Effects of egg yolk inclusion,milk replacer feeding rate,and low-starch (pelleted) or high-starch (texturized) starter on Holstein calf performance through 4 months of age

The objectives of this research were to evaluate milk replacer (MR) feeding rates, alternative protein and fat sources in MR, and calf starter starch concentration and their effects on calf performance to 4 mo of age. Male Holstein calves (42.6 ± 1.2 kg of body weight; n = 192) were assigned at 3 d of age to 1 of 8 treatments in a randomized complete block design with a 2 × 2 × 2 factorial arrangement of treatments. Factors tested from d 0 to 56 (nursery) were low or high MR feeding rates, 0 or 10% inclusion of spray-dried egg yolks in MR, and low- or high-starch calf starter. The low MR rate was 0.66 kg of dry matter (DM) fed for 39 d followed by 0.33 kg of DM for 3 d. The high MR rate was 0.87 kg of DM fed for 5 d, 1.08 kg of DM for 37 d, and 0.43 kg of DM for 7 d. The MR contained 27.5% crude protein and 19.6% fat (DM basis) and starters were 21.2% crude protein; low starch was a complete pellet with 10.2% starch, and high starch was textured using whole corn and oats with 43.3% starch. From d 56 to 112 (grower), calves were randomly assigned to pens (4 calves/pen) maintaining MR rate and starch content while stratifying yolk treatments within pen, resulting in a 2 × 2 factorial arrangement. Starter was blended with 5% chopped hay during the grower trial. Fecal scores and medical treatments were recorded daily. In the nursery trial, calves were weighed initially and weekly thereafter. Hip width and body condition score (BCS) were measured initially and every 2 wk thereafter. In the grower trial, body weight, hip width, and BCS were measured on d 56, 84, and 112. Data were analyzed as repeated measures with calf (nursery) or pen (grower) as the experimental unit. Calf average daily gain, hip width, and BCS change were greater for calves fed high versus low MR, 0 versus 10% yolk, and high versus low starch in the nursery. In the grower trial, calves fed low MR and high starch had the greatest average daily gain (1.09 vs. 0.87 kg/d) and hip width change (5.4 vs. 3.9 cm) compared with calves fed low MR and low starch with other treatments intermediate. From 0 to 112 d, calves fed high MR had 9% greater body weight gain and 4% greater hip width change than calves fed low MR, yet nutrient efficiency was similar despite 80% more MR intake than calves fed low MR. Additionally, calves fed high-starch starter achieved 18% greater body weight gain and 17% greater hip width than calves fed low starch starter overall, a more than 2-fold greater response than the effect of MR feeding rate.     

Effects of corn processing, particle size, and diet form on performance of calves in bedded pens

In a series of 5 trials, Holstein calves from zero to 12 wk old were housed in pens bedded with straw and fed diets to evaluate physical form of starters containing different processed corn on calf performance. Starters were formulated to have similar ingredient and nutrient compositions. Calves, initially less than 1 wk old, were housed in individual pens through 8 wk and weaned at 6 wk in trial 1 and at 4 wk in trials 2 and 3. In trials 4 and 5, calves initially 8 wk old were housed in group pens (6 calves/pen) from 8 to 12 wk. Trial 1 compared feeding calves a pelleted versus textured starter. Trial 2 compared feeding calves a textured starter versus feeding half meal starter with half textured starter. Trial 3 compared feeding calves textured starters containing whole, steam-flaked, or dry rolled corn. Trial 4 compared feeding calves textured starters containing steam-flaked versus dry rolled corn. Trial 5 compared feeding calves textured starters containing whole or dry rolled corn. Measurements included average daily gain (ADG), starter intake, feed efficiency, hip width change, body condition score change, fecal scores, and medical treatments. Physical form of starter feed did not affect any measurements in trials 1, 3, 4, and 5. In trial 2, calves fed starters manufactured with large amounts of fines had 11% less feed intake and 6% slower ADG than calves fed a textured starter. When starters contained similar ingredient and nutrient contents, manufacturing processes did not affect calf performance unless the diet contained a significant amount of fines, which reduced intake and ADG.     

Effects of including corn distillers dried grains with solubles in dairy calf feeds

