Changes in Blood Glucose, Nonesterified Fatty Acids, and Ketones in Response to Weaning and Feed Intake in Young Calves

Abstract

Effects of weaning age on blood glucose, ketones, and nonesterifid fatty acids were examined using 16 Holstein heifer calves. Animals entered the study at 6±3.5 d of age and were fed 1.8kg of milk twice daily to 28 (early weaning) or 56 d (late weaning) and a commercial pelleted calf starter from 0 (early) or 28 d (late). Blood was sampled once weekly for 14wk and analyzed for β-hydroxybutyrate and acetoacetate. Plasma was analyzed for glucose and nonesterifid fatty acids. Blood β-hydroxybutyrate increased with increasing grain intake and was greater during wk 0 to 4 and 5 to 8 in calves weaned early than in those weaned late. Blood acetoacetate followed trends similar to β-hydroxybutyrate and averaged 23.8 and 16.1 μM in calves weaned early and late, respectively. Plasma glucose and nonesterifid fatty acids declined with age and were lower during 5 to 8wk in calves weaned early. Data suggest that ketone concentrations resulted from alimentary ketogenesis, which increased rapidly after weaning.