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.     

Effects of ad libitum milk replacer feeding and butyrate supplementation on behavior,immune status,and health of Holstein calves in the postnatal period

Animal welfare in dairy calf husbandry depends on calf rearing and is probably improved by intensive milk feeding programs. In addition, butyrate supplementation in milk replacer (MR) stimulates postnatal growth and may affect the immune system in calves. We have investigated the combined effects of ad libitum MR feeding and butyrate supplementation on feeding behavior, health, and the immune responses in calves. Holstein calves (n = 64) were examined from birth until wk 11 of age. Calves received MR either ad libitum (Adl) or restrictively (Res) with (AdlB+, ResB+) or without (AdlB?, ResB?) 0.24% butyrate supplementation starting on d 4. From wk 9 to 10, all calves were gradually weaned and were fed 2 L/d until the end of the trial. Concentrate, hay, and water were freely available. Calves were housed in straw-bedded group pens with automatic MR feeders, where feed intake and feeding behavior were documented. Blood was drawn on d 1 before the first colostrum intake; on d 2, 4, and 7; and weekly thereafter until the end of the study to measure plasma concentrations of total protein, albumin, the immunoglobulins IgG₁, IgG₂, and IgM, and the acute phase proteins fibrinogen, serum amyloid A, and haptoglobin. Liver samples were taken on d 50 and 80 to determine gene expression related to acute phase proteins. Body temperature was measured daily for the first 3 wk, and clinical traits were scored daily. Ad libitum MR feeding resulted in greater MR intake, greater MR intake per meal, slower sucking rate, and greater body weight, but in a lower number of unrewarded visits and lower concentrate intake when compared with Res. Butyrate reduced the sucking rate but increased MR intake per meal. Immunoglobulins in the blood plasma increased after colostrum intake in all calves, with only minor differences among groups throughout the study. Plasma fibrinogen and serum amyloid A increased in the first week of life in all calves, and fibrinogen was greater in Res than in Adl on d 21, 49, and 63. Hepatic gene expression of fibrinogen on d 80 was greater in Adl than in Res. Gene expression of SAA2 was greater on d 50 in Adl than in Res and on d 80 was greater in ResB+ than in ResB?. Body temperature was greater in Adl than in Res during the first 2 wk, but neither MR feeding nor butyrate affected the health status. An improved animal welfare in Adl calves is supported by fewer signs of hunger, but intensive milk feeding and butyrate did not affect the health and immune status of the calves in a consistent manner.     

Ad libitum milk replacer feeding,but not butyrate supplementation,affects growth performance as well as metabolic and endocrine traits in Holstein calves

The enhanced growth performance of calves fed a higher plane of nutrition pre-weaning is well documented, and the effect of butyrate on the development of the gastrointestinal tract in calves has been evaluated. The aim of this study was to examine the synergistic effects of ad libitum milk replacer (MR) feeding and butyrate supplementation on growth performance and energy metabolism in calves. Sixty-four (32 male, 32 female) Holstein calves were examined from birth until wk 11 of life. Calves received MR either ad libitum (Adl) or restrictively (Res) with (AdlB+, ResB+) or without (AdlB?, ResB?) 0.24% butyrate supplementation. Colostrum and transition milk were fed in predefined amounts (Res or Adl) for the first 3 d postpartum. Ad libitum and restrictive MR feeding with or without butyrate was performed from d 4 until wk 8 of age. From wk 9 to 10, all calves were gradually weaned and were fed 2 L/d until the end of the trial. Concentrate (CON), hay, and water were freely available. Intakes of MR and CON were measured daily. Calves were weighed at birth and weekly thereafter. Blood was drawn on d 1 before the first colostrum intake; on d 2, 4, and 7; and weekly thereafter until the end of the study to measure plasma concentrations of metabolites and hormones. Liver samples were taken at d 50 and at the end of the study to determine gene expression related to glucose metabolism. Milk, MR, and total nutrient intake were greater, but CON intake was lower in Adl than in Res calves, resulting in a greater body weight, but partially lower gain to feed ratio in Adl than in Res. Plasma concentrations of glucose and insulin were higher during the ad libitum milk-feeding period, whereas plasma β-hydroxybutyrate was lower in Adl than in Res. Plasma concentrations of nonesterified fatty acids, lactate, total bilirubin, and cortisol were lower, but triglyceride and cholesterol concentrations were higher in Adl than in Res at specific time points. Feed intake, growth performance, and metabolic and endocrine changes were insignificantly affected by butyrate, and hepatic gene expression of enzymes related to endogenous glucose production was barely influenced by ad libitum MR feeding and butyrate supplementation. Intensive MR feeding indicated greater stimulation of growth and anabolic metabolism, but butyrate supplementation did not further improve postnatal growth or anabolic processes either in intensive or restrictive MR-fed calves.     

