Effects of population size, floor space, and feeder space upon productive performance, external appearance, and plasma corticosterone concentration of laying hens.

Effects were studied of population size, floor area, and feeder space per hen on variables associated with egg production and corticosterone level. A total of 408 White Leghorn-type laying hens was used in this study. Three treatments were observed: 5 hens per cage with 8.6 cm feeder space per hen, 5 hens per cage with 12 cm feeder space per hen, and 7 hens per cage with 8.6 cm feeder space per hen. Both 5-hen treatments had 420 cm2 of cage area per hen, while the 7-hen treatment had 300 cm2. Increased population size, reduced feeder space, and reduced floor area per hen resulted in a significant (P less than .01) decline in percent egg production. Restriction of feeder space was correlated with reduced feed consumption and mortality but not feed conversion, weight gain, and egg size. As cage space allowance increased, feed consumption and weight gain were higher, whereas mortality, feed conversion, and egg weight were lower. No significant (P greater than .05) differences in shell thickness, specific gravity, Haugh unit, throat skin ateromata, claw length, and corticosterone level were observed. Plumage condition and foot health were improved only when floor area allowances increased.