Genetic Variants of the Ghrelin, Ghsr1a, Mboat4 and NPY Genes Related to Feed Efficiency Traits and Ghrelin Plasma Concentration in Hampshire Lambs

Abstract Reports in the literature suggest that a transient surge of ghrelin secretion (TSGS) just before a scheduled meal may be triggered by an appetite mechanism. Also, it is known that circulating ghrelin concentrations fluctuate relative to nutritional status and influence feeding behavior. The aim of the present study was to search for genetic variants in five selected genes (GHRL, GHSR1a, MBOAT4, NPY and AgRP) within the ghrelin gene (GHRL) interaction network. gDNA was extracted from the six highest- and six lowest-RFI Hampshire non-castrated male lambs, out of a total of 25 lambs in a 56-d GrowSafe SystemsÒ feeding trial and the complete genes were amplified by PCR. Libraries were prepared and sequenced in the ILLUMINA platform MiniSeq Sequencing System. Variations were identified using the genomic variant call format (GVCF) workflow with HaplotypeCaller using the reference genome oviAri 4 - Oar_v4 (GCA_000298732.2). One hundred and ninety-two SNPs were found in the five analyzed genes. Most of them had been reported in the SNPs data base. Linear models including each SNP genotype at a time as fixed effects, in addition to ADG and mid test metabolic body weight as covariates for some variables, were adjusted. Forty-three of these SNPs had different genotype frequencies in the two RFI groups, and appear to be associated (p < 0.05) with traits such as RFI, feed intake (FI), feed conversion (FC) and ghrelin hormone concentration in plasma (GHRL) at the TSGS; especially SNPs rs399405301, rs421869734, rs604106535, rs417836509, rs600356564, rs590893697 at the MBOAT4 gene which resulted highly significant (p < 0.01) for RFI and GHRL. The SNP rs423156356 at the GHSR1a gene was highly significant (p < 0.01) for FI and FC. These SNPs (Table 1) have the potential to be used as genetic markers for improvement of feed efficiency in Hampshire sheep, but validation on a larger sample deserves further research efforts.