The Evaluation of Broiler Lines Divergently Selected for Water Conversion Ratio Under Acute and Chronic Stress

Water conversion ratio (WCR) in broiler production influences bird physiology, environment, and litter quality, and may provide potential solutions to environmental stressors. However, very little is known about how genetic selection for water conversion ratio can affect litter characteristics and performance parameters, specifically under heat stress conditions. This study evaluated the effects of genetic lines, environmental conditions, and time on litter and bird performance characteristics in high water conversion ratio (HWCR) and low water conversion ratio (LWCR) broilers. Live performance parameters, including body weight, water and feed intake, and litter samples, were collected from HWCR and LWCR broilers raised under heat-stress and thermal-neutral conditions. Litter dry matter percentage was greater in LWCR compared to HWCR. Litter pH differed by line and time, while nitrogen, phosphorus, and potassium concentrations increased over time. HWCR broilers exhibited greater feed and water intake, while heat stress reduced feed intake and body weight gain. Water intake, WCR, and water-to-feed ratio increased under heat stress, whereas feed conversion ratio did not differ significantly between genetic lines and environmental treatments. These findings indicate that genetic selection for improved WCR may influence litter moisture and resource utilization patterns, while nutrient accumulation largely reflects temporal deposition. Understanding how genetics and environmental conditions interact to shape litter quality and live performance may support strategies to improve animal health and welfare, address sustainability, and foster environmental stewardship in the face of increasing water scarcity.