Comparative analysis of the performance, egg quality and ovarian immune function of fast and slow feather strains in tianfu green shell laying hens at various stages of egg production

This objective of this experiment was to compare and evaluate the performance, egg quality, and immune function of Tianfu green shell laying hens with varying feather growth rates, in order to provide a reference for their rational utilization. A total of 120 one-day-old healthy Tianfu green shell laying hens were classified into the early-feathering (EF) and late-feathering (LF) groups through phenotypic identification of feather length and qPCR molecular identification. Each group was subdivided into four replicates, with 30 chickens in each replicate. Under the identical feeding and management conditions, the live weight, tibial length, egg production performance, egg quality, serum biochemical indexes, immune protein content, and the expression of related genes in uterine and ovarian tissues were assessed and analyzed. The results indicated that LF hens exhibited significantly greater live weights at 4, 16, 27, and 43 weeks (P < 0.05) and longer tibia lengths at 4 and 16 weeks (P < 0.05) compared to EF hens, suggesting enhanced early growth performance. Conversely, EF hens demonstrated superior egg-laying performance, characterized by a higher laying rate during both peak (27 weeks) and late (43 weeks) laying periods (P < 0.05), despite their eggs being lighter in weight (P < 0.05). Furthermore, EF hens exhibited the production of eggs with significantly thicker and stronger shells during the peak laying period (P < 0.05), while no notable differences were observed in other egg quality parameters. Immunologically, EF hens demonstrated elevated peak serum levels of IgA, IgG, and IgM compared to LF hens. Additionally, the expression levels of IFN-γ and interleukin 6 (IL-6) genes in the ovaries were markedly higher in EF hens. These findings indicate that although LF hens excel in early growth stages, EF hens exhibit superior egg production capabilities and enhanced immune responses.