StettlerLocal.com April 25, 2022 @ 1:45pm
Many newer crops are being used as cattle feed that contain higher sulfur levels than the traditional grass or grass-legume pastures and hay. Cocktail mixes containing brassica species, salvage canola crops cut for silage or greenfeed, or grazing canola regrowth are a few situations where sulfur will be higher than previously experienced. Feeding distiller’s grains containing high amounts of sulfur can also contribute to the problem.
Sulfur contained in water contributes to the total daily sulfur intake. Water from dugouts late in the grazing season or those that did not recharge in the spring tend to have more sulfur than those that are full or have not been previously used as a water source.
The maximum recommended sulfur content in a ration is 0.4%. When levels exceed this amount, Polioencephalomalacia or polio can occur in ruminants. It was first thought that polio was caused exclusively by a lack of thiamine.
Information from the Iowa State University factsheet has further identified the cause of polio (a link to the document is at the bottom of this article). The University has determined that ingested sulfur is converted to hydrogen sulfide in the rumen, which causes the rumen pH to drop. The hydrogen sulfide is absorbed into the bloodstream. The circulation of hydrogen sulfide interferes with cellular energy production. The brain has a high energy requirement and is one of the first organs affected. It takes 1 to 3 weeks for symptoms to appear after high sulfur levels are consumed.
Symptoms of chronic poisoning include visual impairment and uncoordinated movement. The addition of Thiamine can help resolve the problem. Acute poisoning symptoms are blindness, inability to stand, seizures and death.
Feed testing is important when feeding the non-conventional feeds. Well and dugout water analysis is critical, especially in dry, hot years or when dugouts did not fill in the spring.
Barry Yaremcio
Ruminant Nutritionist