Effect of partial replacement of forage neutral detergent fiber with by-product neutral detergent fiber in close-up diets on periparturient performance of dairy cows

The objective of this study was to determine the effect of partial replacement of forage neutral detergent fiber (NDF) with by-product NDF in close-up diets of dairy cattle on periparturient metabolism and performance. Holstein cows (n = 45) and heifers (n = 19) were fed corn silage-based diets containing 1) 30% oat hay, or 2) 15% oat hay and 15% beet pulp from d −21 relative to expected parturition until parturition. After parturition, all animals received the same lactation diet. Animals were group-fed from d −21 to −10 relative to expected parturition and fed individually from d −10 until 14 d in milk. Animals were required to have at least 5 d of prepartum dry matter intake (DMI) data to remain on the study. Data were analyzed as a randomized design and subjected to ANOVA using the MIXED procedure of SAS. Close-up diet did not affect DMI, total tract nutrient digestibility, energy balance, or serum content of nonesterified fatty acids and β-hydroxybutyrate during the last 5 d prepartum. Prepartum body weight and body condition score were similar between treatments. There was no carryover effect of close-up diet on DMI, energy balance, milk yield, body weight, body condition score, or serum content of nonesterified fatty acids and β-hydroxybutyrate during the first 14 d in milk. In summary, partial replacement of forage NDF (oat hay) with by-product NDF (beet pulp) did not affect periparturient metabolism or performance.     

Effect of feeding cows in early lactation with diets differing in roughage-neutral detergent fiber content on intake behavior, rumination, and milk production

This study measured the effects of including soyhulls as partial roughage replacement in total mixed rations (TMR) fed to 25 pairs of cows during early lactation, on the dry matter (DM) intake, particle kinetics, rumination, in vivo DM and NDF digestibility, milk and FCM yields, and BW changes. The 2 diets used in this study differed in the content of roughage and roughage NDF [23.5 vs. 35.0%, and 12.8 vs. 18.7% in the experimental (EXP) and control (CON) TMR, respectively]. The EXP TMR contained 20.5% less physically effective NDF than the CON TMR (11.7 vs. 14.1% of DM, respectively). These differences were expressed in a greater intake per meal (by 13.3%), a higher rate of meal intake (by 23.2%), a similar number of meals per day, a shorter daily eating duration (by 13%), and a higher total daily DMI (by 7.2%) in the EXP cows as compared with the CON cows. The in vivo DM and NDF digestibility was higher by 4.9 and 22.7%, respectively, in the EXP cows than in the CON cows. The rumination time for the TMR in the EXP cows was 12.7% (54.3 min/d) shorter than in the CON cows, and this was probably related to the difference of 12.4% in physically effective NDF intake between the 2 groups. Patterns of daily rumination and feed consumption throughout an average day showed a delay of approximately 1 to 2 h between the eating and rumination peaks. Particle flow from the rumen of the EXP cows was characterized by a longer rumen mean retention time (by 17.8%) and longer rumination time per kilogram of roughage ingested (by 23.5%) as compared with the CON cows. Thus, favorable conditions for NDF digestion were created in the rumen of the EXP cows, as reflected in their rumen pH values (6.67). The advantage of the EXP cows in intake and digestibility was reflected in a concomitant increase of 7.4% in milk production and of 9.2% in FCM yield as compared with the CON cows. No difference was found between the 2 groups with respect to efficiency of feed utilization for milk production and BW changes.     

Intake and milk production of cows fed diets that differed in dietary neutral detergent fiber and neutral detergent fiber digestibility

The objectives of this study were to determine how feeding diets that differed in dietary neutral detergent fiber (NDF) concentration and in vitro NDF digestibility affects dry matter (DM) intake, ruminal fermentation, and milk production in early lactation dairy cows. Twelve rumen-cannulated, multiparous Holstein cows averaging 38 ± 15 d (±standard deviation) in milk, and producing 40 ± 9 kg of milk daily, were used in a replicated 4 × 4 Latin square design with 28-d periods. Treatment diets were arranged in a 2 × 2 factorial with 28 or 32% dietary NDF (DM basis) and 2 levels of straw NDF digestibility: 1) LD, untreated wheat straw (77% NDF, 41% NDF digestibility) or 2) HD, anhydrous NH₃-treated wheat straw (76% NDF, 62% NDF digestibility). All 4 diets consisted of wheat straw, alfalfa silage, corn silage, and a concentrate mix of cracked corn grain, corn gluten meal, 48% soybean meal, and vitamins and minerals. Wheat straw comprised 8.5% DM of the 28% NDF diets and 16% DM of the 32% NDF diets. Cows fed 28% NDF and HD diets produced more milk, fat, and protein than those consuming 32% NDF or LD diets. Dry matter intake was greater for cows consuming 28% NDF diets, but intakes of DM and total NDF were not affected by in vitro NDF digestibility. Intake of digestible NDF was greater for cows consuming HD diets. Ruminal fermentation was not affected by feeding diets that differed in NDF digestibility. Ruminal NDF passage rate was slower for cows fed HD than LD. No interactions of dietary NDF concentration and in vitro NDF digestibility were observed for any parameter measured. Regardless of dietary NDF concentration, increased in vitro NDF digestibility improved intake and production in early lactation dairy cows.     

