LAYER PERFORMANCE IN COLONY CAGES AS RELATED TO STOCKING DENSITY AND POPULATION SIZE

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Abstract
Two commercial strains of White Leghorns were each measured for egg production, egg quality, feed efficiency and net egg income over feed and bird costs. The birds were in populations of 18, 24 and 30 per colony cage each at densities of 310, 387 and 464 cm2 per bird. In addition, a 10th population–density combination of 24 birds, caged singly at 619 cm2, served as controls. A total of 3,840 birds were measured for 60 wk in two tests, each with four replications. Results were also related directly to an earlier experiment with populations of 3, 6 and 12 birds per cage at the same densities. The performances of populations of 18, 24 and 30 birds were equal and poor relative to the controls. All three populations at 387 cm2 per bird were superior to those at 310 cm2 and equal to 464 cm2 in egg production and net egg income. In comparisons with more conventionally caged populations of 3, 6 and 12 birds, colony caged layers yielded significantly (P < 0.01) fewer eggs and less net egg income. Mortality was significantly (P < 0.05) greater for colony caged layers. It was concluded that the general high level of stress in colony cages prevented the expression of declining performance normally expected with population increases, yet effects due to density were still evident.

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