Optimizing Daytime Feed Withdrawal Duration to Modulate Thermophysiological and Metabolic Responses of Broiler Chickens Under Tropical Heat Stress

Abstract

Heat stress remains a major constraint on broiler production in tropical environments, necessitating practical, cost-effective mitigation strategies. This study evaluated the effects of daytime feed withdrawal during peak heat periods on growth performance, thermophysiological responses, metabolic indices, antioxidant status, and welfare of broiler chickens. A total of 240 Ross male 308 broilers were reared under standard conditions until 21 d of age and subsequently assigned to four treatments: ad libitum feeding (AD) or feed withdrawal for 2 h (THW; 12:00–14:00), 4 h (FHW; 12:00–16:00), or 6 h (SHW; 12:00–18:00) daily during the hottest period of the day. Feed withdrawal significantly reduced feed intake (P < 0.05) but improved feed conversion ratio, particularly in the FHW and SHW groups, without affecting final body weight or weight gain. Thermophysiological indices were improved, as evidenced by lower rectal temperature in feed-withdrawn birds, with the most pronounced effects observed in the SHW group. Serum biochemical responses indicated adaptive metabolic adjustments, including reduced glucose concentrations and increased lipid mobilization in feed-withdrawn birds. Antioxidant defense was enhanced, with significantly higher superoxide dismutase, catalase, and glutathione peroxidase activities compared with the control, while lipid peroxidation remained unchanged. Feed withdrawal also modulated endocrine responses, as reflected by reduced triiodothyronine and corticosterone concentrations. Hematological parameters, including packed cell volume and hemoglobin, improved with longer withdrawal durations, suggesting enhanced oxygen-carrying capacity and physiological resilience. Welfare indicators and most carcass traits were not adversely affected. Overall, strategic feed withdrawal during peak heat periods improved thermoregulatory efficiency, antioxidant status, and feed utilization without compromising growth performance. A withdrawal duration of 4–6 h appears most effective under tropical conditions. These findings highlight feeding-time manipulation as a practical strategy to mitigate heat stress and enhance sustainability in broiler production systems.