R. Bras. Zootec.01/Jan/2002;31(1 Sup..):363-8.
Dominant Follicle and Superovulatory Response in Nelore Heifers
DOI: 10.1590/S1516-35982002000200010
Seventeen Nelore heifers were submitted to a superovulation protocol, beginning on the ninth day of the estrous cycle. Eight heifers were superovulated with 250 IU (T1) and nine with 500 IU (T2) of FSH. The animals were monitored by ultrasonography during the superovulation period and on the embryo collection day. There were no differences on the recovery rate and quality of the structures collected among the animals of the two treatments. Animals treated with 250 (T1) and 500 IU (T2) of FSH produced 4.16 and 3.15 embryos viables/donor, respectively. The presence of the dominant follicle in the beginning of the superovulatory treatment did not affect the superovulatory response. The largest diameter follicle and second largest one and number of subordinate follicles during the superovulation from the animals of the treatments did not differ among treatments. The diameter for the largest follicle, the second largest and the number of subordinate follicles for the animals treated with 250 versus 500 IU, were: 11.36 x 11.59 mm; 8.91 x 9.42 mm and 16.93 x 17.44 mm, respectively.
Keywords: dominant follicle; embryos; heifer; Nellore; superovulation; ultra-sound