Hay intake improves performance and rumen development of calves fed higher quantities of milk

Research to date has suggested that access to forage before weaning can limit rumen development in calves, but no research has yet addressed the role of forage for calves fed higher quantities of milk. This study compared performance and rumen development of calves provided high volumes (equivalent to approximately 20% of calf birth weight) of milk with and without access to hay. At d 3 of age, individually housed calves were randomly assigned to treatment (either ad libitum access to chopped grass hay or no forage; n = 15 calves per treatment, 10 heifers, and 5 bulls). All calves were provided ad libitum access to water and starter throughout the study. All calves were offered 8 L of milk/d from a nipple bottle from d 3 to 35, 4 L/d from d 36 to 53, and 2 L/d until weaning at d 56. Solid feed intake and growth parameters were monitored from d 3 to 70. At d 70, males from both treatments were slaughtered to measure rumen development parameters. Overall dry matter (DM) intake from solid feed did not differ between treatments before wk 5. However, during wk 6 to 10, calves fed forage consumed more total DM (starter plus hay) than did calves fed no forage. Hip and wither height, heart girth, and body barrel at d 3, 56, and 70 did not differ between treatments. Reticulorumen weight was heavier in calves fed hay versus those fed only starter (12.77 ± 1.29 vs. 7.99 ± 0.69 kg with digesta; 1.89 ± 0.05 vs.1.60 ± 0.09 kg without digesta). Body weight without digesta was similar in calves fed forage or no forage. Mean rumen pH was higher in calves fed hay compared with those fed no forage (5.49 ± 0.08 vs. 5.06 ± 0.04). In conclusion, provision of chopped hay to calves fed high volumes of milk can promote solid feed DM intake and rumen development without affecting BW gain.     

Pre- and postweaning performance of holstein female calves fed milk through step-down and conventional methods

Milk consumption, dry feed intake, body weight (BW) gain, occurrence of diarrhea, and selected blood metabolites were studied in female Holstein calves fed milk either through conventional or step-down (STEP) methods. In conventional method, the calves (n = 20) were fed colostrum and then milk at the rate of 10% of BW for the entire period of 45 d. In STEP method, the calves (n = 20) were given colostrum and then milk for 25 d at the rate of 20% of BW, which was reduced (between d 26 to 30) to 10% of BW for the remaining 15 d. The calves fed through conventional and STEP methods were weaned gradually by diluting milk with water between d 46 and 50. Feed intake and BW of the calves were monitored until 90 d of age. The STEP calves consumed 92.3, 19.4, and 62.4% more milk than conventionally fed calves during pre-STEP (d 1 to 30), post-STEP (d 31 to 50), and preweaning (d 1 to 50) periods, respectively. Consumption of starter and hay were greater during the pre-STEP period and lesser during the post-STEP and postweaning (d 51 to 90) periods in calves provided milk using conventional method compared with STEP-fed calves. Body weight gain, dry matter intake, and feed efficiency of calves were greater in those on the STEP method than on the conventional method. Lesser blood glucose and greater blood urea nitrogen at weaning (d 50) and postweaning (d 60) possibly indicated a better functioning rumen in calves fed milk through The STEP method than those fed conventionally. Occurrence of diarrhea was higher during wk 3 and 4 of age in calves fed milk through conventional method compared with STEP-fed calves. In conclusion, STEP milk feeding may prevent the problems of depressed solid feed intake associated with ad libitum milk feeding and of poor BW gain with conventional milk feeding in dairy calves.     

Performance,structural growth,and digestibility by Holstein calves fed different amounts of milk through step-up/step-down or conventional methods

