Effect of adding sugars to a carbohydrate-free diet on intestinal disaccharidase activities in the young calf.

Abstract A carbohydrate-free diet formulated to determine the effect of dietary carbohydrates on digestive enzymes in the young calf consisted of 30% fat and 70% of a protein premix which contained 92% protein. After an adaptation of about 3 days, calves consumed this diet readily and gained weight. Sixteen male Holstein calves were fed the basal carbohydrate-free diet from 6 to 21 days of age after which they were divided into four groups, three of which received added carbohydrates: (I) lactose, (II) galactose, or (III) glucose at 4.5 g/kg body weight daily for 2 wk. The fourth group (IV), control, continued to receive the basal only. Lactase activities per milligram protein in the mucosa of the proximal one-third of the small intestine from calves receiving these diets were 10.2, 7.8, 5.8, and 4.7 (× 10 −2 μ M disaccharide hydrolyzed/min). Values from diet I were greater than from either III or IV. Intestinal maltase followed a trend similar to that for lactose, with diet I higher than IV. There were no significant differences between any of the treatments in the distal section. Pancreatic amylase activity was less in calves receiving the glucose-supplemented diet (31.4) than in those fed the carbohydrate-free diet (65.2). Preprandial blood glucose rapidly declined in calves on the carbohydrate-free dietary regime and was not increased by the addition of any sugars to the diet. Glucose disappeared from the blood faster in calves which received carbohydrates for 2 wk than in those on a carbohydrate-free ration. Increases in blood glucose after feeding galactose were low compared to those from either glucose or lactose diets.