This study evaluated the effects of dietary supplementation with N-Carbamylglutamate (NCG) on growth performance, immune function, intestinal metabolites, and microbiota in Danzhou chickens. In a 35-day feeding trial, a total of 480 one-day-old female chicks were randomly assigned to a control group (basal diet) and three experimental groups supplemented with 400, 800, or 1200 mg/kg NCG, with 120 chicks in each group (n = 120). The results demonstrated that NCG, particularly at 400 mg/kg, significantly improved growth parameters, including average daily gain and feed conversion ratio, while enhancing immune function by increasing serum levels of immunoglobulins (IgA, IgY) and malate dehydrogenase (p < 0.05). Metabolomic analysis revealed that NCG modulated key pathways such as sphingolipid metabolism and mTOR signaling pathway, leading to significant changes in metabolites including L-arginine, ceramide, and docosahexaenoic acid (p < 0.05). 16S rDNA sequencing indicated that NCG induced structural shifts in the gut microbiota, primarily affecting Bacteroidota and Firmicutes, with several bacterial genera showing strong correlations with the observed metabolic changes (p < 0.05). Mechanistically, NCG promotes growth by facilitating arginine synthesis via the urea cycle and activating the mTOR signaling pathway, while its regulation of sphingolipid metabolism enhances immunomodulatory capacity. In conclusion, NCG enhances feed efficiency and immune competence by orchestrating the gut microbiota-metabolite network, demonstrating its potential for poultry production.

This study assessed the impacts of dietary net energy (NE) levels on growth performance, meat quality and intestinal health in Tunchang Black pigs. Forty-eight pigs with an initial body weight of 11 kg were allocated into four groups and fed diets containing 10.65 (N1), 10.15 (N2, control), 9.65 (N3) and 9.15 (N4) MJ/kg NE respectively over a 42-day experimental period. The N4 group presented lower average daily gain and carcass weight relative to the N1 group, while no significant differences in growth performance were detected between N2 and N3. The N3 group displayed superior meat quality characteristics, manifested as decreased contents of saturated fatty acids (C10:0, C12:0), elevated selenium concentration, upregulated expression of slow-twitch myosin heavy chain (MyHC I) and downregulated expression of fast-twitch MyHC IIb, alongside increased ileal occludin expression. Moreover, the N3 treatment improved antioxidant capacity, as reflected by higher serum GSH and SOD levels and lower serum MDA content. In conclusion, decreasing dietary NE from 10.15 to 9.65 MJ/kg exerted no detrimental influence on growth performance yet effectively ameliorated meat quality, antioxidant status and intestinal barrier function in Tunchang Black pigs.

Poultry nutrition simultaneously affects animal health, productive efficiency, product quality and the environmental burdens associated with feed production and manure management. Nutritional interventions may generate synergies among these outcomes, but they can also shift costs or environmental impacts across biological and supply-chain boundaries. This review critically evaluates low-protein diets, functional additives, feed enzymes, alternative protein sources, precision-feeding technologies and nutritional approaches to manure-emission mitigation. The evidence indicates that improved intestinal function and nutrient retention can reduce feed requirements and nutrient excretion, whereas excessive protein restriction, unstable additive responses, limited alternative-ingredient supply and poorly validated digital systems may compromise performance, product quality or economic feasibility. Environmental benefits are also sensitive to ingredient origin, processing, transport, crystalline amino acid and additive manufacture, coproduct allocation and life cycle assessment assumptions. To integrate these considerations, we propose a four-level conceptual decision framework comprising physiological adequacy, precision nutrient supply, constraint-specific functional intervention and whole-chain verification. The framework treats health, productive performance, product quality, economic feasibility and environmental impact as simultaneous decision criteria, while genotype, production stage, disease pressure, climate, ingredient availability and market objectives define the conditions of application. Standardized life cycle assessment and commercial validation are required to distinguish reproducible net benefits from improvements confined to individual indicators. This approach provides a structured basis for selecting poultry nutritional strategies that remain biologically effective, economically accessible and environmentally beneficial under practical production conditions.