Effects of feeding unlimited amounts of milk replacer for the first 5 weeks of age on rumen and small intestinal growth and development in dairy calves

The development of the gastrointestinal tract in newborn calves is essential for sufficient nutrient uptake. An intensive milk feeding during the neonatal period may impair the rumen development in calves. The aim of this study was to investigate effects of milk replacer (MR) feeding in unlimited amounts for the first 5 wk of age on the gastrointestinal growth and development in preruminant calves at wk 9 of age. Twenty-eight newborn Holstein and Holstein × Charolais crossbred calves (19 male and 9 female) were fed MR ad libitum (ADLIB) or in restricted amounts (6 L per day; RES) until wk 5 of age. Thereafter, the MR intake of ADLIB was gradually reduced at wk 6 and 7, and all calves received 6 L of MR per day until wk 9 of age. In wk 9, calves were slaughtered and carcass and organ weight as well as rumen papilla size in the atrium, ventral sac, and ventral blind sac, and villus size of the mucosa in the small intestine (duodenum; proximal, mid, and distal jejunum; and ileum) were determined. The expression of mRNA associated with the local insulin-like growth factor (IGF) system was measured in the rumen epithelium. Ad libitum MR feeding increased MR intake and growth in ADLIB without influencing concentrate intake compared with RES. Carcass weight in wk 9 was greater in ADLIB than in RES. The density of the rumen papillae in the atrium and ventral blind sac was greater in RES than in ADLIB calves, but surface area of the epithelium was not different between groups in the investigated regions of the rumen. The mRNA abundance of IGF1 in the atrium tended to be greater and the IGFR1 mRNA abundance in the ventral sac tended to be lower in the ADLIB than in the RES feeding group. The rumen pH and volatile fatty acid concentrations were not affected by MR feeding intensity. In mid-jejunum, villus circumference was greater in ADLIB than in RES calves. In the distal jejunum, villus surface area and the villus height/crypt depth ratio were greater and the villus circumference and height tended to be greater, whereas crypt depth was smaller in ADLIB than in RES calves. The findings from this study indicate that ad libitum MR feeding for 5 wk of age followed by its gradual reduction promotes growth performance without any negative influence on gastrointestinal growth and development in dairy calves at 9 wk of age.     

Effects of parturition and feed restriction on concentrations and distribution of the insulin-like growth factor-binding proteins in plasma and cerebrospinal fluid of dairy cows

Hormones and metabolites act as satiety signals in the brain and play an important role in the control of feed intake (FI). These signals can reach the hypothalamus and brainstem, 2 major centers of FI regulation, via the blood stream or the cerebrospinal fluid (CSF). During the early lactation period of high-yielding dairy cows, the increase of FI is often insufficient. Recently, it has been demonstrated that insulin-like growth factors (IGF) may control FI. Thus, we asked in the present study if IGF-binding proteins (IGFBP) are regulated during the periparturient period and in response to feed restriction and therefore might affect FI as well. In addition, we specifically addressed conditional distribution of IGFBP in plasma and CSF. In one experiment, 10 multiparous German Holstein dairy cows were fed ad libitum and samples of CSF and plasma were obtained before morning feeding on d −20, −10, +1, +10, +20, and +40 relative to calving. In a second experiment, 7 cows in second mid-lactation were sampled for CSF and plasma after ad libitum feeding and again after feeding 50% of the previous ad libitum intake for 4 d. Intact IGFBP-2, IGFBP-3, and IGFBP-4 were detected in plasma by quantitative Western ligand blot analysis. In CSF, we were able to predominantly identify intact IGFBP-2 and a specific IGFBP-2 fragment containing detectable binding affinities for biotinylated IGF-II. Whereas plasma concentrations of IGFBP-2 and IGFBP-4 increased during the periparturient period, IGFBP-3 was unaffected over time. In CSF, concentrations of IGFBP-2, both intact and fragmented, were not affected during the periparturient period. Plasma IGF-I continuously decreased until calving but remained at a lower concentration in early lactation than in late pregnancy. Food restriction did not affect concentrations of IGF components present in plasma or CSF. We could show that the IGFBP profiles in plasma and CSF are clearly distinct and that changes in IGFBP in plasma do not simply correspond in the brain. We thus assume independent control of IGFBP distribution between plasma and CSF. Due to the known anorexic effect of IGF-I, elevated plasma concentrations of IGFBP-2 and IGFBP-4 during the postpartum period in conjunction with reduced plasma IGF-I concentrations may be interpreted as an endocrine response against negative energy balance in early lactation in dairy cows.     

