dairy cows.
      ). Stocking density in the pretreatment (prepartum pen; period 1), treatment (1–20 DIM; period 2), and post-treatment (period 3) periods remained constant throughout the study. As experimental cows moved from one period to the next (i.e., from the prepartum pen to the postpartum pen), an equivalent number of cows were removed to maintain stocking density. Cows that were moved out of the pens were either experimental cows that were eligible to move or “filler cows” (non-experimental cows that were housed in the pen to maintain stocking density). During the prepartum period, all cows were fed the same dry-cow TMR (DTMR), and all 24 cows in the pen had access to all 12 feed bins (Table 1). When cows showed signs of imminent calving (i.e., udder enlargement, milk let-down, relaxation of the tail ligament) they were relocated to an individual maternity pen (located in the same barn as the other experimental pens, directly adjacent to the prepartum pen) for the calving event and then moved to an experimental postpartum pen within 24 h after calving. The postpartum pen was located adjacent to the prepartum pen and also consisted of 24 free stalls, 12 Insentec feed bins, and 2 Insentec water troughs; it was stocked with 24 animals per pen. The system allowed cows on both treatments to be housed in the same group pen. Cows remained in the treatment postpartum pen for 3 wk (d 0 to 21 relative to calving) and were then relocated to an adjacent postpartum pen consisting of 12 free stalls, 6 Insentec feeders, and 1 Insentec water trough; stocking was maintained at 12 cows in the pen for an additional 2 wk of observation (d 22 to 35), during which all cows were provided with the same diet (CTMR). Before and after calving, cows were fed twice daily (0700 h and 1700 h).
      Table 1Composition and component analysis (% of DM unless otherwise noted) of composite samples of 3 TMR types fed to transition cows: dry-cow TMR (DTMR), conventional postpartum TMR (CTMR), and postpartum TMR with added wheat straw (STMR; fed only during the 3-wk postcalving treatment period)
      All cows were fed the CTMR after the treatment period (n = 34 cows per treatment).
      CompositionDTMRCTMRSTMR
      Ingredient
       Grass silage13.0722.2521.0
       Corn silage30.2516.6415.93
       Alfalfa hay16.4311.7211.22
       Concentrate mix
      For DTMR, the major ingredients included 45% Amino Plus (Ag Processing Inc., Omaha, NE), 12% corn gluten meal, 11% soybean meal, 7.36% fine limestone, 5% ground beet pulp, 5% dry cow mineral, 4.32% calcium sulfate, 3.544% distillers corn wheat blend, 1% molasses. CTMR and STMR: 34% rolled barley, 20% fine ground barley, 10% distillers corn wheat blend, 7.3% ground wheat, 6% soybean meal, 6% Amino Plus (Ag Processing Inc.), 5% canola meal, 2.22% fine limestone, 1.18% mill run pellets.
      14.1749.3847.27
       Wheat straw26.0804.27
      Component
       DM49.2852.4553.41
       NEL (Mcal/kg)1.411.611.59
       CP16.0917.5416.92
       NDF42.7631.7333.75
       ADF28.1319.0820.40
       Effective NDF40.9324.0426.38
       Starch13.1626.7525.80
       Sugar7.135.415.25
       Ca1.300.920.89
       P0.310.400.39
       Na0.150.370.36
       Cl0.530.500.50
       K1.651.681.67
       Mg0.420.280.28
       S0.300.240.23
      1 All cows were fed the CTMR after the treatment period (n = 34 cows per treatment).
      2 For DTMR, the major ingredients included 45% Amino Plus (Ag Processing Inc., Omaha, NE), 12% corn gluten meal, 11% soybean meal, 7.36% fine limestone, 5% ground beet pulp, 5% dry cow mineral, 4.32% calcium sulfate, 3.544% distillers corn wheat blend, 1% molasses. CTMR and STMR: 34% rolled barley, 20% fine ground barley, 10% distillers corn wheat blend, 7.3% ground wheat, 6% soybean meal, 6% Amino Plus (Ag Processing Inc.), 5% canola meal, 2.22% fine limestone, 1.18% mill run pellets.

