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Pros and cons of fescue toxicity – part IV

by Wyoming Livestock Roundup

By Anowar Islam

            In my last few articles, I discussed common syndromes of fescue toxicosis in cattle and horses, including abortions, difficult birth (dystocia), longer or prolonged gestation, thickness in placenta, death of foals, retained placentas, little to no milk production (agalactia), mares’ death during foaling and some biology of the causal agent. 

            In this article, I will focus on possible benefits of endophyte remaining inside tall fescue plants.

Symbiotic relationships

            There are several benefits of the fungal endophyte living within tall fescue plants. The endophyte does not cause any harmful effects to tall fescue plants. In fact, both plants and endophyte receive mutual benefits from their association of living together. 

            The benefits for endophyte include food, protection from external harms within the tall fescue plants and the ability to spread their future generations through seeds. 

            On the other hand, tall fescue plants receive many benefits in return for their better survival and competition with other plants, especially in stressed environments. These include tolerance to drought, close or heavy grazing, pests, improved seed germination, seedling vigor, tillering and competition with other plant species.

            Tall fescue plants infected with endophyte are more tolerant than endophyte-free plants. The endophyte-infected plants have greater root volume and depth which helps plants uptake more water from greater depth for longer period. As a result, plants have better survival under moisture stressed conditions. 

Tall fescue benefits

            Endophyte presence in the plants increases germination of seeds, seedling vigor, growth of tiller, production of seed and uptake of nutrients. In addition, endophyte infection improves resistance of plants to some diseases, insects, nematodes and close continuous grazing.

            Although, fescue endophyte has a bad reputation, no doubt, there are some obvious benefits as well from their mutual association with grass. Overall, the endophyte makes tall fescue plants more persistent and competitive with other plants in pasture systems.

            If tall fescue plants can be infected with a non-toxic novel endophyte, this will not only remove all endophyte-related toxicity problems but also provide excellent animal performance. Researchers have identified some non-toxic endophytes and infected them in tall fescue plants for better performance.

            I will continue this discussion on endophytes, 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

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