Effects of milk replacer meal size on feed intake,growth performance,and blood metabolites and hormones of calves fed milk replacer with or without butyrate ad libitum: A cluster-analytic approach

This study intended to classify ad libitum–fed calves according to their milk replacer (MR) meal size using the K-means clustering approach. This study aimed to investigate the effects of MR meal size on feed intake, growth performance, and blood metabolic and hormones of ad libitum MR-fed calves. German Holstein calves (16 male and 16 female) were studied from birth until d 77 of age. All calves received first colostrum (2.5 kg) milked from their dams within 2 h after birth. Subsequent colostrum meals (subsequent 4 meals until 2.5 d of age; 2 meals/d) and MR (125 g of powder/L; 21.7% crude protein, 18.6% crude fat) were fed ad libitum by teat bucket until d 10 ± 2 of age. Afterward, calves were housed in group pens with automatic feeders for MR (maximum of 25 L/d) and concentrate from 10 ± 3 d of age. Half of the calves received MR supplemented with butyrate to improve growth performance. Milk intake was stepped down to 2 L/d from wk 9 to 10, and 2 L/d of MR were offered until the end of the study. On d 1, 2, 4, and 7, and then weekly until wk 11 of age, blood samples were collected for measurement of metabolites and hormones related to energy metabolism and growth. The K-means cluster analysis on the MR meal size data collected from the automatic feeder resulted in 3 clusters (n = 14, n = 12, and n = 6). Two clusters with a sufficient cluster size (n = 14 and n = 12) were included for further statistical analysis using repeated measures mixed-model ANOVA. In both clusters, butyrate supplementation was equally distributed and failed to affect a difference in MR meal size. Cluster 1 showed calves with higher MR meal size (HI; 2.2 ± 0.11 L/visit of MR) and cluster 2 with lower meal size (LO; 1.8 ± 0.07 L/visit of MR) supplemented MR without (HIB?; n = 6; LOB?, n = 7) or with 0.33% calcium-sodium butyrate (HIB+; n = 6; LOB+, n = 7). Dry matter intake of MR did not differ between HI and LO, but intakes of concentrate and total dry matter tended to be greater in HI than in LO and increased more distinctly in HI than in LO at the end of the study. The average daily gain (g/d) was greater in HI than in LO. Plasma concentrations of total protein (g/L), albumin (g/L), glucose (mmol/L), urea (mmol/L), insulin (µg/L), and glucagon (ng/L) were higher, and the concentrations of insulin-like growth factor I tended to be higher, in HI than in LO calves. Plasma β-hydroxybutyrate was higher in LO than in HI at d 63 and lower in calves fed MR with butyrate at d 77. In conclusion, clustering analysis discriminates 2 main groups of calves with different MR meal size and indicates an effect of MR meal size on solid feed intake, growth performance, and metabolic changes.     

Ad Libitum or Twice Daily Feeding of Acidified Milk Replacer to Calves Housed Individually in Warm and Cold Environments

Forty-two Holstein calves were assigned randomly to treatments in a 2 × 2 factorial arrangement of two milk replacer feeding systems (ad libitum vs. twice daily feeding of cold acidified milk replacer) and two housing types (warm vs. cold). The objectives were to compare the cold ad libitum system with a twice daily regimen and to evaluate its use under two housing types. For wk 1 to 5, calves fed ad libitum consumed more dry milk replacer (.86 vs. .65 kg/d), less calf starter (.07 vs. .15 kg/d), and less free choice water (.50 vs. 1.29 kg/d) than calves fed twice daily. Gains for ad libitum vs. twice daily were not different, but were significantly higher for cold than warm housing possibly due to respiratory problems in the barn. Calves did not increase consumption of replacer in response to cold housing. For wk 6 to 8, no differences in intake were observed, but daily gains were higher for calves in warm housing (.74 vs. .49 kg). There were no differences in weights or daily gain at 24, 36, or 52 wk of age. Plasma glucose was higher for calves fed ad libitum (127.1 vs. 110.6 mg/dl). All calves showed two distinct plasma glucose peaks during a day, indicating that calves fed ad libitum may consume two meals per day instead of small frequent meals.Ad libitum feeding of acidified replacer did not result in improved growth despite higher replacer intakes. There were no differences in response to ad libitum feeding in warm or cold housing.     

