Sincronizzazione dei calori mediante l’impiego di HCG e prostaglandine in pecore di razza Appenninica X Bergamasca.

The trial was carried out to evaluate the effectiveness of treatments with human chorionic gonadotropin (hCG) plus Prostaglandin F2α on estrus synchronization in ewes. At the end of seasonal anoestrus 22 adult ewes (Appenninica x Bergamasca), kept separated from males for two months, were distributed into two groups: the first ( A: n° 10) received one injection of hCG (250 I.U, i.m) on -9 d, followed by the administration of a PGF2α analogue Cloprostenol on -2 d (0.125 mg i.m.) before male introduction; while the animals of the second group (B: n° 12) were untreated (control group). All ewes were put together with the rams on 0 d. Blood samples were taken from all animals at days –15, -9, -2, +5, +10, +15, +20, and +30, progesterone plasma concentration was determined by RIA. Pregnancies were checked by echography at +90 d and the births were recorded. At -9 d 14 on 22 (64%) ewes were considered anestrous, showing P4 values < 1 ng/mL in the first two blood samples. The P4 blood concentrations showed that hCG injection was effective in inducing luteal activity in the anestrous animals, and PGF2a administration determined in all animals luteolysis and successive estrus synchronization. In A group 6 ewes had birth within +160 d after males introduction and one of them had twins, while 4 became pregnant on following estrus returns. In B group only 2 animals had births in the first 160 days after the male introduction, while 10 ewes became pregnant on the following estrus returns. No one of them had twins. From these results we could conclude that a treatment with hCG plus Prostaglandin F2α may be useful to obtain synchronized fertile heats in ewes during transitional period.