by Jeremy Sweeten

Alfalfa stem size is influenced by multiple factors. First, it is important to understand the term phenotype. Phenotype is the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment. The phenotype of an alfalfa variety is the largest factor in stem size/diameter across the life of the stand. Second, stand density/seeding rate also account for variations in stem diameter. Other factors include weather, soil type, fertility, plant maturity, moisture, and day length.

The best time to look at a variety for stem diameter is during years 3 and 4 of the test plot or stand life. By this point, the plants have self-selected the true plant population and the number of tillers each plant is going to produce.

Stem diameter is important in picking alfalfa for several reasons. Larger stems are less palatable, generally contain more undigestible fiber (ADF), and can be slower to dry down. Lower leaf-to-stem ratios are lower in quality. When looking for quality alfalfa for the Midwest, consider that stem mass is a large component of yield. In other words, the highest yielding alfalfa may not have the smallest stem diameter.

As a producer, you need to evaluate where your trade-off is on stem diameter versus yield. Forage quality tests are a great way to evaluate alfalfa because visual observation is not always the most effective way to pick a variety. The ultimate goal is to harvest the most quality per acre.

Smaller stems also make the harvested forage more palatable. The more the animals like the “feel” of the alfalfa, the more they will eat. Full rumens of high-quality feed make the most milk or beef.

Enduro 420HD is CISCO’s leading dairy quality alfalfa. It does exhibit relatively smaller stem diameter and was developed for extremely high forage quality.