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Dairy producers and alfalfa growers appear to be valuing hay and haylage that meets and even exceeds the traditional target of 150 RFV. Summary testing data for 2006 haylages (Table 1) show that the averages for legume and mixed haylages were quite close to a target RFV of 150. However, we see a wide range in all measurements of quality, with many forages testing high in CP, NDFD, RFV and RFQ. This may be due to a goal of higher CP content, but more likely reflects goals of greater intake and milk production from the harvested forage.
 
Table 1. Forage quality of legume, grass, and mixed haylages in 2006.
(Source: Dairyland Labs)

With the introduction of RFQ, we have the ability to better predict the digestibility of forages. Should we change our target value? It depends on the animal to which the forage will be fed. For lactating dairy cows, we suggest a target RFQ ≥165. This should provide forage with NDFD >50%, and thus greater intake and milk production due to greater fiber digestibility. For the traditional RFV system, we continue to recommend a target of ≥150 for alfalfa forage for lactating dairy animals. To optimize digestibility, effective fiber, crude protein levels, and alfalfa yield and persistence; a RFV of ~175 is probably the upper end for an optimal range in the final haylage or hay product.

The PEAQ forage quality stick is a useful, cheap method to estimate forage quality of a standing crop of alfalfa to determine when to start cutting. Useful rules of thumb include:

• Generally, ~15 to 30 units of RFV/RFQ are lost during harvest and storage
• During spring growth, standing alfalfa will lose ~5 RFV/RFQ units per day, and gain ~100 lb dry matter per acre per day, on average.

Note that both RFV and RFQ versions of the PEAQ stick are in circulation. Both versions are very useful tools. The PEAQ forage quality stick, whether an RFV or RFQ version, is a reliable indicator of RFV (identical scale on current RFQ sticks); however, the science behind RFQ and its predictability based on maturity and height of alfalfa continues to evolve.

We believe that for first cutting, RFQ sticks may be underestimating true RFQ (but providing a good measure of RFV) since first cutting often has greater NDFD than later cuttings. For example, a RFQ PEAQ stick reading of 180 indicates a RFV of 180, but for spring growth, the true RFQ may be closer to 190 to 210. Thus, a 150 RFV first-cutting alfalfa haylage may well test 165 to 180 RFQ. University of Minnesota and Wisconsin Extension are working collaboratively on this spring’s alfalfa crop with cooperators in both states to attempt to refine RFV, RFQ, height, and maturity inter-relationships.

Please be patient with the science. Our knowledge of how to accurately and economically predict and measure forage quality and predict animal performance has and will continue to evolve. Also remember that the PEAQ forage quality stick is just a predictive tool for quality of standing, not harvested, alfalfa (not grasses or alfalfa-grass mixtures), and not a substitute for a forage test on the hay or haylage itself. Have a good, safe harvest!

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