Analysis of water intake and dry matter intake using different lactation curve models

The objective was to evaluate 6 different lactation curve models for daily water and dry matter intake. Data originated from the Futterkamp dairy research farm of the Chamber of Agriculture of Schleswig-Holstein in Germany. A data set of about 23,000 observations from 193 Holstein cows was used. Average daily water and dry matter intake were 82.3 and 19.8 kg, respectively. The basic linear mixed model included the fixed effects of parity and test-day within feeding group. Additionally, 6 different functions were tested for the fixed effect of lactation curve and the individual (random) effect of cow-lactation curve. Furthermore, the autocorrelation between repeated measures was modeled with the spatial (power) covariance structure. Model fit was evaluated by the likelihood ratio test, Akaike's and Bayesian information criteria, and the analysis of mean residual at different days in milk. The Ali and Schaeffer function was best suited for modeling the fixed lactation curve for both traits. A Legendre polynomial of order 4 delivered the best model fit for the random effect of cow-lactation. Applying the error covariance structure led to a significantly better model fit and indicated that repeated measures were autocorrelated. Generally, the best information criteria values were yielded by the most complex model using the Ali and Schaeffer function and Legendre polynomial of order 4 to model the average lactation and cow-specific lactation curves, respectively, with inclusion of the spatial (power) error covariance structure. This model is recommended for the analysis of water and dry matter intake including missing observations to obtain estimation of correct statistical inference and valid variance components.     

Effects of dietary neutral detergent fiber and starch ratio on rumen epithelial cell morphological structure and gene expression in dairy cows

This study was designed to investigate the effect of dietary neutral detergent fiber to starch ratio on rumen epithelial morphological structure and gene expression. Eight primiparous dairy cows including 4 ruminally fistulated cows were assigned to 4 total mixed rations with neutral detergent fiber to starch ratios of 0.86, 1.18, 1.63, and 2.34 in a replicated 4 × 4 Latin square design. The duration of each period was 21 d including 14 d for adaptation and 7 d for sampling. Rumen epithelial papillae were collected from the ruminally fistulated cows for morphological structure examination and mRNA expression analysis using quantitative real-time PCR of several genes related to volatile fatty acid absorption and metabolism, and cellular growth. Increasing dietary neutral detergent fiber to starch ratio resulted in a linear increase in the thickness of the stratum spinosum and basale. In contrast, expression of HMGCS2 (encoding the rate-limiting enzyme in the synthesis of ketone bodies) decreased linearly, whereas the expression of MCT2 (encoding a transporter of volatile fatty acid) increased linearly with increasing dietary neutral detergent fiber to starch ratio. As dietary neutral detergent fiber to starch ratio increased, expression of IGFBP5 (a gene related to the growth of rumen epithelial papillae) decreased, whereas IGFBP6 expression increased. Both of these IGFBP genes are regulated by short-chain fatty acids. Overall, the data indicate that dietary neutral detergent fiber to starch ratio can alter the thickness of the rumen epithelial papillae partly through changes in expression of genes associated with regulating volatile fatty acid absorption, metabolism, and cell growth.     

Genetic and genomic dissection of dry matter intake at different lactation stages in primiparous Holstein cows

Dry matter intake (DMI) and feed efficiency are economically relevant traits. Simultaneous selection for low DMI and high milk yield might improve feed efficiency, but bears the risk of aggravating the negative energy balance and related health problems in early lactation. Lactation stage-specific selection might provide a possibility to optimize the trajectory of DMI across days in milk (DIM), but requires in-depth knowledge about genetic parameters within and across lactation stages. Within the current study, daily heritabilities and genetic correlations between DMI records from different lactation stages were estimated using random regression models based on 910 primiparous Holstein cows. The heritability estimates from DIM 11 to 180 follow a slightly parabolic curve varying from 0.26 (DIM 121) to 0.37 (DIM 11 and 180). Genetic correlations estimated between DIM 11, 30, 80, 130, and 180 were all positive, ranging from 0.29 (DIM 11 and 180) to 0.97 (DIM 11 and 30; i.e., the correlations are inversely related to the length of the interval between compared DIM). Deregressed estimated breeding values for the same lactation days were used as phenotypes in sequential genome-wide association studies using 681 cows drawn from the study population and genotyped for the Illumina SNP50 BeadChip (Illumina Inc., San Diego, CA). A total of 21 SNP on 10 chromosomes exceeded the chromosome-wise significance threshold for at least 1 analyzed DIM, pointing to some interesting candidate genes directly involved in the regulation of feed intake. Association signals were restricted to certain lactation stages, thus supporting the genetic correlations. Partitioning the explained variance onto chromosomes revealed a large contribution of Bos taurus autosome 7 not harboring any associated marker in the current study. The results contribute to the knowledge about the genetic architecture of the complex phenotype DMI and might provide valuable information for future selection efforts.     

