Association of IGF 1 gene polymorphisms with some morphometric traits of Nigerian indigenous sheep breeds

Abstract

The relationship between IGF 1 gene polymorphisms and some morphometric traits of the Balami, Uda and Yankasa sheep breeds of Nigeria was investigated. Blood samples and morphometric measurements were obtained from 150 sheep (50 for each of the three breeds) at the Maiduguri Livestock market and abattoir while DNA was extracted at the Biotechnology laboratory of the University of Maiduguri. Evaluation of results revealed 2 alleles (A and B) and 3 genotypes (AA, AB and BB) for all the breeds. The Uda and Yankasa breeds had higher frequency of allele B (0.64 and 0.56, respectively) while Balami had higher allele frequency for A (0.61). Balami and Yankasa had high heterozygosity for IGF-1 gene while Uda had high homozygosity for B. For Balami sheep, the genotype BB had higher (P < 0.05) body weight and heart girth (56 kg and 79 cm, respectively) than AB for body weight (45.80 kg) and BB for heart girth (69.67 cm). Conversely, genotype AA had higher body length (94.33 cm) than AB (73.80 cm). IGF 1 gene polymorphisms did not significantly (P < 0.05) affect most morphometric traits of the Yankasa and Uda sheep except height at withers where the genotype AB had higher (P < 0.05) height at withers (71.77 cm) than AA (53.50 cm) for Yankasa sheep. Thus, the three breeds were found to be 100% polymorphic at the regulatory region of IGF-1 locus and this gene may be used as a marker for some morphometric traits in Nigerian indigenous sheep.

Keywords: body weight, heart girth, height at withers, breeds, sheep