Abstract
Haematological studies help in understanding the relationship of blood characteristics to the environment. One of the major environmental factors influencing haematological indicators is season. This study was aimed at the variation in haematological profiles of two strains of laying birds at different seasons. We therefore evaluated the effects of genotype and season on the haematological profile in two strains of laying birds – Dominant brown (D-192) and Hyline brown in the tropics. A total of 50 birds per strain at 30 weeks of age were randomly selected for this study. Packed cell volume (PCV) and platelets were obtained using microhaematocrit whereas red blood cells (RBC) and white blood cells (WBC) were counted using a haemocytometer. The result obtained showed that there was a significant difference (P < 0.05) in the haematological profile of the birds in the two seasons compared (rainy and dry seasons). The haematological indices obtained during the rainy season had significantly higher mean values in packed cell volume (29.65 ± 0.32%), red blood cells (2.65 ± 0.03 × 1012/L), haemoglobin (100.1 ± 0.11 g/L) and eosinophil (2.5 ± 0.16%) while those obtained during the dry season had a higher significant effect on the white blood cells (19.16 ± 0.36 × 109/L). The results further revealed that between the strains, there was no significant difference (P > 0.05) in most of the indicators analysed but Hyline brown had significantly higher values (P < 0.05) of eosinophils and platelets. We concluded that the observed differences could be a result of genetic differences between the two strains of birds which gives room for selection and that the rainy season is more favourable for laying birds production under tropical condition.