Abstract
This study was aimed at identifying genomic regions controlling feeding behavior in Danish Duroc boars and its potential implications for eating behavior in humans. Data regarding individual daily feed intake (DFI), total daily time spent in feeder (TPD), number of daily visits to feeder (NVD), average duration of each visit (TPV), mean feed intake per visit (FPV) and mean feed intake rate (FR) were available for 1130 boars. All boars were genotyped using the Illumina Porcine SNP60 BeadChip. The association analyses were performed using the GenABEL package in the R program. Sixteen SNPs were found to have moderate genome-wide significance (p<5E-05) and 76 SNPs had suggestive (p<5E-04) association with feeding behavior traits. MSI2 gene on chromosome (SSC) 14 was very strongly associated with NVD. Thirty-six SNPs were located in genome regions where QTLs have previously been reported for behavior and/or feed intake traits in pigs. The regions: 64–65 Mb on SSC 1, 124–130 Mb on SSC 8, 63–68 Mb on SSC 11, 32–39 Mb and 59–60 Mb on SSC 12 harbored several signifcant SNPs. Synapse genes (GABRR2, PPP1R9B, SYT1, GABRR1, CADPS2, DLGAP2 and GOPC), dephosphorylation genes (PPM1E, DAPP1, PTPN18, PTPRZ1, PTPN4, MTMR4 and RNGTT) and positive regulation of peptide secretion genes (GHRH, NNAT and TCF7L2) were highly significantly associated with feeding behavior traits. This is the first GWAS to identify genetic variants and biological mechanisms for eating behavior in pigs and these results are important for genetic improvement of pig feed efficiency. We have also conducted pig-human comparative gene mapping to reveal key genomic regions and/or genes on the human genome that may influence eating behavior in human beings and consequently affect the development of obesity and metabolic syndrome. This is the first translational genomics study of its kind to report potential candidate genes for eating behavior in humans.
Highlights
Feed represents a large proportion of the variable costs of breeding
Genetic improvement in feed efficiency was historically achieved as a correlated genetic change resulting from selection for growth rate and carcass lean content for animals tested in groups, where individual feed intake was too expensive to be measured on a large number of pigs
The following feeding behavior traits were defined and calculated for each boar: DFI: total daily feed intake, time spent in feeder (TPD): total time spent at feeder per day, number of daily visits to feeder (NVD): number of visits to the feeder per day, TPV: average duration of each visit ( = TPD/ NVD), FPV: mean feed intake per visit and FR: mean feed intake rate (g/minute) ( = DFI/TPD) [1]
Summary
Feed represents a large proportion of the variable costs of breeding. selection for reducing feed intake is a very important goal in breeding programs, at least in Danish pig breeds. Several studies have shown low to moderate and positive genetic correlation between feeding behavior traits and daily feed intake. Labroue et al [2] found FPV had positive genetic correlation to average daily gain, meaning that animals that eat more per visit tend to grow faster. These genetic associations underline the fact that genetic improvement of feed efficiency is dependant upon genetic changes (improvement) in eating behavior of pigs. GWAS take advantage of a large numbers of SNP markers in population-wide linkage disequilibrium with very small (QTL) regions potentially harboring candidate loci for the complex traits. Some studies have identified QTLs for pig feeding behavior traits, this is is the first GWAS conducted to identify genetic variants and biological mechanisms for eating behavior in pigs
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