Single Nucleotide Polymorphisms in Insulin-Like Growth Factor (IGF) Genes and their Associations with Growth in Local Guinea Fowls (NUMIDA MELEAGRIS) of Ghana

2018

English

Due to the pivotal role of Insulin-like Growth Factor 1 (IGF1) and Insulin-like Growth Factor 2 (IGF2) in growth regulation of poultry, the IGF1 gene (gIGF1) and IGF2 gene (gIGF2) in guinea fowl were examined as candidate genes for early growth in helmeted guinea fowls (Numida meleagris) from three populations of Northern Ghana (TPNG). Keets hatched from eggs collected from 32 sample locations comprising 11 subpopulations across three main populations located in Upper East Region, Upper West Region, Northern Region, North East Region, Savannah Region and an experimental flock maintained at Animal Research Institute (ARI) were raised and appraised for body weight and growth rate traits up to 11 weeks. Protein coding exons of gIGF1 and selected targets of gIGF2 were sequenced, aligned for discovery of novel Single Nucleotide Polymorphisms (SNPs) and genotyping. Effect of the genotypes at each SNP and gIGF1 haplogroups were estimated using linear models. Birds from the TPNG did not vary in body weights and weekly growth rates among the populations and with that of ARI flock from the fourth week (p > 0.05). However, birds from subpopulations within the three main populations varied significantly (p < 0.05) in weekly body weights and growth rates from the second week, with between subpopulation variations becoming pronounced after the sixth week. Although ARI flock did not vary with other three populations in terms of body weight and growth rate, they demonstrated remarkably high survivability. In total six novel SNPs were identified within gIGF1 including two SNPs within 5’ Untranslated Region (UTR), one SNP in the second protein coding exon and three SNPs within 3’UTR. These SNPs were distributed among seven haplotypes and eight haplogroups among local guinea fowls from Northern Ghana. SNPs within the 5’UTR and 3’UTR had significant effects on body weights and weekly growth rates from the second and fourth week, respectively, indicating possible roles for these polymorphisms influencing IGF1 synthesis at the translation level, and need to be further investigated to decipher the underlying molecular mechanisms. The only synonymous SNP located at the second protein coding region in gIGF1 and both SNPs identified in gIGF2 did not influence early growth in local guinea fowls from TPNG. The study provides baseline information on novel SNPs in gIGF1 and their associations with body weight traits and early growth rates in local guinea fowls from Northern Ghana. It is recommended that the effect of the SNPs residing within 5’UTR and 3’UTR in gIGF1 should be further investigated up to slaughter stage in structured breeding programmes aimed at developing fast growing guinea fowl breeds with pedigree data to facilitate their use in Marker Assisted Selection.

Ahiagbe, K. M. J.