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Got Forage? The reality of a drought situation

Jim Paulson
Dairy Educator, University of Minnesota Extension

September 8, 2012

The reality for many livestock producers in the Midwest is that in some way, the drought will have an impact on their forage and feed supply and cost of feeding animals on their operations. Regardless, it is going to be more expensive to feed livestock in the coming year. What are some of the strategies to consider in dealing with the situation we are in?

The starting point would be to determine where you are now with feed and forage supply as well as livestock numbers. You may want to put together a team of family members and key stakeholders to discuss your assessment. They can help you to make sure nothing is overlooked and to develop plan B.

Key elements should include:

  1. An accurate inventory of all feed and animals by age and location.
  2. Feed allotted for each group/category of animals. Prioritize by quality of forage to greatest need of animals.
  3. Shortfall of which feed and forages. Will some crops have to be used for other uses than intended such as silage instead of grain? Possible replacement feeds?
  4. Should you reduce herd size? Which animals could be sold? How soon? Which feed will be saved the most by those actions? Will it be enough?
  5. What are some ways to add to or stretch the forage supply?
  6. Finally, how will these decisions affect cash flow? By selling weanlings early, will they be lighter than we had originally planned in the cash flow? If we cull more milk cows, will we have adequate milk flow? What expenses will increase or decrease? How much equity do we have to work with?

What are some options to increase the forage supply? Corn chopped early for silage can be a very good feed, even if it has very little corn. Typically, we would estimate the feeding value at approximately 70% of normal corn silage. If you need additional forage and there are grain farmers in your area that have drought stressed corn with no grain, you could approach them to buy silage. Price would have to be negotiated on a per ton basis. Consideration should also be given to baling corn stalks in addition to chopping. Other forages that can be considered include sweet corn cannery waste and wheat straw, which can be mixed with regular corn silage to extend the supply. For growing heifers and brood cows, adding wet corn distillers or wet corn gluten feed will add protein and improve palatability.

You might also consider planting a forage crop on fields where the corn was chopped early or on any other early harvested fields. Planting a spring oat, barley or triticale is one option. Wisconsin and Minnesota studies suggest a planting rate of two bushels per acre. You could also add 50 pounds of forage peas to the mix. Many producers are now planting forage turnips in with oats for fall grazing. Turnips are very cold tolerant and will provide grazing forage until covered by snow.

Nitrate poisoning

Questions always come up: What about nitrate poisoning or prussic acid poisoning? What is the difference? Which crops are most susceptible?

Nitrate in itself is not toxic to animals, but at elevated levels, it causes a disease called nitrate poisoning. Nitrates normally found in forages are converted by the digestion process to nitrite and, in turn, the nitrite is converted to ammonia. The ammonia is then converted to protein by bacteria in the rumen. If cattle rapidly ingest large quantities of plants that contain high levels of nitrate, nitrite will accumulate in the rumen.

The majority of nitrate poisoning cases occur with drought-stressed oats, corn, and barley. However, a number of other plants can also accumulate nitrate. Table 1 lists common plants known to accumulate nitrate if conditions are favorable.

Table 1. Common Plants Known to Accumulate Nitrate

Crops Weeds
Barley Canada Thistle
Corn Dock
Flax Jimsonweed
Millet Johnson Grass
Oats Kochia
Rape Lambsquarter
Rye Nightshade
Soybean Pigweed
Sorghum Russian Thistle
Sudangrass Smartweed
Sugar Beets Wild Sunflower
Sweetclover Wheat

Prussic Acid Poisoning

Prussic acid, cyanide, and hydrocyanic acid are all terms relating to the same toxic substance. It is one of the most rapidly acting toxins that affect mammals. A number of common plants may accumulate large quantities of prussic acid (cyanogenic compounds). Sorghums and related species readily accumulate these compounds.

Table 2. Plants with Cyanogenic Potential

Apple Forage Sorghums Poison Suckleya
Apricot Grain Sorghums Sudangrass Hybrids
Arrow Grass Hydrangea Sorghum-Sudangrass Hybrids
Birdsfoot Trefoil Indiangrass Shattercane
Cherry Johnsongrass Velvet Grass
Elderberry Lima Bean Vetch Seed
Flax Peach White Clover

A veterinarian will determine the proper treatment by first taking a blood sample. If the the blood has a dark or chocolate color, it is most likely due to nitrate poisoning. If the blood is bright red, it is very likely due to prussic acid poisoning.

Acknowledgement is given to extension forage resources at University of Wisconsin and North Dakota State University as well as the University of Minnesota.

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