The effect of dystocia on the dry matter intake and behavior of Holstein cows

Dairy cows that have a difficult calf delivery (dystocia) are more likely to develop health complications after calving, reducing productivity and welfare. Understanding the behavioral cues of dystocia may facilitate prompt obstetric assistance and reduce the long-term effect of the challenging delivery. The aim of this study was to describe the effects of dystocia on dairy cow behavior during the period around calving and to assess the use of these behaviors as potential indicators of dystocia. Individual dry matter intake, water intake, feeding and drinking time, meal size, standing time, and number of transitions from standing to lying positions (bouts) were recorded during the 48-h period before and after the time of calf delivery for 22 Holstein cows [11 cows with dystocia and 11 cows with unassisted delivery (eutocia)]. Cows with dystocia consumed 1.9 kg less during the 48 h before calving compared with cows with eutocia (14.3 ± 1.0 vs. 16.2 ± 1.0 kg, respectively), and this difference increased to 2.6 kg in the 24 h before calving (8.3 ± 0.7 vs. 10.9 ± 0.7 kg/d). There were no differences in drinking time between the groups, but cows with dystocia consumed less water 24 h before calving (22.4 ± 4.4 vs. 36.2 ± 4.4 kg/d, respectively) and consumed more water during the 24-h period after calving (56.9 ± 3.1 vs. 48.7 ± 3.1 kg/d) compared with cows with eutocia. Cows with dystocia transitioned from standing to lying positions more frequently than cows without dystocia beginning 24 h before calving (10.9 ± 0.7 vs. 8.3 ± 0.7 bouts/d). Dry matter intake and standing bouts in the 24 h before calving were the most accurate variables in discriminating between cows with and without dystocia, suggesting that cows with dystocia begin to alter their behavior beginning 24 h before calving.     

Short communication: Added value of rumination time for the prediction of dry matter intake in lactating dairy cows

The objective of the current study was to quantify the change in the prediction of dry matter intake (DMI) resulting from the inclusion of rumination time (RT) in the 2001 National Research Council (NRC) DMI prediction model. Forty-one Holstein cows fed the same total mixed ration were involved in a 10-wk study. Individual DMI were measured daily. The accuracy and precision of the original NRC prediction model, based on body weight, fat-corrected milk, and week of lactation as independent variables, was compared with the accuracy and precision of the same model with RT as an additional independent variable. The RT estimate was significant in the model developed but had a low value (0.031 kg/h). Root mean square prediction errors were very similar in the 2 models (1.70 and 1.68 kg/d) as were the other indicators (R², linear bias, random error, and concordance correlation coefficient) selected to compare the models in this study. These results indicate no gain in DMI prediction precision or accuracy when RT is included in the NRC model.     

Predicting the dry matter intake of grazing dairy cows using infrared reflectance spectroscopy analysis

The objective of this study was to compare mid-infrared reflectance spectroscopy (MIRS) analysis of milk and near-infrared reflectance spectroscopy (NIRS) analysis of feces with regard to their ability to predict the dry matter intake (DMI) of lactating grazing dairy cows. A data set comprising 1,074 records of DMI from 457 cows was available for analysis. Linear regression and partial least squares regression were used to develop the equations using the following variables: (1) milk yield (MY), fat percentage, protein percentage, body weight (BW), stage of lactation (SOL), and parity (benchmark equation); (2) MIRS wavelengths; (3) MIRS wavelengths, MY, fat percentage, protein percentage, BW, SOL, and parity; (4) NIRS wavelengths; (5) NIRS wavelengths, MY, fat percentage, protein percentage, BW, SOL, and parity; (6) MIRS and NIRS wavelengths; and (7) MIRS wavelengths, NIRS wavelengths, MY, fat percentage, protein percentage, BW, SOL, and parity. The equations were validated both within herd using animals from similar experiments and across herds using animals from independent experiments. The accuracy of equations was greater for within-herd validation compared with across-herds validation. Across-herds validation was deemed the more suitable method to assess equations for robustness and real-world application. The benchmark equation was more accurate [coefficient of determination (R²) = 0.60; root mean squared error (RMSE) = 1.68 kg] than MIRS alone (R² = 0.30; RMSE = 2.23 kg) or NIRS alone (R² = 0.16; RMSE = 2.43 kg). The combination of the benchmark equation with MIRS (R² = 0.64; RMSE = 1.59 kg) resulted in slightly superior fitting statistics compared with the benchmark equation alone. The combination of the benchmark equation with NIRS (R² = 0.58; RMSE = 1.71 kg) did not result in a more accurate prediction equation than the benchmark equation. The combination of MIRS and NIRS wavelengths resulted in superior fitting statistics compared with either method alone (R² = 0.36; RMSE = 2.15 kg). The combination of the benchmark equation and MIRS and NIRS wavelengths resulted in the most accurate equation (R² = 0.68; RMSE = 1.52 kg). A further analysis demonstrated that Holstein-Friesian cows could predict the DMI of Jersey × Holstein-Friesian crossbred cows using both MIRS and NIRS. Similarly, the Jersey × Holstein-Friesian animals could predict the DMI of Holstein-Friesian cows using both MIRS and NIRS. The equations developed in this study have the capacity to predict DMI of grazing dairy cows. From a practicality perspective, MIRS in combination with variables in the benchmark equation is the most suitable equation because MIRS is currently used on all milk-recorded milk samples from dairy cows.     

