Abstract
Feed efficiency (FE) is an important factor restricting development of the poultry industries. Residual feed intake (RFI) serves as an indicator for measuring FE in breeding initiatives. This study aimed to explore the influence of divergence in RFI on growth performance, carcass traits, meat quality, muscle fiber morphology, and blood chemistry in indigenous chickens. A total of 500 one-day-old male chickens of similar body weight had RFI assessed at 70-120 d. Twenty high RFI (HRFI) and 20 low RFI (LRFI) chickens were evaluated for carcass traits, meat quality, muscle fiber morphology, and blood biochemical parameters. The results showed that although RFI was significantly positively correlated with average daily gain, average daily feed intake (ADFI), and feed conversion ratio (FCR) (P<0.01), no significant correlation existed between the initial, final, and metabolic body weight. Concerning slaughter performance, abdominal fat yield (AFY) and weight (AFW) were lower in the LRFI group (P<0.01). Regarding meat quality, the pH(24h) of the thigh muscle and the shear force of the breast muscle were lower in LRFI group (P<0.01). Muscle fibers did not differ between the HRFI and LRFI groups. Regarding blood biochemical parameters, non-esterified fatty acid, creatinine (CREA), low-density lipoprotein cholesterol (LDL-C), and cholesterol (CHOL) levels were higher in the HRFI group (P < 0.05). Correlation analysis suggested that RFI was positively correlated with FCR and ADFI (P < 0.01). RFI had a significant positive effect on AFY and AFW (P < 0.01). Moreover, RFI demonstrated a positive effect on the pH(24h) of the thigh muscle and the shear force of the breast muscle (P < 0.01). Furthermore, LDL-C, CHOL, and CREA levels were positively correlated with RFI (P < 0.05). In summary, low RFI within a tolerable range decreases fat deposition and increases FE without impacting production performance. LDL-C, CHOL, and CREA are indirect indicators of FE. This study offers significant insights into the biological processes underlying variability in RFI in indigenous chickens.