Postprandial metabolism and endocrine status in veal calves fed at different frequencies

Veal calves fed by bucket often develop postprandial insulin resistance, hy perglycemia, and glucosuria during fattening. Automatic feeding systems all ow feed intake for 24 h, and small ingested portions are expected to decrea se postprandial glucose loads. We have studied metabolic and endocrine trai ts in calves that were either 1) fed identical daily amounts of whole milk plus milk replacer by a computer-programmed automatic feeder (greater than or equal to6 portions from 0800 to 2400 h) (GrA) or 2) fed by bucket at 080 0 and 1630 h (GrB). Calves started at a body weight of 118 kg, and the expe riment lasted for 3 wk. During wk 3, lactose was supplemented to stress pos tabsorptive glucose homeostasis. Feed intake and average daily gains in GrA and GrB were similar. Plasma concentrations during an 8-h period of glucos e tin part), lactate, urea, and somatostatin tin wk 3), and of glucagon and insulin (wk 2 and 3) were smaller in GrA than in GrB, whereas growth hormo ne, insulin-like growth factor I, insulin-like growth factor binding protei n-1 (wk 2), and prolactin concentrations (wk 2 and 3) were higher. Lactose supplementation in wk 3 enhanced transient postprandial hyperglycemia and h yperinsulinemia. Thus, there were marked metabolic and endocrine difference s when calves sucked their feed in six or more portions during a 16-h perio d from an automatic feeder compared with twice daily drinking from a bucket . Ingestion of small portions by calves avoided marked hyperglycemia and la ctate increments, and lower plasma urea concentrations mirrored enhanced ni trogen utilization, possibly mediated by the altered growth hormone, IGF-I and insulin status.