Polioencephalomalacia, fog fever, blue-green algae, and vitamin A deficiency.
Those are just four potential health threats to cattle when conditions are extremely dry.
“The biggest problem we have on the Prairies is water that is high in sulphates,” said Dr. John Campbell, professor in the department large animal clinical sciences at the University of Saskatchewan.
Sulphates can affect cattle in a number of ways. In low levels, they can tie up copper and affect a cow’s reproductivity. At higher levels, they can cause a polio-like condition called polioencephalomalacia.
“Over the summer, sulphate levels can change dramatically in things like dugouts,” said Campbell. “As water evaporates throughout the heat of summer, sulphate levels can become more concentrated in the dugout.”
Sulphates were higher than normal this spring, because of the lack of snowfall. Even dugout water that is OK at the beginning of summer may develop a higher concentration of sulphates as water evaporates.
Signs of polio resemble those of a severe depression, said Campbell. Cattle will have trouble walking, fall down and can appear blind. They can have seizures and will sometimes die very suddenly. (In 2017, high sulphate levels were a factor in the death of 200 cattle at a Saskatchewan pasture.)
During dry periods, cattle are also at greater risk from plants, as they will start grazing toxic plants they won’t normally eat. Another danger is fog fever, which occurs when cattle are moved from an overgrazed pasture to a lush one. The cattle’s rumens have adjusted to the dry pasture, and after a sudden switch to richer fare, the animals can develop a type of toxic bacteria in the rumen, which affects the cells that line the lungs. Symptoms include difficulty breathing, coughing, frothing at the mouth, anxiety, collapse and death.
Fog fever is more common in the fall, and there is no treatment. Cattle can recover from mild cases, but severe ones can be fatal.
Blue-green algae also becomes more common in dugouts in dry years. The toxic cyanobacteria lives in stagnant water, and hot conditions can lead to algae blooms.
Nitrates can also be higher in stressed plants, and plants are likely to have more toxins, said Campbell.
As well, some feeds, such as dried distillers grains, have high sulphate content.
“They don’t have enough sulphate on their own to cause major issues, but if you had feedlot cattle on distillers grains and then you had a well fairly high in sulphates, you could tip them over the edge and cause polio-like conditions in cattle,” he said.
Some deep wells can also have high sulphate levels. Producers may have to look for another water source if sulphate levels are too high. There is no known way to remove sulphates from water.
“Producers do need to be aware of the water quality issues,” said Campbell. “There are other things that could affect water quality other than sulphates, but sulphates are the most dramatic and the thing we worry about most.”
Producers should talk to their vets about their water tests because understanding sulphate levels can be confusing, said Dr. Cody Creelman, a veterinarian with Veterinary Agri-Health Services in Airdrie.
“It’s good to have a veterinarian in the loop to wade through what the actual number is,” he said.
Veterinarians in Alberta will send samples to private labs, interpret the results and help producers make adjustments to ensure that their cattle are not at risk.
Another issue in dry years can occur when producers turn to alternative feeds. Sometimes they feed things that are not good for cattle, such as green flax.
When cows aren’t getting enough vitamin A because of lower quality, there can be a spillover effect.
“Cows will be low in vitamin A, and calves get all their vitamin A from the colostrum of a cow,” said Campbell. “If producers don’t supplement their vitamin A this winter, and the cows are grazing in dry conditions, we should see a vitamin A deficiency in calves next spring because the cow will not have much vitamin A to give them.”
Vitamin A is needed for normal immune function and growth.
After several dry years, finding quality hay and forage has become very challenging for many producers.
“Farmers are going to have to make tough decisions about culling cows and getting feed supplies,” said Campbell. “If you haven’t kept the body condition score up this year, it may be next year that we see the wreck if people can’t keep body condition score up on cows this year and through the winter.”