Haplotype study of the mitochondrial control region of broiler breeds with different growth rates

This study discussed the haplotype characteristics of mitochondrial control region (D-loop region) of broiler breeds with different growth rates as well as the relationships between different haplotypes and growth performance. The D-loop region's sequence size of the 974 individuals from 20 broiler breeds ranged from 1,231 to 1,232bp, as a C base deletion at 859 bp. A total of 52 mutation sites and 72 haplotypes were detected, which were divided into four haplogroups, A, B, C and E. Of these, haplogroup E was the dominant haplogroup among 817 broilers and all medium/fast-growing broiler breeds. While its proportion was not exceed 40.00% among others types breeds. Correlation analysis showed that there was a significant negative correlation between birth weight and haplogroup A and a significant positive correlation between birth weight and haplogroup E. Age in days and feed conversion ratios were positively correlated with haplogroup B but negatively correlated with haplogroup E when the average body weight was approximately 1.8 kg. The cluster analysis showed that haplogroups A and B with Gallus gallus spadiceus and E with Gallus gallus murgha, respectively clustered into one branch. This study provided a theoretical basis for broiler breeding and genetic resource protection, development and utilization.