Effect of Dietary Energy Levels on Performance of Laying Hens in the Hot-Humid Climate of Cross River State

This study examines the effect of different dietary energy levels on the production performance of laying hens under the hot-humid climatic conditions of Cross River State, South South Nigeria. Heat stress in tropical environments increases maintenance energy requirements and reduces voluntary feed intake in laying hens, potentially creating a mismatch between energy supply and the demands of egg production. Optimising dietary energy density for hot-humid tropical conditions is therefore important for maintaining egg production efficiency. This study uses a completely randomised design testing three metabolisable energy levels: 2,600, 2,750, and 2,900 kilocalories per kilogram in isonitrogenous layer mash diets fed to 90 Isa Brown laying hens allocated in groups of 30 birds per treatment at Cross River University of Technology teaching farm in Calabar. Ambient temperature, feed intake, water intake, body weight, hen-day egg production, egg weight, egg mass, feed conversion efficiency, and egg quality are measured over 16 weeks. Findings reveal that hens fed the 2,750 kilocalorie diet show the highest egg mass production of 56.8 grams per hen per day, while the 2,600 kilocalorie diet reduces performance significantly during peak afternoon heat periods. The 2,900 kilocalorie diet produces similar performance to 2,750 but at higher feed cost. Water intake increases significantly with ambient temperature above 32 degrees Celsius at all energy levels. The study concludes that 2,750 kilocalories per kilogram is the optimal energy density for laying hens in Cross River State's hot-humid environment and recommends electrolyte supplementation during extreme heat periods.

Keywords: dietary energy, laying hens, heat stress, egg production, Cross River State.