title: Variation in testosterone production among boards and its relationship to sexual interest and breeding performance.
abstract: Variation in ability to produce testosterone in response to both GnRH and ACTH administration and quatitative relationships between GnRH-stimulated testosterone levels, ACTH-stimulated testosterone levels, sexual interest and breeding performance were assessed in a group of 31 Duroc boars (115.4 +/- 2.5 kg body weight and 212.2 +/- 3.0 days of age). Mean area beneath the testosterone response curve increased (P<0.01) after GnRH and ACTH but the magnitude of response was variable among boars. Post-GnRH testosterone area varied from 7.44 to 50.86 ng/ml X h with a CV = 52.41% while post-ACTH testosterone area varied from 4.99 to 28.78 ng/ml X h with a CV = 45.46%. Mean sexual interest and mean breeding performance scores were correlated (r = 0.67, P<0.01); however, correlations of either variable with testosterone areas were low and nonsignificant. These results indicate that the testosterone-producing ability of boars of similar age and breeding is highly variable and suggest that peripheral testosterone concentrations may not be good indicators of either libido or breeding performance.
authors.affiliation: Reproductive Physiology Research Laboratory Department of Animal Science North Carolina State University Raleigh, N.C. 27695 USA.
authors.forename: P E
authors.initials: PE
authors.lastname: Juniewicz
authors.forename: V D
authors.initials: VD
authors.lastname: Toelle
authors.forename: O W
authors.initials: OW
authors.lastname: Robison
authors.forename: B H
authors.initials: BH
authors.lastname: Johnson