The use of intermittent lighting in broiler raising. 1. Effect on broiler performance and efficiency of nitrogen retention

The purpose of the present experiments was to compare the effects of the intermittent lighting schedule (IL) consisting of repeated cycles of 1 h light (L):3 h darkness (D) with a nearly continuous lighting schedule 23L:1D (CL) on the performance of floor-reared male and female broiler chickens. In addition, N balance trials were performed on caged broilers in order to assess their efficiency of dietary N retention. Changing from CL to IL at Day 7 was followed by a temporary reduction in feed intake and BW gain. However, IL males exhibited compensatory growth during the finisher period in such a way that at Day 41 (market age), a similar BW as that of their CL counterparts was attained. In contrast, IL females did not completely attain a BW equal to that of CL females by 41 d of age. Imposing IL reduced feed intake and improved feed conversion. Abdominal fat pad contents of broilers reared under IL were significantly smaller than those of CL broilers. From the N balance trials, it can be inferred that broilers reared under IL have an improved efficiency of dietary N retention, especially during the period of increased growth velocity. Imposing IL at Day 7 is associated with a temporary reduction in BW gain, followed by complete growth compensation of males by Day 41. Female broilers did not restore BW by this age. As a consequence of the altered growth trajectory, the manifestation of the fat growth wave is shifted to an older age together with an enhanced efficiency of N retention.