Identification of genomic regions controlling plasma FSH concentrations inMeishan-White Composite boars

The Chinese Meishan (ME) breed of pig is unique for many reproductive trait s. Compared with Western breeds of swine, ME females reach puberty earlier, ovulate more ova per estrus, and have greater uterine capacity, while inta ct males (boars) have smaller testes and extremely elevated plasma levels o f pituitary-derived glycoprotein hormones. In an effort to identify the gen etic mechanisms controlling the elevated plasma levels of pituitary-derived glycoprotein hormones [in particular, follicle-stimulating hormone (FSH)] and to determine whether some of these genetic factors are also responsible for differences in other phenotypes, we scanned the entire genome for regi ons that affected plasma FSH in boars from a Meishan-White Composite (equal contributions of Chester White, Landrace, Large White, and Yorkshire) reso urce population. Initially, the entire genome of 121 boars was scanned for regions that potentially influenced plasma FSH. The most significant genomi c regions were further studied in a total of 436 boars. Three genomic regio ns located on chromosomes 3, 10, and X apparently possess genes that signif icantly affect FSH level, and one region provided suggestive evidence for t he presence of FSH-controlling genes located on chromosome 8. The region on the X chromosome also affected testes size. Similar genomic regions to tho se identified on chromosomes 3, 8, and 10 in this study have been identifie d to affect ovulation rate in female litter mates, supporting the hypothesi s that plasma FSH in pubertal boars and ovulation rate in females is contro lled by a similar set of genes.