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Pros and cons of fescue toxicity – Part IX

by Wyoming Livestock Roundup

In my last few columns, I’ve discussed some common syndromes of fescue toxicosis in cattle as well as fescue toxicity related reproduction problems in horses, including abortions, difficult birth (dystocia), longer or prolonged gestation, thickness in placenta, death of foals, retained placentas, little to no milk production (agalactia) and mare death during foaling. 

I have also discussed biology of the causal agent, benefits of fungal endophyte, endophyte-free tall fescue and non-toxic endophytes and their effects on tall fescue and animal performance and level of endophyte infection in pasture. 

My discussion will now focus on other possible solutions for the fescue toxicity problem.

Possible and practical solutions continued 

As I mentioned in my previous article, there are several solutions which can be applied to deal with the fescue toxicity problem. These solutions could be relatively inexpensive to highly expensive.

I’ve previously discussed some practical and less expensive options. Below are a few relatively more expensive options.

A more expensive option is to treat pregnant mares grazing toxic tall fescue pastures. A compound or medication called domperidone can be administered to mares. This allows mares to carry foals without losses. 

However, this is not a feasible option to use in cattle, as the cost of this compound is very high. Also, the effect of domperidone is short-lived in cattle. It is therefore recommended producers should use a little math before deciding to use this expensive compound.

Another option, which is even more expensive, is to destroy existing pastures and replant them. This option can be applied if tall fescue pastures show beef cows with poor pregnancy rates, low weights of weaning calf and frequent visible symptoms of fescue toxicity. 

In this situation, replanting pastures with endophyte-free or novel endophyte tall fescue seeds could improve animal performance and overall farm profitability. Remember though, this is a major decision to consider, because it involves a high cost to replace an existing pasture.

Other considerations 

High animal gains and profitability is essential for grazing young beef animals, especially in a stocker operation. Young steers and heifers are very sensitive to toxic tall fescue. 

It is reported daily weight gains can be reduced by 0.1 pound for each 10 percent increase in toxic endophyte infected tall fescue plants in the pastures dominated by toxic tall fescue. 

Hence, replanting new pastures with non-toxic or endophyte-free tall fescue could be an attractive option for higher animal gains and profitability. It is also suggested a good dewormer can be used in yearlings when grazing infected toxic tall fescue pastures to improve animal performance. 

Therefore, operations may consider replanting and reestablishing toxic infected pastures with endophyte-free or novel endophyte tall fescue as performance of animals and profitability of the pastures may be affected by the toxic endophyte infected pastures over time.

I will continue discussion on solutions of fescue toxicity problems and replanting infected tall fescue pasture in future columns.

Anowar Islam is a professor and the University of Wyoming Extension forage specialist in the Department of Plant Sciences in the College of Agriculture and Natural Resources. He can be reached at 307-766-4151 or

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