Effect of overcrowding stress on haematological parameters of broiler chicken

The study was carried out to determine the effect of overcrowding stress on haemogram of six and eight week old caged broiler chicks in summer and rainy seasons of Kerala. Four week old broiler chicks were randomly divided into two groups with 12 birds in each group. The control group of birds (G-I) were provided with a floor space of 696 cm²/bird. In experimental group (G-II) the floor space of birds was reduced to 50% (348 cm²/bird). The haematological parameters such as total erythrocyte count (TEC), haemoglobin (Hb) concentration, packed cell volume (PCV), erythrocyte indices such as mean corpuscular volume (MCV), mean corpuscular haemoglobin concentration (MCHC) and mean corpuscular haemoglobin (MCH), as well as total leucocyte count (TLC) were estimated. Different leucocytes were counted in stained smears with fresh blood and their percentages, as well as Heterophil: Lymphocyte (H:L) ratio were calculated. The values of TEC, Hb, PCV, Erythrocyte indices, TLC, were not affected by the applied stress of overcrowding in both seasons. A significantly (P≤0.05) high heterophil count and low lymphocyte count were noticed in stressed birds in both summer and rainy seasons. The changes in eosinophil count were inconsistent. The basophil count of G-II birds was also high when compared to G-I birds. The H: L ratio was increased by overcrowding stress. The H: L value of eight week old overcrowded birds in summer was 0.81 indicating high stress in these birds. The high H: L ratio (0.81), heterophilia (43.75%) and basophilia (0.85%) observed in overcrowded birds during summer was indicative of high stress with high stocking densities.