EFFECTS OF MELATONIN ADMINISTRATION ON MORTALITY AND ECONOMICS OF BROILER CHICKENS EXPOSED TO CONTINUOUS LIGHTING AND HEAT STRESS

Abstract

This study was conducted to determine the impact of continuous lighting and heat stress on the mortality and economics of broiler chickens, administered with melatonin during the hot-dry season. Broiler chicks were assigned randomly into three groups, comprising 100 chicks each. Group I was raised under natural photoperiod of 12-h light and 12-h darkness, without melatonin supplementation. Group II was kept under 24-h continuous lighting, without melatonin administration. Group III was raised under 24-h continuous lighting, with melatonin supplementation at 0.5 mg/kg per os, via drinking water. Melatonin was administered once daily for 42 consecutive days at 17:00 h. The weekly mean temperature-humidity index recorded inside the poultry house was lowest at week 4 of the study, with the value of 48.60 ± 0.08 "C; but highest at week 1, with the value of 53.48 ± 0.97 °C (P<0.0001). Groups I, II and III had overall mortality of 5, 6 and 1 %, respectively. The highest profit value of 667:55 was obtained in group III broiler chickens, administered with melatonin. In conclusion, oral administration of melatonin may enhance adaptation to heat stress and productivity of broiler chickens in the tropical zones of the world.