Influence of toe-clipping and stocking density on laying hen performance.

Three experiments were conducted to investigate the influence of toe-clipping and bird density on laying hen performance. Toe-clipping was done on day-old chicks by removal of the digital claws from the front toes. Toe-clipped (TC) and intact (IN) pullets were assigned randomly to laying cages (Experiments 1 and 2, 19 weeks of age) or housed in similar body weight groups (Experiment 3, 18 weeks of age) at caging densities of either 4 (465 cm2/hen) or 5 (372 cm2/hen) hens per cage. Experiment 3 body weight groups were: heavy (greater than or equal to 1475 g), medium (greater than or equal to 1375 g, but less than 1475 g), light (greater than or equal to 1275 g, but less than 1375 g), and extra light (less than 1275 g). Body weights were determined at various ages during the grow-out and egg-laying periods. Beginning at 22 weeks of age, average daily egg weight, feed consumption, feed conversion, hen-day egg production, and mortality measures were made for 12 periods of lay of 28 days each. In Experiments 1 and 2, IN pullets were consistently heavier throughout the grow-out period and consumed significantly more feed during the egg laying period than TC birds. Significantly greater average daily egg weights were found in IN than in TC hens in Experiment 1 but not in Experiment 2. Increasing the number of hens from 4 to 5 hens per cage resulted in a significant reduction in feed intake and body weight gain in Experiments 1, 2, and 3. In Experiment 1, mean daily egg weight was significantly increased (.11 g) upon crowding. In Experiment 2, crowding elevated mortality. In Experiments 1 and 2, but not 3, a significant toe treatment by bird density interaction was observed for hen-day egg production. The IN birds had lowered hen-day egg production rates when crowded than when they were afforded more space, whereas hen-day egg production was elevated in crowded TC hens when compared to TC hens housed at the less crowded density. In Experiment 3, an initial (4 weeks of age) significant depression in pullet body weight was found in the TC pullets but disappeared by the 8th week. Feed usage was also significantly greater in IN than in TC hens in Experiment 3. Toe treatment did not affect any other hen performance variable measured. Egg weight, feed intake, and feed conversion measures varied by body weight groups. In general, the heavier hens consumed more feed and laid heavier eggs, but they were less efficient in converting feed into eggs.