Effects of lighting regimen on metabolic rate in broilers.

Abstract

From hatching to 42 days old, 80 broilers were exposed to varying periods of light (L) and dark (D) within 4-h periods (0.5L to 1.5L and 3.5D to 2.5D). Effects of lighting regimen (LR) and trough position (open (F2) compared with closed (F1)) during D-periods on heat production (H), activity-free (H_acf) and activity-related H (H_ac), and respiratory quotient (RQ) were evaluated. At 0.5L and 0.67L, H_ac was less than in the longer L-periods. The longer the L-period, the less active broilers were at the end of a L-period. In D-periods with F1, H and H_acf decreased more than with F2, while H_ac was similar. After D-periods with F1, H and H_acf increased more than after D-periods with F2. This effect on H was greatest in short L-periods with F1. With 0.5L:3.5D and F1, broilers did not have enough feeding time, because at the end of the L-period afterwards, H and RQ were lower than with the longer L-periods. Thus, broilers will eat feed in the dark and the length of L-period may not be crucial, because in practice, feed will remain available in the dark. (Abstract retrieved from CAB Abstracts by CABI’s permission)