November 2011 Articles

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Hidden Hay Dangers

Hidden Hay Dangers Dr. Karl Harborth , LSU AgCenter
In drought situations, such as the extended one we are facing, it can be difficult to find quality forages for a cow herd. In the search for feed resources, cattle producers have resorted to using forages such as wheat straw, milo and corn stubble, drought-stressed sorghum and corn, and Johnson grass. The problem that arises with utilizing these resources is that some of them are likely to have high nitrate and/or Prussic acid concentrations.
If you recently purchased hay that you think may be at risk, properly sampling it and having it analyzed at an accredited lab (see lab info below) is a must. This is the only way of knowing the full extent of the problem.
LSU AgCenter’s Ag Chemistry Lab
Department of Agricultural Chemistry
Room 102 AG Chemistry Building, LSU
Baton Rouge, LA 70803
Phone (225) 342-5812
Fax (225) 342-0027
Current cost is $15 dollars, and a gallon-size plastic bag with representative sample is required.
If the forage has not been baled, collecting representative samples from the field may prevent you from wasting the time and money involved in putting up hay that is not safe and is risky to feed to the herd. (Disclaimer: Even though you may take the time, effort, and money to sample potential at-risk feedstuffs, you must understand that there could be a huge variation in concentrations within a field that will not be seen in a laboratory test. Thus, you may not catch a problem bale.) In other words, even after you have done everything to make sure you will not have a problem, unless you analyze every bale you feed; you may still be at risk. The range of nitrates (ppm) that are considered safe or unsafe for use in livestock is in Table 1. Any sample analysis that returns with a level of 3,000 ppm of nitrates or less is considered to be safe. If your forage contains 3,000-6,000 nitrates (ppm), it is usable but should be no more than 50% of the animal’s diet. If the test comes back in the range of 6,000-9,000 nitrates (ppm), it becomes very tricky to incorporate this forage into the herd’s diet. It is hard to guarantee, or control, the amount of forage they will consume unless being fed in a Total Mixed ration. If forages are in this range, free choice is not a method of delivery to be used.
Table 1. Nitrate levels in forage (dry matter basis) and level of concern for use in livestock feeds

When forage samples are analyzed the results should be reported as nitrate (ppm). If they are not reported as nitrate, use the conversions in Table 2.
Table 2. Conversion factors for expressing nitrate content forages

If you have any questions about nitrate toxicity, prussic acid poisoning, or sampling and analyzing your feed sources, feel free to contact your local county agent or Karl Harborth (225-578-2416).
Tips for managing potential Nitrate or Prussic acid issues
1. Do not allow animals to graze suspect forages.
2. Test the forage before baling if possible.
3. Sample standing forages at the same level they will be harvested (preferably at least 6 inches above the ground as nitrates accumulate in the base of the plant).
4. Do not feed at-risk feeds to stressed or hungry cattle.
5. Provide clean water.
6. Check water for high nitrates.
7. Post-harvest, proper curing can reduce Prussic acid levels.
8. High nitrate levels in roughages can only be potentially reduced by ensiling.
9. Bales that are stored will leech, and concentrations of the nitrate can build up in the bottom half of the bales,
10. If at all possible, do not take the risk.