Cattle consuming plants experiencing drought stress or plants harvested during drought conditions can be at higher health risks. So what risks are there with feedstuffs during a drought?
Elevated nitrate levels in feedstuffs are common during drought. Some plants are more prone to accumulate nitrates. Small grains and summer annuals are nitrate accumulators. This includes oats, corn, sorghum, sudangrass and even weed species. Testing for nitrates is not expensive (roughly $20). Testing is the only way to know how to properly feed and dilute rations. Most high nitrate levels can be managed around. Using a “low-nitrate” feedstuff to dilute the ration is the most common way. Nitrates tend to accumulate in the bottom third of the plant. When grazing, it is important to graze cautiously by limiting grazing down too far on the suspect plants. If you have drought-stressed forages, get them tested for nitrates and prepare to apply management to your feeding practices.
Mycotoxin risk is normally elevated during drought. Mycotoxins are produced by molds that form on feedstuffs often damaged or stressed by weather conditions. Aflatoxin was prevalent during the drought of 2012. Many challenges arise when dealing with grains high in aflatoxin. Storage, species of livestock, stage of production and inclusion levels for rations all need to be looked at when feeding aflatoxin-bearing corn or grains to livestock. Corn co-products, such as dried distillers grains and corn gluten feed, could have raised levels of aflatoxin. The process occurring to make these feeds does not get rid of aflatoxin. It actually concentrates the aflatoxin; thus the levels seen are normally three times higher than the corn used. Beware of corn and corn co-products that may be higher in aflatoxin.
Poisonous plants are more apt to be consumed by livestock when forage availability is limited. Some plants are more dangerous than others. Thus, it is important to scout pastures short on grass and consult your local extension specialist to aid in identifying common poisonous plants in your area. Intervening with alternative forages that are palatable or removing cattle from high-risk pastures may be necessary.
Malnourishment due to poor-quality feed can put animals at health risk. Overgrazed pastures, lack of hay, substituting cornstalks, straw and Conservation Reserve Program (CRP) hay can all contribute to underfeeding. Palatability will be poor, so consequently intake will be low. A less nutrient-dense feed being consumed at a low level requires more supplemental energy and protein. Purchasing supplemental energy and protein can be costly, so to avoid overspending on supplements, save your good hay for after calving and use these low-quality forages before calving. Less supplement will be needed to meet dry cow requirements.
Forage testing for nutrient analysis and potential risks like nitrates, mycotoxins and contaminants is important in managing through drought.
