We studied the effects of amounts of colostrum consumed on intestinal morphology and proliferation and digestive enzyme activities in neonatal calves. Group GrCmax calves were fed colostrum from the first milking undiluted on d 1-3 and diluted with 25, 50, 75 and 75 parts of a milk replacer on d 4-7. Group GrC1-3 calves were fed colostrum from milkings 1-6 up to d 3 and then a milk replacer up to d 7. Group GrF1-3 calves were fed a milk-based formula (containing only traces of growth factors and hormones) up to d 3 and then a milk replacer up to d 7. Calves were killed on d 8. Differences in feeding affected villus sizes and villus height/crypt depth ratios in the duodenum (GrCmax > GrC1-3), villus areas and villus height/crypt depth ratios in the jejunum (GrC1-3 > GrF1-3) and crypt depths in the colon (GrF1-3 > GrC1-3). Furthermore, different feeding protocols affected the proliferation rates of epithelial cells in the duodenum (GrC1-3 > GrCmax; GrC1-3 > GrF1-3) and the jejunum (GrF1-3 > GrC1-3; based on Ki-67 labeling). Lipase activities in the pancreas were influenced by colostrum feeding (GrC(max) > GrC(1-3)). Colostrum intake differentially affected intestinal epithelial surface and proliferation and enzyme activities. Feeding high amounts of first colostrum seemed to enhance the survival of mature mucosal epithelial cells in selected parts of the small intestine, whereas the lack of colostrum seemed to decrease epithelial growth.

Colostrum intake is important for health and postnatal development of neonatal calves. We studied the effects of enhanced first colostrum feeding on growth, health status, and metabolic and endocrine traits in calves during their 1st wk of life. Calves of group CL (GrCL; n = 7) were fed colostrum of milkings 1 to 6 twice daily during the first 3 d of life, followed by milk replacer (MR) up to d 7. Calves of group CH (GrCH; n = 7) were fed colostrum of the first milking during the first 3 d and then colostrum (of the first milking) twice daily, which on d 4, 5, 6, and 7 was diluted with 25, 50, 75, and 75 parts of MR, respectively. Pre- and postprandial blood samples were taken on d 1, 2, 3, and 7 for the determination of various metabolic and endocrine traits, and on d 5 intestinal absorption capacity was measured using the xylose absorption test. Rectal temperatures and fecal scores were higher (P < .05) in GrCH than in GrCL. Plasma concentrations of total protein and albumin were higher (P < .05) on d 7, IgG on d 2 and 3, and urea on d 2, 3, and 7 in GrCH than in GrCL. Plasma concentrations of triglycerides were higher (P < .05) on d 2 and of phospholipids and cholesterol were higher (P < .01) on d 7 in GrCH than in GrCL. Plasma insulin and glucagon concentrations were higher (P < .05) in GrCH than in GrCL, whereas prolactin and growth hormone concentrations were higher (P < .05) in GrCL than in GrCH. Enhanced colostrum intake had no effects on xylose absorption on d 5. Higher plasma protein, urea, and lipid concentrations in GrCH partly mirrored higher protein and fat intake but additionally pointed to higher protein synthesis and lipid turnover.

Colostrum provides high amounts of nutrients and non-nutrient substances to neonates. To study differences between effects of nutritional and non-nutritional components on growth, health status and metabolic and endocrine traits, a formula was created based on bovine milk components which contained similar amounts of nutrients as bovine colostrum during the first 3 days of lactation, but only trace amounts of growth factors (such as insulin-like growth factor I) or hormones (such as insulin) in whey. Calves were fed either pooled colostrum of milkings 1 to 6, obtained during the first 3 days of lactation (GrC, n = 7) or a formula in the same amounts as colostrum (GrF, n = 7) for the first 3 days, followed by a milk replacer up to day 7. Pre- and postprandial blood samples were taken on days 1, 2, 3 and 7 for the determination of metabolic and endocrine traits and on day 5 we measured intestinal absorptive capacity by testing xylose absorption. Plasma concentrations of total protein and immunoglobulin G and γ-glutamyltransferase activity were lower (p < 0.05), whereas albumin and urea concentrations were higher (p < 0.05) in GrF than GrC during the first week of life. Plasma glucose concentrations were variably affected. Plasma triglyceride, phospholipid and cholesterol concentrations were higher (p < 0.05) in GrC than GrF on days 3 and 7. Insulin and growth hormone concentrations were higher (p < 0.05) in GrC than GrF on days 2 and 3 and on days 1 and 2, respectively, and glucagon concentrations were higher (p < 0.05) in GrC than GrF on day 1 and higher (p < 0.05) in GrF than GrC on day 3. Cortisol concentrations were higher (p < 0.05) on days 2 and 3 in GrF than GrC. Plasma xylose concentrations rose more markedly (p < 0.05) in GrC than GrF. In conclusion, feeding only trace amounts of bioactive substances appears to impair intestinal absorptive capacity and protein and fat metabolism and exert effects on endocrine systems in neonatal calves.