In the Southeast, one of our main forages looks promising – but doesn’t deliver as expected. Tall fescue is a blessing and a curse. It sustains and robs all at the same time. As a blessing, a pasture full of growing grass looks just like the cure for supplying nutrition through the spring and part of fall.

As a curse, cattle with an abundant amount of grass are a body condition score thinner than ideal, conception rates are poor, and late-spring hair coats look like shag carpet sopped in mud.

Most folks understand tall fescue is bad stuff, but they either don’t know the whole impact or feel helpless to do anything about it. If you ever wondered why producers have fall-calving herds, this is one of the reasons.

Breeding seasons in May and June are extremely disappointing when toxic endophyte fescue is the main forage. Although fall calving helps, the growing calves and replacement heifers will be victims come spring, enduring long-term effects.

Research in Georgia and Arkansas showed calves grazing infected endophyte fescues had reduced gains of 50 pounds compared to calves grazing novel (nontoxic) endophyte fescue. The Arkansas study also evaluated tall fescue’s effects on reproductive performance.

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Cattle grazing novel endophyte fescue had significantly better pregnancy rates for mature cows, 85.1 percent versus 44.7 percent.

Calving rates for heifers on novel endophytes were 90.6 percent versus 64.1 percent. The impacts of toxic endophytes in tall fescue are significant. Stocker cattle grazing toxic endophytes have average daily gains reduced by 0.5 pound in the fall and 1 pound in the spring. Feeder cattle on tall fescue enter the feedlot at lighter weights and require more days on feed.

Research shows having clover in tall fescue pasture dilutes some of the effects and helps improve gains in growing calves. Removing toxic fescue and planting a novel variety or some other grass is costly and has some risk, but it can certainly be a worthwhile project if conception rates are improved by 10 percent over the long term.

When pasture renovation is not an option, it may be worthwhile to investigate chemical seedhead suppression or introduce genetic lines that have heat or infected fescue tolerance. end mark

Jason Duggin