Ergot is a fungus that can grow on certain grasses and grain plants, often under certain growing season moisture conditions, but other crop fertility issues can be at play as well. Ergot becomes a problem mainly after a wet season, rarely during dry conditions. The fungus replaces the seed head with a dark brown/black mass and produces toxic alkaloids. One or more of the kernels in the seed head are replaced with this dark, hard “ergot body.”
There are various types of alkaloids in ergot that affect cattle in different ways. One response effects on the nervous system, resulting in muscle spasms in the hind legs, lack of co-ordination, loss of balance, and sometimes a temporary paralysis. Perhaps more commonly the toxic alkaloids impair blood circulation to the extremities (due to constricting of blood vessels), which can result in loss of ears, tail or feet. Mild cases of ergot poisoning may simply show up as poor production (lower weight gain, drop in milk production, inability to handle hot or cold weather, reproductive problems, or abortion). The alkaloids tend to restrict blood flow and milk flow.
Ergot is most common in grains, but can also infect wheatgrass, brome, wild rye and a number of other wild grasses. An ergot fungus that grows mainly on rye produces a condition called ryegrass staggers in cattle. Another type of ergot infects barley and creates another class of toxins.
Alberta Agriculture Beef and Forage Specialist Barry Yaremcio says the ergot and alkaloids produced by the fungi vary around the world. There are also some major differences in North America.
“A lot of research is being done right now in Saskatchewan on ergot, looking at how it develops, and how long it takes for that ergot body to start putting the alkaloids into the seed,” says Yaremico. “Feeding trials are being done at the University of Saskatchewan to determine the level that you’d start to see reduced performance in the animals when the alkaloids are present, due to ergot contamination of feeds.
“They have been testing for about two years at the vet school at Saskatoon, looking at the different alkaloids in these ergots. They are finding that the strains we have in Western Canada are two to four times more virulent and harmful than what is seen in Texas, Oklahoma and Florida, for instance.”
New regulations needed
Yaremcio says the old rules of thumb for feed safety levels (one kernel in 1,000, or about 10 ergot bodies per litre of grain) aren’t really valid. Due to the high toxicity of the fungi, tolerances for ergot are tight, and should be more like one ergot body per 10,000 kernels. The Animal Nutrition Association of Canada has hired Brian Doig, who recently retired from Saskatchewan Agriculture, on contract to work on this ergot problem and co-ordinate information.
“The association is hoping to get the Canadian Food Inspection Agency to readjust the recommendations and actually put forth new limits and regulations, rather than just guidelines for feed,” says Yaremcio. “Many people know that if they have ergot in the feed they will have health problems in cattle such as tails and hooves sloughing off. “Unfortunately these are some of the last symptoms to show up, just before these animals die. We’ve now found that if you’ve got a high level of alkaloids from ergot in a pellet or grain feed, one of the first symptoms you’ll see — two or three days after the feed is supplied to the animals — is that they will back off the feed. They may reduce their intake of that feed by 60 to 70 per cent. This is your warning sign.”
Yaremcio says if animals aren’t taken off that particular feed they will eventually show disease symptoms normally associate with stress, such as at weaning and shipping. “You’ll see things like IBR, shipping fever, pneumonia, and other respiratory problems,” says Yaremcio. “These tend to show up in cattle that have been affected by ergot.” Several ranchers in Western Canada have lost cows, due to ergot contamination in pellets.