Synchronization of ovulation in beef herds: improved conception rate after and interrupted course of progesterone administration

Abstract

Die bronstigheidsiklusse van vleisraskoeie en/of verse is in ses kuddes deur binnespierse progesterooninspuitings gesinkroniseer. Om die koeie wat met die aanvang van die behandeling in die laat fase van 'n siklus verkeer en wat dikwels gedegenereerde ova na sinkronisasie vrystel uit te skakel is die behandeling in twee fases verdeel. Eers is vier 48-uurlikse inspuitings van 50 mg progesteroon in propileenglikol toegedien, dan is 'n periode van 8 dae oorgeslaan voordat die tweede reeks van ses 48-uurlikse progesterooninspuitings hervat is. Met hierdie metode is uiters bevredigende resultate met inseminasie tydens die eerste gesinkroniseerde bronstigheid verkry in 4 uit die 6 kuddes. Konsepsiesyfers wat tussen 69 en 86 % gevarieer het is behaal wat goed vergelyk met die gemiddelde van ongeveer 70%vir eerste inseminasie sonder sinkronisasie en 'n groot verbetering is op die gemiddelde besettingsyfer van 47%(36 tot 58%)wat voorheen na progesterooninspuitings behaal is.

The oestrous cycles of cows and/or heifers were synchronized in six herds by the intramuscular administration of progesterone. In order to exclude those cows that were in the latter third of their cycles at the onset of treatment, the herds were first presynchronized by four 48-hourly injections of 50 mg of progesterone in propylene glycol and after an interval of eight days, treatment was resumed by giving them 6 more such 48-hourly injections. Conception figures varying from 69 to 86 % were attained in 4 of the 6 trials during the synchronized oestrus. These compare favourably with normal first insemination figures uncomplicated by synchronization and represent a marked improvement on
the average figure of 47% (36 to 58%) previously experienced after synchronization with progesterone.