Effects of milk replacer allowances and levels of starch in pelleted starter on nutrient digestibility, whole gastrointestinal tract fermentation, and pH around weaning.

The objectives of this study were to examine the effects of pelleted starter diets differing in starch and neutral detergent fiber (NDF) content when fed differing levels of milk replacer (MR) on nutrient digestibility, whole gastrointestinal tract fermentation, pH, and inflammatory markers in dairy calves around weaning. Calves were randomly assigned to 1 of 4 dietary treatments (n = 12 per treatment) in a 2 × 2 factorial design based on daily MR allowance and amount of starch in pelleted starter (SPS): 0.691 kg of MR per day [dry matter (DM) basis] with starter containing low or high starch (12.0% and 35.6% starch on DM basis, respectively), and 1.382 kg of MR per day (DM) with starter containing low or high starch. All calves were housed in individual pens with straw bedding until wk 5 when bedding was covered. Calves were fed MR twice daily (0700 and 1700 h) containing 24.5% crude protein (DM) and 19.8% fat (DM), and had access to pelleted starter (increased by 50 g/d if there were no refusals before weaning and then 200 g/d during and after weaning) and water starting on d 1. Calves arrived between 1 and 3 d of age and were enrolled into an 8-wk study, with calves undergoing step-down weaning during wk 7. Starting on d 35, an indwelling pH logger was inserted orally to monitor rumen pH until calves were dissected at the end of the study in wk 8. Higher SPS calves showed an increase in rumen pH magnitude (1.46 ± 0.07) compared with low SPS calves (1.16 ± 0.07), a decrease in rumen pH in wk 8 (high SPS: 5.37 ± 0.12; low SPS: 5.57 ± 0.12), and a decrease in haptoglobin in wk 8 (high SPS: 0.24 ± 0.06 g/L; low SPS: 0.49 ± 0.06 g/L). The majority of differences came from increased starter intake in general, which suggests that with completely pelleted starters the differences in starch and NDF do not elicit drastic changes in fermentation, subsequent end products, and any resulting inflammation in calves around weaning.

Performance and visceral tissue growth and development of Holstein calves fed differing milk replacer allowances and starch concentrations in pelleted starter.

The objectives of this study were to investigate how milk replacer (MR) allowance and differing concentrations of starch and neutral detergent fiber in starter alters visceral tissue and overall growth of the calf. Calves were randomly assigned to 1 of 4 dietary treatments (n = 12 per treatment) arranged in a 2 × 2 factorial based on daily MR allowance (MRA) and amount of starch in pelleted starter (SPS) as follows: 0.691 kg of MR/d [dry matter (DM) basis] with starter containing low or high starch (12.0% and 35.6% starch, respectively) and 1.382 kg of MR/day (DM) with starter containing low or high starch. All calves were housed in individual pens with straw bedding until wk 5 when bedding was covered to minimize intake. Calves were fed MR twice daily (0700 and 1700 h) containing 24.5% crude protein (DM) and 19.8% fat (DM), and had access to pelleted starter (increased by 50 g/d if there were no refusals before weaning, and then 200 g/d during and after weaning) and water starting on d 1. Calves arrived between 1 and 3 d of age and were enrolled into an 8-wk study, with calves undergoing step-down weaning during wk 7. Intakes were measured daily, and body weight (BW) and blood samples were recorded and collected weekly. Calves were dissected in wk 8 for visceral tissue measurements. Overall, there was increased MR DM intake for the high- (0.90 ± 0.01 kg/d; ± SE) compared with the low-MRA (0.54 ± 0.01 kg/d) calves, whereas starter DM intake increased in low- (0.47 ± 0.05 kg/d) compared with high-MRA (0.20 ± 0.05 kg/d) calves, which was driven by increases in wk 6, 7, and 8. High-MRA calves had increased BW during wk 2, 3, 4, 5, 6, and 7. The difference in BW disappeared by wk 8, with overall average daily gain having a tendency to be increased in high (0.57 ± 0.04 kg/d) compared with low-MRA (0.50 ± 0.04 kg/d) calves, whereas average daily gain was increased in high-MRA calves during wk 2 and 3 and increased in low-MRA calves during wk 7 and 8. There were several differences throughout visceral tissue measurements, but most notably, an increase in rumen mass (i.e., full, empty, and digesta weights) in low- compared with high-MRA calves, as well as in low- compared with high-SPS calves was observed. The length, width, and 2-dimensional area of rumen papillae were also increased in low- (area: 0.88 ± 0.03 mm2) compared with high-MRA (0.46 ± 0.03 mm2) calves. The majority of differences were attributed to increased MR allowance, which contributed to reduced pelleted starter intake by more than 50% and reduced rumen development, whereas differences in starch intake from the completely pelleted starter had minimal effects on overall growth and tissue measurements.

Effect of ß-carotene supplementation to prepartum Holstein cows on colostrum quality and calf performance.

