Jason Hartschuh, Dairy Management and Precision Livestock, Field Specialist
Warm 
weather this spring especially over the last couple of weeks has rapidly progressed forage maturity. Harvesting forages at the proper time for the livestock you are feeding is critical to farm profitability. Poor quality forages must be supplemented to maintain livestock. In the southern part of the state, many forage grasses are in head while in the northern part of the state, some varieties of Orchard grass and barnyard grass are in head but most are still in the vegetative stage but will be in head within a week.
Many growers may base harvest decisions primarily on alfalfa maturity; however, this method can be misleading due to climatic variations affecting the rate of bud and flower development.
Spring changes of alfalfa %NDF can increase about 5 percentage units each week. Therefore, it is imperative for growers to be monitoring their alfalfa for optimal harvest times. Traditional wet chemistry remains the best method to measure %NDF; however, these traditional methods are often too time consuming when a rapid estimation of NDF is needed to make harvest decisions.
Growers can easily measure %NDF in their fields using a method referred to as PEAQ, Predictive Equations for Alfalfa Quality. This method uses max height and max stage of a pure standing alfalfa crop to determine %NDF. Neutral Detergent Fiber estimations using this method can begin as soon as the alfalfa crop reaches at least 16 inches in height. The protocol for utilizing PEAQ in the fields can be found here and short video describing the method can also be found here or linked below.
The PEAQ method was developed for pure alfalfa stands. Using this method to determine %NDF of alfalfa-grass mixtures will be inaccurate. However, this method can still be beneficial to estimate the %NDF in the alfalfa portion of the field. Grasses continue to follow harvest estimations based on growth stage.
Over the next few weeks ANR Educators and State Specialists across Ohio will be reporting %NDF of pure alfalfa stands. Most of the Alfalfa in the state had reached at least 16 inches which would have a %NDF of 28.5 while the most advanced alfalfa was 21 inches tall with an estimated %NDF of 32.