A year ago, I shared comments in this column illustrating the value of harvesting top-quality alfalfa silage both for your cows and your pocketbook. Harvesting at the right time is the first step to achieving this goal.  
    Plant maturity is the most important factor affecting quality. Scissor cuttings, Predicted Equation for Alfalfa Quality (PEAQ) sticks and monitoring stage of plant maturity are all tools to determine when to start first-cutting hay harvest. How long it takes to complete the harvest – and how much quality is subsequently lost during harvest and fermentation – also impacts the quality of silage available to the cow.  
    When forage is cut, it usually has a moisture content of 75 to 80 percent. This freshly cut forage needs to be dried down to approximately 60 to 65 percent moisture for haylage and closer to 15 percent 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 percent.  
    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 percent of moisture from the plant reduces the loss of fermentable carbohydrates and preserves more total digestible nutrients in the harvested forage.     

Preserve quality with wide swath
    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 amount of stomata open. Many more stomata will close if put into a narrow windrow where it is dark. Research at Penn State University has shown 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 percent to 60 percent 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.  

Condition or not condition?
    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 60 to 65 percent, the ideal moisture for haylage.  
    Conditioning is important for making dry hay, as the crimping allows additional moisture to leave the stems at moisture below 60 percent.  
    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.  
    Have a safe and productive hay harvest.
    Barry Visser is a nutritionist for Vita Plus.