Submitted to: Biology of Reproduction
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/20/2001
Publication Date: 9/1/2001
Citation: Ford, J.J., Wise, T.H., Lunstra, D.D., Rohrer, G.A. 2001. Interrelationships of porcine x and y chromosomes with pituitary gonadotropins and testicular size. Biology of Reproduction. v. 65(3). p. 906-912. Interpretive Summary: A study was conducted to determine the relative contribution of porcine X and Y chromosomes on sperm production and hormone secretion in Meishan by White composite crossbred boars. Sperm production is directly related to testicular size and is a primary concern in the U.S. swine industry due to rapid adaption of artificial insemination within the past 10 years. We observed that in this crossbred population of boars, testicular size and sperm production at 7 months of age are influenced greatly by genes that reside on the X chromosome, and no contribution of the Y chromosome was associated with the wide variation that exists for testicular traits in these crossbred boars. The observed variation in testicular traits was associated with large differences in plasma follicle-stimulating hormone (FSH) concentrations. This finding supports the likelihood that FSH in the blood of pubertal boars should be investigated for its potential to predict sperm production. These data will impact of scientists in design of subsequent studies and will be of interest to swine extension specialists who work with boar studs and users of artificial insemination.
Technical Abstract: Endocrine and testicular responses to unilateral castration on 1, 10, 56 or 112 days of age were characterized in 132 Chinese Meishan (MS) x White composite (WC) crossbred boars in which testicular size associates with a quantitative trait locus (QTL) on X chromosome. At 220 days of age, testicles of boars unilaterally castrated on Day 1 or 10 weighed more and had greater total daily sperm production (TDSP) than one testicle of bilaterally intact boars (P < 0.05); compensation did not double these two responses. Boars with MS alleles at the X chromosome QTL had smaller testicles, darker colored parenchyma and lower TDSP than boars with WC alleles (P < 0.05). MS alleles engendered greater (P < 0.05) plasma FSH and LH during puberty than WC alleles. Plasma FSH increased (P < 0.05) within 48 h of unilateral castration on Days 1, 10 and 56. Subsequent increases occurred earlier during puberty (P < 0.05) after unilateral castration at younger ages than after unilateral castration at older ages. Pubertal increases in plasma FSH and LH were greater (P < 0.05) in boars with MS alleles than in those with WC alleles for the X chromosome QTL. Breed of Y chromosome had no effect on testicular traits, FSH, testosterone or estrone. For LH, boars with a MS Y chromosome had greater (P < 0.01) plasma LH across all ages than boars with a WC Y chromosome. We conclude that a gene or groups of genes, which resides on porcine X chromosome, regulate testicular development and pubertal gonadotropin concentrations.