      Measurements and Data Collection

      Data generated by the Insentec feeders were used to calculate daily as-fed feed intake for individual cows. Samples of TMR feed (fresh feed and orts) were collected weekly throughout the study. A consistent feed formulation of forage and concentrates from the same source and batches was used throughout the study, so the composition of the feeds offered during the study had little variation. Feed samples were used to determine the percent DM of each TMR and for later nutrient analysis; samples were dried at 60°C for 48 h to determine DM content, which was then used to adjust as-fed intakes reported by the Insentec system to DMI. Dried weekly feed samples (DTMR, CTMR, and STMR) were pooled into monthly samples, and 3 samples of each diet were sent to Cumberland Valley Analytical Services Inc. (Maugansville, MD) for analysis of DM (135°C;
      • AOAC International
      Official Methods of Analysis.
      : method 930.15), ash (535°C;
      • AOAC International
      Official Methods of Analysis.
      : method 942.05), ADF (
      • AOAC International
      Official Methods of Analysis.
      : method 973.18), NDF with heat-stable α-amylase and sodium sulfite (
      • Van Soest P.J.
      • Robertson J.B.
      • Lewis B.A.
      Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition.
      ), CP (N × 6.25;
      • AOAC International
      Official Methods of Analysis.
      : method 990.03; Leco FP-528 Nitrogen Analyzer, Leco, St. Joseph, MI), and starch (
      • Hall M.B.
      Determination of starch, including maltooligosacchardies, in animal feeds: A comparison of methods and a method recommended for AOAC collaborative study.
      ). Net energy of lactation was calculated based on
      • National Research Council
      Nutrient Requirements of Dairy Cattle.
      equations.
      All cows' BW were measured weekly from 2 wk before calving to wk 5 postpartum, as well as on the day of calving. Cows' BCS were measured weekly from 2 wk before calving to 5 wk postpartum and at calving using the 5-point scale described by
      • Ferguson J.D.
      • Galligan D.T.
      • Thomsen N.
      Principal descriptors of body condition score in Holstein cows.
      .
      Cows were milked twice per day at approximately 0600 and 1600 h using a parallel milking parlor (12 cows per side). Daily milk production was recorded using milk meters interfaced with DairyComp305 herd management software (Dairy One Cooperative Inc., Lansing, NY). In each of the 5 wk postpartum, a milk sample was obtained from 1 morning and 1 afternoon milking. A composite milk sample was sent to Pacific Milk Analysis Labs/Can. (Chilliwack, BC, Canada) and analyzed for total solids (%), fat (%), protein (%), lactose (%), and SCC using a MilkoScan FT 6000 (Foss Electric, Hillerød, Denmark). The ECM yield was calculated as [(0.3246 × milk yield) + (12.86 × fat yield) + (7.04 × protein yield);
      • National Research Council
      Nutrient Requirements of Dairy Cattle.
      ].
      Blood samples were collected twice per week beginning 2 wk before the expected calving date and continuing throughout the 5 wk postpartum period; samples were collected at approximately 1030 h. Blood was taken from the coccygeal vessel using plain Vacutainer tubes without anticoagulants (Vacutainer Venous Blood Collection Tubes; BD Biosciences, Franklin Lakes, NJ). Immediately after collection, a sample of the blood was tested using a cow-side BHB and glucose kit (Precision Xtra; MediSense, Abbott, Gurnee, IL;
      • Iwersen M.
      • Falkenberg U.
      • Voigtsberger R.
      • Forderung D.
      • Heuwieser W.
      Evaluation of an electronic cowside test to detect subclinical ketosis in dairy cows.
      ). Blood BHB after calving was used to evaluate subclinical ketosis. Cows were diagnosed with subclinical ketosis using a serum BHB threshold of ≥1.0 mmol/L in the wk 1 postpartum (
      • Walsh R.B.
      • Walton J.S.
      • Kelton D.F.
      • LeBlanc S.J.
      • Leslie K.E.
      • Duffield T.F.
      The effect of subclinical ketosis in early lactation on reproductive performance of postpartum dairy cows.
      ) and ≥1.2 mmol/L from d 7 to 35 postpartum (
      • McArt J.A.A.
      • Nydam D.V.
      • Oetzel G.R.
      Epidemiology of subclinical ketosis in early lactation dairy cattle.
      ).
      Postpartum energy balance was calculated daily for each cow using
      • National Research Council
      Nutrient Requirements of Dairy Cattle.
      calculations for energy requirements. We determined net energy intake (NEI; Mcal/d) by multiplying DMI by the calculated mean energy density of lactation diet estimated from feed analysis. Energy requirements for maintenance (NEM; Mcal/d) were calculated as follows: NEM = 0.080 Mcal/kg × BW0.75. Net energy for milk production (NEL; Mcal/d) as follows: NEL = (0.0929 × fat %) + (0.0563 × protein %) + (0.0395 × lactose %) × milk yield (kg/d). Postpartum energy balance (NE) was calculated as follows: NE = NEI − (NEM + NEL).

      Data Analysis

      Individual feed intake was calculated from data provided by the Insentec system. Due to the differences between expected and actual calving dates (i.e., cows calving early) we analyzed feed intake up to 14 d prepartum only; all experimental cows had data recorded on these days. If a cow had less than 24 h of recorded data on a particular day, that day was excluded from further analysis. This generally occurred when cows were moved out of the experimental pens into an individual maternity pen for calving. All data from d −1 and d 0 were excluded from the analyses for every cow, because these days were almost always associated with pen changes, resulting in incomplete feed intake data. On the day a cow was moved between pens to accommodate the experimental design, feed intake data for that day were also removed. Following these adjustments to the feed intake data, we defined 7 experimental periods for feed intake: wk −2 (d −14 to −8), wk −1 (d −7 to −2), wk +1 (d 1 to 7), wk 2 (d 8 to 14), wk 3 (d 15 to 21), wk 4 (d 22 to 28), wk 5 (d 29 to 35). The statistical analysis was performed only for postpartum experimental periods.
      Statistical analyses were performed with SAS (version 9.4; SAS Institute Inc., Cary, NC), using cow (n = 68) as the experimental unit. The MIXED procedure of SAS was used to analyze differences in DMI, milk yield and components, ECM, energy balance, and BHB and glucose concentrations. Data were analyzed in 2 separate periods: treatment (over 21 d of lactation) and post-treatment (following 2 wk).
      The MIXED models included the fixed effects of treatment (STMR vs. CTMR), parity group (primiparous or multiparous), and BCS class (cows with a BCS ≤2.75 were classified as thin; cows with a BCS of 3–3.5 were classified as fair; and cows with a BCS ≥3.75 were classified as fat), with period (weekly periods for DMI, energy balance, milk yield and components, and ECM) or day (for BHB and glucose) specified as repeated measures and the period (or day) × treatment interaction. Cow was treated as a random effect. Data from 68 cows in the first 35 d of lactation were available for evaluation of the treatment effect on SCC. The final model for SCC included treatment (STMR vs. CTMR), day and treatment × day interaction, parity group, BCS class and disease, and the random effect of cow. The distributions of BHB, glucose, and milk fat and protein were skewed to the right and were transformed using the natural logarithm to achieve a normal distribution. All models used an autoregressive covariance structure except BHB, which used a Toeplitz covariance structure (selected on the basis of the smallest Bayesian information criterion). All variables were offered to each model and then removed in a backward stepwise elimination of nonsignificant (P > 0.05) variables. Interactions between treatment and significant covariates were included in the final model. If we found a significant interaction between time and treatment, we reanalyzed the data after stratification by the sample time.
      One of our aims was to determine the effect of adding straw to the early-lactation diet on the prevention and treatment of subclinical ketosis. We evaluated this effect with multivariable logistic regression models using the GENMOD procedure in SAS. The models included treatment, parity group, and BCS class. The wk 1 samples served as the referent for the incidence of subclinical ketosis. The effects of treatment on prevention (cows with BHB <1 mmol/L at wk 1 that remained non-ketotic in the following weeks) and cure (those with subclinical ketosis at wk 1 that were normal when tested in the following weeks) were modeled separately using logistic regression as described above.

