LAUSR

Improving feed efficiency is a primary goal in poultry breeding strategies. Residual feed intake (RFI) in chickens typically calculated at growing period is a measure of feed efficiency that independent of level of production. The objective of this study was to evaluate phenotypic correlations of growth performance, carcass traits, meat quality, and blood variables with RFI in growing native chickens. A total of 1008 chickens were selected for the experiment to derive RFI. After the RFI measurement period of 42 d, the 25 chickens with low RFI values, 25 chickens with medium RFI values, and 25 chickens with high RFI values were selected. The RFI was significantly positively correlated with FCR and ADFI, while it was not significantly correlated with initial BW, final BW, ADG, and MBW0.75. The abdominal fat weight and yield of high RFI group were significantly greater than those of medium and low RFI group. And the abdominal fat yield was significantly positively correlated with RFI. Moreover, the plasma IGF-1 content of low RFI group was significantly greater than those of high and medium RFI groups. The plasma concentrations of ACTH, T3, and cortisol of high RFI birds were significantly greater than that of low RFI birds. RFI was significantly positively correlated with plasma concentrations of T3 and cortisol, while it was significantly negatively correlated with plasma concentration of IGF-1. In addition, the serum levels of GLU and TG of high RFI birds were significantly lower than that of low RFI birds. The serum LDL-C content of high RFI group was significantly greater than that of medium and low RFI groups, and it was significantly positively correlated with RFI. Our data suggested that selection of chickens with low RFI values may be beneficial to reduce fat deposition in native chickens without affecting meat quality. Circulating IGF-1, T3, cortisol, and LDL-C concentrations can be used as indirect selection indicators of feed efficiency in native chickens. The effect of IGF-1, T3, cortisol, and LDL-C on feed efficiency of native chickens should be carefully examined and validated in future breeding programs.