Effect of Age and Season on the Growth of some Endocrine and Lympho-Epithelioid Glands in Nigerian and White Leghorn Pullets

Résumé

THE endocrine glands (pituitary, adrenal, thyroid), and thymus and bursa of Fabricius of Nigerian und White Leghorn pullets were studied from 2 weeks to 32 weeks of age in the wet and dry seasons of Nigeria. Pituitary weights were significantly (P <0.005) greater in the wet season-reared than in the dry season — reared birds. Adrenal weight differences due to breed were significant, but had no significant influence on this parameter, Nigerian pullets had significantly (P <0.005) greater thyroid Weights (absolute and relative) than the Leghorns, and the absolute weights were also significantly (P <0.05) higher in the wet that in the dry season. The differences in thymus weights between breeds and seasons were not significant but the interaction between season and age, and between breed and age were highly significant (P < 0.005). The relative thymus weights were generally and significantly greater (P ... 0.0005, in the Nigerian than in the Leghorn pullets. The interaction between age and season and between breed and age were also highly significant [P <0.005] in respect to the bursa. The effect of season and breed on the growth of the bursa was also highly significant (p <0.005). The possible significance of these findings in relation to the general physiology of the two breeds of chicken were discussed.