      RESULTS

      BCS

      At enrollment, BCS ranged from 2.5 to 4.25 (mean 3.18) for STMR cows and 2.75 to 4.25 (mean 3.26) for CTMR cows. Throughout the study, the range and mean BCS by treatment were as follows: 2 to 4.25 (3.05) for STMR cows and 2.25 to 4.75 (3.15) for CTMR cows.

      DMI

      We found a period × treatment interaction for DMI (P = 0.01), indicating that differences in DMI between treatments varied by week relative to calving. Treatment differences were most pronounced in wk 3 after calving, with STMR cows consuming less feed (Figure 1). In addition, STMR cows tended to have a lower DMI during the post-treatment period (P = 0.08).
      Figure thumbnail gr1
      Figure 1Least squares means (± SE) for DMI (kg of DM/d) during 7 weekly periods around calving (prepartum: wk −2 and −1; treatment phase, shaded area: wk +1, +2, and +3; post-treatment phase: wk +4 and +5). CTMR = conventional postpartum TMR; STMR = postpartum TMR with added wheat straw (n = 34 cows per treatment). Pretreatment (precalving) period data were not analyzed. *Significant difference between groups (P < 0.05).

      Production

      Milk yield and ECM yield were not affected by treatment during the first 3 wk postpartum; however, the residual effects (i.e., during wk 4 and 5 of lactation) of treatment on milk yield and ECM yield were significant (P = 0.01; Figure 2, Figure 3). During the first 3 wk of lactation, milk fat percentage tended to be higher for STMR cows than for CTMR cows. We found no differences in protein or lactose between treatments (Table 2), and no interaction between treatment and day for milk components. We also found no effect of treatment on SCC (STMR: 393,000 cells/mL; CTMR: 378,000 cells/mL; P = 0.92).
      Figure thumbnail gr2
      Figure 2Least squares means (± SE) for milk yield (kg/d) during 5 weekly periods around calving (treatment phase, shaded area: wk +1, +2, and +3; post-treatment phase: wk +4 and +5). CTMR = conventional postpartum TMR; STMR = postpartum TMR with added wheat straw (n = 34 cows per treatment). *Significant difference between groups (P < 0.05).
      Figure thumbnail gr3
      Figure 3Least squares means (± SE) for ECM yield (kg/d) during 5 weekly periods around calving (treatment phase, shaded area: wk +1, +2, and +3; post-treatment phase: wk +4 and +5). CTMR = conventional postpartum TMR; STMR = postpartum TMR with added wheat straw (n = 34 cows per treatment). *Significant difference between groups (P < 0.05).
      Table 2Least squares means (± SE) for DMI, milk production and components, energy balance, and serum constituents in the 7 wk around calving (prepartum: wk −2 and −1; treatment phase: wk +1, +2, and +3; post-treatment phase: wk +4 and +5)
      CTMR = conventional postpartum TMR; STMR = postpartum TMR with added wheat straw (n = 34 cows per treatment).
      VariablePhaseCTMRSTMRP-value
      Group
      Group of treatment (STMR and CTMR).
      TimeGroup × time
      DMI (kg/d)Treatment17.3 ± 0.316.7 ± 0.40.26<0.00010.01
      Post-treatment20.3 ± 0.419.3 ± 0.40.080.0010.77
      Milk production (kg/d)Treatment31.6 ± 1.029.7 ± 0.90.14<0.00010.76
      Post-treatment40.1 ± 1.135.9 ± 1.00.01<0.00010.37
      ECM (kg/d)Treatment33.2 ± 1.131.7 ± 1.10.32<0.00010.13
      Post-treatment40.5 ± 1.136.8 ± 1.10.01<0.00010.94
      Milk fat (%)Treatment4.26 ± 0.034.53 ± 0.030.10<0.00010.54
      Post-treatment3.86 ± 0.023.90 ± 0.020.690.080.28
      Milk protein (%)Treatment3.29 ± 0.013.29 ± 0.010.94<0.00010.27
      Post-treatment2.92 ± 0.012.94 ± 0.010.400.870.01
      Milk lactose (%)Treatment4.47 ± 0.044.45 ± 0.030.68<0.00010.86
      Post-treatment4.61 ± 0.044.58 ± 0.030.610.430.27
      Energy balance (Mcal/d)Treatment−7.81 ± 0.60−7.19 ± 0.570.420.850.30
      Post-treatment−6.11 ± 0.49−4.32 ± 0.470.010.570.83
      BHB (mmol/L)Treatment0.56 ± 0.080.61 ± 0.080.49<0.00010.05
      Post-treatment0.58 ± 0.110.58 ± 0.100.930.790.16
      Glucose (mg/dL)Treatment52.5 ± 0.0350.4 ± 0.030.21<0.00010.97
      Post-treatment53.5 ± 0.0354.6 ± 0.030.520.570.17
      1 CTMR = conventional postpartum TMR; STMR = postpartum TMR with added wheat straw (n = 34 cows per treatment).
      2 Group of treatment (STMR and CTMR).