Early life milk intake can influence the survival and future productivity of replacement heifers. The present study determined the effects of different amounts of milk through step-up/step-down or conventional feeding methods on the performance of dairy calves. Thirty-nine Holstein calves (18 male and 21 female) were used in a completely randomized design. Calves were randomly allocated to 1 of 3 treatments: (1) conventional milk feeding (CONV; 4.5 L/d of milk from d 1 to 50 and 2 L/d of milk at d 51 and 52 of the study; total milk intake = 229 L); (2) low milk intake with step-up/step-down method (L-SUSD, 4 L/d of milk from d 1 to 10, 6 L/d from d 11 to 20, 8 L/d from d 21 to 30, 6 L/d from d 31 to 40, 4 L/d from d 41 to 50, and 2 L/d milk at d 51 and 52 of the study, total milk intake = 284 L); (3) high milk intake with step-up/step-down method (H-SUSD, 6 L/d of milk from d 1 to 10, 8 L/d from d 11 to 20, 10 L/d from d 21 to 30, 8 L/d from d 31 to 40, 6 L/d from d 41 to 50, 4 L/d milk at d 51, and 2 L/d milk at d 52 of the study, total milk intake = 386 L). All calves were weaned at d 52 and followed until d 70. Performance data (every week), skeletal growth (d 52 and 70), and ruminal fermentation parameters and digestibility (d 35, 55, and 70) were analyzed as repeated measurements with PROC MIXED of SAS version 9.3 (SAS Institute Inc.). A treatment × time interaction was observed for total dry matter intake (TDMI) as follows: TDMI differed among all treatments where H-SUSD > L-SUSD > CONV from d 11 to 38 of study, greater for H-SUSD versus other treatments from d 3 to 10 and d 39 to 70 of study. Starter feed intake and average daily gain (ADG) were greater in H-SUSD calves than in CONV calves, and L-SUSD treatment was intermediate for those traits. The H-SUSD calves tended to have greater body weight (BW) and lower feed efficiency than calves fed CONV or L-SUSD treatments. The treatments did not affect structural growth parameters, except for hip width, which tended to be greater in H-SUSD calves than CONV calves. Regardless of treatments, ADG, starter feed intake, BW, and body measurements increased as calves aged, whereas feed efficiency increased from d 1 to 52 of study and decreased from d 52 to 70 of study. The treatments had no effect on digestibility, rumen parameters, or fecal score. Overall, in calves that were weaned at 52 d and fed milk 3 times daily, the high milk intake (386 L) through the SUSD method did not increase diarrhea or decrease digestibility but increased starter feed intake and ADG.     

Effect of weaning age on growth,mammary gland development,and immune function in Holstein Friesian calves fed conserved alfalfa (FiberStart)

This study aimed to evaluate intake, body growth, and the development of the rumen, mammary gland, and immune system in Holstein Friesian calves reared for 100 d on the commercially available feed FiberStart (conserved alfalfa, Medicago sativa; Fiber Fresh Feeds Ltd., Reporoa, New Zealand) and fed calf milk replacer (CMR) for either 56 or 91 d. Eighty calves (40 bulls and 40 heifer calves) were reared indoors in groups (n = 5 of the same sex/pen). All calves were fed 4 L of CMR/d (175 g/L of CMR) in 2 feeds/d for the first 10 d and then 1 feed/d until d 49 or 84. The calves were gradually weaned by d 56 (earlier weaned; n = 8 pens) and d 91 (later weaned; n = 8 pens). All calves were fed FiberStart ad libitum as the only solid feed source from d 1 to 100 of the study. Irrespective of treatment, all calves had similar body weights at d 0 (40.9 ± 3.0 kg) and d 49 (74.2 ± 5.1 kg) of the study. Calf sex had no effect on intake, growth, blood, and immune system parameters. Earlier-weaned calves consumed 18% more solid feed dry matter but had 16% lower body weight gain (28.9 vs. 38.5 kg, respectively) from d 56 to 100 relative to later-weaned calves, resulting in different body weight at 100 d (104 vs. 121 ± 1.3 kg). Although earlier-weaned calves could compensate for the loss of CMR dry matter and crude protein intake from d 56 to 100 by increasing forage intake, they were unable to compensate for the loss of energy from the CMR by increasing solid feed consumption. Plasma β-hydroxybutyrate concentrations were 52% greater in earlier-weaned calves than in later-weaned calves at d 84, indicating greater metabolic activity of the rumen wall. The duration of CMR feeding had no influence on humoral or cell-mediated immune functions of the calves, as evidenced by a lack of effect on antivaccine antibody responses as well as on immune gene expression. Earlier- versus later-weaned heifer calves had 5% lower mammary gland mass, indicating that greater energy supply increased mammary mass. The results of this experiment demonstrate the ability to artificially rear dairy calves on a conserved alfalfa as the only solid feed. Furthermore, earlier weaning off CMR promotes solid feed intake and an associated increase in blood β-hydroxybutyrate, an indicator of rumen development, but increasing the duration of CMR feeding improves growth and mammary gland mass by d 100. The implications of these findings on lifetime growth, health, and milk production in dairy heifers warrant further investigation.     

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.     

