Improve alfalfa quality, profitability with wide-swath hay

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In an era of higher feed prices and lower milk prices, it is hard to argue the value of high-quality forages. The idea of wide-swath cutting is not a new concept. However, it seems questions arise as producers fine-tune this process, upgrade hay equipment and consider the return on what can be a substantial investment, depending on current machinery inventory.
When alfalfa is cut, it usually has a moisture content of 75% to 80%. This freshly cut forage needs to be dried to approximately 55% to 60% moisture for haylage and closer to 15% for dry hay. Exact numbers vary depending on storage structure and harvest method.
Plants continue to respire during the wilting and drying process. This respiration process consumes plant sugars within the plant cell and produces oxygen and water. Respiration rate is the highest at cutting and gradually declines until the plant moisture content has fallen below 60%.
The longer it takes forage to dry to the ideal moisture content for harvest, the longer the forage is respiring in the field. Therefore, rapid initial drying to remove the first 15% of moisture from the plant reduces the loss of fermentable carbohydrates and preserves more total digestible nutrients in the harvested forage.
The concept of “hay in a day” has gained widespread popularity over the past several years to shorten harvest windows and ensure maximum retention of nutrients.
Once alfalfa is cut, the largest portion of the initial water loss is through the leaf surface openings called stomata. These gas-and-moisture-exchange sites open in daylight and close in darkness. By laying forage in a wide swath, the amount of forage exposed to the sunlight is maximized, thus keeping the maximum number of stomata open. Many more stomata will close if put into a narrow, denser windrow where it is darker.      Research at Penn State University showed that wide-swath cutting increases the drying surface of the swath by 2.8 times. In many trials, it has been shown that moisture reduction from 85% to 60% can be reached in as little as five to seven hours.
Some producers may be reluctant to go to a wide swath because they do not want to drive one or both wheels on the cut hay. Research has shown that this causes less loss than making a swath narrow enough to fit between the wheels. Another concern is that driving over a swath will increase ash content in the forage. In most cases, the opposite is true. One theory for lower ash content with wide swath is that that material tends to remain on top of the cut stubble whereas narrow windrows are heavier and result in closer ground contact.
When possible, avoid conditioning on a haylage crop. Conditioning crimps plant stems and disrupts the natural moisture transportation within the plant, reducing the drying rate. If the stems are left intact, the leaves of the plant can pull more moisture out the stems and the hay will dry more quickly to the ideal moisture for haylage (55% to 60%).
Conditioning is important for making dry hay, as the crimping allows additional moisture to leave the stems at moisture below 60%.
Drying forage to the ideal moisture content as quickly as possible is the single most important factor in preserving the harvested forage quality. Wide-swathing allows for fast drying, and the shorter harvest window also reduces the risk of rain damage, further enhancing the opportunity to feed top-quality forage.  
    Barry Visser is a nutritionist for Vita Plus.

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