Abstract
BackgroundFeed accounts for about 70% of the total cost of poultry meat production. Residual feed intake (RFI) has become the preferred measure of feed efficiency because it is phenotypically independent of growth rate and body weight. In this study, our aim was to estimate genetic parameters and identify quantitative trait loci (QTL) for feed efficiency in 3314 purebred broilers using a genome-wide association study. Broilers were genotyped using a custom 55 K single nucleotide polymorphism (SNP) array.ResultsEstimates of genomic heritability for seven growth and feed efficiency traits, including body weight at 28 days of age (BW28), BW42, average daily feed intake (ADFI), RFI, and RFI adjusted for weight of abdominal fat (RFIa), ranged from 0.12 to 0.26. Eleven genome-wide significant SNPs and 15 suggestively significant SNPs were detected, of which 19 clustered around two genomic regions. A region on chromosome 16 (2.34–2.66 Mb) was associated with both BW28 and BW42, and the most significant SNP in this region, AX_101003762, accounted for 7.6% of the genetic variance of BW28. The other region, on chromosome 1 (91.27–92.43 Mb) was associated with RFI and ADFI, and contains the NSUN3 and EPHA6 as candidate genes. The most significant SNP in this region, AX_172588157, accounted for 4.4% of the genetic variance of RFI. In addition, a genomic region containing the gene AGK on chromosome 1 was found to be associated with RFIa. The NSUN3 and AGK genes were found to be differentially expressed in breast muscle, thigh muscle, and abdominal fat between male broilers with high and low RFI.ConclusionsWe identified QTL regions for BW28 and BW42 (spanning 0.32 Mb) and RFI (spanning 1.16 Mb). The NSUN3, EPHA6, and AGK were identified as the most likely candidate genes for these QTL. These genes are involved in mitochondrial function and behavioral regulation. These results contribute to the identification of candidate genes and variants for growth and feed efficiency in poultry.
Highlights
IntroductionResidual feed intake (RFI) has become the preferred measure of feed efficiency because it is phenotypically independent of growth rate and body weight
Feed accounts for about 70% of the total cost of poultry meat production
Residual feed intake (RFI) adjusted for abdominal fat weight (RFIa) was calculated as the difference between the observed and the predicted average daily feed intake (ADFI) using multiple regression of ADFI on metabolic body weight at mid-test (MWT), average daily gain (ADG), and abdominal fat (AbF) weight
Summary
Residual feed intake (RFI) has become the preferred measure of feed efficiency because it is phenotypically independent of growth rate and body weight. Feed efficiency is the most important economic trait in poultry and livestock industries because up to 70% of the total production cost is due to feed [1]. Compared with FCR, one of the main advantages of selection on RFI is reduction of feed intake without jeopardizing production traits, such as body weight and growth rate [5]. RFI adjusted for abdominal fat weight (RFIa) was calculated as the difference between the observed and the predicted ADFI using multiple regression of ADFI on metabolic body weight at mid-test (MWT), average daily gain (ADG), and abdominal fat (AbF) weight
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