      Energy Balance

      During the first 5 wk of lactation, all cows experienced negative energy balance (Figure 4). We found no effect of diet on energy balance (P = 0.42) during the first 21 d of lactation, but we did find a post-treatment difference (P = 0.01) between treatments. The STMR cows had improved energy balance from d 21 to 35 of lactation, after they were switched to the CTMR.
      Figure thumbnail gr4
      Figure 4Least squares means (± SE) for postpartum energy balance (Mcal/d) over 5 wk after parturition (treatment phase, shaded area). CTMR = conventional postpartum TMR; STMR = postpartum TMR with added wheat straw (n = 34 cows per treatment). *Significant difference between groups (P < 0.05).

      BHB and Glucose Concentrations

      Concentrations of BHB were higher in STMR cows than in CTMR cows on d 14 and 17 after calving, driving a treatment × time interaction (P = 0.05; Figure 5). We found no group or group × time interaction on BHB in the post-treatment period (P > 0.05). We observed no effect of parity or BCS on BHB concentrations (P > 0.05).
      Figure thumbnail gr5
      Figure 5Least squares means (± SE) for BHB (mmol/L) for 2 wk before calving and 5 wk after (prepartum: d −14 and −1; treatment phase, shaded area: d +1 to +21; post-treatment phase: d +22 and +35). CTMR = conventional postpartum TMR; STMR = postpartum TMR with added wheat straw (n = 34 cows per treatment). Pretreatment (precalving) period data were used as baselines and were not analyzed. *Significant difference between groups (P < 0.05).
      Multiparous CTMR cows had higher blood glucose concentrations than multiparous STMR cows (51.4 ± 0.03 vs. 46.5 ± 0.03 mg/dL, respectively; P = 0.02; Figure 6) during the 21-d treatment period. This difference was not present in primiparous cows, contributing to a treatment × parity interaction for this measure (P < 0.01). We found no effect of treatment on glucose concentrations in the post-treatment period (P > 0.05).
      Figure thumbnail gr6
      Figure 6Least squares means (± SE) for glucose (mg/dL) of multiparous cows for 2 wk before calving and 5 wk after (prepartum: d −14 and −1; treatment phase, shaded area: d +1 to +21; post-treatment phase: d +22 and +35). CTMR = conventional postpartum TMR; STMR = postpartum TMR with added wheat straw (n = 34 cows per treatment). Pretreatment (precalving) period data were used as baselines and were not analyzed. *Significant difference between groups (P < 0.05).

      Subclinical Ketosis

      We identified 28 cases of subclinical ketosis. Overall, during the first 5 wk of lactation, we observed no difference in the prevalence of subclinical ketosis between STMR and CTMR cows; each treatment had the same number of subclinical ketosis cases (n = 14). However, the prevalence gradually increased in the STMR group over the course of the experiment. Among the 58 cows that did not have ketosis during wk 1 after calving, the STMR cows had a higher risk of developing subclinical ketosis than CTMR cows by wk 3 after calving (odds ratio 4.9, 95% CI: 0.95–25.47; P = 0.06). The STMR diet had no effect on the incidence of subclinical ketosis during wk 2, 4, or 5 of lactation (Table 3). Only 10 cows had ketosis during wk 1 after calving—too few to meaningfully test the therapeutic effect of the STMR diet on subclinical ketosis.
      Table 3Results of logistic regression models testing the effect of postpartum TMR on incidence of subclinical ketosis (serum BHB ≥1 mmol/L in wk 1 and BHB ≥1.2 mmol/L in wk 2 to 5)
      CTMR (conventional postpartum TMR) specified as the reference group; STMR = postpartum TMR with added wheat straw; models accounted for the effects of parity and BCS.
      Among cows with BHB <1 mmol/L at wk 1 (n = 58).
      Time after treatmentTreatmentβ estimateRobust SEOdds ratio95% CIP-value
      Wk 2STMR−0.53900.81730.580.12–2.890.51
      Wk 3STMR1.59500.83804.930.95–25.470.06
      Wk 4STMR1.25280.85433.50.66–18.670.14
      Wk 5STMR0.83290.88512.30.41–13.040.35
      1 CTMR (conventional postpartum TMR) specified as the reference group; STMR = postpartum TMR with added wheat straw; models accounted for the effects of parity and BCS.
      2 Among cows with BHB <1 mmol/L at wk 1 (n = 58).