A series of 5 trials was conducted to determine the effect of distillers dried grains with solubles (DG) in calf diets. Trial 1 compared 0 or 49% DG in 18% crude protein (CP) starters (as-fed basis) fed to calves initially 2 to 3 d old for 56 d. Digestibility was estimated during d 52 to 56 using chromic oxide. Trial 2 compared 0 or 39% DG in 16% CP growers fed to calves from 8 to 12 wk of age from 28 d. Trial 3 compared 0, 10, or 20% DG in 18% CP starters fed to calves initially 2 to 3 d old for 56 d. Trial 4 compared 0 or 20% DG in 16% CP growers fed to calves from 8 to 12 wk of age from 28 d. As DG increased in all diets, acid detergent fiber, neutral detergent fiber, and fat increased and calculated metabolizable energy was similar but not equalized. In trials 1 and 3, calves (n = 48/trial) housed in individual pens were fed 26% CP, 17% fat milk replacer powder and weaned at 28 d. Trials 2 and 4 used calves (n = 48/trial) housed in group pens (6 calves/pen) that had been weaned for 28 d before the trials’ start. Trial 5 (n = 18 calves) had the same starter treatments as trial 3 fed in combination with high or low milk replacer intake, with calves killed at 35 d to determine effects of DG and milk replacer intake on rumen development. In trial 1, average daily gain (ADG) was 6% greater and dry matter digestibility was 10% greater for calves fed 0% versus 49% DG. In trial 2, ADG (9%), feed efficiency (10%), and hip width change (19%) were greater for calves fed 0% versus 39% DG. Performance measures did not differ among starter treatments in Trials 3 and 5. In trial 4, ADG (4%), feed efficiency (5%), and hip width change (19%) were greater for calves fed 0% versus 20% DG. In trial 5, rumen development was not affected by DG inclusion, but was greater for calves fed milk replacer at 630 versus 940 g/d, which had greater starter intake. Overall, we conclude that high levels of distillers in calf starters and growers decrease growth of calves; however, starters with ≤20% DG allow for normal growth rates and rumen development.     

Effects of fatty acids and calf starter form on intake,growth, digestion,and selected blood metabolites in male calves from 0 to 4 months of age

The objective of this research was to determine if form of calf starter (CS) and addition of a fatty acid blend (FA) influenced intake, growth, digestion, and indices of immune status and stress in calves from 0 to 4 mo of age. Male Holstein calves [n = 48; 41.9 kg of body weight (BW), standard error = 0.7; 2 to 3 d of age] were assigned to receive reconstituted whole milk powder [0.66 kg of dry matter (DM)/d to 39 d, then 0.33 kg of DM/d to weaning at 42 d] without or with added FA. Calf starters were textured (pellet, whole oats, whole corn) or pelleted and were offered for ad libitum consumption from 0 to 56 d, then blended with 5% chopped grass hay and fed from d 57 to 112. Starters contained 20% crude protein (CP) and 38 to 40% starch in the DM. From d 0 to 56, calves were housed individually. From d 57 to 112, calves were grouped into pens by treatment (n = 4/pen). Form of CS during the initial 56 d had no effect on intake or growth, though days with fluid feces (fecal score ≥2.5) were greater when calves were fed textured CS. Feeding FA during the initial 56-d increased average daily BW gain, gain-to-feed ratio, and change in hip width, and reduced the number of days calves were treated with antibiotics. During d 57 to 112, CS form had no effects on any performance measure. Adding FA to CS increased average daily BW gain and hip width change, and tended to improve efficiency of BW gain. Total-tract digestibility was estimated at 4, 6, and 8 wk with 5 calves per treatment, and at 10, 13, and 16 wk of age using pen (n = 3 per treatment) as the experimental unit. Feeding FA increased or tended to increase total-tract digestion of DM, organic matter, starch, neutral detergent fiber (NDF), acid detergent fiber (ADF), CP, and fat at one or more measurement periods. Calves fed a textured CS increased or tended to increase digestion of DM, organic matter, starch, sugar, NDF, ADF, and CP during wk 6 and 8. However, during the second 56-d phase, feeding textured CS reduced or tended to reduce digestion of DM, organic matter, starch, NDF, ADF, and fat during wk 13 and 16. Inclusion of FA in milk increased serum bactericidal activity before weaning. Serum haptoglobin concentration increased 3 d postweaning when calves were fed textured CS. Feeding FA improved animal health, digestion, and performance. Form of CS had few effects on animal performance.     

Intake,nutrient digestibility,and growth performance of Holstein dairy calves consuming a milk replacer at moderate or high feeding rates

