What will impact first-cutting alfalfa quality?

According to the calendar, spring is here. We’ve had a hint of this with a few days above 80 degrees in recent weeks. On the flip side, we’ve had some recent nights below freezing. This roller coaster of weather makes us wonder how the 2026 alfalfa crop will be affected. Before we go into panic mode with alfalfa stands, let’s step back and assess the situation.

Cold weather effects on plant growth

Alfalfa is a very frost-hardy plant. It takes temperatures below 24 degrees for more than four hours to freeze alfalfa top growth.; that means the plant will most likely be OK if temperatures stay above 24 degrees or only dip below that mark for a short period of time. That said, if it is cold enough for long enough, frost can kill the terminal bud at the top of the stem where new growth occurs.

This bud is most vulnerable because it is exposed to the elements. The plant will still try to grow if the terminal bud is killed, developing axillary buds at the intersections of lower leaves of the stem, but it will not grow taller. Although the plant may continue to grow and produce some additional forage, yield will be depressed and, at some point, will need to be cut to allow for full regrowth for second cutting.

If we experience cold temperatures in the coming weeks, work with your agronomist and forage advisers to assess your alfalfa stands before rushing out and cutting immediately.

Environmental impacts 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 a 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.

Harvest impact on quality

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 the accumulating NDF also 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. A timely first cut is essential if high-quality forage is the objective.

When should you start first cutting? No simple guidelines apply every year or for every farm. Generally, you can wait longer during periods of cooler temperatures and wetter conditions. Warmer springs with adequate moisture lead to faster growth and a more rapid decline in fiber digestibility. In the Upper Midwest, university researchers generally recommend planning the first cut near the accumulation of 700 growing degrees.

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, or PEAQ, helps you 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. These losses will further lower the relative feed value by 15%-25%.

Preharvest quality estimates have their greatest value for the first crop. Calendar date and visual maturity are useful factors in gauging harvest time for later cuttings. The early bud stage is optimal for both yield and quality. Genetic technologies with lower-lignin alfalfa may allow us to maintain nutritional quality over a longer window of harvest. This is most often utilized in subsequent cuttings after the first cutting.

Better quality equals more milk

Although the maturity and quality of alfalfa silage at harvest are among many factors affecting the bottom line of your dairy, high-quality homegrown forages can save you on purchased feed costs. That’s why putting up top-quality alfalfa silage should be a priority for your forage team. It’s in the best interest of your cows and your pocketbook.

Barry Visser is a nutritionist for Vita Plus.