Performance of dairy cows fed diets with similar proportions of undigested neutral detergent fiber with wheat straw substituted for alfalfa hay,corn silage,or both

This study evaluated the effects of feeding diets that were formulated to contain similar proportions of undigested neutral detergent fiber (uNDF) from forage, with wheat straw (WS) substituted for corn silage (CS), alfalfa hay (AH), or both. The diets were fed to lactating dairy cows and intake, digestibility, blood metabolites, and milk production were examined. Thirty-two multiparous Holstein cows (body weight = 642 ± 50 kg; days in milk = 78 ± 11 d; milk production = 56 ± 6 kg/d; mean ± standard deviation) were used in a randomized block design with 6-wk periods after a 10-d covariate period. Each period consisted of 14 d of adaptation followed by 28 d of data collection. The control diet contained CS and AH as forage sources (CSAH) with 17% of dietary dry matter as uNDF after 30 h of incubation (uNDF₃₀). Wheat straw was substituted for AH (WSCS), CS (WSAH), or both (WSCSAH) on an uNDF₃₀ basis, and beet pulp was used to obtain similar concentrations of NDF digestibility after 30 h of incubation (NDFD₃₀ = 44.5% of NDF) across all diets. The 4 diets also contained similar concentrations of net energy for lactation and metabolizable protein. Dry matter intake was greatest for WSCS (27.8 kg/d), followed by CSAH (25.7 kg/d), WSCSAH (25.2 kg/d), and WSAH (24.2 kg/d). However, yields of milk, 3.5% fat-corrected milk (FCM), and energy-corrected milk did not differ, resulting in higher FCM efficiency (kg of FCM yield/kg of dry matter intake) for WSAH (1.83) and WSCSAH (1.79), followed by CSAH (1.69) and WSCS (1.64). Milk protein percentage was greater for CSAH (2.84%) and WSCS (2.83%) than for WSAH (2.78%), and WSCSAH (2.81%) was intermediate. The opposite trend was observed for milk urea nitrogen, which was lower for CSAH (15.8 mg/dL), WSCS (15.8 mg/dL), and WSCSAH (17.0 mg/dL) than for WSAH (20 mg/dL). Total-tract NDF digestibility and ruminal pH were greater for diets containing WS than the diet without WS (CSAH), but digestibility of other nutrients was not affected by dietary treatments. Cows fed WSAH had less body reserves (body weight change = −13.5 kg/period) than the cows fed the other diets, whereas energy balance was greatest for those fed WSCS. The results showed that feeding high-producing dairy cows diets containing different forage sources but formulated to supply similar concentrations of uNDF₃₀ while maintaining NDFD_30, net energy for lactation, and metabolizable protein constant did not influence milk production. However, a combination of WS and CS (WSCS diet) compared with a diet with CS and AH improved feed intake, ruminal pH, total-tract NDF digestibility, and energy balance of dairy cows.     

Short communication: Evaluation of acid-insoluble ash and indigestible neutral detergent fiber as total-tract digestibility markers in dairy cows fed corn silage-based diets

The objective of this experiment was to evaluate acid-insoluble ash (AIA) and indigestible NDF (iNDF) as intrinsic digestibility markers in comparison with total fecal collection (TC) in dairy cows fed corn silage- and alfalfa haylage-based diets. The experiment was part of a larger experiment, which involved 8 Holstein cows [102 ± 28.4 d in milk, 26.4 ± 0.27 kg/d of dry matter (DM) intake, and 43 ± 5.3 kg/d milk yield]. The experimental design was a replicated 4 × 4 Latin square with the following treatments: metabolizable protein (MP)-adequate diet [15.6% crude protein (CP); high-CP], MP-deficient diet (14.0% CP; low-CP), and 2 other low-CP diets supplemented (top-dressed) with ruminally protected Lys or Lys and Met. Data for the 3 low-CP diets were combined for this analysis. Total feces were collected for 5 consecutive days during each period to estimate total-tract apparent digestibility. Digestibility was also estimated using AIA (digestion with 2 N HCl) and iNDF (12-d ruminal incubation in 25-μm-pore-size bags). Significant diet × digestibility method interactions were observed for fecal output of nutrients and digestibility. Fecal output of nutrients estimated using AIA or iNDF was lower compared with TC and fecal output of DM, organic matter, and CP tended to be higher for iNDF compared with AIA for the high-CP diet. For the low-CP diet, however, fecal output of all nutrients was lower for AIA compared with TC and was higher for iNDF compared with TC. Data from this experiment showed that, compared with TC, AIA underestimated fecal output and overestimated digestibility, particularly evident with the fiber fractions and the protein-deficient diet. Compared with TC, fecal output was overestimated and digestibility of the low-CP diet was underestimated when iNDF was used as a marker, although the magnitude of the difference was smaller compared with that for AIA. In the conditions of the current study, iNDF appeared to be a more reliable digestibility marker than AIA in terms of detecting dietary differences in apparent digestibility of some nutrients, but significant diet × marker interactions existed that need to be considered when estimating total-tract digestibility using intrinsic markers.     