The objective of this study was to evaluate nutrient intake and digestibility, and growth performance of calves when fed a milk replacer (MR) at 2 feeding rates. Male Holstein calves [n = 49; 45.0 ± 5.2 (mean ± SD) kg of body weight (BW); 3 to 4 d of age] were randomly assigned to 1 of 2 MR [27% crude protein (CP), 18% fat, dry matter (DM) basis; 14% solid] feeding programs: (1) 0.66 kg of DM/d for first 39 d divided into 2 equal a.m. and p.m. meals followed by one-half of the allotment per day for 3 d fed in the a.m. feeding only (moderate); (2) 0.96 kg of DM/d for the first 42 d divided into 2 equal a.m. and p.m. meals followed by one-half of the allotment per day for 7 d fed in the a.m. feeding only (high). A textured starter fed to calves contained whole grains with 20% CP and 44% starch (DM basis). At d 56, calves were moved into groups by treatment (4 calves/pen) and fed the same starter blended with 5% hay until d 112. Data were analyzed as a completely randomized design, or as a completely randomized design with repeated measures when applicable. Over the entire nursery period (d 0–56), there were no differences in average daily gain (0.63 vs. 0.64 kg/d) and hip width change (4.44 vs. 4.57 cm) for moderate- versus high-fed calves. Apparent digestibility of DM (76.5 vs. 70.3%), organic matter (77.4 vs. 71.2%), CP (78.8 vs. 72.6%), and neutral detergent fiber (37.2 vs. 22.7%) differed between moderate- and high-fed calves when estimated at d 51 to 55. From d 56 to 112, average daily gain (0.99 vs. 0.91 kg/d), hip width change (5.32 vs. 4.68 cm), and gain/DM intake (0.335 vs. 0.307 kg/kg) were greater, but DM intake per kg of BW (0.028 vs. 0.028 kg/kg) did not differ for calves previously fed moderate versus high. Feeding calves more than 0.66 kg of DM/d from a 27% CP, 18% fat MR did not improve BW gain and structural growth in the nursery period (d 0–56), and decreased these in the grower period (d 56–112) partially through reduction in digestibility of the starter.     

Short- and long-term effects of initial serum total protein,average starter feed intake during the last week of the preweaning period,and rearing body gain on primiparous dairy heifers' performance

The aim of this study was to evaluate the short- and long-term effects of initial serum total protein (STP) concentration, average starter feed intake (SI) during the last week of the preweaning period, and average daily gain (ADG) on the growth, fertility, and performance of Holstein heifers during their first lactation. Eighty-four female Holstein dairy calves were weaned at d 56 of age and then the study continued until the end of the first lactation. Growth performance, including body weight, ADG, withers height, and its change were analyzed monthly from 3 to 450 d of life, and reproduction data and performance in the first lactation of primiparous dairy heifers over a 4-yr period (2015 to 2019) were recorded. In the first 24 h of life, calves received 4 L of colostrum (<2 h and <12 h after birth); on d 2 and 3: 2 feedings/d of 2 L of transition milk; from d 4 to 49: 6 L/d of milk replacer (150 g of powder/L as-fed) in 3 feedings; and from d 50 to 56: 2 L/d of milk replacer in 1 feeding. The calves were fed pelleted starter feed from d 4 to 56, and after that from 8 wk until 3 mo of age, a dry total mixed ration with an 85:15 ratio of weaning pelleted starter to straw. From 3 to 7 mo and from 8 mo of age to calving, the total mixed ration contained 16.9% and ~14.0% crude protein, respectively, on a dry matter basis and ~2.40 Mcal of metabolizable energy/kg on a dry matter basis. The results of the current study showed that the initial STP concentration of primiparous dairy heifers was associated with improved growth performance, especially greater body weight and withers height. In addition, with increasing levels of initial STP concentration, age at first estrus, artificial insemination (AI) service, pregnancy, and calving was decreased by 16, 18, 25, and 25 d, respectively. Initial STP concentration was positively correlated with milk production and increased total milk yield and yield of energy-corrected milk by about 1,558 kg and 1,149 kg during first lactation. Calves with higher average starter feed intake during the last week of the preweaning period had better growth performance, which in turn was positively associated with fertility parameters, accelerated first estrus (by 17 d), and reduced age at AI service (by 13 d). Preweaning ADG was favorably associated with fertility performance of heifers, with faster occurrence of first estrus and a reduction in age at AI service, pregnancy, and calving. Also, increasing preweaning ADG increased milk yield, energy-corrected milk, and 4% fat-corrected milk at 305 DIM by about 829, 754, and 763 kg at first lactation of primiparous heifers. These results indicate that in the rearing period, particular attention should be paid to the initial STP concentration, average SI during the last week of this period, and rearing ADG to increase growth, fertility, and performance in the first lactation of primiparous dairy heifers.     

Replacing soybean hulls with grass hay on growth,intake, total tract digestibility,and rumen microbial nitrogen production of weaned Holstein dairy calves from 8 to 16 weeks of age

