Arginine, an essential amino acid in birds, plays a central role in growth and reproduction. Regulation of the mechanistic target of rapamycin (mTOR) signalling pathway is among its key functions. This study examined how dietary arginine affects reproductive performance, body mass, and hepatic gene expression in adult female Japanese quail (Coturnix japonica). A total of 81 quails were randomly assigned to one of the three dietary treatments for 14 days: a diet containing 1.26% arginine (control), 0.945% arginine (restricted), and 1.575% arginine (supplemented). Body mass, hen-day egg production (HDEP), and egg mass were recorded, and liver samples were analysed using qPCR for mTOR signalling pathway-related genes. Arginine supplementation significantly increased HDEP, whereas neither restriction nor supplementation altered body mass or egg mass. Arginine restriction downregulated the expression of MTOR, IGF1, GHR, FASN, ATG5, ATG9A, SOD1, and SOD2 genes. In contrast, supplementation upregulated ATG5 but downregulated SOD2. Network analysis revealed treatment-dependent shifts: under restriction, SOD2 functioned as a key bridge despite reduced expression, whereas under supplementation, centrality shifted to GHR and FASN, indicating enhanced growth and lipogenic activity. Overall, dietary arginine reshaped the molecular structure of the mTOR pathway without affecting somatic maintenance, instead favouring reproductive output. These findings suggest that dietary arginine regulates egg production and gene expression in the mTOR signalling pathway in adult Japanese quail.

Broiler chickens reared at high altitudes face multiple stressors, including cold and hypoxia, which impair growth and gut health. Sodium butyrate (NaB) has emerged as a promising feed additive to mitigate these effects. This study evaluated the impact of non-encapsulated NaB and encapsulated (E-NaB) sodium butyrate on intestinal morphology, gene expression, and performance metrics in broilers under cold stress at high altitude. A total of 675 one-day-old Cobb broilers were assigned to nine dietary treatments: control, NaB (0.05% or 0.1%), E-NaB (0.05% or 0.1%), and their combinations. Birds were reared at 2100 m and subjected to cold stress. Growth performance, intestinal morphology, gene expression (MUC2, FABP2, GLUT2, TLR2, GPX, SOD1), and pulmonary hypertension syndrome (PHS) index (RV:TV ratio) were assessed. NaB supplementation improved the feed conversion ratio during the starter phase and overall rearing period (P < 0.05). Combined NaB+E-NaB treatments enhanced villus height, width, and surface area in the duodenum, jejunum, and ileum (P < 0.05). Gene expression analysis revealed upregulation of MUC2, FABP2, GLUT2, TLR2, GPX, and SOD1 in supplemented groups, particularly in combined treatments (P < 0.05). The RV:TV ratio, indicating PHS risk, was reduced in NaB0.1% and combined groups (P < 0.05). It is concluded that Sodium butyrate, especially in combined or encapsulated forms, improved gut health, modulated the expression of antioxidant-related genes (GPX and SOD1), and enhanced performance in broilers under cold stress and high-altitude conditions. These findings highlight NaB's potential as a strategic feed additive to enhance resilience in challenging environments.

This study characterized the phenotypic attributes of indigenous Xhosa goats across three agro-ecological zones and developed predictive models for estimating body weight. A total of 450 Xhosa goats were sampled using a stratified random approach based on sex, age, and agro-ecological region. Morphometric traits, including body weight (BW), heart girth (HG), body length (BL), wither height (WH), and body depth (RD), were recorded. Data were analysed using the General Linear Model (GLM) of SPSS (v.20) to assess the effects of zones, sex, and age on body traits, while Pearson’s correlation and stepwise regression identified the best predictors of body weight. Results showed significant (p < 0.05) variations in body measurements across zones, with Savanna goats exhibiting superior traits. Males had significantly (p < 0.05) higher BW and body dimensions than females and castrates. Correlation analysis revealed HG (r=0.80), BL (r=0.84), and RD (r=0.82) as the strongest predictors of BW in males, while BL (r=0.66), HG (r=0.65), WH (r=0.62), and RD (r=0.61) were best for females. Stepwise regression identified HG and BL as the best predictors for males, and HG, BL, and SH for females. The predictive models (R² = 0.74–0.85) provide a practical tool for estimating body weight in field conditions. These findings provide practical tools for field-based weight estimation and highlight the importance of conserving the phenotypic diversity of Xhosa goats for sustainable breeding and genetic improvement programs in South Africa.