ß-Carotene, a pro-vitamin A carotenoid, acts as an antioxidant, able to scavenge free radicals to prevent oxidative damage. It has also been shown to increase rumen microbial production in vitro. When supplemented prepartum, ß-carotene increased colostral fat and protein concentrations. The objective of this experiment was to evaluate the effects of supplementing 700 mg/d ß-carotene (BC) daily for 4 wk prepartum on cow performance, colostrum, and performance in subsequent calves. Eighteen multiparous Holstein cows housed in a tiestall barn were blocked by expected calving date and randomly assigned to treatments at 4 wk prepartum. Blood samples were collected 3 times a week for analysis of nonesterified fatty acids, ketones, ß-carotene, and IgG. Urine samples were also collected 3 times a week for analysis of creatinine and purine derivatives. Colostrum was collected within 90 min after parturition. Calves were removed from their dams before suckling, weighed within 30 min of birth, and received 4 L of maternal colostrum. Blood samples were collected from calves before colostrum administration (0 h) and at 24 h via jugular venipuncture for analysis of IgG concentration and apparent efficiency of IgG absorption. The 18 calves born were blocked based on treatments of dams. All calves were fed 449 g/d dry matter of milk replacer (20% crude protein, 20% fat) and an 18% crude protein textured starter and water ad libitum at 2 d of age until weaning at 42 d. There were no differences in any blood parameters of cows during the prepartum period. Supplemental BC increased the solids content of colostrum compared with control (22.89% control; 27.75% BC). Calves born from control fed cows had greater efficiency of IgG absorption than those born from BC supplemented cows (52.16% control; 39.50%, BC). Calves born from BC fed cows had greater feed efficiency (average daily gain/dry matter intake) compared with those born from control supplemented cows (0.33 for control; 0.44 for BC). These data indicate that although supplementing ß-carotene to cows in the prepartum period negatively affects apparent efficiency of IgG absorption, it improved feed efficiency in calves.

Effects of feeding milk replacer at a moderate rate, ad libitum, or with a step-up program on Holstein calf growth performance to 4 months of age.

The objective of this study was to evaluate 3 milk replacer (MR) feeding programs on calf performance to 4 mo of age. Male Holstein calves (n = 48; 2-3 d old) were randomly assigned to either a moderate rate of MR (MOD; 0.66 kg/d for 39 d, then 0.33 kg/d for 3 d), an ad libitum rate of MR (ADLIB; offered twice daily between 0630 and 0830 h and between 1430 and 1630 h for 35 d, 0.66 kg/d for 4 d, and 0.33 kg/d for 3 d), or a step-up rate of MR (STEPUP; increased from 0.32 to 0.62 kg/d in first 12 d, 0.66 kg/d for 27 d, and 0.33 kg/d for 3 d). The MR (25% CP, 18% fat) was fed twice daily to d 39 and once daily thereafter. During the nursery phase (0-56 d), calves were housed in individual pens and offered textured starter (40% starch, 21% CP on a DM basis) and water ad libitum. Calf body weight (BW) was measured initially and weekly thereafter. Hip widths (HW) were measured initially and every 2 wk thereafter. In the grower phase, (57-112 d), calves were grouped by previous treatment and moved to group pens (4 calves/pen). The same starter used in the nursery phase was blended with 5% chopped grass hay and offered ad libitum. Calf BW and HW were measured on d 56, 84, and 112. Total MR intake per calf averaged 27, 51, and 25 kg for MOD, ADLIB, and STEPUP programs, respectively, with a range of 42 to 63 kg for ADLIB. In the nursery phase, starter intake and feed efficiency were less for ADLIB versus MOD, whereas fecal scores and abnormal fecal score days were greater for calves fed ADLIB versus MOD. Calves fed STEPUP had lesser average daily gain than calves fed MOD. During the grower phase, initial BW was greater for ADLIB versus MOD, though final BW was not different between MOD and ADLIB or STEPUP. Calves previously fed MOD had greater average daily gain, feed efficiency, and HW change than calves fed ADLIB. In this study, feed efficiency was lower when MR was fed ad libitum, and growth advantages observed at 2 mo were lost by 4 mo of age.

Effects of milk replacer feeding rate and fat content on Jersey calf nutrient digestion and performance to 4 months of age.