Influence of weaning method on health status and rumen development in dairy calves

In the artificial rearing of dairy calves, the same feeding plan is applied to all animals during the milk-feeding period, with individual differences attributable to development or health status rarely considered. The aim of this study was 1) to analyze whether the parameters of feeding behavior automatically recorded by a feeding computer and weight gain are suitable for predicting the health status and rumen development of male dairy calves, and 2) to compare a conventional weaning method (end of milk provision at 12 wk of age, n = 23 calves) with a concentrate-dependent weaning method (with reduction in the milk amount depending on the consumption of concentrate, n = 24). The health status of each animal was evaluated daily by a scoring list (health score), and body temperature was measured automatically during each milk intake. In addition, the number of veterinary treatments per calf was recorded. Rumen development was assessed by measuring rumen papillae in 8 rumen areas after slaughter (n = 24, half of each treatment group). During the milk-feeding period, body temperature was elevated (≥39.5°C) on 40.8 and 43.2% of all days for calves on the concentrate-dependent weaning method and the conventional weaning method, respectively. Hay and concentrate intake (but not milk intake) and weight gain were clearly affected by health status. In addition, health score and the probability of being treated by a veterinarian were significantly related to decreases in concentrate consumption. During the milk-feeding period, increased body temperature, an increased number of veterinary treatments, and decreases in milk consumption were all associated with reduced weight gain. Calves on the concentrate-dependent weaning method were weaned at an average age of 76 d, which was significantly shorter than the age at the end of milk provision for conventionally fed calves (84 d). Weight gain and health status did not differ between treatment groups. Weight gain was positively associated with papillae length. A treatment effect on rumen development could not be found. We conclude that the concentrate-dependent weaning method allows a faster physiological development without any negative impact on rumen development, weight gain, or health status; we therefore recommend its use in practice.     

Effects of supplemental butyrate and weaning on rumen fermentation in Holstein calves

The objectives of this study were to determine the effects of the weaning transition and supplemental rumen-protected butyrate on subacute ruminal acidosis, feed intake, and growth parameters. Holstein bull calves (n = 36; age = 10.7 ± 4.1 d; ± standard deviation) were assigned to 1 of 4 treatment groups: 2 preweaning groups, animals fed milk replacer only (PRE-M) and those fed milk replacer, calf starter, and hay (PRE-S); and 2 postweaning groups, animals fed milk replacer, calf starter, and hay without supplemental rumen-protected butyrate (POST-S) or with supplemental rumen-protected butyrate at a rate of 1% wt/wt during the 2-wk weaning transition (POST-B). Milk replacer was provided at 1,200 g/d; starter, water, and hay were provided ad libitum. Weaning took place over 14 d by reducing milk replacer provision to 900 g/d in wk 7, 600 g/d in wk 8, and 0 g/d in wk 9. Rumen pH was measured continuously for 7 d during wk 6 for PRE-S and PRE-M and during wk 9 for POST-S and POST-B. After rumen pH was measured for 7 d, calves were euthanized, and rumen fluid was sampled and analyzed for volatile fatty acid (VFA) profile. Individual feed intake was recorded daily, whereas, weekly, body weights were recorded, and blood samples were collected. Compared with PRE-M, PRE-S calves tended to have a greater total VFA concentration (35.60 ± 11.4 vs. 11.90 ± 11.8 mM) but mean rumen pH was unaffected (6.25 ± 0.22 vs. 6.17 ± 0.21, respectively). Between PRE-S (wk 6) and POST-S (wk 9), calf starter intake increased (250 ± 219 vs. 2,239 ± 219 g/d), total VFA concentrations increased (35.6 ± 11.4 vs. 154.4 ± 11.8 mM), but mean rumen pH was unaffected (6.25 ± 0.22 vs. 6.40 ± 0.22, respectively). Compared with POST-S, POST-B calves had greater starter intake in wk 7, 8, and 9, but POST-B tended to have lower total VFA concentration (131.0 ± 11.8 vs. 154.4 ± 11.8 mM) and lower mean ruminal pH (5.83 ± 0.21 vs. 6.40 ± 0.22). In conclusion, the weaning transition does not appear to affect rumen pH and VFA profile, but supplementing rumen-protected butyrate during the weaning transition increased starter intake and average daily gain. Further, these data suggest that the ability of the rumen to manage rumen pH changes fundamentally postweaning. Why weaned calves with lower rumen pH can achieve higher calf starter intakes is unclear; these data suggest the effect of rumen pH on feed intake differs between calves and cows.     

