Association of Neuropeptide Y, Dopamine Receptor D2, Bone Morphogenetic Protein Receptor 1B and Melanocortin 1C Receptor Genes with Body Weight in Indigenous Chicken Ecotypes

Abstract

The present study aimed to determine the association of single nucleotide polymorphisms (SNPs) within DRD2, BMPR1B, NPY and Mel1C genes with body weight (BW) in indigenous chicken (IC) ecotypes. A total of 234 chickens from six ecotypes of Ethiopia; Afar (n = 16), Amhara (n = 105), Gumuz (n = 13), SNNPR (n = 18), Tigray (n = 43), and Oromia (n = 17) were sampled, their blood drawn from wing vein, and genomic DNA (gDNA) extracted. Contigs of the gDNA were sequenced on a Hamilton MicroLab STAR system and Genologics Clarity LIMS X Edition. Four candidate genes, DRD2, NPY, BMPR1B, and Mel1C, were extracted based on GRCg6a chicken reference genome assembly and used to conduct downstream genomic and association analyses. Body weight (kg) was measured on all sampled chickens. BW ranged from 0.6kg to 2.60kg, with significant differences between sexes (p≤0.01) and among ecotypes (p≤0.01) and ecotype-by-sex interaction (p≤0.5) but no significance (p≤0.05) with age. Average BW was 1.38±0.32kg and 1.20±0.29kg for male and female chickens, respectively. BW was highest in SNNPR (1.39±0.07kg) and lowest in Oromia (1.06±0.04kg) ecotypes. Amhara, Afar, Gumuz and Tigray had average BW of 1.26±0.03kg, 1.13±0.01kg, 1.18±0.06kg and 1.36±0.05kg, respectively. There was no significant (p ≤ 0.05) association between SNPs of NPY, Mel1C, DRD2 and BMPR1B genes with BW. However, some SNPs (rs312679760 of BMPR1B, rs315981851 of NPY and rs314194962 of DRD2) with potential effects on BW showed suggestive associations. These findings demonstrate significant variation of BW across ecotypes and sexes, and no significant association of the genes with BW in the Ethiopian ecotypes, suggestive SNPs warrant further genome-wide research.