Effect of Physical Activities on Heat Production of White Leghorn Hens under Different Lighting Regimes

Abstract

Six Single Comb White Leghorn laying hens (Shaver, Star cross 288) were used to estimate heat production (HP) for physical activities under different lighting regimes (LR) of 12L : 12D, 14L : 10D and 16L : 8D, respectively, fed ad libitum at 25°C. HP of each hen was measured by an open circuit indirect calorimeter for 48 h in each LR. Activity count (ACT), standing time (STN) and eating time (ETN) were also measured for the same 48 h. ACT was measured by the Actigraph, while STN and ETN were detected by the infra-red beam switches. The daily food intake (FI) did not vary significantly with the increase of LR. The daily ACT and STN increased significantly (P <0.05) during 16L : 8D in comparison with that of 12L : 12D, and HP had an increasing tendency with the increase of LR. LR may have no clear effect on the increase of HP. Physical activities increased with the increase of LR. Consequently, HP was also increased with the increasing ACT and STN. But the increase of daily HP for ACT and STN was 7 and 8kJ/kg0.75, respectively, which is very little. ACT-related energy expenditure was approximately 22% of the daily HP. Similarly, the estimated energy expenditure for STN was approximately 21% of the daily HP. © 2002, Japan Poultry Science Association. All rights reserved.