Coronary Arterial Lesions in Chickens

Abstract

Single-comb, Hy-line white leghorns were hatched in one lot, brooded in one flock through 7 weeks, then assigned randomly to cages in one large room with 15 hours of light per day. The birds were studied in the following situations: a) separately caged cocks and hens, b) paired cocks and hens, and c) 3 cock-3 hen groups and 6 cock-6 hen groups. Basic space allowance was 2 square ft per bird which was increased to 8 square ft for some of the larger groups. Commercial rations and water were supplied ad libitum. Stenosing lesions of the intramural coronary arteries began development in cocks and hens before age 7 weeks (10 to 12 weeks before sexual maturity) and progressed with age. Progress, as measured by heart scores, was not influenced by space allowance but was related to social situation. The rate for separately caged cocks was significantly higher than for other birds. Cocks of the larger groups and cocks of the pairs were next in order, while heart scores for cocks of the smaller groups were third but not significantly higher than for grouped hens. Heart scores of grouped hens sometimes exceeded heart scores for cocks of corresponding groups. High mean heart scores for grouped cocks correlated with high mean heart scores for hens of their groups, and low heart scores for grouped cocks with low scores for hens of their groups.