[Strategic hormonal reproductive programs in cows. Part 2: Presynchronization and resynchronization]. / Strategische hormonelle Fruchtbarkeitsprogramme bei Kühen. Teil 2: Präsynchronisation und Resynchronisation.

ABSTRACT

OBJECTIVE: Description of hormonal presynchronization and resynchronization methods in cattle. MATERIAL AND METHODS: Review. RESULTS: As the pregnancy rate of cows treated with the Ovsynch program primarily depends on the stage of the oestrous cycle at the time of program initiation, different methods of presynchronization based on the use of PGF2α and combinations of PGF2α and gonadotropin- releasing hormone analogues have been developed. An additional problem includes the earliest possible insemination of open cows following the Ovsynch program. As a solution to this problem a post- insemination treatment of all animals seven days before the scheduled date of the pregnancy examination is recommended.If a cow is found not to be pregnant by the pregnancy examination, it will be treated with PGF2α to enable a further insemination as soon as possible thereafter. CLINICAL RELEVANCE By utilizing presynchronization and resynchronization programs, the reproductive performance of a dairy herd can be increased.