Effects of population density on layer performance.

Four experiments were conducted to study the effects of population density on layer performance. in each experiment, 20-wk--old White leghorn pullets were housed in 30.5 x 50.8 cm cages at the rate of one, two, three, and four birds per cage for Treatments 1, 2, 3, and 4, respectively. in Experiment 4, there were three additional treatments: for Treatments 5, 6, and 7, birds were placed into identical cages (30.5 x 50.8 cm) at the rate of three, two, and three birds per cage, respectively, at 20 wk of age. At 28 wk of age, one bird was removed from each cage in Treatment 5, and one bird was added to each cage in Treatments 6 and 7. In the first three experiments, all eggs that were collected for 2 consecutive d every 8 wk starting at 28 wk of age were used to measure egg traits. In Experiment 4, egg traits were determined once at 52 week of age. Birds at the highest population density had the lowest percentage hen-day egg production and had one of the poorest feed efficiencies. Egg production was negatively correlated (P < or = .01, Experiments 1, 2, 3; P < or = .05, Experiment 4) with population density. Feed required to produce a dozen eggs was positively correlated (P < or = .01, Experiments 1, 2; P < or = .05, Experiment 3) with population density in three out of the four experiments. The addition or removal of a cage mate to or from a multiple-bird cage in Experiment 4 did not (P > .05) affect egg production or feed efficiency. Final BW, mortality, and egg weight were not (P > .05) affected by population density. Only in one out of the four experiments was feed consumption (Experiment 1), eggshell thickness (Experiment 2), or albumen height (Experiment 3 lowered (P < or = .05) by having more than one bird per cage. This study showed that increasing population density decreased laying performance of the birds.