Use of transrectal ultrasonography to follow ovarian activity in goats.

The efficiency of ultrasound observation of ovaries as a tool to follow ova rian activity in goats has been evaluated in 2 experiments. In the first experiment 29 goats received a progestagen/prostaglandin/eCG t reatment. At oestrus their ovaries were observed by transrectal ultrasonogr aphy in, vivo and within 2 hours, goats were sacrified and the follicles di ssected. The number of follicles equal or greater than 4 mm estimated by ul trasonography was highly correlated to the number determined after dissecti on (r(2) = 0,903), P < 0,01). However, if the Y intercept of the regression Line is not different from zero, the slope of the regression line is signi ficantly (P < 0,0001) different from 1 leading to an over-estimate of 25 % by ultrasonography, The second experiment deals with the time of ovulation which was evaluated in goats after a progestagen/prostaglandin/eCG treatment. The goats were sa mpled every 4 h for the assay of LH and the ovaries were scanned at the sam e frequency beginning 18 h after the occurrence of the LH surge. Ovulation as detected by disappearance of the large follicles, occured from 18(th) h to 26(th) h after the LH peak, which agrees with data obtained by endoscopy . Therefore, for goats as for other species studied so far, ultrasonography s eemed to be a potent tool to study the ovarian function.