This study evaluated effects of milk replacer (MR) feeding rate and fat concentration in MR on total-tract digestion (TTD) and growth performance in Jersey calves. Jersey heifer calves (n = 100, 2 blocks of 50; initially 30 ± 3.0 kg of body weight; 4-11 d of age) were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement of MR feeding rate [454 g for 42 d, and 227 g for 7 d (MOD); or 454 g for 7 d, 681 g for 35 d, and 341 g for 7 d (HI), as-fed basis] and MR fat content (17 or 24% fat as-fed basis). Milk replacers (24% crude protein as-fed basis) were reconstituted to 14% solids and fed in 2 equal feedings for 42 d, and then mornings only for 7 d. Textured calf starter (21% crude protein, 40% starch, dry matter basis) and water were offered for ad libitum consumption. From d 57 to 112, calf starter was mixed with 5% chopped grass hay. Calves were housed individually to d 56 and housed in groups (4-5 calves/pen) from d 57 to 112. Estimates of TTD were measured in 5 calves/treatment (block 1) at wk 3 of the study using acid-insoluble ash as an indigestible marker. From 0 to 56 d, calf starter intake (CSI) was greater for MOD vs. HI and 17 versus 24% fat; average daily gain was greater for HI versus MOD; and hip width change was greater for 17 versus 24% fat. Estimates of organic matter TTD were greater for HI versus MOD, but neutral detergent fiber TTD was greater for MOD versus HI and for 17 versus 24% fat. From 57 to 112 d, hip height change was greater for MOD versus HI, and hip width change was greater for 17 versus 24% fat. In this study, feeding Jersey calves more MR improved preweaning average daily gain, but had a negative effect on CSI and likely rumen development, as neutral detergent fiber TTD was reduced at 3 wk and frame growth was reduced from d 57 to 112. This resulted in similar final calf body weights between MR feeding rates at the end of the study. No benefits were observed for feeding more fat in MR as CSI or for NDF digestibility, and frame growth was reduced.

Models to predict dry feed intake in Holstein calves to 4 months of age.

Voluntary daily dry feed intake (DFI) in Holstein calves was predicted using 60,761 individual daily observations collected from 1,235 Holstein calves in 30 experiments from 4 research stations in the United States and Europe. Consumption of dry feed (calf starter and hay, kg/d or percent of body weight) was measured from 3 to 114 d of age. Linear models and 2- and 3-parameter nonlinear models were evaluated to predict DFI using age of calf, intake of milk replacer, ambient temperature, percent forage, and neutral detergent fiber concentration in ration dry matter (DM) as independent variables. The initial data set was randomly divided within study location into development (80% of all observations) and validation data sets, and initial screening was conducted using the development data set. Five nonlinear models and 3 linear models (candidate models) were identified and used in further model evaluation. Cross-validation studies (n = 20) with the validation data set were conducted by linear regression of DFI with predicted DFI as independent variable. Candidate models were subsequently evaluated with data from 12 published studies in 2 analyses. The exponential model that best predicted daily DFI in Holstein calves in original and external data sets was DFI (kg/d) = 1.3207 × e[(-5.3892 + 0.6376 × MEgap) × EXP(-0.0392 × Age)] - 0.0013 × Temp + 0.0032 × NDFDM + 0.0026 × Age × MEgap - 0.3646 × PctForage [coefficient of determination (R2) = 0.92, concordance correlation coefficient (CCC) = 0.96, and mean square error of prediction (MSEP) = 0.10 kg]; where MEgap (Mcal/d) = difference of daily metabolizable energy (ME) requirement and ME intake from milk replacer; Age = age of calf (d) from 3 to 114, Temp = mean daily ambient temperature (°C), NDFDM = ration neutral detergent fiber (% DM); PctForage = percent forage in ration DM. The linear model that best predicted DFI was DFI (kg/d = -0.1349 + 0.0106 × Age + 0.1808 × MEgap + 0.0013 × Age × MEgap + 0.0001 × Temp + 0.00002 × Age × Temp (R2 = 0.93, CCC = 0.96, and MSEP = 0.10 kg). When Temp and ration characteristics were not included, optimal models were 1.4362 × e[(-4.6646 + 0.5234 × MEgap) × EXP(-0.0361 × Age)] + 0.0025 × Age × MEgap (R2 = 0.92, CCC = 0.96, and MSEP = 0.11 kg) and -0.1344 + 0.0102 × Age + 0.1810 × MEgap + 0.0013 × Age × MEgap [R2 = 0.93, CCC = 0.96, and MSEP = 0.10 kg]. Models of daily DFI may improve prediction of nutrient supply to young Holstein calves to approximately 4 mo of age, thereby increasing prediction of growth performance.

Effect of increasing the amount of hay fed on Holstein calf performance and digestibility from 2 to 4 months of age.

