Timing is everything when harvesting alfalfa
There are two schools of thought for when alfalfa should be harvested. One method is to increase yield, but that comes at the expense of quality. The second method aims for high-quality forage but comes at the expense of yield.
The higher-yield strategy typically starts at or near full bloom, with cuttings every 40 to 45 days through the season. The higher-quality strategy typically starts at late bud, with subsequent cuttings every 32 to 35 days through the season. Both approaches have applications. The higher the animal performance, the more pressure is placed on forage quality over quantity. Quantity is the priority for high-production animals.
The quality of alfalfa is especially sensitive to harvest schedule. Timing is crucial, particularly for the first cutting. Producers aiming for quality alfalfa should focus on the ideal harvest conditions to maximize quality without damaging the stand’s longevity. This, of course, is easier said than done. Spring weather often doesn’t allow for appropriate drying in the windrow to get to proper bale moisture. Delays in drying can then lead to delays in subsequent cuttings. Thus, uncooperative weather in the spring often has ripple effects that cause significant decreases in feed quality and stand longevity.
Making haylage is one strategy to deal with spring weather and harvesting the first cutting in a timely manner, rather than trying to dry the crop in the field. The result can be very advantageous. With haylage, growers can manage the start of the harvest season. This produces a quality first crop without negatively impacting later cuttings.
When making first-cut alfalfa haylage, target wilting the crop to 55% to 65% moisture or 45% to 35% dry matter (DM). Putting up an alfalfa silage at more that 70% moisture (less than 30% DM) tends to make it susceptible to a clostridia fermentation, which produces butyric acid and breaks down proteins into ammonia. This type of fermentation is associated with greater DM losses, reduced animal intake and decreased animal performance.
Depending on weather, it may take a day or more to get to the desired DM content. If the alfalfa is too dry—more than 50% dry matter—it is difficult to pack in a bunker. This increases porosity, which means more air in the mass, heat damage and fungi growth, greatly decreasing the quality and quantity of the feed.
However, if worst comes to worst, it is easier to work with haylage being too dry than too wet. I can feed soybean meal to compensate for heat-damaged protein, but I can’t get cows to eat haylage with a lot of butyric acid.
In addition to moisture content, the length of the chop is important for producing high-quality alfalfa silage. Alfalfa should be at least between 0.75 inch to 1 inch long, depending on your goals. Shorter length increases packing density, while longer length favors physically effective fiber and rumen health.
Alfalfa has a well-deserved reputation for being more difficult to ensile than other forages such as wheat, sorghum or corn. This is because alfalfa in particular, and other legumes in general, have a high natural buffering capacity, due principally to their organic acid content. The higher ash and protein content of alfalfa contributes a small amount to the buffering capacity. The sugar content of alfalfa will be lower than that of corn chopped for silage. The lower sugar and higher buffering capacity make it more difficult for the ensiled crop to quickly achieve a terminal pH, which preserves the crop.
Wet conditions or soiling of the crop at harvest encourage a clostridial fermentation and production of butyric acid. To avoid this, use an effective silage inoculant. This will encourage an efficient fermentation and reduce DM losses due to ensiling. A silage inoculant can be an effective oxygen scavenger. The inoculant speeds the creation of an anaerobic environment that allows lactic acid-producing bacteria to grow efficiently and results in more lactic acid, less acetic acid and a lower terminal pH. Inoculants designed for improved aerobic stability will produce volatile fatty acids that inhibit yeast and mold growth when oxygen is reintroduced at feedout.
Timing alfalfa cutting is the most important management practice to maximize tonnage potential, quality and profitability. For more information and recommendations on alfalfa production, talk with the crop and livestock experts at your local MFA.
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