      DISCUSSION

      The main findings of the present study were that the addition of wheat straw to the TMR of cows in early lactation provided no beneficial effects for feed intake, milk yield, or preventing subclinical ketosis. Our results indicated that adding a small amount of chopped straw to the postpartum diet during the 21 d after calving depressed DMI. Wheat straw has lower NDF degradability than many other forages (
      • Spanghero M.
      • Berzaghi P.
      • Fortina R.
      • Masoero F.
      • Rapetti L.
      • Zanfi C.
      • Tassone S.
      • Gallo A.
      • Colombini S.
      • Ferlito J.C.
      Technical note: Precision and accuracy of in vitro digestion of neutral detergent fiber and predicted net energy of lactation content of fibrous feeds.
      ), and inclusion in the diet has been reported to increase rumen fill and limit DMI, resulting in a slower passage rate (VandeHaar and St. Pierre, 2006;
      • Coon R.E.
      • Duffield T.F.
      • DeVries T.J.
      Effect of straw particle size on the behavior, health, and production of early-lactation dairy cows.
      ). Cows on the STMR diet tended to have a lower DMI during the post-treatment period (P = 0.08), likely an associated adaptation with the transition to the high-energy diet.
      • Allen M.S.
      • Bradford B.J.
      • Oba M.
      The hepatic oxidation theory of the control of feed intake and its application to ruminants.
      stated that diets with moderate forage fiber concentrations benefit cows in early lactation. Some studies have shown that adding finely chopped straw to a TMR at 4% of DM made no difference to feed intake and milk yield in multiparous lactating cows (
      • Humphries D.J.
      • Beever D.E.
      • Reynolds C.K.
      Adding straw to a total mixed ration and the method of straw inclusion affects production and eating behaviour of lactating dairy cows.
      ), and that the inclusion of small quantities of straw in the diets of dairy cows in mid-lactation resulted in small increases in DMI (
      • Ferris C.P.
      • Patterson D.C.
      • Gordon F.J.
      • Kilpatrick D.J.
      The effects of incorporating small quantities of straw in grass/grass silage-based diets for dairy cows.
      ). These differences in DMI response to straw could be attributed to differences in stage of lactation. In early lactation, cows are in a lipolytic state associated with low blood insulin and decreased insulin sensitivity of tissues (
      • Bell A.W.
      Regulation of organic nutrient metabolism during transition from late pregnancy to early lactation.
      ). This state increases the demand for glucose precursors; adding straw to the ration in early lactation limits propionate production and promotes ketogenesis, potentially exacerbating negative energy balance. Elevated plasma ketone concentrations indicate a lipolytic state likely to suppress feed intake (
      • Allen M.S.
      • Piantoni P.
      Metabolic control of feed intake: Implications for metabolic disease of fresh cows.
      ), and we also found that the lower DMI in STMR versus CTMR cows in wk of treatment coincided with higher levels of BHB.
      Milk and ECM yield in the STMR cows were numerically lower than in the CTMR cows during the treatment period and significantly lower into the post-treatment period when all cows were fed the CTMR. These reductions in milk yield with the inclusion of straw were consistent with the work of
      • Ferris C.P.
      • Patterson D.C.
      • Gordon F.J.
      • Kilpatrick D.J.
      The effects of incorporating small quantities of straw in grass/grass silage-based diets for dairy cows.
      on cows in mid-lactation. The lower yield of the STMR cows was due to their lower DMI, because feed intake is a major determinant of milk yield (
      • VandeHaar M.J.
      • St-Pierre N.
      Major advances in nutrition: Relevance to the sustainability of the dairy industry.
      ). The elevated risk of subclinical ketosis may have also played a role, given that it can decrease milk yield in early lactation (
      • Dohoo I.R.
      • Martin S.W.
      Subclinical ketosis: Prevalence and associations with production and disease.
      ;
      • Ospina P.A.
      • Nydam D.V.
      • Stokol T.
      • Overton T.R.
      Associations of elevated nonesterified fatty acids and beta-hydroxybutyrate concentrations with early lactation reproductive performance and milk production in transition dairy cattle in the northeastern United States.
      ;
      • McArt J.A.A.
      • Nydam D.V.
      • Oetzel G.R.
      Epidemiology of subclinical ketosis in early lactation dairy cattle.
      ). Further, the STMR cows were transitioned to the CTMR diet at 21 DIM, resulting in reduced milk production over the next 2 wk. This change in diet likely negatively influenced the rumen environment (
      • Humer E.
      • Petri R.M.
      • Aschenbach J.R.
      • Bradford B.J.
      • Penner G.B.
      • Tafaj M.
      • Südekum K.H.
      • Zebeli Q.
      Invited review: Practical feeding management recommendations to mitigate the risk of subacute ruminal acidosis in dairy cattle.
      ) and thus the cows' ability to consume, ferment, and use nutrients from the diet (
      • Rabelo E.
      • Rezende R.L.
      • Bertics S.J.
      • Grummer R.R.
      Effects of transition diets varying in dietary energy density on lactation performance and ruminal parameters of dairy cows.
      ). Higher milk fat percentage in STMR versus CTMR cows could be attributed to differences in dietary effective NDF (reviewed by
      • Eastridge M.L.
      Major advances in applied dairy cattle nutrition.
      ). Feeding a low-fiber diet can lead to declines in rumen pH, resulting in incomplete biohydrogenation of fatty acids and increases in trans-octadecenoic acids, ultimately causing milk fat depression (
