Impact of insulin-like growth factor-II polymorphisms on growth and reproductive traits in rabbits

Biological effects of the insulin-like growth factor (IGF) system include increased glucose 
uptake, antiapoptotic activity, stimulation of DNA and RNA and protein synthesis. So, the IGF 
system has long been associated with growth and reproduction. Deletion of one bp in a non-coding 
regulatory region of the intron after the first coding exon of rabbit IGF-II was abbreviated to 
c.156+61delA indel and included A and Del alleles. Thus, the aim of the present study was to 
evaluate distribution allele frequency and effects of IGF-II polymorphisms on productive, carcass, 
reproductive and milk yield traits in a population of 284 rabbits. The genomic DNA of rabbit and 
the specific primers for IGF-II c.156+61DelA indel were used in PCR amplification. The IGF-II 
c.156+61DelA indel was genotyped by restriction fragment length polymorphism (RFLP). The 
frequency of A and Del alleles in IGF-II were 0.37 and 0.63, respectively. Association analysis 
indicated that Del/Del genotype was significantly associated (P < 0.05) with heavy weight in the 
bunnies at 10th week of age and high DBWG within interval 5-10 week of age. The IGF-II 
polymorphisms had significant (p<0.05) effects on most of carcass traits. The IGF-II 
polymorphisms did not significant affect milk yield and reproductive traits except the litter size at 
birth in rabbit does.Del allele in IGF-IIc.156+61DelA indel could be a favourable allele in rabbit 
and may be used in marker-assisted selection (MAS) plans to improve growth performance of 
rabbits.