Liability to diseases and their relation to dry matter intake and energy balance in German Holstein and Fleckvieh dairy cows

Dairy cow efficiency is increasingly important for future breeding decisions. The efficiency is determined mostly by dry matter intake (DMI). Reducing DMI seems to increase efficiency if milk yield remains the same, but resulting negative energy balance (EB) may cause health problems, especially in early lactation. Objectives of this study were to examine relationships between DMI and liability to diseases. Therefore, cow effects for DMI and EB were correlated with cow effects for 4 disease categories throughout lactation. Disease categories were mastitis, claw and leg diseases, metabolic diseases, and all diseases. In addition, this study presents relative percentages of diseased cows per days in milk (DIM), repeatability, and cow effect correlations for disease categories across DIM. A total of 1,370 German Holstein (GH) and 287 Fleckvieh (FV) primiparous and multiparous dairy cows from 12 dairy research farms in Germany were observed over a period of 2 yr. Farm staff and veterinarians recorded health data. We modeled health and production data with threshold random regression models and linear random regression models. From DIM 2 to 305 average daily DMI was 22.1 kg/d in GH and 20.2 kg/d in FV. Average weekly EB was 2.8 MJ of NE_L/d in GH and 0.6 MJ of NE_L/d in FV. Most diseases occurred in the first 20 DIM. Multiparous cows were more susceptible to diseases than primiparous cows. Relative percentages of diseased cows were highest for claw and leg diseases, followed by metabolic diseases and mastitis. Repeatability of disease categories and production traits was moderate to high. Cow effect correlations for disease categories were higher for adjacent lactation stages than for more distant lactation stages. Pearson correlation coefficients between cow effects for DMI, as well as EB, and disease categories were estimated from DIM 2 to 305. Almost all correlations were negative in GH, especially in early lactation. In FV, the course of correlations was similar to GH, but correlations were mostly more negative in early lactation. For the first 20 DIM, correlations ranged from ?0.31 to 0.00 in GH and from ?0.42 to ?0.01 in FV. The results illustrate that future breeding for dairy cow efficiency should focus on DMI and EB in early lactation to avoid health problems.     

Effects of different transition diets on dry matter intake,milk production,and milk composition in dairy cows

The primary objective of this study was to evaluate the effect on dry matter intake (DMI), milk yield, milk composition, body weight (BW), and body condition score (BCS) change of cows offered diets differing in energy density in the last 4 wk of gestation and in the first 8 wk of lactation. Three diets (grass silage:straw, 75:25 on a dry matter basis (SS), grass silage (S), and grass silage + 3 kg concentrate daily (C)) precalving, and two diets (4 kg [LC] or 8 kg [HC] concentrate daily + grass silage ad libitum) postcalving were combined in a 3 x 2 factorial design. Sixty Holstein-Friesian cows entering their second lactation were blocked according to expected calving date and BCS into groups of six and were then allocated at random to the treatments. Individual feeding started 4 wk prior to the expected calving date and measurements were made until the end of the 8th wk of lactation. Mean DMI differed between each of the precalving treatments (7.4, 8.1, and 9.9 kg/d for SS, S, and C, respectively) in the precalving period. The DMI also differed between SS and C for wk 1 to 8 (13.5 and 14.2 kg/d) postcalving. Postcalving, milk (24.2, 26.2, and 28.2 kg/d), fat (933, 1063, and 1171 g/d), and protein (736, 797, and 874 g/d) yields differed between SS, S, and C, respectively. The BCS changes differed between SS and C (-0.09 and 0.12 of a BCS) in the precalving period and between SS and S compared with C (0.02, 0.06, and -0.26 of a BCS) for wk 1 to 8 postcalving. The BW change differed between SS and S compared with C in both wk 1 to 4 (-0.23, -0.37, and -1.25 kg/d) and wk 1 to 8 (0.18, 0.10, and -0.58 kg/ d) postcalving. The BW and BCS were lower at calving for cows on SS compared with C. The greater amount of concentrate supplement postcalving increased DMI, yields of milk, fat, and protein and decreased BW loss in the first 8 wk of lactation. In conclusion, these results indicate that a greater energy density diet in the final 4 wk of the dry period improves cow production in early lactation.     

