Effects of a low‐protein diet supplemented with essential amino acids on egg production performance and environmental gas emissions from layer‐manure composting in laying hens in the later laying period

Abstract We fed 330–545 day‐old laying hens (later laying period) a low‐protein diet supplemented with essential amino acids (LPS) and composted their manure. We then investigated the laying performance of the hens, the nitrogen balance and emission of nitrous oxide (N 2 O), methane (CH 4 ), and ammonia (NH 3 ) from the composting, and several characteristics of the finished compost. There were no significant differences in the egg‐laying rate, egg mass, egg weight, proximate compositions in egg yolk and egg white, or feed intake between the laying hens fed a Control diet (Cont) and those fed the LPS diet. However, the LPS‐fed hens had lower excreta levels and nitrogen excretion. In addition, the environmental gas emissions per layer from composting of the manure from the LPS‐fed laying hens were decreased by 9.7% for N 2 O, 40.9% for CH 4 , and 24.8% for NH 3 compared to the Cont‐fed laying hens. The concentrations of total nitrogen in the finished compost were similar between the LPS‐fed and Cont‐fed laying hens. In a vegetable‐growth test, the weights of komatsuna plants grown with compost from LPS‐fed and Cont‐fed hens were also not significantly different. Feeding an LPS diet to 330–545 day‐old laying hens was suggested to reduce environmental gas emissions from manure composting without affecting the egg production performance.