      • Griinari J.M.
      • Dwyer D.A.
      • McGuire M.A.
      • Bauman D.E.
      • Palmquist D.L.
      • Nurmela K.V.
      Trans-octadecenoic acids and milk fat depression in lactating dairy cows.
      ). Alternatively, the addition of straw might have promoted acetate production and an improved acetate-to-propionate ratio in the rumen, which in turn increased the supply of substrate for milk fat synthesis (
      • Rabelo E.
      • Rezende R.L.
      • Bertics S.J.
      • Grummer R.R.
      Effects of transition diets varying in dietary energy density on lactation performance and ruminal parameters of dairy cows.
      ).
      Energy balance during the 21 d after calving was similar between the 2 experimental groups. Two major determinants of energy balance are DMI and milk yield. Because DMI was reduced in the STMR cows (particularly in wk 3 of treatment), energy intake was lower, but the lower milk yield in these cows mitigated the gap in energy balance. After the STMR cows were switched to the CTMR at 21 DIM, they continued to have lower DMI but improved energy balance compared with the CTMR cows, likely because of their lower milk yield.
      Cows on the STMR experienced elevated BHB and increased risk of subclinical ketosis. Reduced DMI postpartum is associated with increased risk of metabolic disorders (
      • Ingvartsen K.L.
      • Dewhurst R.J.
      • Friggens N.C.
      On the relationship between lactational performance and health: Is it yield or metabolic imbalance that cause production diseases in dairy cattle? A position paper.
      ). Reduced DMI in the days after calving can negatively affect energy metabolism later in lactation (
      • Baird G.D.
      • Heitzman R.J.
      • Hibbitt K.G.
      Effects of starvation on intermediary metabolism in the lactating cow. A comparison with metabolic changes occurring during bovine ketosis.
      ;
      • Drackley J.K.
      ADSA Foundation Scholar Award: Biology of dairy cows during the transition period: the final frontier?.
      ). Cows in early lactation experience lipolysis, which in turn can limit DMI, increasing the mobilization of body tissues and production of ketones (
      • Roberts C.J.
      • Reid I.M.
      • Rowlands G.J.
      • Patterson A.
      A fat mobilisation syndrome in dairy cows in early lactation.
      ;
      • Drackley J.K.
      ADSA Foundation Scholar Award: Biology of dairy cows during the transition period: the final frontier?.
      ). When stratified by health status, our results indicated that cows that did not have ketosis during wk 1 postpartum had a higher risk of developing subclinical ketosis when fed the STMR, but this difference was evident only in wk 3 after calving. We speculate that because the STMR group consumed less feed in early lactation, they were at increased risk for greater ketogenesis and thus increased incidence of subclinical ketosis (
      • Drackley J.K.
      • Overton T.R.
      • Douglas G.N.
      Adaptations of glucose and long-chain fatty acid metabolism in liver of dairy cows during the periparturient period.
      ). The increased risk of subclinical ketosis is concerning given that it is associated with increased risk of abomasal displacements (
      • LeBlanc S.J.
      • Leslie K.E.
      • Duffield T.F.
      Metabolic predictors of displaced abomasum in dairy cattle.
      ;
      • Seifi H.A.
      • LeBlanc S.J.
      • Leslie K.E.
      • Duffield T.F.
      Metabolic predictors of post-partum disease and culling risk in dairy cattle.
      ), decreased probability of pregnancy at first AI (
      • Walsh R.B.
      • Walton J.S.
      • Kelton D.F.
      • LeBlanc S.J.
      • Leslie K.E.
      • Duffield T.F.
      The effect of subclinical ketosis in early lactation on reproductive performance of postpartum dairy cows.
      ), decreased milk production (
      • Duffield T.F.
      • Lissemore K.
      • McBride B.W.
      • Leslie K.E.
      Impact of hyperketonemia in early lactation dairy cows on health and production.
      ), and increased duration and severity of mastitis (
      • Suriyasathaporn W.
      • Heuer C.
      • Noordhuizen-Stassen E.N.
      • Schukken Y.H.
      Hyperketonemia and the impairment of udder defense: A review.
      ).
      Adding straw to the fresh cow diet lowered blood glucose concentrations. Glucose demand for milk production increases in early lactation (
      • Oba M.
      • Allen M.S.
      Dose-response effects of intra-ruminal infusion of propionate on feeding behavior of lactating cows in early or mid-lactation.
      ). This demand is greater for multiparous cows than for primiparous cows, likely due to increased milk yield (
      • Ferris C.P.
      • Patterson D.C.
      • Gordon F.J.
      • Kilpatrick D.J.
      The effects of incorporating small quantities of straw in grass/grass silage-based diets for dairy cows.
      ). Forage fiber increases the production of acetate more than propionate, the latter being the major precursor of glucose. Although some observations suggest that acetate spares glucose utilization by extrahepatic tissues for mid-lactation, decreasing the rate of glucose clearance from the blood (
      • Head H.H.
      • Connolly J.D.
      • Williams W.F.
      Glucose metabolism in dairy cattle and the effect of acetate infusion.
      ;
      • Oba M.
      • Allen M.S.
      Dose-response effects of intra-ruminal infusion of propionate on feeding behavior of lactating cows in early or mid-lactation.
      ), acetate might spare glucose to a lesser extent in early lactation compared with mid-lactation (
      • Oba M.
      • Allen M.S.
      Dose-response effects of intra-ruminal infusion of propionate on feeding behavior of lactating cows in early or mid-lactation.
      ).

