Medium wool ewes were injected with vitamin E and(or) Se over a 2-yr period to evaluate the influence of these treatments on reproduction. Ewes were divided randomly into four groups, consisting of a control, plus groups receiving monthly sc injections of either 272 iu vitamin E, 4 mg Se or 272 IU vitamin E plus 4 mg Se during pregnancy. Selenium administration increased (P less than .05) ewe blood Se concentrations, but had no effect (P greater than .10) on fertility (number of ewes lambing of ewes bred), prolificacy (number of lambs born/ewe lambing) or lamb sex ratio. Preweaning survival of lambs was increased (P less than .05) by ewe treatments with either Se or vitamin E and thus, treated ewes weaned approximately 20% more lambs/ewe mated than did control ewes.

To determine the effect of gossypol on growth and reproductive development, Brahman bulls (n = 30) were fed diets containing gossypol (6 or 60 mg.kg BW-1.d-1) or a diet free of gossypol from weaning through puberty. Diets contained cottonseed meal (CSM), whole cottonseed (WCS), or soybean meal (SBM) as the major sources of dietary CP. Diets were formulated to provide similar NEg for medium-framed bulls to gain .9 kg/d. Measurements of BW and scrotal circumference were obtained at 28-d intervals, and beginning at 10 mo of age electroejaculates were collected at 14-d intervals. By 196 d on feed, bulls fed WCS had gained less (P < .05) BW and tended (P < .10) to have lower gain/feed than bulls fed CSM. When spermatozoa were first detected in an ejaculate, bulls fed CSM tended (P < .10) to be younger than bulls fed WCS (357 vs 386 d; SBM = 380 d); bulls fed SBM were heavier (P < .05) than bulls fed gossypol (333 vs 310 kg), but they had similar scrotal circumferences. Bulls fed WCS reached puberty at an older (P < .05) age (613 d) than bulls fed CSM (528 d; SBM = 550 d) but had similar BW and scrotal circumferences. Electroejaculated semen quality and quantity did not differ (P > .10) between treatments at puberty. Seminiferous tubule diameters did not differ (P > .10) among treatments, but bulls fed diets that contained gossypol had larger (P < .01) lumenal diameters, smaller (P < .01) germinal epithelium thickness, and fewer (P < .01) germ cell layers than bulls fed SBM diets.(ABSTRACT TRUNCATED AT 250 WORDS)

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