A good transition from a mainly liquid diet to a solid diet of concentrates and forages is important considering the small size and development of the calf's rumen. However, the optimal amount of hay or other high-fiber ingredients in the diet of recently weaned calves is not well defined. The objective of this trial was to determine the effects of feeding 0, 5, or 10% chopped grass hay (6.5% crude protein, 64.6% neutral detergent fiber) with a textured, high-starch starter (20.5% crude protein, 38.4% starch, 14.1% neutral detergent fiber; protein pellet, whole corn, and oats) on performance and digestion in Holstein steer calves between 2 and 4 mo of age. Forty-eight calves (initial body weight = 90.7 ± 2.15 kg) were housed in group pens (4 per pen) and fed diets and water for ad libitum intake. Feed offered and refused was measured daily. Calf body weight, hip width, and body condition score (1-5 scale) were measured initially and at 28 and 56 d. Fecal samples were collected from the pen floor with care not to sample bedding material and composited by pen during d 5-9, 26-30, and 47-51 to estimate apparent total-tract digestibility using acid-insoluble ash. Data were analyzed as a completely randomized design with repeated measures and pen as the experimental unit. As grass hay increased, dry matter intake (kg/d) decreased linearly but tended to change quadratically. Dry matter intake as a % of body weight changed quadratically with increasing hay, increasing from 0 to 5%, and decreasing from 5 to 10% hay. Average daily gain (1.15, 1.12, and 0.95 kg/d), feed efficiency (0.336, 0.319, and 0.309 kg of average daily gain/kg of dry matter intake), and hip width change (4.6, 4.7, and 4.1) decreased linearly with 0, 5, and 10% hay, respectively. Overall estimates of dry matter, organic matter, neutral detergent fiber, acid detergent fiber, and crude protein digestibility changed quadratically with hay, increasing from 0 to 5%, and decreasing from 5 to 10% hay, whereas digestibility of starch, sugar, and fat decreased linearly with increasing hay. Digestibility of dry matter, organic matter, neutral detergent fiber, and acid detergent fiber increased from 2 to 3 mo of age, and decreased from 3 to 4 mo of age. Digestibility of starch decreased linearly and digestibility of fat and crude protein increased linearly with age. Digestive capacity did not appear mature by 4 mo of age. Feeding 5% chopped hay supported optimal digestion and growth in calves 2 to 4 mo of age, which agrees with previously published research.

Meta-analysis of effects of age on intestinal digestibility of liquid feeds in young calves.

A meta-analysis was conducted to determine the effect of age on digestibility of liquid feeds fed to preweaned Holstein calves. Calves were 4 to 76 d of age and fed whole milk or milk replacer containing all-milk protein. Least squares means of apparent total-tract N, DM, and fat digestibilities (n = 84, 51, and 24, respectively) from 12 publications were used. Broken line regression and mixed model ANOVA were used to determine ages at which digestion of nutrients no longer increased with age, indicating maturation of digestive capacity. Digestibility of DM, N, and fat reached maximum digestibilities of 94.1, 92.7, and 97.5% at 29, 29, and 32 d of age, respectively. These data indicate age-related changes in digestion of liquid feeds in preweaned Holstein calves and allow correction of apparent total-tract digestibility estimates in nutrient supply models. Digestibility of liquid nutrients in calves fed whole milk or all milk containing milk replacers reached maximal capacity at approximately 30 d of age.

Effects of milk replacer feeding rates on growth performance of Holstein dairy calves to 4 months of age, evaluated via a meta-analytical approach.

Our objective was to evaluate effects of feeding milk replacer (MR) at 2 feeding rates on digestion, intake, and growth of young dairy calves, via a meta-analytical approach using individual data. A database was developed from 10 published studies from the Nurture Research Center (Provimi; Brookville, OH), in which 26 dietary treatments and 491 calves from 0 to 8 wk of age in 13 nursery trials, and 22 dietary treatments and 485 calves from 8 to 16 wk of age in 13 grower trials occurred. Male Holstein calves (n = 491; initial body weight 42.8 ± 4.9 kg) were randomly assigned to 1 of 2 treatments: (1) moderate (MOD), 0.64 to 0.66 kg of dry matter (DM)/d for the first 35 to 39 d, followed by half the allotment per d for 3 to 7 d, fed at the a.m. feeding only; (2) high (HI), 0.92 to 1.07 kg of DM/d for the first 35 to 44 d, followed by half the allotment per d for 5 to 7 d, fed at the a.m. feeding only. Calves were weaned at 6 to 7 wk of age. Milk replacer ranged from 24.8 to 28.6% crude protein (CP) and 17.6 to 20.2% fat; starter ranged from 17.3 to 22.2% CP and 3.0 to 4.3% fat on a DM basis. On d 56 calves (n = 485) moved into pens (4 calves/pen) by treatments and were fed starter (19.4 to 22.3% CP and 3.4 to 4.6% fat, DM basis) blended with 5% hay until d 112. In all nursery trials (d 0 to 56), calves fed MOD had lower average daily gain (ADG; 0.634 vs. 0.545 kg/d), gain/DMI (0.488 vs. 0.466 kg/kg), and hip width change (0.069 vs. 0.064 cm/d), but greater starter intake (0.473 vs. 0.696 kg/d) compared with calves fed HI. Apparent total-tract digestibility of DM (73.3 vs. 78.4%), organic matter (OM; 74.1 vs. 79.0%), CP (74.8 vs. 78.9%), and neutral detergent fiber (NDF; 40.8 vs. 53.9%) were greater for calves fed MOD vs. HI when estimated during wk 8. In all grower trials (d 56 to 112), ADG (1.015 vs. 0.976 kg/d), gain/DMI (0.375 vs. 0.349 kg/kg), and hip width change (0.089 vs. 0.081 cm/d) were greater, but dry feed intake per kg of BW0.75 did not differ (87.8 vs. 88.2 g/d) for calves previously fed MOD vs. HI. Apparent digestibility of DM (78.7 vs. 76.0%), OM (79.8 vs. 77.0%), CP (80.5 vs. 78.4%), and NDF (54.8 vs. 45.8%) were greater for calves fed MOD vs. HI when estimated between wk 11 to 13. Over the entire 112-d period, calves fed MOD had lower ADG (0.805 vs. 0.784 kg/d) but tended to have greater hip width change (8.415 vs. 8.589 cm) compared with calves fed HI. Under the conditions of this study, feeding higher MR rates caused calves to partially lose growth advantage during the weaning transition and further decreased BW gain and structural growth in the grower period (d 56 to 112), which could be due to reductions in nutrient digestibility as a result of feeding more MR.

