By Alexis DeCorby, PAg, Livestock and Feed Extension Specialist, Yorkton
July 2024
Sourcing and harvesting winter forage is one of many summer activities livestock producers undertake. Variety selection and timing of harvest play important roles in the final quality of forage, but management to maximize harvested forage doesn’t stop there. Testing for nutritional value and potential toxins can save you money and prevent issues during winter. With good planning and the right information, you can maximize the forage you intend to use during the winter months.
Knowing the nutritional value of your forages is important when building a feeding plan that is both cost effective and maximizes cow performance. Typical parameters tested include protein, energy, fibre and macro mineral content. These values may vary by region (soil type), variety of forage and yearly growing conditions. Each of these parameters are important in building a winter-feeding plan, and can help determine which supplements (minerals, vitamins, grain or pellets) are best suited to your cattle’s requirements.
Similarly to standard nutrient testing, feed can also be tested for toxins under specific growing conditions. Nitrates, mycotoxins and ergot are three common toxins that may be found in forages. Nitrates accumulate in plants because of environmental stressors; these stressors may include frost, hail damage, extreme heat or cold or damp growing conditions with limited heat. Nitrate levels may dissipate over time as the plant regains its ability to continue growing and metabolize the nitrate. However, if you suspect that nitrates may be present, it is best to test so that the level can be managed through adaptation to the feed or dilution of the source. Nitrates most commonly accumulate in cereals, oilseeds and select weeds, such as kochia and lamb’s-quarters. Visit our nitrate toxicity webpage for a full list of crops and weeds susceptible to nitrates.
Mycotoxins are caused by certain moulds and can have detrimental health and production effects on livestock. While visible mould is an indicator that your feed may have mycotoxins, be aware not all feed with mycotoxins have visible mould. Typically, hay or greenfeed that was put up at an elevated moisture level is more likely to produce mycotoxins. Similarly, silages that did not ensile properly may also produce mycotoxins. Signs of mycotoxin toxicity include feed refusal, poor herd health, reduced fertility or death in extreme cases.
Ergot bodies are typically found in cereal and grass crops under prolonged wet soil conditions and cool weather. These conditions favor the development of ergot bodies in crops as they extend the flowering period, which is when crops are susceptible to infection. Small amounts of ergot can be toxic; watch for ergot toxicity symptoms including lameness, abortions, reduced productivity, loss of hooves, portions of the tail or ears and in extreme cases, death.
Whether you’re sampling for general forage analysis or potential toxins, getting a representative sample is key. For baled forages, aim to sample 15 bales per field. For pit silage samples, aim to sample from 15 different locations on the pit. Using a forage probe can help ensure a representative sample is collected. Forage probes are available to borrow from any regional office and select Saskatchewan Crop Insurance offices.
For more information about forage sampling, forage testing, or other livestock related topics, contact your local livestock and feed extension specialist or the Agriculture Knowledge Centre at 1-866-457-2377.