Novel InDels of GHR, GHRH, GHRHR and Their Association with Growth Traits in Seven Chinese Sheep Breeds

Simple Summary It is advantageous to find the potential molecular markers which are associated with the growth and development of mutton sheep through molecular breeding. In this study, four molecular markers were selected from growth hormone receptor (GHR), one was found on growth hormone releasing hormone (GHRH) and growth hormone releasing hormone receptor (GHRHR), respectively. The purposes of this paper were to screen molecular makers in the related genes of the growth hormone (GH) axis and provide theoretical basis for molecular breeding and genetic selection of mutton sheep. In this study, six molecular markers were selected from the genes for growth hormone receptor (GHR), growth hormone releasing hormone (GHRH), and growth hormone releasing hormone receptor (GHRHR). The three molecular markers in GHR and one in GHRHR could potentially be used for marker assisted selection of growing-related traits in mutton sheep. The GH growth axis plays an important role in the growth and development of animals and runs through the whole life of animals. Many studies have shown that molecular mutations in key genes of the GH axis will affect the growth and development of animals. The purpose of this study was to explore the distribution characteristics of InDels of GHR, GHRH, and GHRHR in seven Chinese sheep populations, and to further explore the relationship between InDels and sheep growth traits. GHR showed high variation in Chinese sheep, and GHR-53 showed the highest minimum allele frequency (MAF). There was only one InDel mutation site in both GHRH and GHRHR. The genotype frequencies of Hu sheep (HS), Tong sheep (TS), and Lanzhou fat-tail sheep (LFTS) were quite different from other breeds. The association between GHR, GHRH, and GHRHR InDels and body size traits in seven varieties were analyzed. The results showed that there was no significant relationship between GHRH and body size traits in the seven sheep populations. There was a positive association between GHR-21 and hip height of LFSH (p < 0.05). GHR-43 reduced body height and chest depth of Small tail han sheep (STHS) and hip width of TS. GHR-44 significantly affected the body weight of HS, the body height of STHS and the head depth of TS. GHR-53 significantly reduced cannon girth of HS, chest of STHS and forehead width of TS. GHRHR-2 significantly reduced the body weight of LFHS. To sum up, this study revealed the effects of GHR, GHRH, and GHRHR InDels on sheep phenotypic traits, which indicated their potential application prospects in the genetic improvement of mutton sheep.