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.

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 (N2 O), methane (CH4 ), and ammonia (NH3 ) 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 N2 O, 40.9% for CH4 , and 24.8% for NH3 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.

Conexibacter arvalis sp. nov., isolated from a cultivated field soil sample.

Two bacterial strains, designated KV-962(T) and KV-963, were isolated from soil collected from a field in Japan. Cells of both strains were Gram-staining-positive, non-spore-forming, short rod-shaped and motile. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these strains were related to Conexibacter woesei DSM 14684(T), with a similarity value of 98.6 %. These strains possessed MK-7 (H(4)) as the sole menaquinone and contained C(18 : 1)ω9c, C(17 : 1)ω6c and iso-C(16 : 0) as the major fatty acids. On the basis of genotypic and phenotypic characteristics, strain KV-962(T) and KV-963 were indicated as a novel species of the genus Conexibacter, for which the name Conexibacter arvalis sp. nov. is proposed. The type strain is KV-962(T) ( = DSM 23288(T)  = NBRC 106558(T)).