Leg deformities: inability to increase severity by increasing body weight of chicks and poults.

Five 4-week experiments were conducted to determine the effects of body weight on the severity of leg deformities in broiler chicks and turkey poults reared on raised wire floors. In order to make the influence of body weight independent of genetic, environmental, and nutritional effects, increasing body weight was achieved by harnessing steel weights on the backs of poults and chicks. In the first experiment, 3-day-old male and female chicks were harnessed with 0-, 1-, 2-, or 3-g weights (nine chicks per weight load). Weights were changed every 3 to 4 days until 4 weeks of age such that the artificial weight averaged 0, 3, 4.5, or 8.5% of their body weight. In Experiments 2 and 3, three replicates of 10 female chicks were assigned to isocaloric diets containing 18, 21, or 24% crude protein. Five chicks in each treatment and replicate were harnessed at 3 days of age with weights averaging approximately 13% of their body weight. Weights were changed weekly. Experiments 4 and 5 were designed similar to Experiments 2 and 3 except that male and female turkey poults were fed 22, 25, or 28% dietary crude protein and were harnessed with weights equal to about 8 to 10% of their body weight. Body weights of the birds were recorded weekly.(ABSTRACT TRUNCATED AT 250 WORDS)