Masters Theses

Date of Award


Degree Type


Degree Name

Master of Science


Animal Science

Major Professor

H. G. Kattesh

Committee Members

J. P. Hitchcock, S. A. Kincaid


Thirty-three crossbred boars (47-58 days of age) maintained similarly on concrete were randomly allotted to receive a corn-soybean meal ration containing selenium at the basal level of 50(t1) ppb or supplemented with 100(t2) or 250(t23) ppb (from sodium selenite). All boars were fed their respective diets ad libitum until six months of age and were then hand-fed 2.2 kg/boar/day for the remainder of the study. Body weights and testicular widths were taken on each boar at biweekly intervals until six months of age and at monthly intervals thereafter. Blood samples were also taken at these times by vena cava puncture. Libido was routinely scored upon exposure to ovariectomized-estrogenized gilts, beginning at approximately five months of age. When possible, ejaculates were collected and various sperm cell characteris-tics evaluated by both bright-field and phase-contrast microscopy. Seven animals from each group, from which ejaculates were collected, were slaughtered at nine months of age. Anatomical and histological appraisal of testicular and epididymal tissue was made soon after slaughter. Regression of body weight and libido, measured in all 33 boars, and plasma testosterone levels for the 21 boars slaughtered were differ-ent (P < 0.01), over time, among the three treatment groups. Values for each parameter were found to be greater for boars in t1 than for those in t2. which were greater than those in t3. A similar but less pro-nounced relationship to treatment (P < 0.05) was found for testicular width as regressed over time. No treatment differences were observed in either weights or spermatozoan concentrations in the testes, capita-corporea, or caudae epididymides. Analysis of testicular lengths, weights, and circumferences also revealed no differences. Caudal epidi-dymal spermatozoa, examined using both bright-field and phase-contrast microscopy, revealed no evidence of structural changes due to treatment. Measurements were made of epididymal epithelial heights, with those in capita tending (P < 0.10) to be greater in t1 than in t3. Testicular width as measured on the live animal was unrelated to total testicular spermatozoan concentration. These results suggest that dietary selenium, fed at the levels of 150 and 300 ppb, may act to significantly retard the development of certain reproductive processes in young boars as analyzed over time.

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