Alfalfa (lucerne) is recognized for its high nutritional value, but harvest timing dictates the quality and quantity of the hay. The cut time is the most significant management decision determining the feed’s ultimate value for livestock. Optimal practices balance maximum plant growth with capturing peak nutrient concentration. The goal is to maximize nutritional content per ton and overall yield volume across all cuttings.
The Primary Timing Metric: Plant Maturity Stages
The plant’s stage of development is the most reliable cutting indicator, assessed by the presence of flower buds and blooms. As alfalfa matures, its stems become more fibrous, and the concentration of digestible nutrients in the leaves drops. Farmers use three main maturity stages as benchmarks to target specific quality and yield profiles.
Cutting at the Late Bud Stage, where the plant has visible buds but no open flowers, yields the highest nutritional quality but the lowest tonnage. This aggressive schedule is favored for high-performance animals, such as dairy cattle, that require highly digestible feed.
The First Flower Stage, characterized by open flowers on approximately 10% of the stems, represents the common compromise between quality and yield. This stage optimizes the balance between high-value leaves and accumulating significant biomass. Delaying the cut to the Mid-Flower Stage (50% bloom) results in the highest yield volume but lower feed value, making it suitable for livestock with lower nutritional demands.
Balancing Nutritional Quality and Yield Volume
The decision to cut is an economic trade-off, driven by the inverse relationship between nutritional quality and accumulated biomass. As alfalfa matures, it builds up structural fiber, which dilutes digestible proteins and energy. This decline is quantified using fiber content measurements: Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF).
NDF measures total fiber (cell walls) and indexes the amount of hay an animal can physically consume. As NDF increases, voluntary intake decreases due to “fill” in the rumen.
ADF represents the least digestible components, such as cellulose and lignin. A higher ADF percentage indicates lower digestibility, meaning the animal absorbs fewer nutrients.
Harvesting at the bud stage results in the lowest NDF and ADF values, translating to the most digestible hay. Hay for high-producing dairy cows must have low NDF (often below 40%) to support high energy needs.
Environmental and Seasonal Influences on Harvest Timing
Environmental factors frequently override plant maturity guidelines, especially the need for a clear window of good weather. Alfalfa requires three to five days of dry, sunny conditions after cutting for proper curing. Impending precipitation can force an early cut to avoid quality loss if the hay is rained on while lying in the field.
First Cutting
The first cutting, occurring after winter dormancy, often yields the greatest tonnage. This initial growth can be lower in quality due to weeds or residue. Producers may delay this cut until the early bloom stage to allow the plant to recover fully from winter and build strong root reserves.
Final Cutting and Winter Survival
Managing the final fall cut is sensitive and tied directly to winter survival. Alfalfa must have a rest period of four to six weeks before the first hard killing frost (around 24°F). This period allows the plant to translocate carbohydrates to the roots and crown, replenishing energy reserves. Cutting during this time can severely deplete root reserves, increasing the risk of winterkill and reducing the next year’s yield.
Unpredictable Weather
Unpredictable weather, such as drought or excessive moisture, modifies harvest timing. Extreme dryness can stunt growth, forcing an earlier cut to salvage biomass before the leaves drop. If a field is delayed due to wet conditions, the quality of the standing forage declines rapidly as it matures.