Short communication: Effect of calf starter on rumen pH of Holstein dairy calves at weaning

The objective of this study was to evaluate the effect of feeding calf starter on rumen pH of dairy calves during weaning transition. Twenty Holstein bull calves were paired into 10 blocks by starting date of the study and body weight, and fed either milk replacer and hay (MR) or MR, hay, and a commercial texturized calf starter (MR+S) in a randomized complete block design. All calves were fed 750 g/d of milk replacer as the basal diet. Calves on MR+S treatment were also fed a calf starter ad libitum to maintain similar energy intake between calves within blocks, and MR calves were fed additional milk replacer that was equivalent to energy from calf starter intake. When MR+S calves consumed a calf starter at 680 g/d for 3 consecutive d, rumen pH of a MR+S calf and his MR counterpart was measured continuously for 3 d using a small ruminant rumen pH measurement system. Treatment did not affect minimum pH, mean pH, maximum pH, standard deviation of mean pH, and duration or area under pH 5.8, indicating that calf starter consumption did not appear to affect rumen pH. However, hay intake was negatively correlated to area under pH 5.8, with a breakpoint at 0.080 kg/d intake, suggesting hay intake might play an important role in mitigating ruminal acidosis in dairy calves during weaning transition.     

Intensive liquid feeding of dairy calves with a medium crude protein milk replacer: Effects on performance,rumen, and blood parameters

The objective of this study was to evaluate the effects of different liquid-feeding systems using a medium crude protein milk replacer on performance, rumen, and blood parameters. Thirty newborn Holstein calves were blocked according to birth weight and date of birth, and randomly distributed to different liquid-feeding systems: conventional (4 L/d), intensive (8 L/d), or step-up/step-down (wk 1, 4 L/d; wk 2 to 6, 8 L/d; wk 7 and 8, 4 L/d). The commercial milk replacer (12.5% solids, 20.2% crude protein, 15.6% fat) was fed twice daily (0700 and 1700 h) until calves were weaned, at 8 wk of age. Calves were individually housed in wood hutches, with free access to water and starter concentrate, and to hay only after weaning. They were followed through 10 wk of age. Milk replacer and starter intake were inversely affected by feeding system. After weaning, starter intake and hay intake were similar among feeding systems. Total dry matter intake was higher during the liquid-feeding period for calves on the intensive system compared to calves on the conventional system, but conventional feeding resulted in the highest dry matter intake after weaning. Feed efficiency was similar among feeding systems before and after weaning. Average body weight and daily gain were not affected by feeding system before or after weaning. During liquid feeding, diarrhea occurrence was lower for calves on the conventional system; however, when calves on the step-up/step-down system were fed lower volumes of liquid feed, diarrhea occurrence was similar to that of calves on the conventional system. Plasma concentrations of β-hydroxybutyrate were higher for calves on the conventional system, reflecting starter intake. Rumen pH, short-chain fatty acids, and N-NH₃ were not affected by feeding system. Feeding higher volumes of milk replacer with a medium crude protein content had no beneficial effect on the performance of calves up to 10 wk of age.     

Starch source evaluation in calf starter: II. Ruminal parameters, rumen development, nutrient digestibilities, and nitrogen utilization in Holstein calves

Ruminal parameters, rumen development, nutrient digestibilities, and N utilization were estimated in Holstein calves fed starch from different sources. Ground corn, ground barley, ground wheat, and crimped oats were used to formulate 4 isostarch (25% of starter dry matter) pelleted diets. These diets were randomly allocated to calves (16 calves per treatment, 8 female and 8 male) and fed ad libitum along with mixed grass hay throughout the experiment. Ruminal contents and blood were sampled at d 35, 50, and 70 of age to estimate ruminal parameters and plasma β-hydroxybutyrate, respectively. At d 70, twenty-four male calves (6/treatment) were randomly selected, euthanized, and forestomach weight, papillae length (PL), papillae width (PW), rumen wall thickness (RWT), and papillae concentration were measured. At d 63, twenty-four female calves (6/treatment) were randomly selected and moved to metabolism stalls to estimate total tract apparent nutrient digestibilities and N utilization. Female calves were given 2 wk for adaptation to experimental facilities and then total collections of feces and urine were made from d 77 to 84 of age. Ruminal pH at d 35 of age was higher in calves fed corn and oat diets than in those fed barley and wheat diets. Ruminal pH at d 50 and 70 of age was the lowest in calves on barley diets followed by those on oat and wheat diets and then by those on the corn diet. Ruminal total volatile fatty acid concentrations at d 35 of age were greatest in calves fed corn or wheat diets followed by those fed barley and oat diets. Calves on corn and wheat diets maintained greater ruminal volatile fatty acids concentrations at d 50 and 70 of age. Ruminal ammonia, acetate, propionate, butyrate, and blood β-hydroxybutyrate concentrations were also greater in calves on the corn and wheat diets. Full and empty weights of forestomach, PL, PW, RWT, and papillae concentrations were greater in calves on corn and wheat diets. Daily average intake of nutrients (dry matter, crude protein, neutral detergent fiber, starch, Ca, and P) was greater in calves fed corn and wheat diets than in those fed barley and oat diets. Starch source did not influence the total tract apparent digestibilities of nutrients in calves. Daily N retention (g/d) was greatest on the corn diet followed by the wheat diet and then the barley and oat diets. In conclusion, calves on a corn diet have greater ruminal capacity to accommodate feed bulk. More physically and metabolically functional rumens in calves on corn and wheat diets probably resulted in greater feed consumption and N retention.     

