Performance of brown layers fed reduced dietary protein levels in two rearing systems

ABSTRACT An experiment was conducted aiming to evaluate the effect of different levels of crude protein, based on the ideal protein concept and two rearing systems, on productive performance of brown laying hens. A total of 400 Hisex Brown laying hens between 30 and 45 weeks of age were distributed in a completely randomized design and a 2×4 factorial arrangement, with main effects including two rearing systems (cage and floor) and levels of crude protein (140, 150, 160, and 180 g kg−1), totalizing eight treatments. Five replicates with 10 birds each were used per experimental unit. The following parameters were evaluated: egg production, feed intake, body weight gain, feed conversion ratio, and quality traits such as dirty, cracked, or broken eggs. No interaction effect was observed between dietary protein levels and rearing systems for body weight gain, feed intake, egg production, egg weight, and feed conversion ratio. Feed intake and egg production were higher in the floor rearing system. Feed conversion ratio (kg/dz) was improved in birds reared in the cage system. The rate of cracked and broken eggs was higher in the cage system. The layers reared in the floor system produced a higher percentage of dirty eggs. The dietary protein level did not affect the evaluated parameters. Thus, we conclude that a floor rearing system is an option for layers, and the dietary protein level can be reduced up to 140 g kg−1 for Hisex Brown hens from 30 to 45 weeks of age.

摘要 本试验基于理想蛋白理念，设置不同粗蛋白水平与两种饲养系统，旨在评估其对褐壳蛋鸡生产性能的影响。试验选取400只30~45周龄的海塞克斯褐（Hisex Brown）蛋鸡，采用完全随机设计与2×4因子排列方案，主效应包含两种饲养系统（笼养与地面平养）以及4个粗蛋白质水平（140、150、160、180 g·kg⁻¹），共计8个处理组。每个试验单元设置5个重复，每个重复含10只试验鸡。本试验测定的指标包括产蛋率、采食量、体重增重、料重比，以及脏蛋、裂纹蛋、破蛋等蛋品质性状。结果显示，日粮粗蛋白水平与饲养系统的交互作用对体重增重、采食量、产蛋率、蛋重及料重比无显著影响。地面平养组的采食量与产蛋率更高；笼养组的料重比（kg/打）更优异，但裂纹蛋与破蛋率更高。地面平养组的脏蛋占比显著更高。日粮粗蛋白水平对本次试验测定的各项参数均无显著影响。综上，地面平养可作为蛋鸡饲养的可选方案，对于30~45周龄的海塞克斯褐蛋鸡，日粮粗蛋白水平可降至140 g·kg⁻¹。