The objective of this experiment was to determine the effects of replacing soybean hull (SBH) pellets with grass hay (GH) on growth, intake, total-tract digestibility, and rumen microbial nitrogen production of weaned dairy calves from 8 to 16 wk of age. Holstein calves (n = 16) were randomly assigned to 1 of 4 rations containing, on a dry matter (DM) basis, 76% grower with the remaining 24% being made up of different amounts of SBH pellets and GH [0% GH, 24% SBH (0GH); 8% GH, 16% SBH (8GH); 16% GH, 8% SBH (16GH); and 24% GH, 0% SBH (24GH)]. Calves were weaned at 6 wk, housed individually, and studied from 8 to 16 wk of age. From 8 to 9 wk of age calves were offered a ration consisting of 50% of texturized starter (20% CP and 35% starch), which was offered from 3 d of age, and 50% of their assigned ration. From 9 wk until the end of the study, calves were offered 100% of their assigned ration. Intake and body weight were measured weekly, and frame measurements were taken at the beginning and end of the study. Animal behavior observations were recorded every 5 min over a 24-h period at 10 and 14 wk of age. Total fecal and urine collection was conducted for 4 d consecutively at 11 and 15 wk of age. Feed and feces were evaluated for DM, N, neutral detergent fiber, acid detergent fiber, and starch to determine total-tract digestibility. Feces were evaluated for geometric mean particle length (X_gm) and particle size distribution. Urine was evaluated for N, creatinine, urea, and total purine derivatives to estimate microbial N yield. Calves offered 0GH and 8GH had a 20% increase in intake, average daily gain (1.23, 1.27, 0.89, and 0.71 kg/d for 0GH, 8GH, 16GH, and 24GH, respectively), and feed efficiency compared with 16GH and 24GH. Calves offered 8GH had the greatest levels of neutral detergent fiber and acid detergent fiber digestibility, as well as the greatest estimated microbial N yields. Inclusion of forage increased rumination time (2.75, 6.89, 7.18, and 8.16 h/d for 0GH, 8GH, 16GH, and 24GH, respectively) and decreased fecal X_gm by ~35% compared with calves offered 0GH. In the current study, increasing the replacement of SBH with GH beyond 8% was detrimental to weaned calf performance. These results indicate that when diets containing 8% GH and 16% SBH were fed to recently weaned calves, rumen functionality and feed efficiency were optimized compared with the other GH-SBH combinations     

Ruminal in situ disappearance and whole-tract digestion of starter feeds in calves before,during, and after weaning

Ten bull calves (n = 5/diet) were cannulated at 3 wk of age and used in a 2 × 2 factorial design with repeated measures over time to compare rumen and whole-tract degradability of 2 calf starter diets and to describe an in situ technique for estimating ruminal degradability of diets in calves at different ages. Calves received milk replacer and 1 of 2 starter diets through wk 7. Mean birth weight was 38.7 ± 1.3 kg. Weaning occurred in wk 8, and calves received only starter (up to 4,500 g/d) through wk 15. Starter diets were a complete pellet (PEL; 42% starch, 13% neutral detergent fiber, NDF) or texturized feed (TEX; 31% starch, 22% NDF). Portions of each diet were dried and ground through a 2-mm screen, and 1.25 g was inserted into concentrate in situ bags (5 cm × 10 cm, 50-µm porosity). Each calf received duplicate bags of each diet for a total of 8 bags/calf (2 diets × 2 time points). All bags were inserted at the time of starter feeding. Half of the bags were removed at 9 h, and the other half were removed at 24 h. After removal from the rumen, bags were rinsed, dried (55°C), and composited by diet and by calf within week for NDF, nitrogen (N), and starch analyses. This process was repeated over 3 d during wk 5, 7, 9, 11, 13, and 15. Daily starter intake and total fecal excretion were recorded during the same 3-d periods. Diets, refusals, and feces were subsampled, dried, ground, composited by calf by week, and analyzed for NDF, N, and starch content. Apparent digestibility coefficients, total intake, and fecal excretion were calculated and analyzed with a mixed models procedure. Intake and fecal excretion of all measured nutrients increased from wk 5 through wk 15 of age and were greater for calves fed TEX, whereas the proportion of dry matter (DM), N, and starch apparently digested through the total tract decreased from wk 5 to 15 and was greater in calves fed PEL. Ruminal disappearance of DM, N, and starch after 9-h incubations increased linearly with age. Likewise, DM, NDF, and N disappearance after 24-h incubations also increased. Ruminal disappearance of DM and NDF was greater for PEL than for TEX. Ruminal disappearance was estimable for DM, NDF, N, and starch. In addition, changes over time and changes due to rumen environment were clearly demonstrated. Based on these data, there is potential to design specific rations and feed processing methods for calves based on their ability to utilize nutrients.     

Effects of starter protein content and alkali processing of wheat straw on growth,ruminal fermentation,and behavior in Holstein calves

