Death by soybeans: Cattle fatalities caused by acute rumen acidosis

WEST LAFAYETTE, Ind. – Twelve cattle on a southern Indiana farm died of a condition called grain overload, which caused acute rumen acidosis, according preliminary findings of Purdue University veterinarians.
Tests were run on one of the 12 animals that died after they consumed an excessive amount of soybeans, a feed they didn’t normally eat, said Duane Murphy, codirector of the Heeke Animal Disease Diagnostic Laboratory at the Southern Indiana-Purdue Agricultural Center.
Further tests were being run at another facility, and the final report is expected in several weeks.
What happens. Rumen acidosis is when grains ferment in the rumen – the first chamber of the four-chamber bovine stomach. This causes a sudden change in acid levels in the rumen that damages the stomach lining and allows acid to be absorbed into the bloodstream.
With grain overload, the cattle may or may not exhibit rumen bloat.
The incident in southern Indiana occurred when the owner cleaned out a grain cart as he was switching from his soybean crop to his corn crop and spread the leftover soybeans across a field.
Alternative feeds. Various grains, crop remnants and nontraditional feeds can be substituted for normal hay, but the amount fed, the moisture in the feed and the time of year it’s fed need to be considered to make sure livestock receive a safe and healthy balanced ration.
“You can put together nutritional rations for cattle when there is limited hay,” said Ron Lemenager, a Purdue Extension beef cattle specialist.
“You have to make feed changes gradually, especially with grain, but also if a field has a lot of legume, such as alfalfa, and the cows have been out on grass-based forage.”
It’s possible to substitute some lesser-used feeds, such as corn silage and soybean hay, but farmers must make sure they use these properly, said Keith Johnson, a Purdue Extension forage expert.
“In hard times, you can use nontraditional measures, but you have to take into account the type of animal and the animal’s stage of production and feed accordingly,” he said.
Wheat, soybean and oat hays can be used as substitutes for other more traditional hays, Johnson said. Winter rye, annual ryegrass and winter wheat has already have emerged might allow some grazing before winter if fall growing conditions are favorable.
Harmful plants. Livestock owners also need to be aware that some plants that look attractive to animals might be harmful.
“When pastures are bad, animals will go after things they would ordinarily snub, and some of the plants might be toxic,” Johnson said.
“The Japanese yew is leafy and green, and it’s tempting to throw it over the fence to the cattle. It is palatable to them and they’ll eat it, but it’s poisonous.”
Field residue. When feeding cattle corn or soybean residue in a field, farmers should make sure piles of grain or a lot of dropped ears are not left on the ground, he said.
These should be cleaned up because cattle that aren’t used to the grain can develop acute acidosis and/or bloat.
If cattle are switched from a grass hay field to a field with alfalfa or other legume, it should be done when the cows have full stomachs and the dew is off the plants, he said. This means the animals won’t eat the richer hay too quickly and they’ll salivate more.
This minimizes the chance they will get bloat.
Sorghum and sudangrass fields should be grazed out before a frost, otherwise there is a potential for prussic acid poisoning, Lemenager said.
Horses. Changes in feed also can affect other livestock, including horses. In horses, overeating of grain or a sudden alternation in the type of forage can produce colic and/or founder.