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TESTICULAR DEVELOPMENT AND ENDOCRINE FUNCTION OF BOARS SELECTED FOR EITHER HIGH OR LOW TESTIS SIZE
Abstract
Testicular development and levels of gonadotrophic and gonadal hormones were investigated in 36 Landrace x Large White boars selected from litters with either high or low estimated breeding values for 150-d testes weight. Blood samples were taken via jugular venipuncture at 8 ages (42, 56, 70, 84, 98, 112, 126 and 140 d). At each age, blood samples were taken at 30 min intervals. Luteinizing hormone (LH) was determined on individual serum samples. Concentrations of follicle stimulating hormone (FSH), estradiol-17(beta) (E(,2)) and testosterone (T) were determined on pooled (within boar) samples. Testicular growth of the boars was compared by obtaining in situ measurements of testes width and length, excised tissue weights and histological data. High testes weight (HTW) boars were heavier (P < .05), had higher backfat probes (P < .01) and had consistently larger in situ testes measurements than low testes weight (LTW) boars. The HTW line had heavier (P < .01) testes and epididymides at 140 d of age. The HTW line had significantly larger (P < .01) seminiferous tubules and a higher (P < .05) percentage of tubules with spermatogenesis occurring than the LTW line. There was pubertal rise in LH concentration and maximum LH concentrations occurred from 84 to 112 d of age. The HTW line had higher (P < .05) LH concentrations which were more variable (P < .01) than those of the LTW line. Concentrations of FSH increased rapidly from 84 to 112 d of age and were similar for the two lines. Concentrations of T increased (P < .01) in a linear fashion with age and were higher (P < .10) for the HTW line. Concentrations of E(,2) fluctuated from 42 to 84 d of age and increased thereafter. The HTW line had higher (P < .05) E(,2) concentrations. Pooled within line correlations between hormone concentrations from 42 to 140 d age and measures of testicular development at 140 d of age were estimated. Correlations of mean LH concentration with testicular traits ranged from .24 to .49. Testicular measurements were correlated with number of LH peaks (r = .31 to .43) but not with the pooled within boar-age sample variance of LH concentration. Correlations of mean FSH concentration with testicular traits ranged from -.20 to .19. Testicular traits were more highly correlated with mean E(,2) concentration (r = .22 to .41) than with mean T concentration (r = .12 to .33).
Subject Area
Livestock
Recommended Citation
SCHINCKEL, ALLAN PAUL, "TESTICULAR DEVELOPMENT AND ENDOCRINE FUNCTION OF BOARS SELECTED FOR EITHER HIGH OR LOW TESTIS SIZE" (1982). ETD collection for University of Nebraska-Lincoln. AAI8308791.
https://digitalcommons.unl.edu/dissertations/AAI8308791