This study aimed to investigate the effect of summer and winter on slaughter performance, muscle quality, flavor-related substance content, and gene expression levels related to the fat metabolism of pheasants. One-hundred 1-day-old pheasants were fed for 5 months starting in March and July and then, respectively, slaughtered in summer (August) and winter (December). The results revealed that compared with summer, winter not only increased pheasant live weight, dressed percentage, fulleviscerated yield, and muscle yield (p < 0.05) but also enhanced the activities of SOD and CAT in serum (p < 0.05). Winter significantly increased meat color, the contents of inosinic acid, and flavor amino acid in muscle. Amino acid contents in leg muscles of pheasants in winter were significantly higher than in summer except for histidine (p < 0.05). Winter increased the contents of muscle mono-unsaturated fatty acid, reducing saturated fatty acid. Summer improved fat synthesis in liver, promoted the deposition of triglycerides and cholesterol, and reduced the expression levels of fat metabolism-related genes in muscle, while winter increased the expression levels of genes related to muscle fat metabolism to provide energy for body and affect muscle fatty acid profile. Overall, pheasants fed in winter had better sensory quality and flavor than summer.

The high cost of feed and nitrogen pollution caused by high-protein diets have become major challenges restricting sustainable development in China's animal husbandry sector. Properly reducing protein levels and improving protein utilization in feed are effective approaches to solving this problem. To determine the optimal dose of methionine hydroxyl analogue chelated zinc (MHA-Zn) in broiler diets with a 1.5% reduction in crude protein (CP), a total of 216 1-day-old broilers were randomly assigned into 4 groups (each group consisted of 3 replications with 18 broilers per replicate), and growth and development indexes were assessed after 42 days. The broilers in control group were fed a basic diet, whereas those in the three test groups were fed diets with a 1.5% reduction in CP. The results showed no significant difference in the edible parts of broilers between low-protein (LP) diet group (90 mg/kg MHA-Zn) and normal diet group (p > 0.05), and adding 90 mg/kg MHA-Zn to LP diet significantly improved ileum morphology and apparent total tract digestibility (ATTD) of nutrient (p < 0.01; p < 0.05). A 16S rRNA sequencing analysis indicated that supplementing the LP diet with 90 mg/kg MHA-Zn was adequate for production performance of broilers and promoted beneficial bacteria in the cecum (Lactobacillus, Butyricoccus, Oscillospira, etc.) (p < 0.01). In summary, adding an optimal dose of organic zinc (90 mg/kg MHA-Zn) in low protein diets led to enhanced production performance of broilers and optimized cecum microbiota. Additionally, the reduction of crude protein consumption in broiler production proved to be a cost-effective measure, while also mitigated nitrogen pollutant emissions in the environment.

The high cost of feed and nitrogen pollution caused by high protein diets, which have become major challenges restricting sustainable development in China’s animal husbandry. Properly reducing the protein level and improving protein utilization in feed are a promising approach in solving this problem. To determine the optimal dose of methionine hydroxyl analog chelated zinc (MHA-Zn) in reduced 1.5% protein diets of broilers, total 216 1-day-old broilers were randomly allotted into 4 treatments and assess the index of growth and development at 42-days. Results showed no significant difference was observed for edible part between low protein (LP) diet group (90 mg/kg MHA-Zn) and normal diet group (P > 0.05), and adding 90 mg/kg MHA-Zn in LP diet significantly improved ileum morphology and apparent total tract digestibility (ATTD) of nutrients (P < 0.01; P < 0.05). A 16S rRNA sequencing analysis indicated that supplementing LP diet with 90 mg/kg MHA-Zn was adequate for production performance of broilers, it can promote beneficial bacteria of cecum (Lactobacillus, Butyricoccus, Oscillospira et al.) (P < 0.01). These findings will be useful for guiding organic Zn concentration optimization in LP of broilers to improve production performance through restoring the imbalance of intestinal microbiome under the premise of reducing environmental pollution.