The use of progestagens in anoestrus cows

One of the advantages of progestagen-based treatments such as Crestar® is that they are capable of inducing onset of oestrus cycles in anoestrus cows. In non-cyclic cows the progestagen sensitises the hypothalamo-pituitary-gonadal axis and facilitates a normal lifespan of the corpus luteum. The administration of PMSG when the progestagen is removed further stimulates follicular maturation and ovulation.

Progestagens are especially recommended as the method for oestrus management in beef cows. Combination of oestrus management with products such as Crestar with temporary partial calf weaning allows for oestrus induction and successful breeding of cows with high pregnancy rates.

The success rate of Crestar® and other progestagen based methods in anoestrus can be variable (50-70%) depending on the post partum interval at time of treatment, body condition of the cow and other underlying causes of anoestrus. Nonetheless Crestar® and other progestagen based systems should be seen as the method of choice to manage oestrus in beef cows as they allow for compact breeding early in the season with high percentage of cows conceiving in the first synchronised oestrus. This in turn facilitates fast re-breeding of cows that have not conceived during the first oestrus and allows for a tight calving season.

Oestrus and ovulation, after treatment with progestagens, occur earlier and with more precise timing than occur following prostaglandin injection. For Crestar® a single, fixed time insemination is recommended.

beef and dairy cows