Effect of partial exchange of lactose with fat in milk replacer on ad libitum feed intake and performance in dairy calves

Compared with Holstein whole milk, commercial milk replacers (MR) for calves deliver relatively high levels of lactose and low levels of fat, and protein levels are rather comparable, resulting in a lower energy density and energy-to-protein ratio of the diet. Thus, the objective of this study was to determine the effects of partially exchanging lactose with fat in MR on voluntary feed intake, growth performance, and feeding behavior. Thirty-two male Holstein calves (2.1 ± 0.16 d of age, 46.4 ± 0.77 kg of body weight; BW) were assigned to 16 blocks of 2 calves per block based on arrival date and serum IgG. Within each block, calves were randomly assigned to 2 treatments: a high-lactose MR (HL; 17% fat; 44% lactose), or a high-fat MR (HF; 23% fat; 37% lactose). Lactose was exchanged by fat on a weight per weight basis, resulting in a 6% difference in metabolizable energy density per kilogram of MR. The experiment was divided into 3 phases: preweaning (P1; 0–35 d), weaning (P2; 36–56 d), and postweaning (P3; 57–84 d). For the first 2 wk of P1, calves were individually housed, fed their respective MR ad libitum through teat buckets, and provided access to water. At 14.2 ± 0.5 d of age, calves were group-housed (4 blocks/pen, 8 calves) and housed in group pens for the remainder of the study. In the group pens, calves were fed ad libitum MR, starter feed, chopped wheat straw, and water via automated feeders. During P2, calves were gradually weaned until complete milk withdrawal by 57 d and then monitored until 84 d (P3). Measurements included daily intakes and feeding behavior (rewarded and unrewarded visits), weekly BW and body measurements, and biweekly blood samples. Increasing fat content at the expense of lactose decreased MR intake during P1 by 15% (HL = 1.32 ± 0.04; HF = 1.17 ± 0.04 kg of dry matter per day), whereas total starter intake was not affected by MR composition. Once MR was restricted during P2, HL calves were reported to have more unrewarded visits to the automatic milk feeder than HF calves (11.9 ± 0.95 vs. 8.4 ± 1.03 visits/d, respectively). Crude protein intake was higher for HL calves during P1 (352.1 ± 11.2 vs. 319.6 ± 11.6 g/d), which was attributed to the higher intake of MR during that period, and metabolizable energy intake and protein-to-energy ratio remained comparable between treatments. Plasma cholesterol and nonesterified fatty acids levels were higher in HF calves as a consequence of the diet. Nevertheless, final BW (84 d) did not differ between treatments. Overall, calves fed ad libitum seemed to regulate their intake of MR based on its energy density, without significant effects on solid feed intake and overall growth.     

Effects of milk replacer composition on selected blood metabolites and hormones in preweaned Holstein heifers

We investigated the effects of increasing dietary protein and energy on concentrations of selected blood metabolites and hormones in Holstein heifers. Twenty-four heifers were fed 1 of 4 milk replacer (MR) diets for 9 wk (n = 6/diet): control [20% crude protein (CP), 21% fat MR fed at 441 g of dry matter (DM)/d], HPLF (28% CP, 20% fat MR fed at 951 g of DM/d), HPHF (27% CP, 28% fat MR fed at 951 g of DM/d), and HPHF+ (27% CP, 28% fat MR fed at 1,431 g of DM/d). Heifers were fed twice daily; water and starter (20% CP, 1.43% fat) were offered free choice and starter orts recorded daily. Serum and plasma aliquots from blood samples collected twice weekly after a 12-h fast were analyzed for insulin-like growth factor (IGF)-I, IGF-binding proteins (IGFBP), growth hormone (GH), insulin, glucose, nonesterified fatty acids, triglyceride, and plasma urea nitrogen concentrations. Only plasma glucose, IGFBP-2, and IGFBP-3 were affected by diet. Dietary treatment differences were only noted when the control was compared with the average of the other 3 diets. The addition of fat to the MR (HPLF vs. HPHF) and increased volume of MR (HPHF vs. HPHF+) had no effect on plasma glucose concentration or relative abundance of IGFBP-2 or IGFBP-3. Heifers fed the control diet had less glucose, greater IGFBP-2, and less IGFBP-3 than the average of the other 3 diets. There was a diet by week interaction for IGF-I. Serum IGF-I concentration in control heifers varied in a quadratic manner with a nadir (20 ± 4 ng/mL) at wk 4, whereas IGF-I increased linearly in heifers on other diets. Both insulin and triglyceride changed over time in a complex pattern (significant linear and quadratic contrast effects). The greatest concentrations were measured at wk 0.5 with nadirs at wk 6 for both insulin and triglyceride. Serum GH concentration decreased in a linear manner from wk 0.5 to wk 9 in all heifers. Relative abundance of IGFBP-2 was quadratic over time with the greatest amount of IGFBP-2 observed at wk 5. With the exception of glucose, IGF-I, IGFBP-2, and IGFBP-3, the blood variables measured were not influenced by treatment. The IGF-I -GH-IGFBP axis requires further study in heifers to deduce effects of nutrition on hypothalamic regulation of metabolism. We expected to see more treatment differences in concentrations of metabolites involved with protein and fat metabolism. It is likely that the diets used in this study were not diverse enough in composition to elicit such changes or that the efficiency of use of absorbed protein and fat was not different in these animals.     

