Abstract
Heat-stress is one of the major factors militating against poultry production particularly in the tropics, such as Nigeria. Supplementation of vitamin C, which is an antioxidant, has been used to reduce effects of heat-stress in poultry. Therefore, a four-week experiment was designed to assess the effects of vitamin C on heat-stressed finisher broiler chickens at Ibadan, Oyo State, Nigeria. Seventy two 4-week old unsexed Arbor Acre finisher broilers were used during January and February. They were randomly allotted to three groups replicated thrice including T1 (control), T2 (heat) and T3 (heat + 100 mg/kg vitamin C) in a completely randomized design. Each replicate had eight birds. They were acclimatized for one week and given Finisher Top Feed® and clean water ad-libitum during the experiment. T2 and T3 groups were subjected to heat-stress by covering 3 out of 4 sides of rectangular pens and the heat sustained by two 100 watts electric bulbs per pen during the night. Daily feed intake and weekly weight gain were recorded throughout the experiment. On the 28th day, 3 ml of blood was aspirated from any 3 birds per replicate for haematological analysis. Data were analyzed and Duncan’s test was used to separate significant means. Results showed no significant effect (P>0.05) on daily weight gain and feed conversion ratio but a decrease in feed intake by T2. Mortality was significantly high (P<0.05) in T2 compared to T1 and zero in T3. Haematological parameters showed no significant difference (P>0.05) but for white blood cells where T3 differed (P<0.05), heterophils and heterophil/lymphocyte (H/L) ratio where T2 significantly (P<0.05) differed, and basophils with significantly (P<0.05) higher T2 and T3. In conclusion, 100 mg/kg vitamin C had no effect on growth but improved feed intake, and reduced mortality. It enhanced leucocyte count, and reduced heterophils and H/L ratio that were elevated by heat-stress.