engleski

Ovsynch efficiency in anoestrous dairy goats

Oestrus induction and synchronization protocols in small ruminants are mainly based on the use of progestagens and eCG, comprising AI during and out of the sexual season. These methods result in acceptable kidding rate, but there is a worldwide intention of avoiding use of steroid hormones for oestrus synchronization due to micro residues in food chain. At the same time, there is a tendency of restricting the use of these hormones in the EU (Directive 96/22/EC), and new protocols, that allow the use of AI and result in sufficient kidding rate are being investigated. The aim of our research was to establish the efficiency of modified Ovsynch protocol with TAI in dairy goats. The modification of standard Ovsynch included longer interval between PG and second GnRH application, and we expected decrease in percentage of goats with short luteal phase. The research was conducted on 20 Saanen goats during September in northern parts of Croatia, when all goats were expected to be in full season. Animals received GnRH analogue, 7 days later PGF2α, and 64 h later second GnRH. TAI with deep frozen semen was performed 16 h later, with intracervical deposition of semen. Six weeks later all goats were checked for pregnancy. In order to establish synchronization success by analysing progesterone concentration, blood was drawn from all animals from jugular vein on days of GnRH application. Conception rate was 0 %, and progesterone concentration at first GnRH administration in Ovsynch was 0.318 ± 0.13 ng/ml. Though the protocol was conducted in September, when the goats in NW area of Croatia are supposed to be in full season, progesterone concentration suggests that there was no luteal activity on high yielding goats ovaries, thus they were still in anoestrus. Therefore, conception rate of 0 % indicates that Ovsynch is inadequate protocol for use in anestric goats.

small ruminants, synchronization, Ovsynch

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