The present study was conducted to investigate the effects of crude protein (CP) content of starter feed and wheat straw (WS) processing on growth performance, digestibility, ruminal fermentation, and behavior of Holstein calves. Sixty calves (28 male and 32 female) were randomly assigned to 1 of 4 treatments in a randomized complete block design. Treatments in a 2 × 2 factorial arrangement were (1) lower-CP ground starter feed mixed with alkali-processed WS (LP-PWS), (2) lower-CP ground starter feed mixed with unprocessed WS (LP-WS), (3) higher-CP ground starter feed mixed with alkali-processed WS (HP-PWS), and (4) higher-CP ground starter feed mixed with unprocessed WS (HP-WS). Wheat straw was fed at 4.75% of dry matter (DM), and low-protein (LP) and high-protein (HP) starter feed contained 19.5 and 23.5% CP, respectively. The calves were weaned on d 60 and remained in the study until d 75. During the experiment, the calves received 4.2 kg of whole milk per day and had free access to fresh water and starter feed. The interaction between WS processing and protein content of starter tended to be significant for starter feed intake, average daily gain (ADG), and body weight (BW); calves fed HP-PWS tended to have greater ADG and final BW than other treatments. The results showed that feeding HP ground starter feed increased ADG and feed efficiency compared with LP groups during the preweaning and the overall periods. Moreover, weaning and final BW were higher in HP-fed calves than in LP-fed calves. Apparent digestibilities of acid detergent fiber (ADF), starch, and CP were greater in calves fed HP than in calves fed LP starter feed. The HP ground starter feed increased rumen propionate and ammonia concentrations. Wheat straw processing had no effect on intake and growth of calves but increased DM, ADF, and neutral detergent fiber digestibilities and decreased ruminal pH. Using processed wheat straw (PWS) mixed with starter feed tended to decrease rumination time and ruminal acetate concentration in calves. Final body barrel and withers height tended to be greater in calves fed PWS. Overall, the results indicated that HP content of ground starter feed (23.5%) could be recommended for Holstein calves. Furthermore, PWS inclusion in the ground starter diet increased fiber digestibility but had no effect on calf performance. Moreover, calves fed HP-PWS had greater ADG and final BW than other treatments.     

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 supplemental yeast (Saccharomyces cerevisiae) culture on rumen development, growth characteristics, and blood parameters in neonatal dairy calves

Yeast (Saccharomyces cerevisiae) culture was added to a texturized calf starter at 0 (control), 1, or 2% of dry matter to determine effects on intake, growth, blood parameters, and rumen development. Seventy-five Holstein calves (38 male; 37 female) were started on the experiment at 2 +/- 1 d of age and were studied for 42 d. Starter intake was measured, and fecal scoring was conducted daily. Growth and blood parameter measurements were recorded at weekly intervals. A subset of 6 male calves (2 per treatment) was euthanized at 5 wk of age, and rumen tissue was sampled for rumen epithelial growth measurements. An additional 6 male calves were euthanized at 6 wk of age for rumen epithelial growth measurements. Inclusion of yeast culture at 2% of the starter ration significantly increased starter and total dry matter intake, average daily gain, and daily hip width change when compared with the control treatment. Average daily gain was improved by 15.6% for the 2% yeast treatment. Daily change in hip height was also significantly greater for calves receiving 2% supplemental yeast culture than for calves receiving 1%. No significant treatment differences were observed for any other variables. These data suggest that the addition of yeast culture in a dairy calf starter at 2% enhances dry matter intake and growth and slightly improves rumen development in dairy calves.     

Effects of colostrum and milk replacer feeding rates on intake,growth, and digestibility in calves

Newborn Holstein male calves (n = 50) born on a single dairy farm were assigned randomly at birth to receive 3 feedings of 1.8 L of pooled maternal colostrum (MC) at 1, 6, and 12 h of age or 1 feeding of 500 g of a colostrum replacer reconstituted to 1.8 L at 1 h of age, followed by 2 feedings of 227 g of a commercial milk replacer (MR) reconstituted to 1.8 L at 6 and 12 h of age (CR). All feedings were administered by esophageal feeder. At 2 to 3 d of age, calves were transported to the experimental facility and assigned within colostrum group to receive 0.66 kg/d dry matter (DM) of MR to 39 d, and then 0.33 kg/d to 42 d (MRM) or 0.77 kg/d of MR DM to d 13, 1.03 kg/d for 22 d, and 0.51 kg/d for 7 d (MRH). The MR contained 25.8% crude protein and 17.6% crude fat (DM basis) and was based on whey proteins and lard as the primary fat source. Calf starter (21.7% crude protein, 15.7% neutral detergent fiber, 37.4% starch, DM basis) and water were available for ad libitum consumption throughout the 56-d study. Serum IgG and total protein were measured at 2 to 3 d of age. Intakes of MR and calf starter were monitored daily. Calf health and fecal scores were also monitored daily. Body weight was measured weekly, and hip width and body condition score were monitored every 2 wk. Digestion of DM, organic matter, crude protein, and ether extract were determined at 1 and 3 wk from 5 calves randomly selected within treatment and using chromic oxide as a digestibility marker added to the MR. Calves fed CR had lower serum IgG and total protein than calves fed MC. Also, calves fed CR grew more slowly, consumed less calf starter, and were less efficient to 56 d than calves fed MC. The number of days calves were treated with veterinary medications was higher when calves were fed CR. Calves fed MC-MRH gained more BW than other calves from 3 to 8 wk of age. Calves fed CR-MRH consumed less calf starter than other calves during wk 7 and 8. Digestion of nutrients at 1 and 3 wk of the study was unaffected by type of colostrum or level of MR fed and did not change from 1 to 3 wk. Over the first 2 mo of life, the calves fed MRH consumed less calf starter than calves fed MRM, but average daily gain or hip width change did not differ. One feeding of CR followed by 2 feedings of MR in the first 24 h likely reduced absorption of IgG from CR and contributed to differences in health and growth. Differences in animal performance observed in this study were unrelated to MR digestibility.     