Effect of various levels of forage and form of diet on rumen development and growth in calves

The effect of form of starter grain (coarse vs. ground) and inclusion of various levels of hay on body weight gain and rumen development was evaluated. Two experiments were conducted to determine the effect of form of diet and forage inclusion on intake, growth, feed efficiency, and weaning age in dairy calves. Diets consisted of commercial coarse starter (C), ground starter (G), coarse starter with 7.5% bromegrass hay of consistent particle size (8 to 19 mm) (H1), and coarse starter with 15% hay (H2). In experiment 1, intake was held constant across treatments until weaning, when feed was offered ad libitum. Calves receiving H1 and H2 were heavier and had greater body weight gain and greater feed efficiency than calves receiving C. There were no differences in intake. Total volatile fatty acid concentrations were higher, and the proportion of acetate was lower for calves fed G vs. C. In experiment 2, calves (n = 56) were offered diets on an ad libitum basis and weaned according to intake. There were no differences in body weight gain, average daily gain, feed efficiency, and age at weaning with respect to treatment. Starter and total dry matter intake tended to be greater in calves fed H1 and H2 vs. C. The addition of controlled particle size hay to diets of young calves appears to favorably alter rumen environment, resulting in increased intake and improved feed efficiency. Forage of a consistent particle size can be successfully utilized in starter rations of young calves.     

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 adding extra molasses to a texturized calf starter on rumen development, growth characteristics, and blood parameters in neonatal dairy calves

A texturized calf starter containing 5 (control) or 12% molasses [on a dry matter (DM) basis] was fed to dairy calves to determine effects on intake, growth, blood parameters, and rumen development. Forty-six Holstein calves (26 male and 20 female) were started at 2 +/- 1 d of age and studied for 42 d. Starter DM intake was measured and fecal scoring was conducted daily. Growth and blood parameter measurements were conducted weekly. A subset of 6 male calves (3 per treatment) was euthanized at 4 wk of age, and rumen tissue sampled for rumen epithelial growth measurements. Starter sugar content was significantly increased in the starter containing extra molasses. Postweaning and overall starter DM intake, overall total DM intake, daily heart girth change, and final heart girth were significantly decreased, whereas overall average daily gain tended to decrease when calves received starter containing 12% molasses. However, blood volatile fatty acid concentrations were significantly increased when calves received a starter containing 12% molasses. No significant differences were observed between calves receiving starters containing 5 or 12% molasses for all other variables. The data indicates that adding extra molasses to a texturized calf starter decreases intake and structural growth, possibly causing decreased weight gain, but increases blood volatile fatty acid concentrations and slightly increases ruminal development. However, feed handling and physical prehension problems in addition to the negative influences on calf growth and intake do not support increasing starter molasses content to 12% of the supplement.     

Effects of ad libitum milk replacer feeding and butyrate supplementation on the epithelial growth and development of the gastrointestinal tract in Holstein calves

