Examination of oestrus cycle and early pregnancy in sheep using transrectal ultrasonography
2002
Strmsnik, L., Ljubljana Univ. (Slovenia). Veterinary Fac. | Pogacnik, M. | Cebulj- Kadunc, N. | Kosec, M.
The subject of our research was the oestrus cycle and period of early pregnancy in primiparous Jezersko Solcavska - Romanov cross-breed sheep. In particular, we investigated variations in the size and number of follicles and the concentrations of progesterone and 17-beta-estradiol as well as the reliability of a transrectal linear 7.5 MHz ultrasound probe. Twenty days after ovulation the animals, whose oestrus cycles were synchronised by using progesterone sponges, were divided into two groups; one group of pregnant animals and another of non-pregnant animals. After the progesterone sponges were removed, 65 % of the animals ovulated within 48 to 72 hours and a further 20 % within 72 to 96 hours. Prior to ovulation, the number of follicles ≥ 4 mm in both groups averaged 2.32 0.91, the diameter of ovulatory follicles averaged 5.52 +/-1.12 mm and the average ovulation rate was 1.76. The number of follicles ≥ 4 mm was indistinguishable between the pregnant and non-pregnant animals until the 16th day of their cycle or pregnancy and in follicles ≥ 2 4 mm until the 20th day. Based on the appearance of luteolysis and changes in the uterus, it can be concluded that the level of early embryo mortality amounted to 36.5 % and that it occurred in 40.5 % of the animals. In both groups, the concentration of progesterone reached its highest level on the 6th day of their cycles. The reliability of the transrectal ultrasound examination was 83 % on the 16th day of pregnancy and reached 100 % by the 20th day. On the 23rd day of pregnancy the heartbeat of all foetuses was visible.
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