Effects of feeding milk replacer at 2 rates with pelleted,low-starch or texturized,high-starch starters on calf performance and digestion

Milk replacer (MR) feeding programs have traditionally fed at less than ad libitum amounts to promote calf starter (CS) intake and allow early weaning. More recently, increased amounts of MR preweaning have been shown to increase preweaning ADG, although postweaning growth may be reduced. Several studies suggest that limited postweaning digestion of nutrients in CS may contribute to postweaning growth impairment. It is not clear whether CS formulation might also contribute to differences in postweaning nutrient digestion when calves are fed different MR programs. A 56-d feeding and digestion trial was conducted to compare growth and digestion in 2- to 3-d-old male Holstein calves (n = 48; initially 41.9 kg of body weight) fed a moderate (MRM) or high (MRH) MR program and either a pelleted CS containing 9.9% starch or a texturized CS containing 41.3% starch. Programs were 0.66 kg of dry matter (DM)/d of MR to d 46, then 0.33 kg/d to d 49 (MRM) and 0.85 kg of DM/d to d 5, then 1.07 kg/d to d 42, then 0.53 kg/d to d 49 (MRH). The MR contained 25% crude protein and 18.6% fat and was reconstituted to 13 (MRM) or 15% (MRH) solids. Calves were also assigned randomly to receive a pelleted CS (9.9% starch, 36.9% NDF) or a textured CS (41.3% starch, 13.3% NDF) and water for ad libitum intake for 56 d. During d 31 to 35 and 52 to 56, fecal samples were collected from 5 calves per treatment for estimates of digestibility. Selected nutrients and chromic oxide (d 31–35) or acid-insoluble ash (d 52–56) were analyzed in feed and feces to estimate digestibility. Data were analyzed as a completely randomized design. Repeated measures analysis was performed when data were measured by week. Calves fed MRH gained more body weight (but not hip width) and were more efficient to weaning compared with calves fed MRM, although fecal scores and days treated with medications were greater. We found no effect of CS on animal performance, although calves fed textured CS had higher fecal scores. Digestibilities of nutrients were affected by treatment and time of sampling (5 or 8 wk). At 5 wk, digestion of DM, organic matter, crude protein, and fat were lower and digestion of acid detergent fiber, neutral detergent fiber, and starch were higher in calves fed MRM and reflected greater CS intake. Also, digestion of DM, organic matter, acid detergent fiber, starch, crude protein, and fat were greater in calves fed textured CS at 5 wk. By 8 wk, when CS was the only source of nutrients, digestion of DM, organic matter, acid detergent fiber, and neutral detergent fiber were greater in calves fed MRM and digestion of DM and organic matter were greater, and acid detergent fiber and neutral detergent fiber digestion were lower in calves fed textured CS. Formulation of CS as well as amount of MR offered to young calves influenced animal performance and digestion in this study.     

Relationships between protein and energy consumed from milk replacer and starter and calf growth and first-lactation production of Holstein dairy cows

The objective was to determine relationships between protein and energy consumed from milk replacer and starter and calf growth and first-lactation production of Holstein heifer calves. Milk replacer and starter protein intake and metabolizable energy (ME) intake data were collected from 4,534 Holstein heifer calves for growth and 3,627 Holstein cows for production from birth year of 2004 through 2014. Calves from 3 commercial dairy farms were assigned to 45 different calf research trials at the University of Minnesota Southern Research and Outreach Center, Waseca, Minnesota, from 3 to 195 d of life. Calves were moved to heifer growers at 6 mo of age, and calves were returned to their farm of birth a few weeks before calving. Most calves (85%) were fed a 20% crude protein and 20% fat milk replacer at a rate of 0.57 kg/calf daily. Metabolizable energy and protein consumed from milk replacer and starter were calculated for each individual calf for 6 and 8 wk of age. Mixed model analyses were conducted to determine the effect of protein and energy consumed from both milk replacer and starter on calf growth and first-lactation 305-d production of milk, fat, and protein, adjusting for herd, season of birth, year, average daily gain (ADG), and calf trial. Calves with ADG >0.80 kg/d consumed more combined protein and ME than calves with lower ADG. Protein and ME intake from calf starter affected growth more than protein and ME intake from milk replacer because most calves were fed the same fixed amount of milk replacer. Calves born during the fall and winter had greater combined protein and ME intake than calves born during the spring and summer. Milk replacer protein and ME intake did not have a relationship with first-lactation 305-d milk, fat, and protein production. However, starter protein and ME intake during the first 6 and 8 wk of age had a significant positive relationship with first-lactation 305-d milk, fat, and protein production. Consequently, combined protein and combined ME intake had a positive effect on 305-d milk, fat, and protein production. Variance in protein and ME intake was high, suggesting that additional factors affect calf growth during the first 8 wk of life and milk production in first lactation.     