Effect of starter form, starch concentration, and amount of forage fed on Holstein calf growth from 2 to 4 months of age.

Young, weaned calves are commonly offered ad libitum forage with limited amounts of starter, in contrast to the suggested amount of approximately 5% forage in the diet due to the limited capacity of the rumen, as well as limited ability to digest high fiber feeds. The objective of this research was to compare 2 types of starters (low starch, pelleted vs. high starch, textured), both fed either ad libitum with 5% chopped hay, or fed at restricted rates with ad libitum long grass hay to calves between 2 and 4 mo of age. In trial 1, 48 calves were housed in group pens (68.4 ± 3.37 kg of initial body weight ± standard deviation; 3 pens of 4 calves/pen) and randomly assigned to 1 of 4 diets: (1) low starch pelleted starter (8% starch) blended with 5% chopped hay fed free choice; (2) high starch textured starter (45% starch) blended with 5% chopped hay fed free choice; (3) low starch pelleted starter (8% starch) fed at a rate up to 2.3 kg of dry matter (DM)/d, with free-choice long grass hay; or (4) high starch textured starter (45% starch) fed at a rate up to 2.3 kg of DM/d, with free-choice long grass hay. Trial 1 was analyzed as a completely randomized design using a 2 × 2 arrangement of treatments. Repeated measures were used as appropriate. Pen was the experimental unit. In trial 2, 48 calves (76.4 ± 1.55 kg of initial body weight; 6 pens of 4 calves/pen) were randomly assigned to 1 of 2 diets: (1) ad libitum access to a blend of 95% high starch textured starter (42% starch) and 5% chopped grass hay; or (2) high starch textured starter fed up to 2.7 kg of DM/d with free-choice long grass hay. Trial 2 was analyzed as for trial 1, without factorial arrangement. Trials were 56 d long. In trial 1, feed efficiency, average daily gain (ADG), and change in hip width were greater for calves fed high versus low starch diet. Final hip width, ADG, DM intake, and change in hip width were greater for calves fed limited chopped versus free-choice long hay diets. In trial 2, intake, feed efficiency, and all growth measurements were greater in calves fed the ad libitum mixed diet compared with those limit-fed starter up to 2.7 kg as fed with ad libitum hay. Ad libitum hay intake was highly variable among pens and differed up to 2.5-fold by the last week of the trials. In both trials, restricted feeding of starter with ad libitum long grass hay reduced total DM intake by 13 to 17%, ADG by 20%, and hip width change by 10 to 23% compared with a blend of 95% starter and 5% chopped grass hay fed ad libitum.

Supplementation of nicotinic acid to prepartum Holstein cows increases colostral immunoglobulin G, excretion of urinary purine derivatives, and feed efficiency in calves.

We evaluated the effects of incremental levels of unprotected nicotinic acid (NA) supplementation prepartum (0, 16, 32, or 48 g/d; CON, 16NA, 32NA, and 48NA, respectively) on colostrum yield and composition and cow and calf performance. Previous research indicated that 48 g/d of NA prepartum increased colostrum IgG concentration. Exact mechanisms for this increase are not clear. The effects of NA supplementation to prepartum cows on growth and performance of their calves have not been studied. Thirty-six multiparous Holstein cows housed in a tie-stall barn were blocked by expected calving date and randomly assigned to treatments at 4 wk prepartum. Blood samples were collected 3 times weekly for analysis of nonesterified fatty acids, ketones, and IgG. Urine samples were also collected 3 times weekly for analysis of creatinine and purine derivatives. Colostrum was collected within 90 min after parturition. Calves were removed from their dams before suckling, weighed within 30 min of birth, and received 4 L of maternal colostrum. The 38 calves born were blocked based on treatments of dams. All calves were fed 449 g dry matter (DM) of milk replacer (19.3% crude protein, 19.5% fat, DM basis) and a textured starter (41% starch, DM basis) at 2 d of age until weaning at 42 d, with water available ad libitum. Feeding NA resulted in linear decreases in DM intake in cows, but colostrum yield was not affected. Yield of metabolizable energy (ME) tended to change cubically, decreasing from control (CON) to 16NA, increasing from 16NA to 32NA, and decreasing from 32NA to 48NA. Concentration of IgG, protein, ash, and solids increased linearly with NA. Concentration of ME showed a tendency to increase quadratically with NA. Yield of IgG, fat, protein, and solids content increased quadratically with NA, while allantoin and total purine derivatives increased linearly. Calf 24-h IgG and apparent efficiency of absorption were not affected by NA. Calf ME intake from colostrum tended to increase quadratically with NA, but calf starter intake was not affected. Feed efficiency of calves increased quadratically with NA. Calf average daily gain changed cubically with NA, decreasing from CON to 16NA, increasing from 16NA to 32NA, and decreasing from 32NA to 48NA. Hip width gain, body length gain, and final body length changed cubically with NA, decreasing from CON to 16NA, increasing from 16NA to 32NA, and decreasing from 32NA to 48NA. Calf blood concentrations of ketones increased quadratically with NA. These data suggest that increasing levels of NA can be fed prepartum to increase colostral components and 32 g/d NA can improve calf performance.

