The objective of this study was to determine the biostimulatory effect of bull exposure on follicular dynamic traits and pregnancy rate of lactating Nelore cows subjected to a fixed-time artificial insemination protocol. A total of 150 postpartum cows were randomly assigned to either a non-biostimulated or (C) and biostimulated (BS) group. Ovarian follicular dynamics was monitored by using transrectal ultrasonography. Females in both groups showed follicular regression after beginning the hormonal protocol. Daily follicular growth and percentage of ovulating females did not differ (P > 0.05) between groups. The interval between the start of the follicular wave and the ovulation was smaller (P < 0.05) in the C group; however, the pregnancy rate was greater (P < 0.05) in the B group. Furthermore, the BS group required less services per pregnancy (P < 0.05). In summary, the results allow to conclude that the association between the male effect and the Fixed Timed Artificial Insemination (FTAI), does increase the pregnancy rates and reduce the number of services per female, although there is no effect on follicular dynamics.

这项研究的目的是确定公牛暴露对接受固定时间人工授精实验的泌乳内罗尔牛的卵泡动力学特征和妊娠率的生物刺激作用。将总共​​150只产后母牛随机分为非生物刺激组或（C）和生物刺激组（BS）。通过经直肠超声检查监测卵巢卵泡动力学。两组女性在开始荷尔蒙治疗后均表现出卵泡退化。 两组之间的每日卵泡生长和排卵女性的百分比没有差异（P > 0.05）。 C组卵泡波开始和排卵之间的时间间隔较小（P <0.05）。但是，怀孕率更高（P B组中<0.05）。此外，BS组每次妊娠所需的服务较少（P  <0.05）。总而言之，研究结果可以得出结论，尽管对卵泡动力学没有影响，但男性效应与固定定时人工授精（FTAI）之间的关联确实增加了妊娠率并减少了每位女性的服务次数。