Dry season juvenile growth and physiological parameters in exotic and Nigerian indigenous chicken

Abstract

This study evaluated early growth and plasma hormonal profile in exotic strains of broiler and Nigerian indigenous chicken. A total of 1200 hatching eggs, 300 each from four strains of chicken were used for this study. The strains included the Nigerian indigenous chicken (NIC), the Arbor acre, Hubbard, and Marshall broiler strains. Chicks weights were monitored weekly. Blood samples were collected at hatch (day-old), weeks 1, 2, 3 and 4 post-hatch for triiodothyronine (T 3 ) and corticosterone level determination. The chicks were randomly distributed into four rearing pens for a 28-d assessment of growth rate. Results showed that the body weights (g) in the broiler strains were higher than that of the NIC throughout the rearing period. There was no significant difference (p>0.05) in the levels of T 3 at day-old and at week 1 until later in the growth phase. Corticosterone levels did not differ significantly at day-old but became different from week 1 post-hatch. The levels of T 3 were not statistically different in the first week of growth. In the second week of post-hatch growth, there was a statistical difference in the levels of T 3 among the four strains of chicken. The level in the NIC was comparable (p<0.05) to those of Arbor acre and Marshall strains. The level in the Hubbard was significantly lower than that of the NIC, Arbor acre and Marshall. In the third week of growth, the level in the NIC was similar to that of Marshall strain and higher than those of Hubbard and Arbor acre strains. This study showed that at hatching, there was no difference (p>0.05) in the metabolic rate and the stress level among the strains of chicken as shown by the levels of T 3 and corticosterone respectively. The day-old chick weight and the weights in subsequent weeks post-hatch were smaller in the NIC than the broiler strains possibly as a result of low hatching weight. The early growth difference could not be explained by physiological parameters such as T 3 and corticosterone. However, the differences in post- hatch physiological and metabolic parameters may be due partly to genetic differences.