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

摘要

Intensive milk feeding and butyrate supplementationin calves stimulate body growth and affect gastrointestinaldevelopment. The aim of the present study wasto investigate the synergistic effects of ad libitum milkreplacer (MR) feeding and butyrate supplementation ofMR on rumen and small intestinal growth and on geneexpression in the small intestine related to growth andenergy metabolism at weaning. Male Holstein calves (n= 32) received colostrum from birth to d 3 of age andMR either ad libitum (Adl) or restrictively (Res; 6 L ofMR/d; 12.5% solids) with (AdlB+, ResB+) or without(AdlB−, ResB−) 0.24% butyrate from d 4 until wk 8 ofage. From wk 9 to 10, all calves were weaned and werefed 2 L/d until the end of the trial. Concentrate, hay,and water were freely available. At d 80, calves wereslaughtered, volatile fatty acids were measured in rumenfluid, and rumen and small intestine samples were takenfor histomorphometric measurements. The expressionof mRNA associated with the local insulin-like growthfactor (IGF) system and glucose metabolism as well aslactase and maltase activities were measured in the intestinalmucosa. The small intestine was 3 m longer inAdl than in Res. In the atrium ruminis, papilla widthwas 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 inthe proximal, mid, and distal jejunum and ileum weregreater in calves treated with butyrate. Crypt depthin the duodenum and proximal jejunum was greater inAdl than in Res and in the ileum was smaller in calvestreated with butyrate. The villus height: crypt depthratio was greatest in AdlB+ calves. In the proximaland mid jejunum, IGF1 mRNA abundance was lower incalves treated with butyrate. In the proximal jejunum,INSR mRNA abundance was greater in Res than inAdl. The abundance of PCK2 mRNA was greater inRes than in Adl in the duodenum and was greatest inResB− in the mid jejunum. Lactase activity tended tobe greater in Res than in Adl and after butyrate treatmentin the proximal jejunum. The results indicated anelevated growth of the small intestinal mucosa at weaningdue to intensive milk feeding and butyrate supplementation,and the local IGF system was involved inintestinal growth regulation. Rumen development wasnot affected by butyrate supplementation of MR andwas slightly delayed due to ad libitum MR feeding.