Ergot is a fungal disease that can infect open-pollinated grass species. It is commonly found in cereal crops such as rye, triticale, wheat, oats and barley. Grass species such as brome, wheat grasses, orchard grass, quack grass and bluegrasses are susceptible. The main concerns are reduction in crop yield and the negative impact on animal health and performance.
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Early in the growing season, there is no method to determine if ergot will be a problem. It will depend on growing conditions, temperature, and humidity. If the disease was present last year, and moisture levels are good the risk increases. Ergot bodies (sclerotia) that were in the seed heads and not captured during harvest overwinter on the surface of the ground. In the following growing season, these sclerotia produce mushrooms. When the mushrooms mature, ascospores are released into the air and infect seed heads when the growing crops are in the flowering stage. Instead of pollen fertilizing the seed embryo, it is infected by the spores. Cool conditions and high humidity cause the plants to have a longer pollination period and a greater risk of infection. Rye has a longer pollination period compared to oats or barley putting it more at risk for infection.
It is common for brome and timothy found in ditches to be the first plants to be infected. The disease is then spread into pastures and cropland. Once the seed is infected, honeydew (a liquid), develops in the seed head. This liquid can be spread and infect more plants by the wind, bees or other pollinators, and wildlife walking through the pasture, hayfield or cereal crop. Wind can spread the disease by 100 meters in a year.
If cattle graze pastures with ergot, the ingested ergot can impair sperm motility and reduce cow fertility due to the high estrogenic content in the honeydew or infected seed. The alkaloids also reduce blood flow to the limbs, ears, tail, and outer regions of the body. In hot conditions, this reduces the animal’s ability for heat loss which results in panting. The alkaloids will also reduce feed intake due to the resulting heat stress.
Ergot alkaloids, the toxic compounds form at the honeydew stage. The toxins remain in the infected seeds as they mature. The enlarged banana-shaped seed becomes visible over time. New research conducted at the University of Saskatchewan has determined that the 4 strains of ergot found in Western Canada are 2.5 to 3 times more toxic than strains reported in the southern USA. Animal type, stage of production, environmental conditions, duration of exposure, and alkaloid concentration in the feed all need to be considered when determining if problems will occur. Intake limits are much lower than previously reported. Alkaloid levels above 100 parts per billion (ppb) will reduce blood flow to the mammary glands resulting in lower milk production. It will also impair reproduction at 200 parts per billion. The number of abortions can also increase.
Previously, recommended safe level for ergot contamination in grains was 1 ergot body per 1000 kernels of grain. This is not an acceptable method considering the University of Saskatchewan results. They have reported cases where 4 ergot bodies per 10,000 kernels of grain have caused hooves to slough off. It is recommended to send in a representative grain sample to a lab that tests for ergot alkaloid content. There are 40 different alkaloids that can be present, but the main concerns are seven alkaloids that are commonly tested for.
One of the first symptoms of ergot toxicity is a dramatic reduction in feed intake within 3 to 4 days of high exposure. Feed intake can be reduced by 35 to 50%. Noticing a reduced feed intake is relatively simple when confined animals are fed grain or a TMR in a bunk. It is difficult to notice this on pasture. Along with the feed intake problems, there could also be respiratory concerns that appear to be shipping fever or atypical interstitial pneumonia. Consult with your veterinarian if respiratory problems exist. In many situations, a reduced calf weaning weight in the fall may be the only indication that ergot was a problem on pasture.
The impact of ergot on animals is long-lasting. The animal can detoxify the alkaloids in 12 hours, but the impact can last two weeks. In cold conditions, an alkaloid concentration of 500 ppb can cause hair loss. If ergot is fed continually, sloughing of hooves occurs 4 to 6 weeks after the start of the feeding period. The gangrenous effects are not reversible and animals need to be euthanized.
If ergot is a problem, the sclerotia that remain in the field after harvest are viable for one year if left on the soil surface. With annual cereal crops, tilling the land and burying the sclerotia to a depth of 2 inches prevents germination of the sclerotia the following year. Plant canola, peas, or other non-grass crops in these fields. With pastures, use rotational grazing to prevent the grasses from reaching the pollination stage. Preventing the seed heads from reaching the pollination stage is necessary to stop the spread of the disease.
Barry Yaremcio
Ruminant Nutritionist
Yaremcio Ag Consulting Ltd.
403-741-6032
https://www.beefconsultant.com