Hematological, metabolic, and endocrine effects of feeding vitamin A and lactoferrin in neonatal calves

There are reports of important interactions among vitamin A, lactoferrin (Lf), and components of the insulin-like growth factor (IGF) system. Newborn calves are deficient in vitamin A and have a low Lf status. Colostrum contains vitamin A, Lf, and members of the IGF system, including IGF binding proteins (IGFBP), and these compounds may exert mutual interactions in neonatal calves. Effects of feeding different amounts of vitamin A and Lf on hematological, metabolic, and endocrine traits during the first 5 d of life were studied in neonatal calves. Calves were fed a milk-based formula without (F) or with added vitamin A [F(A); 351, 402, 490, and 490 micromol/kg dry matter (DM) on d 1, 2, 3, and 4, respectively], Lf (F(L); 3850, 1990, 660, and 660 mg/kg DM on d 1, 2, 3, and 4, respectively), or vitamin A + Lf (F(AL)) and colostrum (C). Blood samples were taken preprandially on d 1 to 5 and postprandially on d 1, 2, and 4 for the study of hematological, metabolic, and endocrine traits. As intestinal absorption of Lf in formula-fed calves was obviously lower than in colostrum-fed calves, Lf supplementation did not influence the metabolic and endocrine status. Plasma vitamin A concentrations increased from d 1 to 5 in F(A), F(AL), and C, but remained low in F and F(L). Addition of vitamin A to F affected concentrations of vitamin A from d 2 to 5; hemoglobin and triglycerides on d 3; and tended to influence IGFBP-3 levels on d 5. On d 1, preprandial insulin concentrations in F and F(L) were higher than those in F(A) and F(AL) and growth hormone concentrations on d 3 in F(A) were higher than in F(AL). In C, plasma Lf concentrations increased on d 1 and then decreased until d 5, whereas plasma urea and IGF-I concentrations remained stable. Compared with F-fed calves, C-fed calves had higher plasma concentrations of Lf from d 1 to 4, higher concentrations of vitamin A on d 5, higher concentrations of total protein from d 2 to 5, higher concentrations of triglycerides on d 3 and 4, and higher concentrations of IGF-I on d 4 and 5, but lower urea concentrations on d 4 and 5 and lower basal growth hormone concentrations than in F, F(L), and F(A). In conclusion, metabolite and hormone concentrations were influenced by differences in feeding. Addition of vitamin A influenced concentrations of vitamin A, hemoglobin, and triglycerides and tended to affect IGFBP-3 levels. Lactoferrin and vitamin A did not interact with respect to the IGF-I and IGFBP-3 status.     

Different milk feeding intensities during the first 4 weeks of rearing in dairy calves: Part 1: Effects on performance and production from birth over the first lactation

We aimed to test the effects of ad libitum feeding of whole milk (WM) or milk replacer (MR) versus restrictive feeding of MR during the first 4 wk of life on growth performance and on milk yield in the first lactation. We studied 57 German Holstein calves (29 females, 28 males) from birth until d 110 of life (trial 1). The 28 females from trial 1 were further studied during their first lactation (trial 2). In trial 1, all calves were randomly allocated at birth to 1 of 3 groups: MR-res [n = 20, 6.78 kg MR (11.5% solids)/calf per day], MR-ad lib (n = 17, 13.8% solids) or WM-ad lib (n = 20). All calves received colostrum ad libitum from their dam until d 3 of age. From d 4 to 27, calves were fed according to their group regimen. From d 28 to 55, all calves received MR-res feeding and were then gradually weaned until d 69. We recorded body weight (until d 110) and feed intake (amount, metabolizable energy, and frequency of liquid feed intake until weaning). We estimated the profitability of the different feeding regimens, taking into account income from milk yield (trial 2) and feed costs during rearing. In trial 1, the calves from WM-ad lib and MR-ad lib had total metabolizable energy intakes 2.02- and 1.65-fold greater than the MR-res group during the first 4 wk of life. During this period, concentrate intake did not differ among groups, but tended to be greater in WM-ad lib than in MR-ad lib calves from d 28 to 69. The MR-res calves visited the automatic feeders more often than the ad libitum-fed groups during differential feeding, but 70% of the visits were unrewarded (<10% in the ad libitum-fed calves). When all calves were fed at the MR-res level, the average proportion of unrewarded visits was 65% in all groups. Average daily gain and body weight were greater among MR-ad lib and WM-ad lib calves than among MR-res animals during the first 4 wk of life, but not from d 1 to 110. In trial 2, age at first calving, dry matter intake, and body weight over the first 10 mo of lactation were not different among groups, nor was milk composition. Milk yields (305 d) were numerically but not statistically greater in the ad libitum-fed groups during the first lactation (+765 kg for WM-ad lib vs. MR-res; +612 kg for MR-ad lib vs. MR-res). Feeding WM-ad lib and MR-ad lib was 1.37- and 1.21-fold more costly than MR-res, respectively, but amounted to 18, 15, and 13% of the total estimated feed costs until first calving in WM-ad lib, MR-ad lib, and MR-res, respectively. Our study confirms that ad libitum feeding is an attractive measure for rearing dairy calves, both for animal welfare and—with the caveat of a small sample size in trial 2 that led to insufficient power—economic profit from milk.     