Intensive milk feeding and butyrate supplementation in calves stimulate body growth and affect gastrointestinal development. The aim of the present study was to investigate the synergistic effects of ad libitum milk replacer (MR) feeding and butyrate supplementation of MR on rumen and small intestinal growth and on gene expression in the small intestine related to growth and energy metabolism at weaning. Male Holstein calves (n = 32) received colostrum from birth to d 3 of age and MR either ad libitum (Adl) or restrictively (Res; 6 L of MR/d; 12.5% solids) with (AdlB+, ResB+) or without (AdlB−, ResB−) 0.24% butyrate from d 4 until wk 8 of age. From wk 9 to 10, all calves were weaned and were fed 2 L/d until the end of the trial. Concentrate, hay, and water were freely available. At d 80, calves were slaughtered, volatile fatty acids were measured in rumen fluid, and rumen and small intestine samples were taken for histomorphometric measurements. The expression of mRNA associated with the local insulin-like growth factor (IGF) system and glucose metabolism as well as lactase and maltase activities were measured in the intestinal mucosa. The small intestine was 3 m longer in Adl than in Res. In the atrium ruminis, papilla width was greater in Res than in Adl. Villus circumference, cut surface, and height in the duodenum, proximal jejunum, and ileum were greater in Adl than in Res and in the proximal, mid, and distal jejunum and ileum were greater in calves treated with butyrate. Crypt depth in the duodenum and proximal jejunum was greater in Adl than in Res and in the ileum was smaller in calves treated with butyrate. The villus height:crypt depth ratio was greatest in AdlB+ calves. In the proximal and mid jejunum, IGF1 mRNA abundance was lower in calves treated with butyrate. In the proximal jejunum, INSR mRNA abundance was greater in Res than in Adl. The abundance of PCK2 mRNA was greater in Res than in Adl in the duodenum and was greatest in ResB− in the mid jejunum. Lactase activity tended to be greater in Res than in Adl and after butyrate treatment in the proximal jejunum. The results indicated an elevated growth of the small intestinal mucosa at weaning due to intensive milk feeding and butyrate supplementation, and the local IGF system was involved in intestinal growth regulation. Rumen development was not affected by butyrate supplementation of MR and was slightly delayed due to ad libitum MR feeding.     

Transition milk stimulates intestinal development of neonatal Holstein calves

Colostrum stimulates gastrointestinal development. Similar to colostrum, transition milk (TM; the first few milkings after colostrum) contains elevated nutrient levels and bioactive components not found in milk replacer (MR), albeit at lower levels than the first colostrum. We hypothesized that feeding neonatal calves TM, compared with MR, for 4 d following colostrum at birth would further stimulate intestinal development. Holstein bull calves were fed 2.8 L of colostrum within 20 min of birth, allocated to 1 of 11 blocks based on birth date and body weight (BW), randomly assigned to MR (n = 12) or TM (n = 11) treatments within block, and fed treatments 3 times per day. Milk from milkings 2, 3, and 4 (TM) of cows milked 2 times daily was pooled by milking number and fed at 1.89 L per feeding; milking 2 was fed at feedings 2 through 5, milking 3 at feedings 6 through 8, and milking 4 at feedings 9 through 12. TM was not pasteurized and contained 17% solids, 5% fat, 7% protein, 4% lactose, and 20 g of IgG per liter on average, whereas MR (as fed) contained 15% solids, 4% protein, 3% fat, 6% carbohydrate, and no IgG. Refusals were similar, so calves fed TM consumed 1.0 Mcal of metabolizable energy per day more than those fed MR. On the morning of d 5, calves were injected i.v. with 5 mg of bromodeoxyuridine per kg of BW and slaughtered 130 min later; then, intestinal sections were excised. Feeding TM, instead of MR, doubled villus length, villus width, villus to crypt ratio, and mucosal length in all intestinal sections, increased submucosal thickness 70% in the proximal and mid jejunum, and tended to increase submucosal thickness in duodenum and ileum. Mucosal surface area was also increased in both the ileum and mid jejunum when feeding TM by 19 and 36%, respectively. Treatment did not alter crypt depth. Bromodeoxyuridine labeling was increased 50% by TM compared with MR in the cells along the epithelium of the crypts and within the villi of all sections, indicating that TM increased cell proliferation compared with MR. Calves fed TM gained more BW than calves fed MR and had improved cough, fecal, nose, and ear scores. We conclude that feeding TM for 4 d following an initial feeding of colostrum stimulates villus, mucosal, and submucosal development in all sections of the small intestine in the first few days of life and improves health and growth.     