Starch–protein interaction in the rumen of weaned dairy calves

The objectives of this study were to investigate the effect of starch and protein interaction on rumen environment, in situ digestion, and total-tract digestibility of nutrients in weaned dairy calves between 8 and 16 wk of age. Sixteen rumen-cannulated calves were randomly divided into 4 dietary treatment groups with 4 calves fed in each treatment. The treatment diets had 2 levels of starch [18%, low starch (LS), or 38%, high starch (HS)] and 2 levels of protein [16%, low protein (LP), or 22%, high protein (HP)] on a dry matter (DM) basis in calf grower: (1) LPLS, (2) LPHS, (3) HPLS, and (4) HPHS. Calves were fed for ad libitum intake (95% assigned grower and 5% grass hay), and refusals were collected weekly. Total-tract digestibility collection and in situ digestibility procedures were performed for each calf at 11 and 15 wk. Samples for in situ digestibility, grass hay (GH), soybean hulls (SBH), wheat middlings (WM), ground corn (GrC), and soybean meal (SBM) were incubated for 9 and 24 h. There was no starch and protein interaction on total-tract digestibility of calves. Total-tract DM, neutral detergent fiber (NDF) and acid detergent fiber (ADF) digestibility, and feed efficiency were affected by both protein and starch inclusion level in calf diet. Total-tract starch digestibility was lower for LS diets. Dry matter digestibility and feed efficiency were greater in calves fed HP and HS diets compared with calves fed LP and LS diets, respectively. Fiber digestibility (NDF and ADF) was less in calves fed HS diets compared with calves fed LS diets but was greater in calves fed HP diets compared with calves fed LP diets. Level of protein did not affect in situ DM and NDF disappearance of GH, but HP increased in situ DM and NDF disappearance of SBH. High-starch diets decreased DM and NDF disappearance of both GH and SBH. At 20 h after feeding, ruminal pH was 0.51 unit higher in calves fed HPHS compared with calves fed LPHS. Total ruminal VFA and proportion of propionate was greater with HS versus LS, whereas proportion of acetate was greater with LS versus HS. The DM disappearance of SBM and WM and NDF disappearance of WM was greater for calves fed HPHS compared with calves fed LPHS at 11 wk of age. In our study, when HP was fed with HS, rumen pH, in situ digestion of WM and SBM, and total-tract digestion of DM, NDF, and ADF increased. This provides evidence for starch–protein interaction in the rumen of recently weaned dairy calves. Improvements in total-tract and in situ digestibility suggest that both protein and starch levels are important for 8- to 16-wk-old calves.     

Relationships between early-life growth,intake, and birth season with first-lactation performance of Holstein dairy cows

The objective was to determine the relationships between early-life parameters [including average daily gain (ADG), body weight (BW), milk replacer intake, starter intake, and birth season] and the first-lactation performance of Holstein cows. We collected data from birth years 2004 to 2012 for 2,880 Holstein animals. Calves were received from 3 commercial dairy farms and enrolled in 37 different calf research trials at the University of Minnesota Southern Research and Outreach Center from 3 to 195 d. Upon trial completion, calves were returned to their respective farms. Milk replacer options included varying protein levels and amounts fed, but in the majority of studies, calves were fed a milk replacer containing 20% crude protein and 20% fat at 0.57 kg/calf daily. Most calves (93%) were weaned at 6 wk. Milk replacer dry matter intake, starter intake, ADG, and BW at 6 wk were 21.5 ± 2.2 kg, 17.3 ± 7.3 kg, 0.53 ± 0.13 kg/d, and 62.4 ± 6.8 kg, respectively. Average age at first calving and first-lactation 305-d milk yield were 715 ± 46.5 d and 10,959 ± 1,527 kg, respectively. We conducted separate mixed-model analyses using the REML model-fitting protocol of JMP (SAS Institute Inc., Cary, NC) to determine the effect of early-life BW or ADG, milk replacer and starter intake, and birth season on first-lactation 305-d milk, fat, and true protein yield. Greater BW and ADG at 6 wk resulted in increased first-lactation milk and milk component yields. Intake of calf starter at 8 wk had a significant positive relationship with first-lactation 305-d yield of milk and milk components. Milk replacer intake, which varied very little in this data set, had no effect on first-lactation 305-d yield of milk and milk components. Calves born in the fall and winter had greater starter intake, BW, and ADG at 8 wk. However, calves born in the summer had a higher 305-d milk yield during their first lactation than those born in the fall and winter. Improvements were modest, and variation was high, suggesting that additional factors not accounted for in these analyses affected first-lactation performance.     

