Q: Will nitrates be a problem in winter feedstuffs this year?
A: Generally we associate the danger of high levels of nitrates in forages such as sorghum-sudangrass, forage sorghum, sudangrass, proso millet or foxtail millet with drought. During the normal growth process, the plant brings nitrogen in through the roots and uses it to create new plant tissue. If some type of stress prevents or severely slows that process, then the nitrate begins to accumulate in the plant. The stress could be from drought, fertility imbalance, hail or a freeze. This can be a temporary condition depending on the timing of the stressor and conditions that follow. The nitrate that is present at the time of harvest or a killing freeze will remain in the plant as it dries. If livestock consume enough of the high nitrate feed it can cause abortion or death.
It is hard to make any global statements about potential toxicity levels in these species this year because of the wide range in planting times, soil fertility, and timing and amount of rainfall received. It is a prudent management decision to check for nitrates every year before feeding since the cost of the test is so low compared to the consequences of dead animals or lost pregnancies.
When submitting the forage sample for nitrate testing also have it tested for crude protein and energy (TDN). Use the analysis of forage quality so that the highest quality hay can be used when the need is greatest (i.e., during lactation for cows) and that appropriate levels of supplementation can be provided as needed. If nitrate levels are high, forages can often be ground and mixed with a low nitrate hay to dilute the nitrate to a safe level. The saying ‘you can’t manage what you don’t measure’ certainly applies in this situation.
If you have questions about forage testing or nitrates in feedstuffs, contact Sandy Johnson, Extension Beef Specialist for K-State Research and Extension at 785-462-6281 or sandyj@ksu.edu.