Preweaning to postweaning rumen papillae structural growth,ruminal fermentation characteristics,and acute-phase proteins in calves

This study evaluated pre- to postweaning ruminal structural development, fermentation characteristics, and acute-phase protein levels in calves with a high milk replacer (MR) feeding rate prior to weaning. Six ruminally cannulated Holstein bull calves were fed MR (150 g/L) at 15% of body weight (BW) in 2 equal volumes daily. Volumes were adjusted weekly based on BW. Calves were weaned using a 1-step weaning method, with MR decreased by 50% at the end of wk 5 and full weaning at the end of wk 6. Calf starter, chopped straw, and water were offered ad libitum. Intake was recorded daily, and BW was recorded weekly. From wk 5 to 12, ruminal pH was continuously measured using a ruminal pH bolus. Ruminal fluid was collected weekly from wk 5 to 12 for measurement of short-chain fatty acid concentrations and quantification of total bacteria and protozoa. Rumen papillae were obtained at wk 5, 6, 7, 8, and 12 for histological analysis. Serum amyloid A and lipopolysaccharide-binding protein were measured weekly. Data were analyzed using GLIMMIX procedure of SAS (SAS Institute Inc., Cary, NC), with week as a fixed effect and calf as a random effect. During the weaning step-down, starter intake was 3-fold higher and continued to increase until wk 12. Body weight increased from birth to wk 12; however, BW did not change during wk 6, 7, and 8, possibly due to low metabolizable energy intake caused by the weaning strategy. Preweaning ruminal pH was below 5.8 for approximately 936.3 ± 125.99 min/d, implying ruminal acidosis. Furthermore, ruminal pH below 5.8 reached a peak at wk 8 with 1,203.9 ± 227.65 min/d below pH 5.8 and slowly decreased to 388.1 ± 189.82 min/d below pH 5.8 at wk 12. Papillae surface area, length, and width increased during wk 12 compared with wk 5. Corneum thickness increased by week, whereas spinosum/basale thickness only increased during wk 8 compared with wk 5. The acute-phase protein concentration was highest at wk 1 and then decreased and remained constant until wk 12. In conclusion, even before step-down weaning, calves experienced ruminal acidosis despite low starter intake. Further, the observed prolonged ruminal pH depression suggests that dietary rumen adaptation after weaning can take several weeks in calves with a high MR feeding rate preweaning. The prolonged depressed ruminal pH did not affect acute-phase proteins and this finding, along with the other results, suggests that rumen epithelium barrier integrity is not compromised during weaning.     

Effects of compound probiotics on growth performance,rumen fermentation,blood parameters,and health status of neonatal Holstein calves

This study aimed to investigate the effects of compound probiotics (consisting of 10⁸ cfu/g of Lactobacillus plantarum, 10⁸ cfu/g of Pediococcus acidilactici, 10⁸ cfu/g of Pediococcus pentosaceus, 10⁷ cfu/g of and Bacillus subtilis) on growth performance, rumen fermentation, bacteria community, blood parameters, and health status of Holstein calves at the first 3 mo of age. Forty-eight newborn calves were randomly divided into the following 3 groups: control group (milk replacer with no compound probiotics), low compound probiotics group (milk replacer + 0.12 g of compound probiotics per head per day), and high compound probiotics group (HP; milk replacer + 1.2 g of compound probiotics per head per day). Starter pellets of the low compound probiotics and HP groups were coated with 0.05% compound probiotics. Milk replacer was provided from 2 to 63 d of age (6 L at 2–10 d, 8 L at 11–42 d, 6 L at 43–49 d, 4 L at 50–56 d, and 2 L at 57–63 d), and starter pellets were provided ad libitum from 7 to 90 d of age. Body weight and body size (d 1, 30, 60, and 90), blood (d 40 and 80), and rumen fluid (d 90) were analyzed using the one-way ANOVA procedure; fecal score was recorded daily and analyzed as repeated measures using the mixed model procedure. Results showed that diet supplemented with compound probiotics had no effects on the body weight, average daily gain, dry matter intake, and feed efficiency. At 90 d of age, diet supplemented with compound probiotics decreased the withers height. Immunity activities increased in the HP group, supported by the increased concentrations of serum total protein and immunoglobulins at 40 d of age, and by the increased activity of superoxide dismutase at 80 d of age. Diet supplemented with compound probiotics altered rumen fermentation, indicated by the decreased rumen acetic acid and propionic acid, and the increased butyric acid concentrations. Diet supplemented with compound probiotics improved the health status of calves, indicated by the decreased fecal score at 3 wk of age and the decreased medicine treatments. In summary, although diet supplemented with HP decreased the withers height, this level of probiotics is recommended to improve rumen development and health status of newborn Holstein calves.     

