Short communication: Effect of delaying the first colostrum feeding on small intestinal histomorphology and serum insulin-like growth factor-1 concentrations in neonatal male Holstein calves

摘要

The primary objective of this study was to determinethe effect of delaying the first colostrum feeding onsmall intestinal histomorphology and serum insulin-likegrowth factor-1 (IGF-1) concentrations, and the secondaryobjective was to characterize the ultrastructureof the small intestine of neonatal calves at 51 h of life.Twenty-seven male Holstein calves were fed pooled,pasteurized colostrum (7.5% of birth body weight; 62 gof IgG/L) at 45 min (0H, n = 9), 6 h (6H, n = 9), or 12h (12H, n = 9) after birth. At 12 h after their respectivecolostrum feeding, calves were fed milk replacer at 2.5%of birth body weight per meal and every 6 h thereafter.Blood samples were collected every 6 h using a jugularcatheter and analyzed for serum IGF-1 concentrationsusing an automated solid-phase chemiluminescent immunoassay.At 51 h of life, calves were euthanized to facilitatecollection of the duodenum, proximal and distaljejunum, and ileum. All segments of the small intestinewere assessed for histomorphology, whereas scanningelectron and transmission electron microscopy analyseswere conducted only for the proximal jejunum and ileum.The results revealed that there was no overall effect ofcolostrum feeding time on serum IGF-1 concentrations;however, serum IGF-1 concentrations were influencedby time. Specifically, concentrations of serum IGF-1 at48 h were 29% greater than concentrations at 0 h oflife (312.8 ± 14.85 vs. 241.9 ± 14.06 ng/mL). Althoughthere was no overall effect of colostrum feeding time onall histomorphological measures assessed, treatment ×segment interactions were observed. Villi height was 1.4times greater in the distal jejunum of 0H calves thanin 6H and 12H calves, and 0H calves tended to have1.2 times greater ileal villus height than 12H calves. Inaddition, 0H calves had 1.2 and 1.3 times greater ilealcrypt depth than 6H and 12H calves, respectively, and1.3 times greater surface area index than 12H calves inthe distal jejunum. Qualitative ultrastructural evaluationof small intestinal enterocytes conducted irrespectiveof colostrum treatment revealed the presence oflarge vacuoles of electron-dense material, apical mitochondria,and apical canalicular systems in the jejunumand ileum. These results indicate that the calf intestineat 51 h of life contains unique enterocyte characteristicssimilar to fetal enterocytes and that delaying colostrumfeeding may negatively influence intestinal growth anddevelopment.