Gonadotropic action of medication administered in various doses to synchronise the oestrus of anoestral sheep

Abstract

The experiment included 20 ewes of the Tsigai breed, allocated in two groups of 10 animals each. Inducing of oestrus synchronisation was performed during anoestral season (April-May) through vaginal sponges containing gestagens, and administration of Gravohormon (Vetbiopharm, Bulgaria)-500 UI in group 1 ewes and 1000 UI in group 2 ewes. Macromorphological study of the ovaries was carried out by means of laparoscopy after the adopted methods-on the 56 th hour, 72 nd hour and 5 th day following sponge withdrawal and injection of gonadotropin. The levels of the steroid hormones progesteron and 17ß-oestradiol were recorded in three ewes per each group at different times according to the experiment scheme. The histological structure of the ovaries was determined in seven animals subjected to ovariectomy.

The influence of the time of implementation of PMSG on some of the reproductive parameters in sheep with synchronized oestrus

“…Progesterone concentration started to increase 50 h after injection and at 122 h it already exceeded 0.5 ng/ml. Our results corresponded closely to the findings of Ralchev et al (2008) who studied the changes in plasma progesterone concentrations in Tsigai ewes injected with 500 and 1000 UI gonadotropin at the time of sponge removal during the non-breeding season. In both groups of sheep progesterone concentration began to increase 72 h after gonadotropin injection reaching the peak levels of 0.47 and 0.33 ng/ml, respectively, by the 5 th day posttreatment.…”

“…Ungerfeld et al (2002) recommended the application of progestagens in the form of vaginal sponges for a period of 6-14 days in combination with PMSG. It was found that gonadotropins stimulate follicular growth, increase the ovulation rate and fertility and improve synchronization (Cline et al, 2001;Maurel et al, 2003;Ralchev et al, 2008).…”