Tight Profits on Beef Cow Herds Bring Focus to Toxic Fescue Losses

When beef herd profit margins shrink, the losses from grazing toxic tall fescue gain attention.

Convincing cow herd owners to eradicate their old fescue and plant new novel-endophyte fescue is difficult in the best of times. Now, the case will be remade by the Alliance for Grassland Renewal.

“Changes in pasture management are more important than ever,” says Craig Roberts, forage agronomist with University of Missouri Extension.

Three schools will be held March 6-9 in Kansas, Missouri and Kentucky. “One school, one day, in each state,” Roberts says.

“What makes it difficult to sell the idea of conversion is that most farmers never see the serious silent losses,” he says.

Cows that must be put down because of fescue foot grab attention, he adds. However, greater losses come from poor reproduction, reduced gains of calves, low milk production in cows and more, Roberts says.

“When all calves in a herd gain only a half-pound per day instead of a pound a day, that’s not noticed in day-to-day checking the herd,” he says. “If all herds in the region are on toxic fescue, low gains look normal.”

From the beginning, farmers liked Kentucky-31 tall fescue. It is productive and persistent. Roberts says, “It is almost impossible to kill the old fescue with mismanagement.”

The reason K-31 tall fescue survives is an endophyte fungus. That’s an unseen fungus between plant cells that protects grass from insects, drought, diseases – and grazing.

The endophyte toxin causes heat stress. Cattle that graze infected fescue soon stop and go cool down. They head to the pond or to stand in the shade.

In winter the vasoconstrictors in the endophyte cause frozen feet, tails and ears. Blood flow is reduced. That is bad in the heat of summer and the cold of winter. Constriction costs money year-round.

The biggest unseen loss is at the beginning of the life cycle. Heat stress keeps cows from conceiving. Cow herds on toxic fescue have lower calving rates.

Calves that do survive gain slower from birth to sale as feeder calves. The main symptom of calves on toxin is a shaggy hair coat that does not shed. That adds to heat stress.

The Alliance for Grassland Renewal, a national group formed in Missouri, works to convince farmers to convert.

Now many varieties of tall fescue are bred with endophytes that do not create toxins. Those novel endophytes protect the grass and don’t cause financial losses.

Source: Craig A. Roberts, University of Missouri