      CONCLUSIONS

      Feeding a TMR containing a small amount of wheat straw during the 3 wk immediately after calving offered no metabolic or production benefits for lactating dairy cattle. Under the conditions used in this study, the addition of wheat straw to TMR reduced feed intake and milk yield and increased the incidence of subclinical ketosis.

      ACKNOWLEDGMENTS

      General funding for the UBC Animal Welfare program is provided by the Natural Science and Engineering Research Council's Research Chair in Dairy Cattle Welfare awarded to MvK and DMW with contributions from our industrial partners including the Dairy Farmers of Canada (Ottawa, ON, Canada), Saputo Inc. (Montreal, QC, Canada), British Columbia Dairy Association (Burnaby, BC Canada), Alberta Milk (Edmonton, AB, Canada), Intervet Canada Corporation (Kirkland, QC, Canada), Boehringer Ingelheim Animal Health (Burlington, ON, Canada), BC Cattle Industry Development Fund (Kamloops, BC, Canada), The Semex Alliance (Guelph, ON, Canada), Lactanet (Sainte-Anne-de-Bellevue, QC, Canada), Dairy Farmers of Manitoba (Winnipeg, MB, Canada), and SaskMilk (Regina, SK, Canada). The authors declare no competing financial interest in the work reported.

      REFERENCES

        • Allen M.S.
        • Bradford B.J.
        • Oba M.
        The hepatic oxidation theory of the control of feed intake and its application to ruminants.
        J. Anim. Sci. 2009; 87 (19648500): 3317-3334
        • Allen M.S.
        • Piantoni P.
        Metabolic control of feed intake: Implications for metabolic disease of fresh cows.
        Vet. Clin. North Am. Food Anim. Pract. 2013; 29 (23809892): 279-297
        • AOAC International
        Official Methods of Analysis.
        17th ed. AOAC International, Arlington, VA2000
        • Baird G.D.
        • Heitzman R.J.
        • Hibbitt K.G.
        Effects of starvation on intermediary metabolism in the lactating cow. A comparison with metabolic changes occurring during bovine ketosis.
        Biochem. J. 1972; 128 (4345357): 1311-1318
        • Beauchemin K.A.
        • Eriksen L.
        • Nørgaard P.
        • Rode L.M.
        Short communication: Salivary secretion during meals in lactating dairy cattle.
        J. Dairy Sci. 2008; 91 (18420637): 2077-2081
        • Bell A.W.
        Regulation of organic nutrient metabolism during transition from late pregnancy to early lactation.
        J. Anim. Sci. 1995; 73 (8582872): 2804-2819
        • Bradford B.J.
        • Yuan K.
        • Farney J.K.
        • Mamedova L.K.
        • Carpenter A.J.
        Invited review: Inflammation during the transition to lactation: New adventures with an old flame.
        J. Dairy Sci. 2015; 98 (26210279): 6631-6650
        • Canadian Council on Animal Care
        The CCAC guidelines on: the care and use of farm animals in research, teaching and testing.
        Canadian Council on Animal Care, Ottawa, ON, Canada2009
        • Chapinal N.
        • Veira D.M.
        • Weary D.M.
        • von Keyserlingk M.A.G.
        Technical note: Validation of a system for monitoring individual feeding and drinking behavior and intake in group-housed cattle.
        J. Dairy Sci. 2007; 90 (18024766): 5732-5736
        • Coon R.E.
        • Duffield T.F.
        • DeVries T.J.
        Effect of straw particle size on the behavior, health, and production of early-lactation dairy cows.
        J. Dairy Sci. 2018; 101 (29705431): 6375-6387
        • Dohoo I.R.
        • Martin S.W.
        Subclinical ketosis: Prevalence and associations with production and disease.
        Can. J. Comp. Med. 1984; 48 (6713247): 1-5
        • Drackley J.K.
        ADSA Foundation Scholar Award: Biology of dairy cows during the transition period: the final frontier?.
        J. Dairy Sci. 1999; 82 (10575597): 2259-2273
        • Drackley J.K.
        • Overton T.R.
        • Douglas G.N.
        Adaptations of glucose and long-chain fatty acid metabolism in liver of dairy cows during the periparturient period.
        J. Dairy Sci. 2001; 84 (19164667): E100-E112
        • Duffield T.F.
        • Lissemore K.
        • McBride B.W.
        • Leslie K.E.
        Impact of hyperketonemia in early lactation dairy cows on health and production.
        J. Dairy Sci. 2009; 92 (19164667): 571-580
        • Eastridge M.L.
        Major advances in applied dairy cattle nutrition.
        J. Dairy Sci. 2006; 89 (16537963): 1311-1323
        • Ferguson J.D.
        • Galligan D.T.
        • Thomsen N.
        Principal descriptors of body condition score in Holstein cows.
        J. Dairy Sci. 1994; 77 (7814740): 2695-2703
        • Ferris C.P.
        • Patterson D.C.
        • Gordon F.J.
        • Kilpatrick D.J.
        The effects of incorporating small quantities of straw in grass/grass silage-based diets for dairy cows.
        Grass Forage Sci. 2000; 55: 146-158
        • Gozho G.N.
        • Plaizier J.C.
        • Krause D.O.
        • Kennedy A.D.
        • Wittenberg K.M.
        Subacute ruminal acidosis induces ruminal lipopolysaccharide endotoxin release and triggers an inflammatory response.
        J. Dairy Sci. 2005; 88 (15778308): 1399-1403
        • Griinari J.M.
        • Dwyer D.A.
        • McGuire M.A.
        • Bauman D.E.
        • Palmquist D.L.
        • Nurmela K.V.
        Trans-octadecenoic acids and milk fat depression in lactating dairy cows.
        J. Dairy Sci. 1998; 81 (9621226): 1251-1261
        • Grummer R.R.
        • Mashek D.G.
        • Hayirli A.
        Dry matter intake and energy balance in the transition period.
        Vet. Clin. North Am. Food Anim. Pract. 2004; 20 (15471620): 447-470
        • Hall M.B.
        Determination of starch, including maltooligosacchardies, in animal feeds: A comparison of methods and a method recommended for AOAC collaborative study.
        J. AOAC Int. 2009; 92 (19382561): 42-49
        • Head H.H.
        • Connolly J.D.
        • Williams W.F.
        Glucose metabolism in dairy cattle and the effect of acetate infusion.
        J. Dairy Sci. 1964; 47: 1371-1377
        • Humer E.
