Published in Scientific Papers. Series D. Animal Science, Vol. LXIII, Issue 2
Written by Radka MALINOVA, Svetoslav KARAMFILOV, Vasil NIKOLOV
Two protocols for planned synchronization and resynchronization of estrus and ovulation of heifers (n-25), aged between 11 and 18 months, of the Aberdeen Angus breed, bred in Bulgaria, have been studied. An experiment was designed to evaluate pregnancy rates in beef heifers synchronized in two different protocols with consecutive synchronization and resynchronization. The first protocol is a combination of two standard and may in principle be divided into two consecutive stages. In the first stage, a group of 11 heifers are under Select Synch protocol extended period of observation and detection of estrus (6-20 days). In the second stage, after 32 days and ultrasound pregnancy detection, standard PRID-Synch protocol and timed artificial insemination, are applied for the resynchronization. In second protocol standard PRID-Synch protocol and timed artificial insemination are applied for synchronization and resynchronization of group of 14 heifers with sex-sorted semen. We found that the total pregnancy rate for the first protocol is 32.39 ± 10.54 % and for the second protocol is 23.8 ± 8.92 %.
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