Protein and energy relations in the broiler chicken. Chronic or acute effects of alternating protein or intermittent feeding regimens on broiler lipid metabolism.

Abstract

1. Broiler chickens growing from 7 to 28 d of age were given: (1) a 210 g protein/kg control diet for the entire experimental period, (2) an intermittent feeding regimen (210 g protein/kg diet for either 1 or 2 d followed by a 1 d fast), or (3) a daily change in the dietary protein level from 120 to 300 g/kg diet. Treatment variables examined were lipogenesis and glucose production in vitro, and circulating concentrations of insulin, triiodothyronine (T3) and thyroxine (T4) to determine the effects of chronic or acute dietary treatments. 2. Giving the 300 g protein/kg diet or withholding feed for 1 d decreased (P less than 0.05) lipogenesis in vitro compared with controls. 3. Giving the 120 g protein/kg diet or refeeding with a 210 g protein/kg diet for 1 or 2 d increased (P less than 0.05) lipogenesis in vitro compared with controls. Glucose production was affected in the same manner. 4. Fasting decreased (P less than 0.05) plasma insulin and T3 and increased T4. Both refeeding and a low-protein diet increased T3. Refeeding increased and a low-protein diet decreased insulin. 5. Chronic use (7-28 d of age) of either an alternating protein or intermittent feeding regimen caused greater responses compared with acute bouts (single cycle) of either of the regimens.