Hormonal therapy in dairy cows to reduce the effects of heat stress

Hormonal therapy does not address the causative effects of heat stress, however amelioration of some of its direct effects on the endocrine reproductive axis offers an opportunity to overcome the decrease in reproductive performance in cattle during summer and early autumn.

Hormonal therapy should never be the only measure implemented in the situation of heat stress. Organisational and managerial measures should be also implemented accordingly, preferably before pharmacological intervention.

The following strategies can be adopted to improve reproductive results during the period of heat stress:

1. Oestrus synchronisation for timed AI
   Ovsynch protocol has been advocated as the method of choice for reproduction management in dairy cattle exposed to high ambient temperatures.

For Ovsynch treatment protocol, click on the thumbnail below.



For benefits of using the Ovsynch protocol, click on the thumbnail below


2. GnRH administration at oestrus
   Induction of ovulation with GnRH not only decreases the incidence of delayed ovulation (one of the major consequences of the heat stress) but also provide additional luteotrophic support for early CL.
   
   
   

   For GnRH administration at oestrus in cows subjected to heat stress, click on the icon on the right.

3. GnRH or hCG administration post AI
   Administration of hCG or GnRH post Ai supports the luteal function through a creation of additional corpora lutea and prevents precocious luteolysis through elimination of growing luteal phase follicles
   
   
   

   For GnRH administration post AI in cows subjected to heat stress, click on the icon on the right. For more information see: Results of treatment with GnRH after AI