Impact of low crude protein diets containing animal byproducts on growth performance, nitrogen excretion, meat yield, and quality in broiler chickens

This study examined the impact of a low crude protein (CP) diet incorporating meat and bone meal (MBM) as an alternative (AD) to standard diet, on broiler performance, nitrogen intake, excretion, and meat quality. A total of 846 male Ross 308 chicks were assigned to two diets in a randomized complete block design with 9 replicates of 47 birds/replicate. The diets were a plant-based control (20.4% and 19.5% CP) and an AD (-2.0% CP, +2.5% MBM) in the grower and finisher phases. Compared to the control, the AD reduced nitrogen intake (P = 0.01) and excretion (P < 0.01) while improving nitrogen retention efficiency (P < 0.001) without affecting body weight, feed conversion, or carcass yield. Breast yield was higher in the AD group (P < 0.001). The ultimate pH of breast meat increased slightly (P = 0.07), cooking loss decreased (P = 0.002), sarcoplasmic protein solubility tended to increase (P = 0.09) in the AD group, while muscle protein emulsifying properties remained unchanged. Breast meat proximate composition was not affected by the AD. In conclusion, the alternative diet can reduce nitrogen loss and emissions without negatively impacting broiler production, provided that amino acid requirements are met.