Every growing season is different, and this spring is no exception. Excluding a few bursts of summer-like temperatures, cooler weather has blanketed much of the Midwest. As a result, we are significantly behind on growing degree days for alfalfa maturity. Surprisingly, alfalfa has continued to progress. By the time this reaches print, some of our southern readers will have already taken a first cutting of hay.
For some farms, inventories are tight and new-crop haylage cannot be harvested soon enough. Strong milk prices kept barns full the past several months, and many areas reported lower-than-average yields in 2021 as a result of drought conditions. The option to purchase historically high-priced hay or fibrous byproducts is not feasible for many.
Most alfalfa stands have been evaluated for winter survival at this point. Reports of mild to severe winterkill are present across the Midwest. In most cases, interseeding or other corrective actions have already occurred. If you are in the unfortunate position of dealing with a high percentage of winterkill, work with your agronomist and nutritionist to devise an alternative cropping plan.
Environmental impact on quality
The environment in which plants develop plays an important role in what the actual forage quality will be at a specific stage of maturity. Temperature is the driving force behind most physiological processes that occur in a plant, including photosynthesis, respiration and cell wall formation. Alfalfa grown during cooler conditions has a tendency for slower rate of maturity, larger stem diameter, increased plant height and less lignification, resulting in higher fiber digestibility.
Soil moisture also has a significant impact on alfalfa growth and forage quality. Wetter conditions tend to accelerate plant maturity, increase plant height, decrease the proportion of leaves to stems and generally increase fiber percentages. Cooler temperatures have resulted in fewer growing degree days this spring, but moisture has been plentiful in most areas. As these two environmental interactions offset, the potential exists for high-quality haylage.
First-cut quality can decrease rapidly
Plant maturity is the most important factor affecting quality. With maturity comes more cell wall constituents, including lignin, cellulose and hemicellulose. Proportionally, we see a drop in the digestible cellular contents such as soluble proteins, sugar, starch, fats and pectins. Not only does neutral detergent fiber increase and forage energy content drop with maturity, but also the accumulating NDF becomes less digestible.
Although first-cutting alfalfa offers the opportunity for harvesting the highest amount of digestible fiber in the growing season, forage quality declines at a faster rate for first cutting compared to subsequent cuttings. It can change even faster if grass is present in the stand. Timely first cut is essential if high forage quality is the objective.
When should you start first cutting?
No simple guidelines apply to every year or every farm. Generally, you can wait longer during periods of cooler temperatures and wetter conditions like most areas have experienced this spring. Several farms are dealing with an added challenge of managing unplanted corn or soybean acres at about the same time first cut is ready. With a few rare exceptions, the best decision is to put up the haylage.
Scissor cutting is a tool that has been around for many years to determine the ideal time to cut. A second tool, the Predicted Equation for Alfalfa Quality, helps make your own field estimates. Both measurements evaluate the standing crop and do not account for the change in quality due to wilting, harvesting and storage. A good rule of thumb as hay nears cutting is an average decline in relative feed value of four units per day under average weather conditions.
Although maturity and quality of alfalfa silage at harvest is one of many factors affecting the bottom line of your dairy, high-quality homegrown forages can save you in purchased feed costs. That’s why putting up top-quality alfalfa silage should be a priority of your forage team. It’s in the best interest of your cows and your pocketbook.
Barry Visser is a nutritionist for Vita Plus.
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