Effects of dietary metabolizable energy and crude protein levels on laying performance, egg quality and fecal microbiota of Taihe Silky Fowl during the peak laying period

Objective: The experiment aimed to study the effect of dietary metabolizable energy (ME) and crude protein (CP) on laying performance, egg quality, serum routine biochemical and lipid metabolism indicators, the apparent digestibility of nutrients, and fecal microbiota of Taihe Silky Fowl (TSF) during the peak laying period. Methods: A total of 540 26-week-old TSF female fowls were randomly allocated to 9 groups with 5 replicates per group and 12 fowls per replicate. The fowls were fed with a 3×3 factorial arrangement of treatments diets (ME:10.88,11.30, or 11.72 MJ/kg; CP: 15, 16, or 17%). Results: With the increasing CP level, the egg weight (p = 0.023), egg production (p = 0.047), and egg mass (p = 0.022) enhanced, while the feed conversion rate (FCR) (p = 0.023) decreased. As the ME levels grew, the average daily feed intake (p<0.001) and FCR (p = 0.045) decreased. With enhanced ME, the triglycerides (p = 0.037), total cholesterol (p = 0.041), and high-density lipoprotein cholesterol (p = 0.028) increased, whereas the lowdensity serum lipoprotein cholesterol (p = 0.039) decreased. The apparent digestibility of CP increased as the ME level increased (p = 0.029) and as the CP level decreased (p = 0.027). At the same time, the apparent digestibility of gross energy increased as the ME level increased (p = 0.018). Different levels of ME or CP changed the composition of fecal microbiota, 17% CP increased the abundance of Bifidobacterium. Conclusion: It is suggested that 10.88 MJ/kg dietary ME and 17% CP level are suitable for the nutritional requirements of TSF during the peak laying period.