Supplementation of sodium butyrate to postweaned heifer diets: Effects on growth performance, nutrient digestibility, and health.

The objective of this study was to determine the effect of varying levels of sodium butyrate (SB) supplementation in feed on the growth, digestibility, and health of postweaned heifers. Forty Holstein dairy heifers with a mean age of 84 d and average body weight (BW) of 100.9 ± 11.2 kg were housed in a naturally ventilated freestall barn. Heifers were blocked by birth date and randomly assigned to 1 of 4 treatments in a completely randomized block design: (1) 100 g of soybean meal carrier (control), (2) 0.25 g of SB/kg of BW plus carrier, (3) 0.50 g of SB/kg of BW plus carrier, and (4) 0.75 g of SB/kg of BW plus carrier. Carrier with or without SB was top-dressed and hand-mixed into a total mixed ration once daily. Heifers were fed to provide 10% orts. Initial BW, hip and withers heights, heart girth, and body length were measured before the start of the study and every week thereafter until the 14-wk trial was over. Blood samples were obtained and plasma urea nitrogen, plasma glucose, and whole-blood ß-hydroxybutyrate concentrations were determined before the start of treatment and weekly thereafter until the conclusion of the study. Fecal samples were taken before treatment and every other week from each heifer for coccidia counts. Apparent total-tract nutrient digestibility was determined using acid detergent insoluble ash as an internal marker. Each heifer underwent this phase from d 47 until d 54 of the study. Sodium butyrate had a positive effect on average BW and overall BW gain. Feed efficiency tended to improve as SB supplementation increased. Coccidia counts were lowest in the treatment with 0.25 g of SB/kg of BW plus carrier. Sodium butyrate had no effects on skeletal growth or plasma urea nitrogen concentration. Blood glucose concentration decreased linearly and ß-hydroxybutyrate increased linearly with increasing levels of SB supplementation. Sodium butyrate supplementation did not affect apparent total-tract nutrient digestibility. Sodium butyrate supplementation offers positive results in the growth performance and feed efficiency of postweaned heifers.

The impact of direct-fed microbials and enzymes on the health and performance of dairy cows with emphasis on colostrum quality and serum immunoglobulin concentrations in calves.

Thirty-six cows were blocked by calving date and randomly assigned to one of three treatments. Cows were on treatments 3 weeks prepartum through 8 weeks post-partum. Treatments were as follows: (i) no direct-fed microbial (DFM) or cellulase and amylase enzymes (C), (ii) 45.4 g/day of DFM (D) or (iii) 45.4 g/day of DFM and 18.2 g/day of enzyme (DE). Total mixed ration fed and refused were measured daily to determine dry matter intake (DMI). Blood samples were taken three times weekly and analysed for ß-hydroxybutyrate, glucose and non-esterified fatty acids. Body weight (BW) was measured weekly. Colostrum was weighed and analysed for IgA and IgG concentration. Calves were fed 4 L of colostrum within 2 hr of birth. Calf blood samples were taken at 0 and 24 hr for analysis of IgA and IgG concentrations and apparent efficiency of absorption. Milk yield was measured daily and samples collected weekly. Initial BW was different among treatments with D being lesser than C or DE treatments. Body weight, weight gain, efficiency of gain, DMI and blood parameters were unaffected. Treatment did not affect colostrum yield. Ash percentage of colostrum tended to increase with D and DE, while IgA and total solids yield decreased with D. Colostrum fat yield was decreased in D and DE. Treatments did not impact BW, serum IgA and IgG concentrations or apparent efficiency of absorption of calves. Post-partum BW, DMI, blood parameters, milk production and composition were unaffected by treatment. However, cows on D gained more BW and tended to have greater efficiency of gain compared to those on DE, but were similar to C. Somatic cell scores were greatest for D. Results indicate that DFM and enzyme supplementation did not improve health and performance of dairy cattle during the pre- and post-partum periods under conditions of this study.

Production and nitrogen utilization in lactating dairy cows fed ground field peas with or without ruminally protected lysine and methionine.