Abomasal pH, nutrient digestibility, and growth of Holstein bull calves fed acidified milk replacer

Our objective was to compare nutrient digestion and utilization, amount and pattern of intake, and pH profile over time of abomasal contents in calves offered acidified milk replacer ad libitum or regular (sweet) milk replacer twice daily at 10% of body weight per day. Ten Holstein bull calves were fed replacers reconstituted to 13% dry matter for 4 wk. Daily milk replacer and water consumption and weekly body weight were recorded. Other variables were measured during the 2nd and 4th wk. Calves offered acidified replacer consumed more dry matter and gained more body weight than did calves fed sweet replacer; however, there was no difference in feed conversion ratio. Apparent digestibility of dry matter, ether extract, nitrogen, and retention of absorbed nitrogen were not affected by treatment. Acidified milk replacer offered ad libitum lowered the pH of abomasal contents and feces compared to regular replacer offered at 10% of body weight per day. Feeding patterns of calves offered acidified replacer ad libitum were variable. No adverse effects of feeding acidified milk replacer were noted.     

Abrupt weaning reduces postweaning growth and is associated with alterations in gastrointestinal markers of development in dairy calves fed an elevated plane of nutrition during the preweaning period

The benefits of feeding elevated quantities of milk to dairy calves have been well established. However, there is a reluctance to adopt this method of feeding in commercial dairy production because of concerns around growth, health, and ruminal development during weaning. The objective of this study was to characterize the effect of an abrupt (0 d step-down) or gradual (12 d step-down) feeding scheme when calves are fed an elevated plane of nutrition (offered 1.35 kg of milk replacer/d). For this experiment, a total of 54 calves were randomly assigned to an abrupt or a gradual weaning protocol before weaning at 48 d of life. Calves were housed and sampled in individual pens for the duration of the experiment, and milk, starter, and straw intake were measured on a daily basis. Body weight was measured every 6 d, whereas blood, rumen fluid, and fecal samples were collected on d 36 (pre-step-down), 48 (preweaning), and 54 (postweaning) of the experiment. Although the growth rates of the step-down calves were lower from d 37 to weaning (0.62 ± 0.04 vs. 1.01 ± 0.04 kg/d), the postweaning average daily gain was greater compared with the group that was abruptly weaned (0.83 ± 0.06 vs. 0.22 ± 0.06 kg/d). Total ruminal volatile fatty acid was greater in the step-down group on the day of weaning (d 48; 59.80 ± 2.25 vs. 45.01 ± 2.25 mmol), whereas the fecal starch percentage was lower during postweaning compared with the abruptly weaned calves (d 54; 3.31 ± 0.76 vs. 6.34 ± 0.76%). Analysis of the digestive tract of bull calves on d 55 revealed minimal differences between gross anatomy measurements of gut compartments as well as no morphological differences in rumen papillae development, yet the total mass of rumen when full of contents was larger in the step-down calves (7.83 ± 0.78 vs. 6.02 ± 0.78 kg). Under the conditions of this study, the results showcase the benefits of a step-down feeding strategy from an overall energy balance standpoint, due to increased adaptation of the gastrointestinal tract preweaning.     

Maternal rumen and milk microbiota shape the establishment of early-life rumen microbiota in grazing yak calves

Early-life gut microbial colonization and development exert a profound impact on the health and metabolism of the host throughout the life span. The transmission of microbes from the mother to the offspring affects the succession and establishment of the early-life rumen microbiome in newborns, but the contributions of different maternal sites to the rumen microbial establishment remain unclear. In the present study, samples from different dam sites (namely, oral, rumen fluid, milk, and teat skin) and rumen fluid of yak calves were collected at 6 time points between d 7 and 180 postpartum to determine the contributions of the different maternal sites to the establishment of the bacterial and archaeal communities in the rumen during early life. Our analysis demonstrated that the dam's microbial communities clustered according to the sites, and the calves' rumen microbiota resembled that of the dam consistently regardless of fluctuations at d 7 and 14. The dam's rumen microbiota was the major source of the calves' rumen bacteria (7.9%) and archaea (49.7%) compared with the other sites, whereas the potential sources of the calf rumen microbiota from other sites varied according to the age. The contribution of dam's rumen bacteria increased with age from 0.36% at d 7 to 14.8% at d 180, whereas the contribution of the milk microbiota showed the opposite trend, with its contribution reduced from 2.7% at d 7 to 0.2% at d 180. Maternal oral archaea were the main sources of the calves' rumen archaea at d 14 (50.4%), but maternal rumen archaea became the main source gradually and reached 66.2% at d 180. These findings demonstrated the potential microbial transfer from the dam to the offspring that could influence the rumen microbiota colonization and establishment in yak calves raised under grazing regimens, providing the basis for future microbiota manipulation strategies during their early life.