Diurnal rhythms of cloacal temperature in broiler chickens administered with graded levels of Bactofort® during the cold-dry (harmattan) season

Abstract

ABSTRACT The study evaluated the effects of graded levels of Bactofort® on cloacal temperature fluctuations in broiler chickens during the cold–dry season. Complete randomised sampling was used to assign 225 broiler chicks into 5 groups with 3 replicates. The broiler chicks from Group I were fed a basal diet without Bactofort® supplementation, Group II 0.25 g of Bactofort® per kg of feed, Group III 0.35 g of Bactofort® per kg of feed, Group IV 0.45 g of Bactofort® per kg of feed and Group V were fed 0.55 g of Bactofort® per kg of feed. Beginning from day old, the treatment groups were fed with Bactofort® supplementation daily for 6 weeks. Dry-bulb temperature (DBT), relative humidity (RH) and temperature–humidity index (THI) inside the pen and cloacal temperature of each broiler chick were obtained hourly over a 12-h period from 06:00 to 18:00 h (GMT + 1), on days 28 and 42 of the study. Mean values of DBT (32.00 ± 0.42°C), THI (29.55 ± 0.60) and RH (43.27 ± 0.79%) obtained inside the poultry house were outside the thermoneutral zone for broiler chickens, and suggestive of thermal stress. The administration of Bactofort® in the treatment groups decreased the mean and amplitude and increased the robustness of cloacal temperature on days 28 and 42. Overall, the mean of cloacal temperature in the control group (42.00 ± 0.20°C) was higher (P < 0.0001) than those of the Bactofort®-treated groups at the dosages of 0.25 g/kg (41.06 ± 0.15°C), 0.35 g/kg (40.94 ± 0.10°C), 0.45 g/kg (40.92 ± 0.08°C) and 0.55 g/kg (40.80 ± 0.09°C). In conclusion, Bactofort® administration stabilised cloacal temperature of broiler chicken on days 28 and 42 by decreasing its values. The use of the probiotic may be beneficial in modulating diurnal rhythm of cloacal temperature and reducing adverse effects of thermal stress on broiler chickens.