Pros and cons of fescue toxicity – Part V

By Anowar Islam 

In my last few articles, I have discussed common syndromes of fescue toxicosis in livestock. Fescue toxicity issues in horses include reproduction problems in mares including abortion, dystocia, longer or prolonged gestation, thickness in placentas, death of foals, retained placentas, little to no milk production or agalactia and mare death during foaling.  

Additionally, I have discussed some biology of the causal agent, and benefits of fungal endophyte.  

In this column, I will focus on endophyte-free tall fescue. 

Endophyte–free tall fescue 

Seeds of tall fescue can be treated to make them endophyte-free. If we plant endophyte-free tall fescue, this will produce excellent animal performance and eliminate toxicity problems associated with toxic endophyte.  

However, there can be adverse effects of using endophyte-free tall fescue. Endophyte-free tall fescue lacks stress tolerance, which is an important factor for livestock production.  

Especial cares, such as soil fertility, planting date, seeding rate and planting depth, need to be taken in establishing endophyte-free tall fescue, especially in limited irrigation or rain-fed conditions. In areas where tall fescue is marginally adapted, it is hard to establish endophyte-free tall fescue in stressful conditions. 

Grazing considerations 

Stands of endophyte-free tall fescue can get relatively easily weakened from overgrazing and drought to a much greater extent, compared to toxic endophyte-infected tall fescue. In general, endophyte-free tall fescues are more palatable, which results in stand losses due to overgrazing, particularly during summer. Hence, it is important to better manage grazing systems for maintaining endophyte-free tall fescue stands and their productivity. 

It is generally recommended, endophyte-free tall fescue planted in the fall should not be grazed until the stands are well established in late spring the following year. Also, greater attention should be put on not overgrazing or close grazing the newly established endophyte-free tall fescue pastures in the summer. This can weaken the endophyte-free tall fescue stands and reduce the production in the next fall. 

Overall, environmental stresses are greater in areas where endophyte-free tall fescue is marginally adapted and grown. Therefore, it is important to pay close attention to ensure endophyte-free tall fescue pastures are not overgrazed, especially in stressed environments. 

I will continue discussion on endophytes, especially non-toxic endophyte, their effects on tall fescue and animal performance and possible solutions of fescue toxicity. Please keep an eye on my future writings. 

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 mislam@uwyo.edu.