Promotion of growth rate by improving hormonal and metabolic functions by rumen-bypass starch in suckling calves

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The aim of this study was to investigate the kinetics of glucose and nitrogen metabolism when rumen-bypass starch particles were given to suckling calves and kids. Furthermore, we also analyzed the effects on the expression of sodium-dependent glucose transporter (SGLT-1) in the gastrointestinal (GI) tract epithelium. Twelve animals were used for each animal species. Rumen-bypass particles were given to the animals at the age of 6 to 13 weeks. Tissue samples were taken at the age of around 3 and 13 weeks. Glucose and nitrogen metabolism was measured by the stable isotope dilution method with ^2H, ^<13>C-glucose and ^<15>N, ^<13>C-urea, respectively. The plasma concentration of insulin, GH and insulin-like growth factor-I (IGF-I) was measured by radioimmunoassay. The expression of SGLT-1 mRNA was analyzed by the semi-quantitative RT-PCR method. The metabolism of glucose and nitrogen, and plasma concentration of metabolic hormones changed around weaning. In animals fed rumen-bypass particles, plasma concentrations of amino-N and insulin tended to decrease, but other parameters did not change significantly. Although SGLT-1 mRNA was confirmed to express commonly along the suckling kid GI tract with marked expression in the epithelium of duodenum, jejunum and ileum, it was substantially reduced after weaning (at the age of 13 weeks old). However, after weaning, there was no significant difference between control group and the particle-fed group.