Phosphorus On Pastures Fights Grass Tetany

Phosphorus applications increase the magnesium level in tall fescue, which in turn helps prevent grass tetany in grazing cattle.

That's according to University of Missouri graduate student Ryan Lock. At the university's Southwest Research and Education Center near Mount Vernon, MO, he grazed three groups of cattle in separate pastures for 56 days.

The control group grazed tall fescue with a soil test of 5 lbs of available phosphorus per acre. Another group's pasture tested nearly 30 lbs/acre of available phosphorus. The third group was put in a pasture with only 5 lbs/acre of available phosphorus, but those cows had free-choice access to a magnesium block.

The cows in the phosphorus-fertilized and magnesium-block pastures had magnesium blood serum levels 24% and 20% higher, respectively, than that of the control group.

The experiment indicates that fescue in pasture with 30 lbs/acre of available phosphorus “provided the same protection against grass tetany as supplying free-choice magnesium supplement,” says Lock.

The high-phosphorus pastures also greened up earlier in spring. “We think that when plants have enough phosphorus around the roots, it opens a gateway in the roots that's specific to allowing the magnesium to get in and hasten the process of chlorophyll production,” he says.

Alfalfa Buffers Horse Stomachs

University of Tennessee research indicates that alfalfa may act as a buffering agent for horses, protecting their stomach linings from damaging acids.

In a study on the impact of diet on gastric ulcers in racehorses, three horses were fed only bromegrass hay for two weeks while three others received alfalfa hay and grain. Then the diets were switched for two weeks.

“We thought that the high-energy alfalfa and grain diet of racehorses would lead to more acid and ulcers,” says doctoral student Jennifer Nadeau. “We found, however, that when the horses were fed alfalfa and grain diets, the pH of their gastric juice was higher (less acidic) and they had fewer ulcers.”

The researcher speculates that the calcium in alfalfa may account for the findings. “There is evidence that calcium works as an antacid of sorts in other animals,” says Nadeau. “Perhaps that's what's happening in horses.”