Row crop harvest is in full swing across the state. Farmers are picking peanuts, defoliating and harvesting cotton, wrapping up corn, and moving into soybean harvest. With this comes an increase in questions about baling or grazing crop residue and stubble. While crop residues can offer good forage value in many situations, there are several important considerations before turning cattle onto them or baling them for feed. Some of those considerations include pesticide label restrictions for grazing or harvesting, nitrate accumulation, aflatoxins, forage quality, and nutrient removal from the field.
Pesticide label restrictions:
Row crop management often includes the use of pesticides outside of those used for cattle and livestock. Make sure you discuss with your producer about which of these pesticides they may have used to evaluate concerns with grazing or harvesting restrictions from crop residues. Harvesting restrictions will apply to both hay and baleage production.
Nitrate accumulation:
Nitrates can build up in crop residues, especially in drought-stressed plants or those that received high nitrogen applications without significant rainfall. Often, we see high nitrates in dryland crops because of the amount of nitrogen applied to produce the crop especially when rainfall has been sparce. Legumes like soybeans or peanuts, naturally fix their own nitrogen. While they are traditionally less susceptible to excessive nitrate accumulation, they can accumulate additional nitrates that can be toxic to cattle when those plants are stressed from drought, frost, etc. Anything under 4500 ppm is safe to feed most cattle with adequate feed and water.
Aflatoxins:
Stressed crops can host molds that produce toxins that are dangerous to cattle. Aflatoxin production can occur in corn, cottonseed, peanuts, and sorghum. High levels of aflatoxins are associated with above-average temperature and below-average rainfall. Mature crops undergoing drought and insect stress during prolonged periods of hot weather and drought provides an ideal environment for aflatoxin production. Cattle fed hay containing aflatoxin can suffer from reduced performance, health concerns, and in extreme situations, abortions and death. Dairy cattle can also test positive for aflatoxins in their milk. The acceptable level of aflatoxins will depend on the class of livestock. Action levels for aflatoxins in feed grain include 20 ppb (parts per billion) for young animals and dairy cattle. 100 ppb for beef cattle and 300 ppb for finishing beef cattle.
Quality Concerns:
While some crop residues can provide good energy or protein supplementation, that is not always the case. Crop residues are variable for total digestible nutrients and crude protein depending on the year and management. In addition to crude protein and total digestible energy, baled crop residue tend to carry higher ash content depending on the baling and harvesting processes associated with the row crop than we are used to with grass hay. Soil contamination increases the amount of indigestible material in the bale, lowering the feed value, reducing cattle intake, increasing toxic trace minerals, or causing impaction. Forages with more than about 13 or 14% ash (assuming it is soil contamination as indicated by very high iron) should probably be diluted with feeds not contaminated with soil. Careful baling practices, including adjusting rake height and minimizing the number of times residue is handled, can help reduce ash content and improve feeding value.
Nutrient Removal:
For a landowner or row cropper, baling or grazing crop residue always results in significant nutrient removal from the land. In years where fertilizer prices are high, leaving the residue on the land may provide greater economic and soil health benefits.
Management Strategies:
Prior to purchasing or grazing crop residue, there are a few management strategies that can prevent concerns with our livestock.
-Before feeding or buying any hay or baled cropped residue, UGA always recommends taking a forage sample to determine quality or concerns. A traditional hay sample will usually check for forage quality and nitrates but ash and aflatoxins may need to be requested depending on your lab.
-Make a feeding plan. Typically, providing more of a “buffet” style of feeding can help reduce concerns with any forages. For example, providing winter grazing with cottonseed with bermudagrass hay and potentially limiting a specific crop percentage in any feeding program can greatly reduce concerns of nitrates or aflatoxins or quality concerns as a whole.
-Balance the economics. Compare the cost savings in hay with the long-term cost of replacing lost fertility in the crop field but also the potential for having to additionally supplement nutrients from poorer quality forages. Consider all diets on a cost per unit of energy and protein instead of just the cost of the bale itself!
Crop residues can be a helpful feed option in the right situations, but careful evaluation and planning are key. Testing for nutrients and potential toxins in addition to weighing the economic returns will help farmers make informed decisions that protect both their cattle and their land. For more questions about feeding crop residues, contact your local county extension agent.
