Association of GnRH1 Gene with Growth Traits in Two Breeds of Sheep

Abstract

The present study was conducted to identify the associations between the genetic polymorphisms of GnRH1 gene and growth traits in Awassi and Karakul breeds of sheep. Two GnRH1 amplicons of 313 bp and 323 bp were designed to cover exon 1, exon 2, and their flanking regions, respectively. Genotyping experiments were performed using PCR-SSCP and DNA sequencing. No polymorphism was observed in 323 bp amplicons, while two SSCP-banding patterns were detected in 313 bp amplicons with the presence of two genotypes (AA and AB). Two novel mutations in AB genotype were observed, namely 5 0 -UTR:50 A [ C and intron1:264 G [ C. In addition to these detected genotypes, results indicated that several growth traits were significantly associated with breed, sex, and dam-age in the first 6 months of birth. However, a tendency of individuals with AA genotype to exert better performance in the majority of measured growth traits than individuals with AB genotype was also observed. With the advent of the month-9 and onward, this tendency developed to be significant (P \ 0.05), in which the association of all growth traits with the GnRH1 genotypes was dominated over other factors. Furthermore, more significant associations were observed in the month-12, in which individuals with AA genotype had higher growth traits measurements than individuals with AB genotype (P \ 0.01). In conclusion, we detected a tight linkage between the polymorphisms of the GnRH1 gene and growth traits at sexual maturity. Therefore, this study strongly suggests the GnRH1 gene as a new candidate in marker-assisted selection for growth traits in sheep.

Effect of Breed and some Non-Genetic Factors on Productive Performance in Two Sheep Breeds

“…Body weights and measurements are quantitative traits that are determined through the interaction between environment and genetics, as studies have indicated the role of genes carried by the breed and the surrounding environmental conditions are responsible for the difference in the development of body weight through the influence of many genes that act differently [8,23]. The results of the current study were supported by [24], on Karakul sheep at birth and weaning weights and six months of age, and [25], when studied on Awassi sheep. While the results of our study did not agree with [26], in the Indian Marwari and Karakul breeds.…”

Relationship of some metabolic Hormones with Increased Live Body Weight of Male and Female of Karakul and Awassi Lambs

“…However, no significant effect of the sex of the lambs was reported on the live body weights and weight gain in the Syrian Awassi sheep (Aljubouri et al, 2020b). The difference in the live body weight measurements between males and females with the progress of age may be due to the increasing differences in the endocrine system and the role of the male hormones, which are essential for building bones and muscle growth (Karsenty & Olson, 2016).…”

“…However, the growth of lambs is affected by many factors, including genetic factors, the birth season, the age of dams, the sequence of birth, the sex of lambs and the weaning period (Jawasreh et al, 2019). Improving sheep's growth traits is the main concern of many researchers, and growth trait is the most important economic factor in animals, which is controlled by several genes (Aljubouri et al, 2020b;Imran et al, 2021). One of the most prevalent sheep breeds in Iraq is Awassi, with 58.2% of prevalence over other breeds, such as Arabi (21.8%) and Karadi (20%) (Aljubouri & Al-Shuhaib, 2021).…”

Comparison of Growth Hormone Genetic Polymorphism in Awassi Ewes and Their Newborns Using PCR-RFLP Technology

“…However, the growth of lambs is influenced by many factors, including genetic factors, birth season, age of birth, sequence of birth, sex of lambs and weaning period [10]. Improving sheep growth traits is the basis of concern for many researchers, and growth traits is the most important economic factors in animals controlled by several genes [11,12].…”