To explore high-quality phage resources for controlling Enterococcus faecalis (E. faecalis) contamination, a virulent phage vB-Efa1 was isolated and purified from poultry slaughterhouse sewage in this study. Its biological characteristics, whole-genome features, and potential in ensuring poultry product processing safety were systematically investigated. The phage belongs to the Siphoviridae family, with an optimal multiplicity of infection (MOI) of 0.1 and a titer of 8.87 lg PFU/mL; it has a 30 min latent period and stable lytic activity, retaining good stability at 25–37 °C, pH 6–8, and 4 °C. Its circular whole genome is 166,586 bp in length with a GC content of 35.46%, encoding 276 genes; no antibiotic resistance genes were detected, and only one low-pathogenic-risk virulence-related sequence was identified. Application tests in poultry products revealed that temperature is the key factor regulating phage titer: the titer stably maintained 5.5–6.6 lg PFU/mL at 4 °C, while proliferating significantly at 25 °C, reaching 7.55–8.38 lg PFU/mL at 12 h. Collectively, vB-Efa1 exhibits superior biological traits, environmental adaptability, and biosafety, making it a promising biocontrol candidate for mitigating E. faecalis contamination in poultry products.

Herein, 364 one-day-old male Jiangnan white goslings were divided into four groups: PM (18.55% crude protein (CP) + main amino acids (AA)), PA (18.55% CP + all AA), LPM (15.55% CP + main AA), and LPA (15.55% CP + all AA). The main AAs were Lys, Met, Thr, Trp, Arg, and Cys, while all AAs included an additional six (Met, Lys, Arg, His, Ile, Leu, Cys, Phe, Tyr, Thr, Trp, and Val). At 28 days, all geese were switched to a 15.55% CP + main AA diet until 63 days. The results showed: (1) No significant impacts on average daily gain or feed-to-gain ratio at 29-63 days. Although numerical differences in average daily feed intake (ADFI) were observed between groups, statistical analysis indicated that the reduction in ADFI due to early low protein was marginal (P = 0.06). This suggests that the dietary protein level may influence feed intake patterns in goslings, but further studies with larger sample sizes are needed to confirm this effect. (2) Early low protein significantly affected abdominal fat percentage and leg muscle cooking loss at 63 days (P < 0.05). Pretreatment affected breast muscle rate at 63 days (P < 0.05). (3) Early low protein significantly increased Cys content in breast muscle at 63 days and increased Asp, Thr, Cys, and His in feces at 62-64 days (P < 0.05). (4) Early low protein led to a significant reduction in nitrogen excretion and an increase in nitrogen utilization (NU) in feces at 62-64 days (P < 0.05). Low-protein diets reduced nitrogen excretion by 12.3% (1.60 vs. 1.78 g/bird, P < 0.05) and improved nitrogen utilization from 56.03% to 59.48%. Leg muscle cooking loss decreased by 15.2% in the LPA group (15.01%) compared to PA (19.58%, P < 0.05). To conclude, different AA supplementation patterns with low protein (15.55%) in the early stage (1-28 days) had no significant effects on body weight, slaughter performance, and meat quality at 63 days. However, early low protein significantly reduced nitrogen excretion and improved NU, suggesting it is feasible for meat goslings to adopt a low-protein diet supplemented with main AAs during the early stage.

Astragalus polysaccharides (APS) have potential as functional feed additives, but their effects on physiological and intestinal responses in geese remain incompletely characterized. A total of 432 one-day-old Taihu goslings were assigned to diets containing 0, 100, or 200 mg/kg APS, with six replicates per treatment and 24 geese per replicate. Organ indices, serum biochemical and intestinal barrier-related parameters, and intestinal length were evaluated using six independent experimental replicates per treatment (n = 6), whereas intestinal histomorphology and cecal microbiota were assessed using four biological replicates per treatment (n = 4) at each sampling age. Samples were collected at 30, 60, and 90 d, with intestinal metabolites analyzed using four biological replicates per treatment (n = 4) and jejunal mucosal metabolic indicators evaluated using six experimental replicates per treatment (n = 6) at 90 d. Compared with the control, 200 mg/kg APS increased thymus index at 30 d, serum superoxide dismutase activity at 30 and 60 d (p = 0.038 and 0.020, respectively), and jejunal and ileal villus height at 30, 60, and 90 d. APS reduced serum diamine oxidase activity at 30 d (p = 0.001), and the 200 mg/kg group remained lower at 90 d. Cecal microbial community structure differed among treatments at 30 and 60 d (PERMANOVA p = 0.047 and 0.006, respectively), whereas Shannon diversity was unchanged. At 90 d, APS altered jejunal and cecal organic acid profiles with selected responses remaining significant after Benjamini–Hochberg false discovery rate correction (q < 0.05) and increased jejunal mucosal citric acid content at 200 mg/kg. APS affected selected physiological and intestinal outcomes, with additional changes in cecal microbial community structure and intestinal metabolism, while 200 mg/kg produced the clearest changes in serum superoxide dismutase activity and intestinal morphology.

Sampling age-associated microbial and intestinal transcriptional responses to Astragalus polysaccharides (APS) remain unclear in geese. In a 90-day experiment, 150 one-day-old Taihu geese received 0, 100, or 200 mg/kg APS, with five replicate cages per diet. Cecal 16S rRNA gene profiles were obtained at days 30, 60, and 90 (n = 4 per diet and age); ileal and jejunal RNA sequencing was performed at day 90 (n = 4 per diet and tissue). Sampling age explained 15.1% of the Bray–Curtis variation (q = 0.0012), APS explained 6.7% after age adjustment (q = 0.0144), and their interaction was significant (q = 0.0128). Community associations were stable across amplicon sequence variant filtering thresholds; no APS association with alpha diversity or an individual genus survived correction. For 100 and 200 mg/kg APS, respectively, 43 and three ileal genes and nine and seven jejunal genes met q < 0.05 and |log₂ fold change| ≥ 1. Jejunal expression was associated with RNA integrity, limiting transcriptomic interpretation. Chicken single-cell markers contextualized part of the ileal signature at 100 mg/kg APS; no diet-adjusted paired microbiome–pathway association survived correction. APS-associated community and transcriptional patterns remain exploratory within the phase-specific feeding program.