Evaluation of sexual behavior of hair sheep rams in a tropical environment.

ABSTRACT

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.