The objective of the study was to investigate the effects of low-protein amino acid-balanced (LPAB) diets supplemented with Astragalus polysaccharides (APSs) on the production performance, antioxidants, immunity, and biochemical index of laying hens in an elevated-temperature environment. Fifty-two-week-old Hy-Line Brown chickens (n = 768) were randomly divided into four groups, with eight replicates of 24 hens each. The control group was kept at 24 °C with a basal diet (CON), while the treatment groups were exposed to 32 °C and given the following diets: basal (HB), LPAB (HL), and LPAB with 0.5% APSs (HLA). Under heat stress, APSs increased the egg production rate and number of small white follicles, improved the yolk color, and lowered the feed conversion ratio. LPAB diets increased follicle-stimulating hormone, antioxidant enzyme activities, and anti-inflammatory cytokine activity and up-regulated related genes, whereas they reduced stress-related hormones, malondialdehyde concentrations, and triglyceride concentrations and down-regulated related genes. The addition of APSs enhanced immunoglobulin concentrations and cholesterol recovery and altered the expression of related genes. The study found that the adverse effects of high temperatures are directly related to oxidative stress. LAPB diets and APSs relatively alleviate these adverse effects. Therefore, the importance of feeding strategies such as LPAB diets and APSs for laying hens under heat stress conditions has been identified.

This review article focuses on the role of choline in ovarian follicular development, regulated by nutrient–epigenetic interactions. Choline, a key feed additive, participates in DNA methylation and steroid hormone synthesis via its methyl donor function. However, its role in follicular hierarchy and maturation is unclear. Research lacks an understanding of species-specific choline metabolism, follicular fluid methylation dynamics, and toxicity thresholds. This study combines animal nutrition, epigenetics, and reproductive endocrinology. Using in vitro follicle culture models, metabolomics analysis, and cytochrome P450 family 19 subfamily A member 1 (CYP19a1) methylation site screening, it reveals that choline regulates follicle hierarchy through the betaine-S-adenosylmethionine (SAM) pathway. Proper dietary choline reduces homocysteine (HCY) and boosts CYP19a1 demethylation, enhancing theca cell estradiol (E₂) production and accelerating follicle maturation. In contrast, inadequate or excessive choline causes mesoderm-specific transcript (MEST) gene methylation abnormalities or trimethylamine N-oxide (TMAO)-mediated β-oxidation inhibition, increasing follicle atresia. A phenomenon of steroidogenic factor 1 (SF-1) methylation has been observed in poultry, showing that choline affects offspring egg-laying persistence by altering the adrenal–ovarian axis DNA methylation imprint. Future research should establish a precise choline supply system based on the HCY/TMAO ratio in follicular fluid and the CYP19a1 methylation map to improve animal reproduction.

This study evaluated how embryonic choline supplementation (ECS) via in ovo injection and gosling choline supplementation (GCS) via diet jointly influence embryonic development, endocrine status, growth performance, and muscle development. A total of 1,250 hatching eggs were allocated to five ECS treatments: non-injected control (E_NC), sham-injected control (E_PC), and 0.5 mL of choline chloride at 0.5 (E_0.5), 1.0 (E₁), and 1.5 (E_1.5) mg/mL. Following hatch, 720 female goslings (144 per ECS group) were randomly assigned to three GCS levels: 0 (G₀), 200 (G₂₀₀), and 400 (G₄₀₀) mg/kg. ECS significantly increased embryo weight and relative embryo weight (embryo weight as a percentage of initial egg weight) at embryonic day 18 (DE18; P < 0.001) and DE27 (P = 0.005), while no significant effects were observed at DE20 (P > 0.05). Circulating growth hormone (GH), adrenocorticotropic hormone (ACT), and corticosterone (CORT) responded to choline in dose-dependent patterns (P < 0.001). Post-hatch body weight was significantly affected by the ECS × GCS interaction throughout the post-hatch period (P ≤ 0.016 at 7, 14, 21, and 28 days of age). GCS at 400 mg/kg significantly improved 28-day body weight (P < 0.001) and feed conversion ratio (P < 0.001). Pectoralis and leg muscle myofiber diameter and cross-sectional area were enhanced by higher choline supply (ECS: P ≤ 0.041; GCS: P < 0.001), accompanied by reduced pectoral fiber density (P < 0.001). Notably, myofiber hypertrophy occurred without changes in myogenin (MyoG), myogenic regulatory factor 4 (MRF4), or myogenic factor 5 (Myf5) expression (P > 0.05). Instead, choline exerted treatment-dependent modulation of IGF-1 and MSTN primarily in the pectoralis (P < 0.001), indicating that choline promotes muscle growth via the IGF-1/MSTN axis. For growth rate and feed efficiency, E₁G₄₀₀ is preferable; for muscle yield, E_1.5G₄₀₀ offers additional fiber gains; for immune organ development, E₀G₀ is preferable given the increased bursa weights at lower supplementation. These findings provide a scientific basis for targeted choline nutritional strategies in goose production systems.