        • Petri R.M.
        • Aschenbach J.R.
        • Bradford B.J.
        • Penner G.B.
        • Tafaj M.
        • Südekum K.H.
        • Zebeli Q.
        Invited review: Practical feeding management recommendations to mitigate the risk of subacute ruminal acidosis in dairy cattle.
        J. Dairy Sci. 2018; 101 (29153519): 872-888
        • Humphries D.J.
        • Beever D.E.
        • Reynolds C.K.
        Adding straw to a total mixed ration and the method of straw inclusion affects production and eating behaviour of lactating dairy cows.
        Adv. Anim. Biosci. 2010; 1: 95
        • Ingvartsen K.L.
        • Dewhurst R.J.
        • Friggens N.C.
        On the relationship between lactational performance and health: Is it yield or metabolic imbalance that cause production diseases in dairy cattle? A position paper.
        Livest. Prod. Sci. 2003; 83: 277-308
        • Iwersen M.
        • Falkenberg U.
        • Voigtsberger R.
        • Forderung D.
        • Heuwieser W.
        Evaluation of an electronic cowside test to detect subclinical ketosis in dairy cows.
        J. Dairy Sci. 2009; 92 (19447994): 2618-2624
        • Lacasse P.
        • Vanacker N.
        • Ollier S.
        • Ster C.
        Innovative dairy cow management to improve resistance to metabolic and infectious diseases during the transition period.
        Res. Vet. Sci. 2018; 116 (28688615): 40-46
        • LeBlanc S.J.
        • Leslie K.E.
        • Duffield T.F.
        Metabolic predictors of displaced abomasum in dairy cattle.
        J. Dairy Sci. 2005; 88 (15591379): 159-170
        • Mann S.
        • Yepes F.A.
        • Overton T.R.
        • Wakshlag J.J.
        • Lock A.L.
        • Ryan C.M.
        • Nydam D.V.
        Dry period plane of energy: Effects on feed intake, energy balance, milk production, and com-position in transition dairy cows.
        J. Dairy Sci. 2015; 98 (25771059): 3366-3382
        • McArt J.A.A.
        • Nydam D.V.
        • Oetzel G.R.
        Epidemiology of subclinical ketosis in early lactation dairy cattle.
        J. Dairy Sci. 2012; 95 (22916909): 5056-5066
        • McCann J.C.
        • Luan S.
        • Cardoso F.C.
        • Derakhshani H.
        • Khafipour E.
        • Loor J.J.
        Induction of subacute ruminal acidosis affects the ruminal microbiome and epithelium.
        Front. Microbiol. 2016; 7 (27242724): 701
        • Mertens D.R.
        Creating a system for meeting the fiber requirements of dairy cows.
        J. Dairy Sci. 1997; 80 (9241608): 1463-1481
        • Nandra K.S.
        • Hendry A.
        • Dobos R.C.
        A study of voluntary intake and digestibility of roughages in relation to their degradation characteristics and retention time in the rumen.
        Anim. Feed Sci. Technol. 1993; 43: 227-237
        • National Research Council
        Nutrient Requirements of Dairy Cattle.
        7th rev. ed. Natl. Acad. Press, Washington, DC2001
        • Neave H.W.
        • Weary D.M.
        • LeBlanc S.J.
        • Huzzy J.M.
        • von Keyserlingk M.A.G.
        Behavioral changes before metritis diagnosis in dairy cows.
        J. Dairy Sci. 2018; 101: 4388-4399
        • Oba M.
        • Allen M.S.
        Dose-response effects of intra-ruminal infusion of propionate on feeding behavior of lactating cows in early or mid-lactation.
        J. Dairy Sci. 2003; 86 (14507028): 2922-2931
        • Ospina P.A.
        • Nydam D.V.
        • Stokol T.
        • Overton T.R.
        Associations of elevated nonesterified fatty acids and beta-hydroxybutyrate concentrations with early lactation reproductive performance and milk production in transition dairy cattle in the northeastern United States.
        J. Dairy Sci. 2010; 93 (20338437): 1596-1603
        • Rabelo E.
        • Rezende R.L.
        • Bertics S.J.
        • Grummer R.R.
        Effects of transition diets varying in dietary energy density on lactation performance and ruminal parameters of dairy cows.
        J. Dairy Sci. 2003; 86 (12703628): 916-925
        • Roberts C.J.
        • Reid I.M.
        • Rowlands G.J.
        • Patterson A.
        A fat mobilisation syndrome in dairy cows in early lactation.
        Vet. Rec. 1981; 108 (7233778): 7-9
        • Seifi H.A.
        • LeBlanc S.J.
        • Leslie K.E.
        • Duffield T.F.
        Metabolic predictors of post-partum disease and culling risk in dairy cattle.
        Vet. J. 2011; 188 (20457532): 216-220
        • Spanghero M.
        • Berzaghi P.
        • Fortina R.
        • Masoero F.
        • Rapetti L.
        • Zanfi C.
        • Tassone S.
        • Gallo A.
        • Colombini S.
        • Ferlito J.C.
        Technical note: Precision and accuracy of in vitro digestion of neutral detergent fiber and predicted net energy of lactation content of fibrous feeds.
        J. Dairy Sci. 2010; 93: 4855-4859
        • Suriyasathaporn W.
        • Heuer C.
        • Noordhuizen-Stassen E.N.
        • Schukken Y.H.
        Hyperketonemia and the impairment of udder defense: A review.
        Vet. Res. 2000; 31 (10958241): 397-412
        • Van Soest P.J.
        • Robertson J.B.
        • Lewis B.A.
        Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition.
        J. Dairy Sci. 1991; 74: 3583-3597
        • VandeHaar M.J.
        • St-Pierre N.
        Major advances in nutrition: Relevance to the sustainability of the dairy industry.
        J. Dairy Sci. 2006; 89 (16537960): 1280-1291
        • Vickers L.A.
        • Weary D.M.
        • Veira D.M.
        • von Keyserlingk M.A.G.
        Feeding a higher forage diet prepartum decreases incidences of subclinical ketosis in transition dairy cows.
        J. Anim. Sci. 2013; 91 (23230110): 886-894
        • Walsh R.B.
        • Walton J.S.
        • Kelton D.F.
        • LeBlanc S.J.
        • Leslie K.E.
        • Duffield T.F.
        The effect of subclinical ketosis in early lactation on reproductive performance of postpartum dairy cows.
        J. Dairy Sci. 2007; 90 (17517719): 2788-2796

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