Published in Scientific Works. Series C. Veterinary Medicine, Vol. LXVI, Issue 1
Written by Mihai CENARIU, Emoke PALL, Mihai BORZAN, Remus CHIOREAN, Ioan Stefan GROZA
Pregnancy rates obtained after artificial insemination following Ovsynch in lactating dairy cattle are currently around 40-45%. Therefore, various fertility programs have been established in an attempt to increase these percentages. The aim of the present research was to use a simple and cost-effective presynchronization protocol, that would allow maximization of ovulatory response after the first GnRH of Ovsynch, and therefore improve fertility of treated animals, in comparison to those in which Ovsynch was used alone. A total of 240 non-pregnant and lactating dairy cows were divided in two groups (n = 120). Group 1 was synchronized with Ovsynch alone, while in group 2, PGF2α and GnRH were administered almost simultaneously, in different injection sites, 7 days before the initiation of Ovsynch. Ovarian structures were observed by ultrasonography on the day when the first GnRH injection of Ovsynch was made and 4 days later. Results showed a 42.5% pregnancy rate in group 1 and a 57.5% pregnancy rate in group 2. Therefore, presynchronization treatments allowed an improved pregnancy rate of 15%, which totally covers the supplemental costs implied by such measures.
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