Diets during far-off and close-up dry periods affect periparturient metabolism and lactation in multiparous cows

The objectives of this study were to determine the effects of far-off and close-up diets on prepartum metabolism, postpartum metabolism, and postpartum performance of multiparous Holstein cows. From dry-off to −25 d relative to expected parturition (far-off dry period), cows were fed a control diet to meet National Research Council (NRC) recommendations for net energy for lactation (NE_L) at ad libitum intake (100NRC; n = 25) or a higher nutrient density diet, which was fed for either ad libitum intake to provide at least 150% of calculated NE_L requirement (150NRC; n = 25) or at restricted intake to provide 80% of calculated NE_L requirements (80NRC; n = 24). From −24 d relative to expected parturition until parturition (close-up period), cows were fed a diet that met or exceeded NRC nutrient recommendations at either ad libitum intake (n = 38) or restricted intake (n = 36) to provide 80% of the calculated NE_L requirement. After parturition, all cows were fed a lactation diet and measurements were made through 56 d in milk (DIM). Prepartum metabolism was consistent with the plane of nutrition. During the first 10 DIM, far-off treatments had significant carryover effects on dry matter intake, energy balance, serum nonesterified fatty acid (NEFA) concentration, and serum β-hydroxybutyrate concentration. Cows with the lower energy balance during the far-off period (100NRC and 80NRC) had higher dry matter intake and energy balance and lower serum NEFA and β-hydroxybutyrate during the first 10 DIM. There were no effects of close-up diet and no interactions of far-off and close-up treatments. During the first 56 DIM, there were no residual effects of far-off or close-up diets on dry matter intake, milk yield or composition, body weight, body condition score, serum glucose and insulin concentrations, or muscle lipid concentration. Serum NEFA was higher for 150NRC than 80NRC; 100NRC was intermediate. Thus, the effects of far-off and close-up treatments on postpartum variables diminished as lactation progressed. Overfeeding during the far-off period had a greater negative impact on peripartum metabolism than did differences in close-up period nutrition.     

Effects of neutral detergent fiber and roughage source on dry matter intake and milk yield and composition of dairy cows

Data were from 20 experiments that utilized early to midlactation Holstein cows fed complete mixed diets or fed at constant forage:concentrate ratios. Within-cow diet comparisons (1688 cow-periods) were analyzed by least squares analysis of variance; mathematical model included experiment, cow in experiment, period, body weight, and source of roughage. Objectives were to determine relationships between neutral detergent fiber content of diet and milk yield and dry matter intake. Roughages and number of cow-periods were: sugarcane bagasse/silage (507), cottonseed hulls (504), corn silage (268), ground corrugated boxes (170), alfalfa/peanut hay (132), and others (107). Dry matter intake and estimated net energy intake had linear effects on milk yield and explained 21.6 and 24.0% of its residual variation; milk yield had curvilinear (quadratic) effect and explained 22.4% of dry matter intake residual variation. Interaction between neutral detergent fiber and source of roughage on milk yield, 4% fat-corrected milk, and dry matter intake resulted in reductions of 5.6, 5.6, and 13% in residual variations. Results suggest neutral detergent (% of dry matter) has greater effect on dry matter intake than on milk yield and its use in formulating diets for dairy cows will be within roughage source.     

The effect of Lolium perenne L. ploidy and Trifolium repens L. inclusion on dry matter intake and production efficiencies of spring-calving grazing dairy cows

The objective of this study was to investigate the effect of perennial ryegrass (Lolium perenne L.; PRG) ploidy and white clover (Trifolium repens L.) inclusion on milk production, dry matter intake (DMI), and milk production efficiencies. Four separate grazing treatments were evaluated: tetraploid PRG only, diploid PRG only, tetraploid PRG with white clover, and diploid PRG with white clover. Individual DMI was estimated 8 times during the study (3 times in 2015, 2 times in 2016, and 3 times in 2017) using the n-alkane technique. Cows were, on average, 64, 110, and 189 d in milk during the DMI measurement period, corresponding to spring, summer, and autumn, respectively. Measures of milk production efficiency were total DMI/100 kg of body weight (BW), milk solids (kg of fat + protein; MSo)/100 kg of BW, solids-corrected milk/100 kg of BW, and MSo/kg of total DMI. Perennial ryegrass ploidy had no effect on DMI; however, a significant increase in DMI (+0.5 kg/cow per day) was observed from cows grazing PRG-white clover swards compared with PRG-only swards. Sward white clover content influenced DMI as there was no increase in DMI in spring (9% sward white cover content), whereas DMI was greater in summer and autumn for cows grazing PRG-white clover swards (+0.8 kg/cow per day) compared with PRG-only swards (14 and 23% sward white clover content, respectively). The greater DMI of cows grazing PRG-white clover swards led to increased milk (+1.3 kg/cow per day) and MSo (+0.10 kg/cow per day) yields. Cows grazing PRG-white clover swards were also more efficient for total DMI/100 kg of BW, solids-corrected milk/100 kg of BW, and MSo/100 kg of BW compared with cows grazing PRG-only swards due to their similar BW but higher milk and MSo yields. The results highlight the potential of PRG-white clover swards to increase DMI at grazing and to improve milk production efficiency in pasture-based systems.     

