Effects of anti-heat diet and inverse lighting on growth performance, immune organ, microorganism and short chain fatty acids of broiler chickens under heat stress.

The present study investigated the effects of night restricted feeding of extreme heat diet (EHD) containing heat stress resistance nutrients, with inverse lighting program, on their growth performance in broiler chickens exposed to extreme heat stress (33 ± 2°C). EHD 1 contained soy oil, molasses, methionine and lysine. EHD 2 contained all nutrients of EHD 1 and vitamin C additionally. Three hundred broiler chickens (Ross 308) were randomized into four dietary treatment groups according to a randomized block design on the day they were hatched. The treatment groups were: T1 (EHD 1, 10:00-19:00 dark, 19:00-10:00 light), T2 (EHD 2, 10:00-19:00 dark, 19:00-10:00 light), T3 (EHD 1, 09:00-18:00 dark, 18:00-09:00 light) and T4 (EHD 2, 09:00-18:00 dark, 18:00-09:00 light). The body weight gain of the broilers increased most significantly in T2, followed by T1, T4 and T3 (p < 0.05). Weights of the immune system, thymus and bursa of Fabricius recorded higher in T1 and T2 than in T3 and T4. The spleen was higher in T1, T2 and T3 than in T4 (p < 0.05). Blood triglyceride, total cholesterol and blood sugar were higher in T1 and T2 than in T3 and T4 (p < 0.05). LDL-C recorded high in the order of T4, T3, T2 and T1, but HDL-C showed the inverse order (p < 0.05). IgG, IgA and IgM were higher in T1 and T2 than in T3 and T4, however, the corticosterone concentration showed the inverse order (p<0.05). Lactobacillus in feces was higher in T1 and T2 than in T3 and T4, but total aerobic bacteria, E. coli, Coliform bacteria was higher in T4 and T3 than in T2 and T1 (p < 0.05). Contents of acetic acid, propionic acid and total Short chain fatty acid were significantly higher in the order of T2, T1, T3 and T4. Butyric acid, isobutyric acid, valeric acid and isovaleric acid were higher in T4 and T3 than in T1 and T2 (p < 0.05).