Short communication: The effects of offering a high or low plane of milk preweaning on insulin-like growth factor and insulin-like growth factor binding proteins in dairy heifer calves

Although positive effects on growth have been shown when calves are placed on high planes of nutrition, little information exists regarding the effect of this feeding strategy on insulin-like growth factor-1 (IGF-1), a hormone whose fundamental action is to stimulate growth, and its binding proteins during the preweaning period. The objective of this study was to characterize IGF-1 and insulin-like growth factor binding protein (IGFBP) concentrations in plasma during the pre- and immediate postweaning period, when calves were offered a high or low plane of whole milk. Twenty-six female Holstein calves were randomly assigned to either a high (HI; 10 L/d; n = 13) or low (LO; 5 L/d; n = 13) plane of milk following colostrum feeding at d 3 of life. Calves were fed their respective diet as whole milk until d 48 when a 10-d weaning transition began. During this transition, milk was reduced by 10% per day such that all calves received no milk on d 59 of life. Blood samples were collected bi-weekly to measure IGF-1 and IGFBP in plasma. Calves fed HI gained more body weight than calves fed LO during the preweaning period (d 1–48 of life; 0.90 vs. 0.65 kg/d); however, no differences in average daily gain or metabolizable energy intake during the weaning transition (d 48–58 of life) or postweaning period (d 59–70 of life) occurred. Concentrations of IGF-1 were higher in HI calves during the preweaning period, which was associated with high levels of IGFBP-3 at wk 5 and lower IGFBP-2 during each measured time point preweaning as compared with LO. Insulin-like growth factor binding protein-4 was lower in HI calves only during wk 1, and IGFBP-5 was not affected by the dietary treatment. Overall, offering a high plane of nutrition was associated with changes in plasma IGF-1 and IGFBP that would indicate greater growth and development preweaning but not necessarily postweaning.     

Competition during the milk-feeding stage influences the development of feeding behavior of pair-housed dairy calves

This study investigated how the feeding behavior of pair-housed calves develops in response to reduced teat and feed place availability. Twenty Holstein bull calves were pair housed and provided with milk replacer (MR) and grain concentrate ad libitum via either (1) 1 teat and feed bucket/pen, such that calves could not feed simultaneously [competitive feeding (CF)] or (2) 2 teats and feed buckets/pen [noncompetitive feeding (NCF)]. The calves were weaned during wk 7 of life by incrementally diluting the MR. Postweaning, all pens were managed identically and offered a complete pelleted diet ad libitum via 2 feed buckets/pen (NCF) in period 1 (wk 8 and 9) and period 3 (wk 12 and 13) and exposed to a competitive challenge with CF in period 2 (wk 10 and 11). Feeding times and competitive interactions were recorded from video for 3 d/wk in wk 2, 4, and 6 and 2 d/wk in wk 8 to 13. Meal criteria were used to calculate daily meal frequency, meal time, and synchronized meal time (the percentage of meal time when calves within the pen were engaged in simultaneous meals). Milk replacer intake was subject to a treatment × week interaction, with calves in CF pens having lower MR intake (wk 2: 8.3 vs. 10.0 L/calf per day for CF vs. NCF), but compensating by increasing intake to a greater extent over time (wk 4–5: 13.3 vs. 11.7 L/d for CF vs. NCF). Corresponding to MR intake, meal frequencies and feeding times evolved differently over this period, increasing in CF pens and decreasing in NCF pens (wk 2: 5.8 vs. 11.1 and wk 4–6: 6.2 vs. 5.1 meals/d for CF vs. NCF). Calves in CF pens also spent less time engaged in synchronized meals (28 vs. 51% of meal time; standard error = 7.1) and displaced each other 5 times more frequently during synchronized eating. Postweaning, calves in previously CF pens maintained 5 times greater displacement frequencies and had fewer overlapping meals than calves in previously NCF pens (34.5 vs. 40.7% of meals, respectively). Postweaning, when calves were all fed noncompetitively (2 buckets/pen in periods 1 and 3), calves previously fed CF had greater intakes in period 3 (4.87 vs. 4.44 kg/d) and a tendency for greater intake in period 1 (2.80 vs. 2.63 kg/d), greater rates of intake in period 3 (87.8 vs. 72.0 g/min) and a tendency for greater rates of intake in period 1 (44.3 vs. 38.9 g/min), and greater meal frequencies in both periods (11.1 vs. 9.9 meals/d). In the competitive challenge period (1 bucket/pen in period 2), intake, rates of intake, and meal frequencies were subject to treatment × week interactions: calves in NCF pens had lower intake and meal frequencies, but increased meal frequency, intake, and rate of intake over time to a greater extent than calves previously in CF pens. These results indicate that calves are able to adapt to moderate competition by increasing meal frequency and that behavioral responses to competition persist postweaning.     

