A novel 22-bp InDel in the intron 1 of the IGF1 gene is associated with slaughtering performance of Chinese Jiaji duck

Context Insertion/deletion can affect poultry growth traits and slaughter performance. Poultry performance can be progressively improved by selecting poultry individuals carrying favorable variants for breeding. Aims The aim of this study was to analyze the correlation between insertion/deletion (InDel) polymorphisms in insulin-like growth factor 1 (IGF1) gene and slaughter performance and growth traits of Jiaji ducks. Methods We measured the growth traits and slaughter performance of 102 Jiaji ducks randomly selected at 90 days of age. The polymerase chain reaction products of Jiaji duck were genotyped using 2% agarose gel electrophoresis. One 22-bp InDel variant was found in the intron 1 of the IGF1 gene. General linear-model (GLM) procedures were used to determine the growth traits and slaughter performances with different InDel genotypes. Key results This 22-bp InDel variant exerted a significant influence on pre-slaughter bodyweight, carcass weight, eviscerated weight, percentage of skin fat, percentage of lean meat and percentage of leg muscle. The 22-bp InDel was adjacent to the transcription start site of the IGF1 gene and predicted to be nearby the core promoter of the IGF1 gene. The InDel mutation resulted in the loss of four transcription factor binding sites. The expression level of IGF1 mRNA was significantly reduced in the breast muscle of mutant individuals. Conclusions The results showed that the 22-bp InDel of the IGF1 gene had a significant effect on the slaughtering performance. Among the growth traits, the bodyweight showed significant effects, whereas no significant impacts were observed on other traits. Implications The InDel locus of the IGF1 gene can be used as a useful molecular marker for genetic breeding of Jiaji ducks.