| | What happens to a crop quality when it over winters in the swath?
Straw deteriorates from microbial activity. The straw turns grey from weathering, bacterial and fungal growth, and spores formation. If the cereal grain or oilseeds sprout, starch is converted to sugar, and bushel weights drop. In canola and flax, the free fatty acid content of the seed increases due to oxidation and rancidity can be a problem.
What impact does this have on the nutritional quality of the grain and straw?
Grain that has stayed in the swath over winter typically looses bushel weight. The drop in weight is from the loss of starch because of microbial activity. Energy content per pound of grain is lower than for the same grain in the fall. Protein levels remain constant or tend to increase slightly.
Straw can be partially degraded by microbial activity before consumption. The digestion rates of the straw may be improved. Fungi produce spores, which can cause atypical interstitial pneumonia in cattle.
How do you compensate for energy loss as bushel weights drop?
Energy content in grains is not dramatically affected until 10% of normal bushel weight is lost. At 44-pounds per bushel for barley, energy content and utilization is reduced. Increase barley fed in the ration by 5 to 10% to maintain energy content in the ration. The same recommendations apply to oats and other cereal grains when bushel weights are lower than normal.
Can cows be turned out into the crop to graze the swaths that are not combined?
No. Crops that over winter typically are fully mature. The amount of grain in the swath is 40 to 60% of the total weight. There is a high risk of bloat, grain overload, scours, or acidosis if allowed free access to the swaths.
If grazing is used to clean up areas that are too wet and soft to combine, controlled grazing in these situations is a must. An electric fence is needed to limit feed the remaining swaths. A high level of management is required for success with this grazing system. Adjust the mineral supplement program to compensate for low calcium and magnesium levels in the swath material.
What contaminants can be present in the grain?
Deer and mouse excrement are the biggest concern. Manure and urine found in the swath results in fouled grain and contaminated straw. The smell from the urine, or fecal contamination can result in feed refusal. Cleaning or screening out the manure, or diluting down the spring threshed grain with other grains may be necessary to improve intake.
Salmonella contamination may also be present. If young calves are offered spring threshed grain that contains salmonella, digestive upset and scours may occur. If in doubt, feed this grain to older or mature animals.
Mycotoxins. Are there any compounds in spring threshold grain that can harm livestock?
Some molds form mycotoxins if weather conditions are continually warm and high humidity is present. Fusarium and ergot are two problems that contain mycotoxins that can create illness, reduced performance or kill animals.
Symptoms vary. Green, blue, pink or red molds are more likely to produce mycotoxins.
Are there health hazards to humans when handling spring-threshed grains?
Hantavirus from deer mouse droppings is possible. Wear a respirator mask to prevent inhaling the particles that may contain the hantavirus. Wear gloves and coveralls to minimize skin contact with the grains.
Salmonella can also be present. Salmonella is spread through the feces from animal to animal, or animal to humans. Good sanitation practices and avoiding direct contact is the best preventative measure. Always wear gloves and coveralls to prevent contact.
Prepared by Barry Yaremcio, Beef/Forage Specialist, Ag-Info Centre, Alberta Agriculture and Forestry |
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