Previous research has shown that cows fed ≥24% of the diet dry matter (DM) as field peas decreased milk yield as well as concentration and yield of milk protein, possibly due to reduced DM intake and limited supply of Lys and Met. Twelve multiparous and 4 primiparous lactating Holstein cows were randomly assigned to 1 of 4 diets in a replicated 4 × 4 Latin square design. The diets contained (DM basis) 34.8% corn silage, 15.2% grass-legume silage, 5.9% roasted soybean, 2.4% mineral-vitamin premix, 2.0% alfalfa pellets, and either (1) 36% ground corn, 2.4% soybean meal, and 1.3% urea (UR), (2) 29.7% ground corn, 9.8% soybean meal, 0.13% ruminally protected (RP) Lys, and 0.07% RP-Met (CSBAA), (3) 25% ground field peas, 12.3% ground corn, and 2.4% soybean meal (FP), or (4) FP supplemented with 0.15% RP-Lys and 0.05% RP-Met (FPAA). Our objective was to test the effects of FP versus UR, FPAA versus CSBAA, and FPAA versus FP on milk yield and composition, N utilization, nutrient digestibility, ruminal fermentation profile, and plasma concentration of AA. Milk yield did not differ across diets. Compared with cows fed UR, those fed FP had greater DM intake, concentration and yield of milk true protein, apparent total-tract digestibility of fiber, urinary excretion of purine derivatives, and concentrations of total volatile fatty acids in the rumen and Lys in plasma, and less milk urea N and ruminal NH3-N. The concentration of milk urea N, as well as the concentration and yield of milk fat increased in cows fed FPAA versus CSBAA. Moreover, cows fed FPAA had greater ruminal concentration of total volatile fatty acids, increased proportions of acetate and isobutyrate, and decreased proportions of propionate and valerate than those fed CSBAA. The plasma concentrations of His, Leu, and Phe decreased, whereas plasma Met increased and plasma Lys tended to increase in cows fed FPAA versus CSBAA. Concentration of milk true protein, but not yield, was increased in cows fed FPAA versus FP. However, cows fed FPAA showed decreased concentrations of His and Leu in plasma compared with those fed FP. Overall, compared with the CSBAA diet, feeding FPAA did not negatively affect milk yield and milk protein synthesis. Furthermore, RP-Lys and RP-Met supplementation of the FP diet did not improve milk yield or milk protein synthesis, but decreased urinary urea N excretion.

Predicting colostrum quality from performance in the previous lactation and environmental changes.

Nine New Hampshire Holstein dairies contributed to a study to investigate if colostrum quality could be predicted by cow performance in the previous lactation and by environmental factors during the 21-d prepartum period. The numbers of days below 5°C (D<), days above 23°C (D>), and days between 5 and 23°C (D) were used in the development of the regression equation. Between 2011 and 2014, 111 colostrum samples were obtained and analyzed for IgG. Producers recorded cow identification number, calf date of birth, sex of the calf, colostrum yield, hours from parturition to colostrum harvest, and weeks on pasture during the dry period (if any). Dairy Herd Improvement data from each cow and weather data were compiled for analysis. Information accessed was predicted transmitting abilities for milk, fat (PTAF), protein (PTAP), and dollars; previous lactation: milk yield, fat yield, fat percent, protein percent, protein yield, somatic cell score, days open, days dry, days in milk, and previous parity (PAR). Colostrum yield was negatively correlated with IgG concentration (r=-0.42) and D (r=-0.2). It was positively correlated with D> (r=0.30), predicted transmitting ability for milk (r=0.26), PTAF (r=0.21), and PTAP (r=0.22). Immunoglobulin G concentration (g/L) was positively correlated with days in milk (r=0.21), milk yield (r=0.30), fat yield (r=0.34), protein yield (r=0.26), days open (r=0.21), PAR (r=0.22), and tended to be positively correlated with DD (r=0.17). Immunoglobulin G concentration (g/L) was negatively correlated with D> (r=-0.24) and PTAF (r=-0.21) and tended to be negatively correlated with PTAP (r=-0.18). To determine the best fit, values >0 were transformed to natural logarithm. All nontransformed variables were also used to develop the model. A variance inflation factor analysis was conducted, followed by a backward elimination procedure. The resulting regression model indicated that changes in Ln fat yield (ß=2.29), Ln fat percent (ß=2.15), Ln protein yield (ß=-2.25), and Ln protein percent (ß=2.1) had largest effect on LnIgG. This model was validated using 27 colostrum samples from 9 different farms not used in the model. The difference between means for actual and predicted colostrum quality (IgG, g/L) was 13.6g/L. Previous lactation DHI data and weather data can be used to predict the IgG concentration of colostrum.

Short communication: Cinnamaldehyde taste preferences of weaned dairy heifers.

