Copy number variation of amylase alpha 2B gene is associated with feed efficiency traits in Large White pigs--title not given--

Abstract

Copy number variation (CNV) of the AMY gene in humans has been enthusiastically studied for its association with starch digestibility and obesity. The alpha-amylase (AMY) is a major starch digestive enzyme in mammals. This study aimed to determine the association between CNV of the porcine pancreatic amylase (AMY2B) gene and feed efficiency. Improvement of feed efficiency in growing pigs is of great economic interest. We assayed the copy number of AMY2B by using real-time quantitative PCR (qPCR) in a Large White pig population. We identified three genotypes for AMY2B CNVs, namely I/I (homozygotes of haplotype I; a chromosome with one copy of AMY2B), I/II (heterozygotes of haplotype I and II; a chromosome with two copies) and II/II (homozygotes of haplotype II). We tested the genotypes of the parental generation consisting of six males, 21 females and 265 offspring piglets to validate the AMY2B CNV genotyping. With very few mistyping exceptions, copy numbers of AMY2B were transmitted to piglets in segregation ratios following Mendelian inheritance. Finally, we performed an association analysis between the CNV of the AMY2B gene and feed efficiency traits in 207 uncastrated male pigs. The generalised linear model analysis showed the significant effects of AMY2B CNV genotype on average daily feed intake, total feed intake and feed conversion ratio during growth from 30 kg to 100 kg body weight. However, it was not associated with average daily gain, backfat thickness and loin eye muscle area. Individuals with the genotype I/I had about 76.6 ± 27.1 g lower average daily feed intake, 5.35 ± 1.90 kg lower total feed intake and 0.089 8 ± 0.026 5 lower feed conversion ratio than individuals with I/II and II/II genotypes. Thus, AMY2B CNV has the potential to be an effective genetic marker that could reduce feed costs for pig farming.