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 photoperiod and glucose-supplemented drinking water on the performance of dairy calves

Long-day photoperiods (LDPP) have been shown to increase milk production in lactating dairy cattle. The objective of this study was to determine the effects of supplemental light and glucose-supplemented drinking water on starter dry matter intake (DMI), water intake, serum and rumen metabolites, and growth performance of calves from birth to 8 wk of age. The experiment was conducted as a completely randomized design with a 2 × 2 factorial arrangement of treatments. The calves were assigned at birth to 1 of 4 treatments: 1) 10 h of light, 14 h of dark (short-day photoperiods; SDPP), ad libitum intake of water, and no glucose supplementation; 2) 10 h of light, 14 h of dark, and ad libitum intake of water supplemented with 50 g of glucose/L; 3) 18 h of light, 6 h of dark (LDPP), and ad libitum intake of water, and no glucose supplementation; and 4) 18 h of light, 6 h of dark, and ad libitum intake of water supplemented with 50 g of glucose/L. Fluorescent lights were used to provide lighting at an intensity of approximately 600 lx at the eye level of calves. The calves were bucket-fed 2 L of whole milk offered twice daily at 0700 and 1600 h and had a free access to a textured calf starter. The calves on LDPP were heavier at d 56 than SDPP calves regardless of level of glucose supplementation. The average daily gain of the calves on LDPP from d 29 to 42 and from d 43 to 56 was greater than for SDPP calves regardless of the level of glucose supplementation. The greater average daily gain of LDPP calves from d 29 to 56 coincided with the greater calf starter DMI of these calves. Body widths through hooks were highly (r = 0.72) correlated with body weights, which in turn were related to calf starter DMI. Calves on LDPP had greater ruminal osmolarity and greater concentrations of acetate, propionate, butyrate, and total volatile fatty acids than SDPP calves regardless of the level of glucose supplementation. Calves on LDPP had lower Ca:P ratio than the SDPP calves regardless of level of glucose supplementation. The concentrations of serum glucose and sodium for the glucose-supplemented calves were greater than for nonsupplemented calves regardless of lighting regimen. These results suggest that LDPP encouraged greater consumption of calf starter, which stimulated faster rumen development in the LDPP calves as evidenced by greater volatile fatty acid concentrations.     

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.     

Macronutrient profile in milk replacer or a whole milk powder modulates growth performance,feeding behavior,and blood metabolites in ad libitum-fed calves