Within a dairy enterprise, one major cost is raising young calves. Optimizing the feeding programs of dairy calves is imperative for the sustainability and profitability of dairy operations. Essential oils appear to be natural alternatives to antibiotics and function similarly to ionophores. Supplemental antibiotic ionophores have been very successful in improving feed efficiency and rate of gain in calves, as well as decreasing disease incidences; however, calves may be developing resistance to ionophores and the use of antibiotics in animal feeds has been a major concern for consumers. No current research has examined the value or palatability of supplementing essential oils to dairy heifers. The purpose of this sequential elimination experiment was to evaluate the taste preferences of 6 weaned dairy heifers [approximately 3mo old; 95±10.8kg of body weight (BW)] provided with 0 (control), 1, 2, 3, or 4mg/kg of BW of cinnamaldehyde daily. Heifers had 2 d of adaptation to the new feeding regimen before the experiment started and were then offered the 5 experimental diets for 5 d. The most preferred diet was removed and the study continued with the 4 remaining diets. The most preferred diets were again eliminated sequentially, so that only 2 diets remained on d 13 and 14. Each diet was ranked based on the weight of feed refused at the end of each feeding segment. Overall ranking of the 5 treatments were control, 2, 1, 3, and 4mg/kg of BW of cinnamaldehyde. Results indicated that heifers preferred diets without cinnamaldehyde; however, when only cinnamaldehyde diets remained, dry matter intake was not negatively affected regardless of the concentration of cinnamaldehyde provided.

Prepartum supplementation of nicotinic acid: Effects on health of the dam, colostrum quality, and acquisition of immunity in the calf.

Nicotinic acid (NA) has been shown to reduce lipolysis, alter milk components and the ruminal environment, and increase blood flow. Increased blood flow to the mammary gland during colostrogenesis might increase nutrients and immunoglobulin concentration of colostrum. Twenty-six multiparous Holstein cows were housed in a tiestall barn. Cows were blocked by expected calving date and randomly assigned to 1 of 2 treatments 4 wk prepartum: (1) 0g/d of NA (control, CON) or (2) 48g/d of NA (NA). Total mixed ration amounts fed and refused were measured daily to determine dry matter intake. Blood samples were collected from dams every Monday, Wednesday, and Friday from the coccygeal vein or artery and were analyzed for glucose, nonesterified fatty acids (NEFA), and ß-hydroxybutyrate (BHB). Colostrum was collected and weighed within 90 min of parturition. Colostral immunoglobulin G (IgG) concentration was analyzed using radial immunodiffusion assay. Calves were removed from their dams before suckling and weighed within 30 min after birth. Calves received 3 L of a lacteal-based colostrum replacer that provided a total of 225.8g of IgG within 2h of birth. Calf blood samples were collected via jugular venipuncture at 0 and 24h of age and analyzed for IgG concentration and determination of apparent efficiency of absorption. Colostrum yield, dry matter intake, IgG yield, and fat and solids percentage of colostrum did not differ between treatments. Serum concentrations of glucose and BHB were not affected by treatment. We detected an effect of week on serum glucose concentrations at calving and on serum BHB concentrations at 1 wk postpartum. There was a treatment by week effect for serum NEFA concentrations at 1 wk postpartum, where cows that received NA prepartum had higher serum NEFA concentration than CON cows, indicating that a NEFA rebound occurred. No differences were observed for calf body weight, 0- or 24-h serum IgG concentration, or apparent efficiency of absorption. Supplementation of NA increased IgG concentration in colostrum from 73.8 to 86.8g/L. Results indicate that 48g/d of supplemental NA during the prepartum period improved colostrum quality.

Effects of lasalocid and intermittent feeding of chlortetracycline on the growth of prepubertal dairy heifers.

Forty Holstein heifers entered the 12-wk study at approximately 12 wk of age. At enrollment, heifers were blocked by birth date and assigned to 1 of 4 treatments: (1) carrier (30 g; control); (2) lasalocid + carrier (1 mg/kg of body weight; L); (3) chlortetracycline + carrier (22 mg/kg of body weight; CTC); (4) L + CTC + carrier (CTCL). Heifers on CTC and CTCL were provided treatment Monday through Friday and carrier only on Saturday and Sunday. These heifers were provided their respective treatment during wk 1 to 4, 6, and 10; wk 5, 7 to 9, and 11 to 12 heifers were provided the nonmedicated carrier. Heifers were individually fed a total mixed ration with treatments top-dressed at 1200 h daily. Dry matter intake was monitored for each heifer and feed provided was adjusted according to individual intakes. Skeletal measurements were taken weekly and blood samples were obtained every Monday, Wednesday, and Friday. Blood samples were analyzed for thyroxine concentration via radial immunoassay. Heifers supplemented with L had lower average daily gain , overall body weight gain, and trends for lower daily body length gain and overall girth gain compared with CTC heifers, but similar to control and CTCL heifers. Heifers fed L had lower hip height gain and overall hip height gain compared with CTCL heifers, but similar to control and CTC heifers. Heifers fed L had lower overall withers height gain compared with control heifers, but similar to CTC and CTCL heifers. No treatment effect on thyroxine concentrations was observed. These data indicate that L did not increase growth. Results from this experiment indicate that supplementing heifers with L was not beneficial and no benefits to supplementing heifers with CTC or the combination of CTC and L were evident compared with control heifers. Heifers in this study experienced minimal health problems and were regarded to be under low stress levels. Supplementing CTC and L may be beneficial to growing heifers under conditions where disease exposure and stressors are greater.