Influence of Colostrum Insulin Supplementation on Brush Border Carbohydrase Activity in Neonatal Holstein Bulls.

Insulin concentrations are variable in bovine colostrum (5 to 263 μg insulin/L) and its effects on gastrointestinal function in neonatal calves are unknown. The objective of this study was to determine if varying concentrations of insulin in colostrum would influence intestinal carbohydrases in neonatal Holstein bulls. Calves (n = 26; 49.11 kg, SD = 3.24) were removed from their dams after calving. They were fed 3 meals of colostrum (7% BW or 3.10 ± 0.02 L) at 2, 14 and 26 hours after birth containing one of 3 insulin concentrations: basal (16.8 μg/L; n = 8), or supplemental colostrum containing either a 5× (83.4 μg/L; n = 10) or 10× (167.5 μg/L; n = 8) increase in colostrum insulin respective to basal concentrations. At 30 hours, the animals were killed, and the gastrointestinal tract was removed for mucosal scrapings of the duodenum, proximal jejunum, and ileum. Intestinal mucosal scrapings were assayed for the following brush border carbohydrases: maltase, isomaltase, lactase and glucoamylase. Data were analyzed using the MIXED procedure of SAS with treatment and dam parity modeled as fixed effects. There was no treatment effect (P > 0.05) on intestinal maltase, isomaltase and glucoamylase concentrations. However, there was a linear increase (P < 0.05) in jejunal lactase activity (Unit/g of jejunum and U/g of protein) with increasing amount of insulin inclusion. These data indicate that insulin supplementation has minimal effects on activities of brush border starch degrading enzymes, but increases lactase activity in the proximal jejunum of neonatal calves. [ABSTRACT FROM AUTHOR]