Effect of Crowding and Cage Shape on Productivity and Profitability of Caged Layers: A Survey

We studied research published between 1971 and 1983 on the effects of crowding and cage shape on performance of layers. Three density categories were selected for analysis based on cage floor area per hen: 1) low, ranging from 432 to 561 cm2, averaging 516 cm2; 2) medium, ranging from 355 to 426 cm2, averaging 387 cm2; and 3) high, ranging from 271 to 348 cm2, averaging 310 cm2. Comparisons were made of exactly reversed, deep vs. shallow cages and not exactly reversed, deep vs. shallow cages. Although direct comparisons of all three densities were seldom available within studies, the overall results suggest a curvilinear relationship with performance traits decreasing more rapidly at higher densities. Reducing floor space per hen from an average of 387 cm2 (medium) to 310 cm2 (high) reduced eggs per hen housed by 16.6 (P<.001), increased mortality 4.8% (P<.001), decreased feed consumption 1.9 g/hen/day (P<.05), and increased feed consumption per dozen eggs by 68 g (P<.001). Data from the comparison of 516 cm2 (low) vs. 387 cm2 (medium) showed the increase in crowding reduced egg production by 7.8 eggs per hen housed (P<.01), increased mortality by 2.8% (P<.05), and decreased feed consumption/hen/day by 4.3 g (P<.05). Egg production was significantly (P<.05) affected by cage shape. Hens in shallow cages produced 5.8 more eggs per hen housed than those in deep cages.