A toxic grass that threatens a quarter of U.S. cows is spreading. Can it be stopped?

A toxic grass that threatens a quarter of U.S. cows is spreading. Can it be stopped?

Robert Langellier writes:

America’s “fescue belt,” named for an exotic grass called tall fescue, dominates the pastureland from Missouri and Arkansas in the west to the coast of the Carolinas in the east. Within that swath, a quarter of the nation’s cows — more than 15 million in all — graze fields that stay green through the winter while the rest of the region’s grasses turn brown and go dormant.

But the fescue these cows are eating is toxic. The animals lose hooves. Parts of their tails and the tips of their ears slough off. For most of the year, they spend any moderately warm day standing in ponds and creeks trying to reduce fevers. They breathe heavily, fail to put on weight, and produce less milk. Some fail to conceive, and some of the calves they do conceive die.

The disorder, fescue toxicosis, costs the livestock industry up to $2 billion a year in lost production. “Fescue toxicity is the most devastating livestock disorder east of the Mississippi,” said Craig Roberts, a forage specialist at the University of Missouri Extension, or MU, and an expert on fescue.

By the early 20th century, decades of timber-cutting and overgrazing had left the ranching region in southern states barren, its nutrient-rich native grasses replaced by a motley assortment of plants that made poor forage. Then, in the 1930s, a University of Kentucky professor spotted an exotic type of fescue growing in the mountains of eastern Kentucky, which seemed to thrive even on exhausted land. Unlike most native grasses, Kentucky-31, as it was called, stayed green and hearty through the winter. Ranchers found the species remarkably resilient and, if not beloved by cattle, edible enough to plant. Over the next 20 years, much of the country’s southern landscape was transformed into a lush, evergreen pasture capable of supporting a robust cattle industry.

As early as the 1950s, however, ranchers began to notice tall fescue’s disturbing effects: One study showed that cattle had to be fenced out of other grasses before they’d touch fescue. When they did eat it, the cows saw only one-sixth of their normal weight gain and lost eight pounds of milk production a day. [Continue reading…]

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