Ameliorative effects of different additives on growth, meat quality, and histological indices in heat-stressed broilers exposed to prolonged fasting

While 'fasting' is a common practice for reducing heat stress (HS) in broilers, it may negatively impact the birds' growth and other physiological functions. This study aimed to evaluate the beneficial effects of four different biological additives—prebiotic, probiotic, synbiotic, and betaine—on reducing HS as well as the negative effects of fasting in broiler chickens raised in the hot and humid conditions of Bangladesh. A total of 600 mixed-sex day-old chicks were divided into six treatment groups: T₁ = received a basal diet with no fasting and no supplementation (NF-NS); the other five groups underwent 8- h fasting, with T₂ = no supplementation (F8-NS), T₃ = ‘prebiotic’ supplement (F8-PRE), T₄ = ‘probiotic’ supplement (F8-PRO), T₅ = ‘synbiotic’ supplement (F8-SYN), and finally, T₆ = ‘betaine’ supplement (F8-BETA). Each treatment was replicated five times. All the birds were raised under identical care and management with ad libitum feed supply until the third week of age and subsequently underwent different treatment applications. Data on growth, carcass metrics, meat quality, gut histomorphology, and cost-benefit parameters were recorded and analyzed using SPSS. Results revealed significantly increased (P < 0.01) body weight, body weight gain, and better FCR with various supplementations compared to control (NF-NS or F8-NS) groups. The abdominal fat (%) was decreased, however, various meat quality indices, gut histomorphology, and the net profit per kg of live birds were significantly enhanced (P < 0.01) with the incorporation of different supplements. In conclusion, administering probiotics, synbiotics, and betaine via drinking water to broilers fasted for 8 h may effectively alleviate HS and the adverse effects of fasting, resulting in improved growth, carcass characteristics, and intestinal histomorphology in broilers raised in the hot and humid climate of Bangladesh. Of the four additives evaluated, the probiotic demonstrated better performance and economic return.