Abstract：
This study aimed to assess the effect of inbreeding on production traits using a long-term closed-line population recorded for residual feed intake (RFI). The study first used data from a previously reported population to determine the appropriate period of divergent selection for RFI. The results showed that RFI had similar moderate heritability estimates (0.28-0.34) during the fast-growing period (7-12 wk), and RFI at 7 to 10 wk had the highest heritability (0.34). Therefore, divergent selection was performed in a Chinese broiler population for RFI at 7 to 10 wk; the total sample size from generations zero (G0) to 13 was 9050. The divergence between the 2 lines increased steadily throughout generations, resulting in G13 with average RFI values of 304.55 in high RFI (HRFI) males, -160.31 in low RFI (LRFI) males, 296.30 in HRFI females and -157.55 in LRFI females. The feed intake (FI) and feed conversion ratio were almost higher in HRFI broilers than in LRFI broilers, and the magnitude of the difference in FI increased from approximately 4% for both sexes in G1 to approximately 33% in G13. Body weight gain was irregular from G1 to G13 and higher in LRFI broilers than in HRFI broilers after G10. Indeed, the HRFI broilers consumed more food, but they were lighter than LRFI broilers. In G13, LRFI males had heavier slaughter weight, longer cecum length, more white blood cells (WBC), red blood cells (RBC) and hemoglobin (HGB), but triglycerides, lower dressed percentage, percentage of half eviscerated yield, and eviscerated yield than HRFI males. LRFI females had a higher percentage of breast muscle and gizzard yield, longer cecum length, and more WBCs, RBCs and HGB but less abdominal fat and serum total cholesterol than HRFI females. This study was the first to verify that long-term divergent selection for RFI in Chinese broiler chickens is positive and beneficial.
摘要：
这项研究旨在使用记录残留采食量（RFI）的长期封闭种群来评估近交对生产性状的影响。该研究首先使用来自先前报道的人群的数据来确定RFI的不同选择的适当时期。结果表明，RFI在快速生长期（7-12周）具有相似的中等遗传力估计（0.28-0.34），7至10周的RFI具有最高的遗传力（0.34）。因此,在7至10周的中国肉鸡种群中进行了不同的RFI选择；从零代（G0）到13代的总样本量为9050。两条线之间的差异在整个世代中稳步增加，导致G13在高RFI（HRFI）男性中的平均RFI值为304.55，-160.31在低RFI（LRFI）男性中，HRFI女性为296.30，LRFI女性为-157.55。HRFI肉鸡的采食量（FI）和饲料转化率几乎高于LRFI肉鸡，FI差异的幅度从G1中两性的约4％增加到G13中的约33％。从G1到G13的体重增加是不规则的，LRFI肉鸡的体重增加高于G10后的HRFI肉鸡。的确,HRFI肉鸡消耗更多的食物，但它们比LRFI肉鸡轻。在G13中，LRFI雄性的屠宰重量较重，较长的盲肠长度，更多的白细胞（WBC），红细胞（RBC）和血红蛋白（HGB），但是甘油三酯，穿着百分比较低，半内脏产量的百分比，和内脏产量比HRFI男性高。LRFI女性的胸肌和g的产量百分比更高，较长的盲肠长度，和更多的WBC，RBC和HGB但比HRFI女性少腹部脂肪和血清总胆固醇。本研究首次验证了中国肉鸡对RFI的长期分歧选择是积极有益的。
