Effects of tocopherol and age on physiological and blood parameters in growing broiler breeder cocks under humid tropical conditions

Abstract

This study evaluated the effect of tocopherol and age on the physiological and blood parameters of growing broiler breeder cocks. Day-old chicks (n=36) were randomly assigned to 4 treatments consisting 0, 50, 100, 150 mg tocopherol/kg feed. The experiment lasted for 12 weeks, phased into three (1-4, 5-8 and 9-12 weeks). Blood sampling for haematology and plasma biochemistry was done at age 4, 8 and 12 weeks. Data obtained were subjected to ANOVA in 4x3 factorial arrangement. Tocopherol had no significant (P>0.05) influence on heart (HR), respiratory rate (RR) and body temperature. However, age affected HR (P<0.001), RR (P<0.001), and breast (BT; P<0.001) and wing temperature (WT; P<0.05). Older cockerels had higher HR than the younger ones. RR decreased as age increased. Cockerels of 1-4 weeks had higher BT and WT than 5-8 weeks. Eosinophil (EOS) and monocyte were significantly (P<0.01) affected by tocopherol. EOS was lower in 50 mg/kg than others, except 100 mg/kg. Tocopherol decreased monocyte in dose-dependent manner. Age had significant effect on PCV (P<0.001), WBC (P<0.01) and EOS (P<0.001). Younger (4 weeks) cockerels exhibited higher PCV than older ones (8 and 12 weeks). WBC was higher in 4-week-old than in 12-week-old cockerels. Eight weeks cockerels had higher EOS than others. There was no significant (P>0.05) effect of dietary tocopherol on plasma biochemical parameters in cockerels but age affected plasma total protein (P<0.05), albumin (P<0.05), uric acid (P<0.001), creatine kinase (P<0.001) and creatinine (P<0.001). Eight-weeks-old cockerels had lower TP, ALB and CRE than 12-weeks-old. However, higher URI and CK activity were recorded in 8 than in 12-weeks-old. Interaction between tocopherol and age was not (P>0.05) significant in the physiological, haematological and biochemical parameters measured. In conclusion, 50mg tocopherol/kg feed may be efficacious in reducing skin temperature. Age as a factor affects thermoregulation and blood constituents in growing broiler breeder cockerels.