What’s the deal with fescue grass and horses?

You may have heard that fescue grass is dangerous for pregnant mares.  Yes, not necessarily, and also stallions, too. So what’s the deal?  Fescue grass is prevalent in the US because it’s hardy.  It tolerates drought, it’s easy to grow, horses love the taste, it’s nutritious.  But, what makes it so hardy is the little fungus buddy growing INSIDE of it.  The endophyte.  This little endophyte does a few things - give the grass some great staying power in your pasture, and it also likes to create some chaos in pregnant mares, foals, and even stallions.  Seems the endophytes really like to interfere with the reproductive systems of horses and other grazing animals.  


A pregnant mare can abort a pregnancy, or develop other complications such as a prolonged gestation (sometimes months longer, resulting in difficult births), an absence of milk (this can lead to starvation of the foal) and retained placentas.  Foals, if they survive, can starve, are often weak and immature.  Stallions have been found to have reduced amounts of ejaculate volume, which of course will impact the bottom line on his breeding business.  


A simple lab test can determine if your horse's pasture has endophytes, and then any breeding stock you have can be properly cared for. 


However, there is a medication available from your Veterinarian if your pregnant mare is on endophyte infested fescue.  The key is to know a few things - that your fescue pasture has endophytes (a laboratory can test and confirm thisfor you), and that your mare is pregnant, and how far along.  


You should also know that non breeding horses are unaffected by endophytes in the fescue grass.  So, if your barn is full of geldings and non breeding mares and/or stallions you are ok!  



Yum - delicious!


You do have the option of starting over in your pastures if you need to rid them of endophytes in your fescue grass.  You can use herbicides and start from scratch to be sure the fescue won’t return.  Time consuming!  You can also sprinkle in other grasses with the fescue to dilute the amounts of endophytes, but at some point you will not be able to accurately guess how that is working for you.  


There are also endophyte free fescue grasses available for pastures as well.  There are also loads of other types of pasture grasses, some grow better in different climates.  Your local agriculture extension service will be able to help you determine what’s in your pasture, as well as what could work better if you need to start from scratch! 




Does your horse graze on fescue?