Navigating Through a Wet Haying Season

Every year comes with challenges. The past two hay seasons (2017 and 2016) have certainly been a test to our patience as we attempt to put in adequate supply of good quality forage for cattle. Last year we experienced extremely dry conditions and poor yields in many parts of the province while this year we're facing the opposite problem - too much precipitation and concerns about forage quality. For many farmers, precipitation has interfered with hay crop harvest. Producers have had little choice but to wait to cut as forage matures or take a risk and attempt to make hay between the rains. Unfortunately, there are many opportunities for nutrient losses during a hay season that is characterized by high precipitation, particularly when hay gets rained on or when there's a prolonged drying process. Leaf loss, plant enzymatic activity, and leaching of nutrients, including soluble carbohydrates and minerals, all contribute to reduction in forage quality when cut hay gets rained on in the field. The rate of breakdown of protein to non-protein nitrogen is also rapid at high moisture levels. The most effective and accurate way to get a sense of forage quality after harvest is to take a representative sample and test.

The risk of spoilage is another threat to quality in wet years. All harvested forage contains fungal spores; however, the extent to which these spores reproduce and develop into mold depends on the growing conditions. Microbial activity, including activity of fungal spores, increases in hay that is harvested and stored at moisture levels that are too high (greater than 15% moisture).

What is it about mold that causes concern? The answer to that is multifaceted and complex in many ways. We know that mold impacts the nutritional integrity of feed. Since molds require nutrients to grow (in addition to moisture and other specific environmental conditions), they utilize nutrients from feed to propagate and feed value and digestibility are compromised as a result. Heating of forage, due to increased microbial activity, also contributes to decreased energy and vitamin levels in hay. Feed values can be reduced by 5-10%. Furthermore, moldy forage impacts palatability and can result in reduced dry matter intake or even feed refusals by cattle.

The other notable concern with moldy feed is that it can cause health issues in cattle, including reproductive and respiratory issues. Mold spores can irritate the respiratory tract and cause respiratory disease in cattle. The same mold spores are responsible for causing farmer's lung in humans, so care must be taken when handling moldy feed. Some moldy feeds may contain certain molds that have the potential to cause mycotic abortion. Dicoumarol, a toxin produced by certain molds in sweet clover, has an anti-clotting effect. It is important to consider that there are many things that can cause abortion and health issues in cattle. If you are experiencing health issues within your herd, consider all management aspects and seek veterinary consultation.

The challenge of anticipating the health and performance impact of moldy hay is that it is difficult to do through visual assessment or even to quantify through lab analysis. Although spore counts provide some idea of the extent of fungal contamination, they may not adequately capture the capacity of moldy hay to cause performance and health issues. Only certain species are toxic. The ability of molds to produce mycotoxins, toxic secondary metabolites, depends on the fungal species and growing conditions. A separate test can be conducted through laboratory analysis to test for a subset of mycotoxins.

So what can we do in years that aren't conducive to making good quality dry hay? The rain this year may have impeded your ability to get sufficient quantity of hay in. Now is the time to start taking inventory of your feed supplies for winter feeding - considering both quality and quantity. For circumstances where feed shortages are possible, consider options for feeding alternative feeds and extending the grazing period. Something else to consider now is proper hay storage that will help minimize spoilage and nutrient losses. Since dry matter losses in uncovered hay can occur at 20% or greater, it is a best practice to store hay out of the elements to preserve quality where possible. It is also important to develop a strategy for spoiled forage. Although it is ideal to avoid feeding spoiled hay altogether, it is not always possible and in this case it is important to manage how much is fed. Prioritize pregnant cows and heifers by excluding moldy hay from their ration where possible. Otherwise, dilution is the solution to minimize risk of poor performance and health issues. If moldy hay must be fed, blend it with good quality hay at a low rate. Be careful of how forage is blended as dominant cows can outcompete submissive cows for good quality hay. Always monitor for feed refusals and body condition scores of cattle and prevent performance slumps by supplementing poor quality hay. Contact your nutritionist or feed industry representative to advise on ration balancing and to help you interpret laboratory test results.

For more information on alternative feed options, visit OMAFRA's website.

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