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We evaluated sexual behavior of St. Croix White (SC; n = 5) and Barbados Blackbelly hair (BB; n = 4) rams under two environmental conditions in the tropics. Sexually naive rams were individually exposed for 15 min to a restrained, ovariectomized ewe, three times during a 3-wk period in June, in a pen with shade (SHADE; 33.1+/-.3 degrees C) or without shade (SUN; 38.3+/-.3 degrees C). Rectal temperature (RT) of rams was measured before and after each test. Sexual behaviors were recorded by observers outside the pens. The number of mounts and ejaculations were similar (P > .10) between the SUN (12.1+/-2.8 and 3.6 +/-.5, respectively) and SHADE (10.7+/-2.9 and 3.4+/-.4, respectively) tests. There was no breed x test pen interaction for any of the behaviors recorded (P > .10). The BB rams mounted the ewe more (P < .04) than did the SC rams (15.7+/-2.8 vs 7.3+/-2.7 mounts, respectively). The overall level of activity (foreleg kicks, attempted mounts, mounts, and ejaculations) was similar (P > .10) between BB and SC rams (64.9 +/-8.5 vs 45.4+/-8.5 events, respectively). Rectal temperature before testing was similar (P > .10) in BB and SC rams (39.4+/-.1 vs 39.4+/-.1 degrees C, respectively). The change in RT of rams was not different (P > .10) between SUN and SHADE tests (.6 +/-.1 vs .8+/-.1 degrees C), but BB rams had a greater (P < .02) change in RT than SC rams (.9+/-.1 vs .5+/-.1 degrees C, respectively). The change in RT was positively correlated with time to first service (r = .39, P < .01) and number of mounts (r = .52, P < .001) and negatively correlated with number of services (r = -.47, P < .0008). These results show that under tropical conditions, hair sheep rams exhibit a full repertoire of sexual behaviors. There does not seem to be a negative influence of elevated ambient temperature during testing on the level of sexual behavior of these rams.

Our objectives were to determine the effects of incremental increases in dietary gossypol on metabolic homeostasis and reproductive endocrine function in postpubertal beef heifers and the long-term effects of elevated dietary gossypol on various metabolic and reproductive endocrine characteristics in mature cows. In Exp. 1, heifers (n = 6/group) were fed either 0, .5, 2.5, 5, 10, or 20 g.animal-1 x d-1 of dietary free gossypol for 62 d. Erythrocyte membrane osmotic fragility was increased (P < .0001) in both the 10- and 20-g groups. Slight alterations in plasma concentrations of sorbitol dehydrogenase and K+ were also detected in the latter group. Treatment did not affect ADG, body condition scores, or concentrations of progesterone during the estrous cycle; however, mean concentrations of LH were higher (P < .001) in heifers fed 20 g/d of gossypol than in heifers in all other groups. In Exp. 2, lactating cows (n = 17) exhibiting regular estrous cycles were fed a control (no gossypol, n = 8) or high-gossypol (20 mg.kg BW-1 x d-1 free gossypol, n = 9) diet for 33 wk. Mean BW and body condition scores did not differ during the feeding period. Erythrocyte membrane fragility was greater (P < .05) in the high-gossypol than in the control group. Magnitude of the preovulatory LH surge, luteal phase concentrations of progesterone, follicular fluid concentrations of estradiol and progesterone, in vitro granulosa cell estradiol production, and 60-d pregnancy rates were similar between groups. The amounts of gossypol fed in these experiments are not likely to affect reproductive performance adversely in beef heifers or cows.