Sex differences in the effect of intermittent compared with continuous light on growth rate, testes and body weight of broilers reared under commercial conditions.

The effect of intermittent light (IL) on the growth of broilers was tested under commercial conditions. One-d-old chickens were subjected to continuous light (CL) until 7 d of age and then received either CL or 7.5L:4.5D:7.5L:4.5D until 53 d. Body and testes weights were measured. At 53 d of age, the mean body weight of males was greater on IL than on CL; for females there was no difference. The testes of males on IL weighed more than those on CL. Growth of broilers was greater (P less than 0.05) at 35, 49 and 53 days of age if light was provided continuously from hatch to 7 d of age and then switched to IL than those remaining on CL during the entire periods.