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Title: NEGATIVE RELATIONSHIP BETWEEN BLOOD CONCENTRATIONS OF FOLLICLE-STIMULATING HORMONE AND TESTICULAR SIZE IN MATURE BOARS

Author
item FORD, JOHNY
item WISE, THOMAS
item LUNSTRA, DONALD

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sperm production by boars is positively correlated with testicular size; thus, the current increase in usage of artificial insemination by swine producers places greater value on sperm production by individual boars. We determined that blood concentrations of follicle-stimulating hormone (FSH) were correlated negatively with testicular size and sperm production. This sis contrary to expectations because FSH plays a significant role in regulation of testicular development and function. These findings will impact scientists through their design of subsequent studies. Additionally, this research established a method that could be used by producers to identify pubertal boars with greater potential for increased sperm production as adults.

Technical Abstract: Relationships between blood concentration of follicle stimulating hormone (FSH) and testicular size along with daily sperm production were evaluated with data obtained from five studies originally designed to investigate regulation of FSH secretion in Meishan (MS), White composite (WC) and crossbreds of these. A minimum of three blood samples/boar was obtained at tgreater than 4-d intervals for determination of FSH, and testes were obtained at castration or slaughter. In a random sample of boars, FSH was sixfold greater (P < .01) in MS than in WC boars (n = 22/group). Daily sperm production (DSP)/g of testis (estimated by counting elongated spermatid nuclei in testicular homogenates) was similar in these groups, but testicular weight (TWT), adjusted for body weight, was less (P < .01) in MS than in WC yielding lower total daily sperm production (TDSP; P < .05) in MS boars. In four populations (1 with MS, 1 with WC, and 2 with crossbreds; n = 34 males), boars were selected for extremes in FSH concentrations from larger groups. Threefold greater FSH was associated with smaller TWT of 1.6-fold (P < .01). Coincident with increased FSH, TDSP decreased twofold (P < .05). In 48 MS x WC boars that were selected for divergence in plasma FSH during pubertal development, this divergence was retained at one year (P < .01). Retrospectively, this divergence was also apparent at 2 and 8 wk of age (P < .05), and the boars with elevated FSH had smaller testicles, lower DSP and lower TDSP (P < .01). These studies document a negative relationship in mature boars between FSH secretion and testicular size accompanied with decreased TDSP.