Genetic effect of growth hormone gene on yearling weight and wool traits in Zel sheep (Brief Report)

Abstract. The growth hormoe (GH) gene is a candidate for growth in sheep, since plays an important role in growth regulation and development (Boyd & Bauman 1989). Most genetic studies on the growth of sheep have concentrated on birth weight, weaning weight and yearling weight (Bathaei & Leroy 1998). Pereira et al. (2005) found significant effect for bovine growth hormone (bGH) genotype on yearling weight. Tambasco et al. (2003) observed a positive association between genotype LV and daily body weight gain from weaning to yearling in Bos Taurs x Bos indicus crosses.

Wool traits like greasy fleece weight, clean yield, fiber diameter and its coefficient of variation are very important selection goals in sheep breeding programs, however new traits such as staple strength and staple length are of increasing importance in the wool industry (Forgarty 2006). Initial observations using daily injections of crude pituitary extracts showed that wool growth decreased by 17 % during the second treatment period (Ferguson 1954). Allain et al. (1998) found segregation for coefficient of variation of fiber diameter and staple length on chromosomes 3 and 4 in a composite sheepline (INRA401). Zel sheep is raised in North of Iran. This sheep is a native non-fat tailed breed with small-sized (Saadat-Noori & Siah-Mansoor 1990). The aim of this study was to investigate the relationship between GH genotypes and wool traits and yearling weight using single strand conformation polymorphism (SSCP) method in Zel sheep.