Genetic variability in IGFBP-3 and GH genes and their association with body weight and growth performance at birth, weaning and six-month in sheep 

Abstract

Body weights at birth, weaning and six-month and growth performance in lambs are economic traits that could be strongly used in sheep breeding objectives. Moreover, previous genetic studies recommended strong associations between these economic traits and polymorphisms in several candidate genes in different livestock species. The aim of this investigation was to study the polymorphism in IGFBP-3 and GH genes using DNA sequencing and RFLP, and their association with body weights and growth performance of Rahmani, Barki, Rahmani X Barki cross, Awassi/Awassi X Suffolk cross and Ossimi sheep breeds. Digestion of 654 bp for IGFBP-3/HaeIII yielded only one restriction pattern of 8 fragments in all animal groups revealing the absence of polymorphism also, DNA sequencing confirmed that. While, sequencing analysis of the amplified fragment of GH gene revealed polymorphism in nucleotide sequencing, and the amino acid sequences for GH gene of Rahmani were different from those of other breeds in 4 amino acids, while, each of Rahmani X Barki cross and Ossimi amino acid sequences were different in 3 amino acids. The genetic differences in GH gene coincided with differences in birth, weaning and six-month weights of the breeds under study. Thus, the current results suggest that body weights and growth performance of tested sheep breeds at different stages of growth are statistically affected by GH gene which could be considered as a candidate gene for growth in breeding programs.