Milk replacers (MR) for calves usually contain more lactose and less fat than bovine whole milk (WM). There are insufficient data to determine whether these MR formulations are optimal for calves fed at high planes of nutrition. Thus, the effect of 3 MR formulations and a WM powder were evaluated on growth, feeding behavior, and blood metabolites in 96 male Holstein calves fed ad libitum and with 45.5 ± 4.30 kg (mean ± standard deviation) BW at arrival. Calves were blocked based on arrival sequence, and randomly assigned within block to one of the 4 treatments (n = 24 calves/group): a high-fat MR (25.0% fat, dry matter basis; 22.5% protein, 38.6% lactose; 21.3 MJ/kg; HF), a high lactose MR (44.6% lactose, 22.5% protein, 18.0% fat; 19.7 MJ/kg; HL), a high protein MR (26.0% protein, 18.0% fat, 41.5% lactose; 20.0 MJ/kg; HP), and a WM powder (26.0% fat; 24.5% protein, 38.0% lactose; 21.6 MJ/kg; WP). In the first 2 wk after arrival, calves were individually housed and were fed 3.0 L of their respective liquid feed 3 times daily at 135 g/L. They were then moved to group housing and fed ad libitum until d 42 after arrival. Weaning was gradual and took place between d 43 and 70 after arrival; thereafter, calves were fed solids only. Concentrates, chopped straw, and water were available ad libitum throughout the study. Body weight was measured, and blood was collected at arrival and then weekly thereafter from wk 1 to 12. Weight gain and height were greater in HL than WP calves. In the preweaning phase, HL and HP-fed calves consumed more milk than WP, and HL-fed calves consumed more milk than HF calves. In wk 10, starter feed intakes were lower in HF calves than in the other groups. In the preweaning phase, ME intakes were the same for all treatments. This suggests that milk intakes were regulated by the energy density of the milk supplied. The percentage of calves requiring therapeutic interventions related to diarrhea was greater in WP-fed calves (29%) than HF and HL calves (4%), whereas HP (13%) did not differ with other groups. This was coupled with lower blood acid–base, blood gas, and blood sodium in WP than in MR-fed calves. Calves fed HF had greater serum nonesterified fatty acids compared with other groups, and greater serum amyloid A compared with WP and HL calves. Among the serum parameters, insulin-like growth factor-1 and lactate dehydrogenase correlated positively with ME intake and average daily gain. The high lactose and protein intakes in HL and HP calves led to greater insulin-like growth factor-1 concentrations than in WP-fed calves. Although growth differences were limited among MR groups, the metabolic profile largely differed and these differences require further investigation.     

Replacing concentrates with a high-quality hay in the starter feed of dairy calves: II. Effects on the development of chewing and gut fermentation,and selected systemic health variables

Early development of the rumen, rumination, and fermentation is highly important in dairy calves. Yet, common rearing practices with feeding of concentrate-rich starters may jeopardize them because of lacking physically effective fiber (peNDF). The main objective of this study was to establish the influence of the composition of the calf starter feed (only forage with 2 different qualities or concentrate-rich starter diet) on chewing behavior, rumen development, rumen and hindgut fermentation, and selected systemic health and stress variables of dairy calves. The experiment was carried out with 40 newborn Holstein-Friesian calves, randomly assigned to 4 different solid feed treatments: MQH = 100% medium-quality hay (9.4 MJ metabolizable energy, 149 g of crude protein, and 522 g of neutral detergent fiber/kg of dry matter); HQH = 100% high-quality hay (11.2 MJ of metabolizable energy, 210 g of crude protein, 455 g of neutral detergent fiber/kg of dry matter); MQH+C = 30% MQH + 70% starter concentrate; HQH+C = 30% HQH + 70% starter concentrate). All calves were up to 14 wk in the trial and received acidified whole milk ad libitum in the first 4 wk of life, thereafter in reduced quantity until weaning on 12 wk of age. Water and the solid feed treatments were available ad libitum throughout the trial. Chewing activity was measured in wk 4, 6, 10, and 12 using RumiWatch halters. Until wk 3, rumen fluid, feces and blood were sampled weekly, thereafter every 2 wk. Rumen mucosal thickness (RMT) was measured on the same days with rumen fluid samples. Data showed that calves fed the HQH diet consumed more peNDF and this was associated with longer rumination time (591 min/d) and more ruminating boli (709 boli/d) than calves fed concentrate-rich diets (MQH+C: 430 min/d, 518 boli/d; HQH+C: 430 min/d, 541 boli/d), whereas the MQH group was intermediate (539 min/d, 644 boli/d). Ruminal and fecal pH were higher in calves fed only hay (especially MQH) compared with calves with concentrate supplementation. In both hay-fed groups, ruminal and fecal short-chain fatty acids were shifted toward acetate, whereas only the HQH diet increased the butyrate proportion in the ruminal short-chain fatty acids profile. Ruminal ammonia concentration was at a high level only in the first 3 wk and decreased thereafter. Feeding HQH tended to increase ruminal ammonia, likely because of its high crude protein content and ruminal degradability as well as lower assimilation from rumen microbes. The RMT similarly, though nonlinearly, increased in all groups over the course of the experiment. When using RMT as an indicator of rumen development in dairy calves in the practice, our data suggest an RMT of 1.7 mm and >2 mm at wk 5 and 10 of life, respectively. Feeding did not affect the blood levels of aspartate aminotransferase, gamma glutamyl transferase, glutamate dehydrogenase, and cortisol. In conclusion, feeding high-quality hay, instead of concentrate-rich starter feeds, resulted in improved rumination and ruminal fermentation profile, without affecting ruminal pH and systemic and stress health variables.