CONICET | Buscador de Institutos y Recursos Humanos

In the present work we re-examine an apparent relationship between the performance of young broiler chicks in a T-maze and their later body weight, taking into account the body weight variations throughout the 7 weeks of breeding plus the gender (male or female) and season (summer and winter). The objective was to determine if selected birds showed differences in the body weight development, at what age are the differences found and if development is the same in both seasons. The time taken to traverse a T-maze and thereby regain visual contact with their companions was measured at 2 or 3 days of age. Chicks were then categorized according to whether they completed this task quickly (HP, high performance, < 25s), moderately (MP, moderate performance, among 25 - 75s) or more slowly (LP, low performance, >75s). Chicks were marked for identification and then housed in mixed-category flocks of approximately 2000 birds at commercial farm until they were 49 days old (slaughter age). One of these flocks was reared in winter and the other during the summer. In each of these flocks we weighed 90 birds of each sex and category at weekly intervals. There were no significant differences in body weight at 3 days of age between categories. Male HP chicks reared in summer were heavier (p<0,05) at 28, 42 and 49 days of age (4.9, 4.0 and 3.5% respectively) than the LP males; female HP chicks were also heavier (p<0,05) at 42 and 49 days of age (3.2 and 4.6% respectively) than LP ones. HP males also tended to be heavier than their LP counterparts in the winter flock but there were no significant differences. The superior growth rate of HP chicks might reflect a greater resistance to social and/or environmental stressors. If so, we might further predict that any problems that arose during breeding might be less likely to compromise their growth and well-being. In conclusion, the present findings suggest that early T-maze behavior might be a useful predictor of subsequent growth in broiler chicks.

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