Effect of dietary cation-anion difference on acid-base status and dry matter intake in dry pregnant cows

The objective was to determine if the reduction in dry matter (DM) intake of acidogenic diets is mediated by inclusion of acidogenic products, content of salts containing Cl, or changes in acid-base status. The hypothesis was that a decrease in intake is mediated by metabolic acidosis. Ten primigravid Holstein cows at 148 ± 8 d of gestation were used in a duplicated 5 × 5 Latin square design. The dietary cation-anion difference (DCAD) of diets and acid-base status of cows were manipulated by incorporating an acidogenic product or by adding salts containing Cl, Na, and K to the diets. Treatments were a base diet (T1; 1.42% K, 0.04% Na, 0.26% Cl; DCAD = 196 mEq/kg); the base diet with added 1% NaCl and 1% KCl (T2; 1.83% K, 0.42% Na, 1.23% Cl; DCAD = 194 mEq/kg); the base diet with added 7.5% acidogenic product, 1.5% NaHCO₃, and 1% K₂CO₃ (T3; 1.71% K, 0.54% Na, 0.89% Cl; DCAD = 192 mEq/kg); the base diet with added 7.5% acidogenic product (T4; 1.29% K, 0.13% Na, 0.91% Cl; DCAD = ?114 mEq/kg); and the base diet with 7.5% acidogenic product, 1% NaCl, and 1% KCl (T5; 1.78% K, 0.53% Na, 2.03% Cl; DCAD = ?113 mEq/kg). Periods lasted 14 d with the last 7 d used for data collection. Feeding behavior was evaluated for 12 h in the last 2 d of each period. Reducing the DCAD by feeding an acidogenic product reduced blood pH (T1 = 7.450 vs. T2 = 7.436 vs. T3 = 7.435 vs. T4 = 7.420 vs. T5 = 7.416) and induced a compensated metabolic acidosis with a reduction in bicarbonate, base excess, and partial pressure of CO₂ in blood, and reduced pH and strong ion difference in urine. Reducing the DCAD reduced DM intake 0.6 kg/d (T1 = 10.3 vs. T4 = 9.7 kg/d), which was caused by the change in acid-base status (T2 + T3 = 10.2 vs. T4 + T5 = 9.6 kg/d) because counteracting the acidifying action of the acidogenic product by adding salts with strong cations to the diet prevented the decline in intake. The decline in intake caused by metabolic acidosis also was observed when adjusted for body weight (T2 + T3 = 1.75 vs. T4 + T5 = 1.66% BW). Altering the acid-base status with acidogenic diets reduced eating (T2 + T3 = 6.7 vs. T4 + T5 = 5.9 bouts/12 h) and chewing (T2 + T3 = 14.6 vs. T4 + T5 = 13.5 bouts/12 h) bouts, and extended meal duration (T2 + T3 = 19.8 vs. T4 + T5 = 22.0 min/meal) and intermeal interval (T2 + T3 = 92.0 vs. T4 + T5 = 107.7 min). Results indicate that reducing the DCAD induced a compensated metabolic acidosis and reduced DM intake, but correcting the metabolic acidosis prevented the decline in DM intake in dry cows. The decrease in DM intake in diets with negative DCAD was mediated by metabolic acidosis and not by addition of acidogenic product or salts containing Cl.     

Prediction of dry matter intake throughout lactation in a dynamic model of dairy cow performance

In the dynamic modeling of dairy cow performance over a full lactation, the difference between net energy intake and net energy used for maintenance, growth, and output in milk accumulates in body reserves. A simple dynamic model of net energy balance was constructed to select, out of some common dry matter intake (DMI) prediction equations, the one that resulted in a minimum cumulative bias in body energy deposition. Dry matter intake was predicted using the Cornell Net Carbohydrate and Protein System, Agricultural Research Council, or National Research Council (NRC) DMI equations from body weight (BW) and predicted fat-corrected milk yield. The instantaneous BW of cows at progressive weeks of lactation was simulated as the numerical integral of the BW change obtained from the predicted net energy balance. Predicted DMI and BW from each DMI equation, using either of 2 equations to describe maintenance energy expenditures, were compared statistically against observed data from 21 herd average published full lactation data sets. All DMI equations underpredicted BW and DMI, but the NRC DMI equation resulted in the minimum cumulative error in predicted BW and DMI. As a general solution to prevent predicted BW from deviating substantially over time from the observed BW, a lipostatic feedback mechanism was integrated into the NRC DMI equation as a 2-parameter linear function of the relative size of simulated body reserves and week of lactation. Residual sum of squares was reduced on average by 52% for BW predictions and by 41% for DMI predictions by inclusion of the negative feedback with parameters taken from the average of all 21 least squares fits. Similarly, root mean square prediction error (%) was reduced by 30% on average for BW predictions and by 23% for DMI predictions. Inclusion of a feedback of energy reserves onto predicted DMI, simulating lipostatic regulation of BW, solved the problem of final BW deviation within a dynamic model and improved its DMI prediction to a satisfactory level.     

