Haematology and hormonal assay of heat-stressed broiler chickens managed by feather clipping and ascorbic acid supplementation

Abstract

Introduction: High ambient temperature (HAT) induces stress in birds and affects their wellbeing. This study investigated the haematology and serum levels of corticosterone, triiodothyronine and thyroxine of heat-stressed broilers managed by feather clipping (FC) and ascorbic acid (AA) supplementation. Methods: One hundred Anak broiler chicks were distributed into five treatments of 20 chicks each in 2 replicates and were all fed basal diets. The positive control (PC) birds were intact (not feather clipped) and managed under controlled (28 – 30℃) environment. Other groups were managed in open pen under HAT (43.0 ± 2.0℃). The negative control (NC) birds were intact. The treatment 1(T1) birds were feather-clipped, the treatment 2 (T2) groups were intact, together with 200 mg AA/kg feed supplemented while the treatment 3 (T3) birds were feather-clipped and fed with 200mg AA supplemented feed. Data were analysed using ANOVA. Results: The results showed that feather clipping and AA supplementation did not affect blood parameters of the birds except white blood cell count and heterophil-lymphocyte ratio. The levels of the three hormones differed significantly (P <0.05) in the PC group compared to HAT-exposed groups. Corticosterone levels decreased in T1 (8.20 ng/mL) and T3 (7.99 ng/mL) significantly against 9.70 ng/mL in NC, the lowest value of 7.88 ng/mL was recorded in PC. Triiodothyronine (4.04 ng/mL) and thyroxine (11.29 ng/mL) levels were highest in PC, lowest triiodothyronine (2.78 ng/mL) and thyroxine (7.97 ng/mL) concentrations were recorded in NC and T1 groups respectively. Significance: Therefore, feather clipping and/or AA supplementation ameliorated adverse effect of extreme heat in the broiler chickens.