top of page

Concerns When Grazing Mouldy Standing Corn

With corn crops maturing early this year, the warm conditions and higher overnight humidity, makes the crop more susceptible to mould formation. Saprophytic moulds that cause deterioration are noticeable on the leaves and husks. This reduces feed quality especially the amounts of energy and protein left in the forage.

The bigger problem is with mouldy cobs. When infected by certain moulds, T-2, HT-2, and DON mycotoxins can form. These mycotoxins can cause mouth irritations and the first symptoms is the reduction in feed intake. The cows may eat the tassel, leaves, and some of the stalk, but the cobs will remain intact on the grazed plants or will be on the ground. Cobs have the highest energy and protein content in the plant. Check the grazing area. If cobs are left behind, the cows will not be receiving adequate amounts of protein and energy to meet requirements especially in the last 3 months of pregnancy.

Providing supplemental protein and grain is one option to increase protein and energy available to the animals. Feeding up to 4 to 5 pounds of grain and 1 to 1.5 pounds of a 32% protein supplement per day or every three days help meet requirements. Watch the cows. If protein requirements are not met, the manure will be blockyin texture. The cows may also appear to have full rumens because of slow feed digestion rates. This is because there is insufficient protein to keep rumen microbial populations healthy which results in a reduced feed passage rate.

When cows do not consume sufficient energy, the fat in their bodies is mobilized to make up the shortfall. Without supplementation, the cows could potentially lose up to two pounds of weight per day. This will negatively impact the animals’ ability to withstand cold windy conditions, reduce colostrum and milk production and increase calving difficulties. Calf health could be compromised as well.

Substituting in 2.5 pounds of peas instead of the 32% supplement is another option to provide additional protein. A molasses lick tub (32 or 20% protein) can supply additional protein when consumed at 1.5 and 2.5 pounds per day. But, to meet energy requirements; it might be necessary to have the animals consume 3 to 4 pounds of the molasses product. Evaluate options and associated costs.

Feeding 50% of the daily ration as a high quality alfalfa grass hay or silage are additional possibilities. Consult with a nutritionist to develop a feeding program that works for the situation at hand.

For additional information, contact Barry at 403-741-6032 or


bottom of page