Association of subclinical hypocalcemia dynamics with dry matter intake,milk yield,and blood minerals during the periparturient period

Subclinical hypocalcemia (SCH) affects many high-producing dairy cows in the postpartum period. Recent work has shown that cows experiencing prolonged or delayed SCH are at increased risk for disease and produce less milk than cows experiencing a transient reduction in or normal concentrations of plasma Ca following parturition. Our objective was to determine the association between different postpartum SCH dynamics with pre- and postpartum dry matter intake (DMI), milk yield, and blood mineral concentrations. Data were retrospectively collected from multiparous Holstein cows (n = 78), and cows were classified into 1 of 4 SCH groups based on mean blood total Ca (tCa) concentrations at 1 and 4 d in milk (DIM): normocalcemic (NC; [tCa] >1.95 mmol/L at 1 DIM and >2.2 mmol/L at 4 DIM, n = 28); transient SCH (tSCH; [tCa] ≤1.95 mmol/L at 1 DIM and >2.2 mmol/L at 4 DIM, n = 27); delayed SCH (dSCH; [tCa] >1.95 mmol/L at 1 DIM and ≤2.2 mmol/L at 4 DIM, n = 6); and persistent SCH (pSCH; [tCa] ≤1.95 mmol at 1 DIM and ≤2.2 mmol/L at 4 DIM, n = 17). Linear mixed models were created to analyze the change in pre- and postpartum DMI, milk yield, and blood mineral concentrations over time as well as differences between SCH groups. Prepartum intake was similar between groups, but the NC and tSCH cows consumed more feed than the pSCH or dSCH cows during the first 3 wk of lactation. The tSCH cows produced more milk than the other 3 groups during the first 6 wk of lactation. Postpartum blood tCa and Mg were different between SCH groups and were highest in the NC cows and lowest in the pSCH cows. Our results suggest that the high level of DMI consumed by the NC and tSCH cows in the postpartum period supported an appropriate homeostatic response to the increased Ca demands of lactation, allowing for higher milk yield compared with their counterparts experiencing delayed or prolonged episodes of SCH.     

Association of dry matter intake and energy balance prepartum and postpartum with health disorders postpartum: Part II. Ketosis and clinical mastitis

The main objective of this study was to determine the association of dry matter intake as percentage of body weight (DMI%BW) and energy balance (EB) prepartum (−21 d relative to parturition) and postpartum (28 d) with ketosis (n = 189) and clinical mastitis (n = 79). For this, DMI%BW and EB were the independent variables and ketosis and clinical mastitis were the dependent variables. A secondary objective was to evaluate prepartum DMI%BW and EB as predictors of ketosis and clinical mastitis. For this, ketosis and clinical mastitis were the independent variables and DMI%BW and EB were the dependent variables. Data from 476 cows from 9 experiments were compiled. Clinical mastitis was diagnosed if milk from 1 or more quarters was abnormal in color, viscosity, or consistency, with or without accompanying heat, pain, redness, or swelling of the quarter or generalized illness, during the first 28 d postpartum. Ketosis was defined as the presence of acetoacetate in urine that resulted in any color change [5 mg/dL (trace) or higher] in the urine test strip (Ketostix, Bayer, Leverkusen, Germany). Cows that developed ketosis had lesser DMI%BW and lesser EB on d −5, −3, −2, and −1 than cows without ketosis. Each 0.1-percentage point decrease in the average DMI%BW and each 1-Mcal decrease in the average of EB in the last 3 d prepartum increased the odds of having ketosis by 8 and 5%, respectively. Cut-offs for DMI%BW and EB during the last 3 d prepartum to predict ketosis were established and were ≤1.5%/d and ≤1.1 Mcal/d, respectively. Cows that developed ketosis had lesser postpartum DMI%BW and EB and greater energy-corrected milk (ECM) than cows without ketosis. Cows that developed clinical mastitis had lesser DMI%BW but similar prepartum EB compared with cows without clinical mastitis. Each 0.1-percentage point decrease in the average DMI%BW and each 1-Mcal decrease in the average EB in the last 3 d prepartum increased the odds of having clinical mastitis by 10 and 8%, respectively. The average DMI%BW and EB during the last 3 d prepartum produced significant cut-offs to predict clinical mastitis postpartum, which were ≤1.2%/d and ≤1.0 Mcal/d, respectively. Cows that developed clinical mastitis had lesser postpartum DMI%BW from d 3 to 15 and on d 17; greater EB on d 18, from d 21 to 23, and on d 26; and lesser ECM. The main limitation in this study is that the time-order of disease relative to DMI%BW and ECM is inconsistent such that postpartum outcomes were measured before and after disease, which was diagnosed at variable intervals after calving. In summary, measures of prepartum DMI were associated with and were predictors of ketosis and clinical mastitis postpartum, although the effect sizes were small.