Genetic variability in GH and IGFBP-3 genes and their association with growth performance in Egyptian sheep

Abstract

The polymorphisms in Insulin-like Growth Factor Binding Protein-3 (IGFBP-3) and Growth Hormone (GH) have an effect on mammalian growth control, development and reproduction activity. This investigation aimed to study the polymorphism in IGFBP-3 and GH genes, and detect their association with body weights and growth performance of several sheep breeds (Ovis aries) namely; Rahmani, Barki, Rahmani x Barki cross, Awassi/Awassi x Suffolk cross and Ossimi. Digestion of 654 bp for IGFBP-3/HaeIII yielded only one restriction pattern of 8 fragments in all studied breeds revealing the absence of polymorphism and this agrees with gene sequencing. While, sequencing analysis of the amplified fragment of GH gene revealed polymorphism in nucleotide sequencing. 4 SNPs out of 11 (C1776G, T1772A, G1769C and C1765A) in Rahmani, while 1 SNPs out of 2 (A1544G) in Barki, whilst 3 SNPs out of 4 (A1678G, A1558G and A1544G) in Rahmani x Barki cross, whereas 2 SNPs out of 4 (C1765A and G1550A) in Awassi /Awassi x Suffolk cross and 3 SNPs out of 8 (T1772A, G1769C and G1756C) in Ossimi were very important. The amino acid sequence for GH gene of Rahmani was 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 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.