Starch source evaluation in calf starter: I. Feed consumption, body weight gain, structural growth, and blood metabolites in Holstein calves

Holstein calves were fed pelleted iso-starch (25% of starter dry matter) diets containing barley (n = 16), corn (n = 16), oat (n = 16), and wheat (n = 16) starch for 12 wk of age. Feed consumption, nutrient intake, body weight (BW) gain, skeletal growth, and selected blood metabolites in calves during preweaning (d 1 to 49) and postweaning (d 50 to 84) periods were measured. Average daily starter consumption during pre-weaning and postweaning periods was the greatest in calves fed corn died followed by those fed a wheat diet and then in those fed barley and oat diets. During the preweaning period, the calves provided corn and wheat diets consumed greater amount of mixed grass hay than those fed barley and oat diets. During the postweaning period, mixed grass hay intake was the greatest in calves provided corn diet followed by those fed a wheat diet and then in those fed barley and oat diets. Nutrients (dry matter, crude protein, starch, and neutral detergent fiber) intake followed the solid feed consumption pattern in calves. Body weight and body measurements (body length, body barrel, heart girth, wither height, and hip height) at birth and at weaning (d 49) in calves fed different starch sources were similar. Body weight and body measurements at postweaning (d 84) were the greatest in calves fed a corn diet followed by those fed a wheat diet and then in those fed barley and oat diets. Overall average BW gain and total dry matter intake were the greatest in calves fed a corn diet than in those fed wheat, barley, and oat diets. Feed efficiency was greater in calves fed corn and wheat diets than in those fed barley and oat diets. Blood glucose, blood urea N, triglycerides, cholesterol, and creatinine were reduced with the advancing age of calves. Lesser blood glucose and greater blood urea N concentrations at wk 8, 10, and 12 of age were noticed in calves fed corn diet than in those fed barley, oat, and wheat diets. Occurrence of diarrhea was more frequent in calves fed oat diet than in those provided barley, corn, and wheat diets. Starch sources did not influence respiratory score, rectal temperature, and general appearance score. In conclusion, the calves on corn diet consumed more solid feed and gained greater BW than those fed barley, oat, and wheat diets.     

Soybean oil supplementation and starter protein content: Effects on growth performance,digestibility, ruminal fermentation,and urinary purine derivatives of Holstein dairy calves

This study investigated the effects of feeding dairy calves starter diets containing 19% or 22% crude protein (CP) content on a dry matter basis and either supplemented or not with soybean oil (SBO, 0 vs. 3%, dry matter basis) on growth performance, digestibility, urinary nitrogen, and purine derivatives (PD) excretion. A total of 48 female Holstein dairy calves (mean 39.8 kg of body weight) were randomly distributed to experimental diets in a 2 × 2 factorial arrangement of treatments. The 4 dietary treatments were (1) starter diet without SBO supplement and 19% CP (NSBO-19CP), (2) starter diet without SBO supplement and 22% CP (NSBO-22CP), (3) starter diet with 3% SBO and 19% CP (SBO-19CP), and (4) starter diet with 3% SBO and 22% CP (SBO-22CP). Milk feeding value was similarly based on a constant protocol across experimental treatments and calves had ad libitum access to water and starter diets throughout the study. All calves were weaned on d 63 of age and remained in the study until d 83 of age. Calves supplemented with SBO had lower starter feed intake and average daily gain (ADG) and lower feed efficiency (FE) but had a higher fecal score indicating a higher likelihood of diarrhea occurrence compared with unsupplemented calves. Wither heights, digestibilities of organic matter, CP, and neutral detergent fiber were decreased, and ruminal volatile fatty acids tended to be reduced, and the molar proportion of ruminal butyrate (preweaning) and acetate (postweaning) reduced by supplemental SBO. The urinary allantoin and total PD excretion were reduced; however, urinary nitrogen excretion was increased when calves were supplemented with SBO. The CP amount did not affect starter feed intake, FE, or diarrhea occurrence rate, whereas the 22CP diets increased neutral detergent fiber digestibility, improved ADG (tendency), and increased allantoin and urinary PD excretion compared with the 19CP diets. The starter feed intake, ADG, FE, diarrhea occurrence rate, nutrient digestibility, and ruminal fermentation were not affected by the interaction between starter SBO and CP level; however, hip height and total PD in calves that received the SBO-22CP diets were higher than those fed the SBO-19CP diets. In conclusion, based on our experimental conditions, supplemental SBO could not be recommended for dairy calves. Furthermore, our findings indicate that SBO has negative effects on performance more attributed to reducing starter intake, digestibility, and ruminal volatile fatty acid concentration rather than because of a limitation of starter metabolizable protein supply and intestinal amino acid availability. Therefore, our results indicate that feeding the higher starter CP content is not a viable strategy to compensate for the negative effects of SBO supplementation on the growth performance of dairy calves.     

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.