July 3, 2012
Drought conditions have depleted many pastures and reduced hay yields. Thus producers naturally want to use low-producing grain crops as replacement feedstuffs. But not so fast...The drought conditions have plants in survival mode. Sometimes these built-in survival tactics in plants can be deadly to livestock.
Nitrate levels are known to increase in drought-stricken forages. Due to lack of moisture to distribute nitrates throughout the plant they become concentrated in the stalk. Most of the time in the lower portions of the stalk.
Plants that are common to experience high nitrate levels in drought are corn, sorghum, sudangrass hybrids, and millet. However, other grasses and legumes can have excessive levels.
Nitrates are usually higher in young plants, following a rain during drought, fields that have had excess nitrogen applied, and in the lower stalk of the plant. Thus it is important to avoid these scenerios as much as possible to mitigate risk.
Cattlemen can avoid harvesting the lower 8-10 inches of the stalk if for corn silage. Also, ensiling the forage can reduce nitrate levels by 30-40%. If grasses, allow 4-6 weeks of age and do not graze lower than 6 inches. Rotate animals or remove them to eliminate overgrazing. Strip grazing works well as long as the cattle are moved before they eat the nitrate rich stalk or lower portions and.The most important thing to do if you are planning to feed drought stressed feedstuffs is to take a sample of the feed and test it for nitrates. If tests are high, the feed can be blended with other feeds to ensure non-toxic levels. "Testing for nitrates is roughly $30 and well worth it.