Rake Type Effects on Forage Quality

Putting up the highest-quality forage requires making many impactful choices during the haying season. Previously we discussed smart raking decisions to help conserve available nutrients and reduce crop losses. In addition to good management practices, there is a larger discussion to be had. What’s the best hay rake for your operation?

To help producers determine what hay rake is best, we conducted field studies comparing three popular rake types — wheel, parallel bar and rotary. There are pros and cons to each rake type and a lot depends on the specifics of your operation. This data will help you determine if you have the right hay rake for the job. Or maybe it’s time to reevaluate your process — and your hay-gathering machine.

Wheel Rake Benefits in Alfalfa

Wheel rakes are the most popular rake in the United States. These ground-driven implements center-deliver hay into a windrow. For the most part, wheel rakes are simple and easily adjustable, making them a versatile choice for hay producers. However, this simplicity comes at a cost.

A University of Minnesota field study, in conjunction with Pennsylvania State University and the University of Wisconsin, determined wheel rakes resulted in a greater ash content post-raking. Ash is a naturally occurring inorganic compound present in all forage. Internal ash is beneficial to forage growth and mineral portions of animal nutrition. The average internal ash content in alfalfa is about 8% and about 6% in grasses. High levels of external ash, on the other hand, are negatively correlated with animal performance to a very dramatic degree. For every 1% ash contamination — from dirt, bedding, sand, etc. — producers see a 1% decrease in total digestible nutrients (TDN). As a ground-driven tool, wheel rakes incorporate more external ash than other models.

Table 1. Ash content of standing (Stand), post-cut (Cut), post-raked (Rake), and post-baled or chopped (Bale) alfalfa hay after first and subsequent cutting in Minnesota, Pennsylvania and Wisconsin in 2015. Hay was raked with hay merger (Merger), rotary rake (Rotary), sidebar rake (Sidebar) and wheel rake (Wheel).

Our own field study confirmed prior findings. The trial was conducted on third cutting alfalfa in Pasco, Washington, where the volcanic ash-type soil provided valuable data. We compared ash content and windrow formation with a Massey Ferguson 802 double rotary rake, a parallel bar rake and wheel rake. All rakes were driven at 5, 7 and 9 mph.

Table 2. Ash content after baling. Hay was raked with a MF 802 double rotary rake (Rotary) parallel bar rake (Parallel) and wheel rake (Wheel).

In the end, higher ash content resulting from a wheel rake cuts into hay profits. With lower ash levels, hay producers can charge more per ton. For example, one ton of alfalfa hay with an ash content of 14% would contain 120 pounds of soil contamination compared to 60 pounds of soil contamination when the ash content is reduced to 11%. Assuming good-quality hay selling at 220 USD/ton, a premium of about 2 USD/ton for lower ash hay could result in a 12 USD/acre gain.

Parallel Bar Rake Results in Alfalfa

In addition to ash content, windrow formation is an important part of the hay-making process. A uniform windrow leads to even dry down, reducing high moisture spots and mold within the bale. It also makes for more uniform bales, resulting in easier baling.

Parallel bar rakes are another popular ground-driven rake type. In our research, this model resulted in lower ash contents than the wheel rake, at 7 and 9 mph. However, “Roping” was evident with both the wheel and parallel bar rake trials. Roping can reduce air flow through the formed windrow, delaying dry down and baling.

Windrow formed by the MF 802 center-delivery double rotary rake (left) and the parallel bar rake (right).

Additionally, we saw significant height variability in the parallel bar windrows.

Table 3. Windrow formation variability across all rake types and ground speeds.

Benefits of a Rotary Rake

Rotary rakes work well in both grass and legume forage, such as alfalfa, and are finding acceptance with hay producers across the country.

In both the UMN and our own field trials, the rotary rake resulted in the lowest external ash content. This is a result of the design. Unlike wheel or parallel bar rakes, a rotary rake is not ground driven. Hay producers can adjust rake height to cutting height for maximum forage collection without external ash contamination.

Additionally, we saw more uniform windrows with the rotary rake and no roping. This is again thanks to design. Forage passes along overlapping wheels in both wheel and parallel bar rake design. This excessive handling leads to roping. It can also result in greater losses due to leaf shatter when raking at less-than-ideal moisture.

One perceived drawback of the rotary rake is speed. Producers believe they have to rake slower. We conducted several speed and PTO tests to determine the validity of this notion. At the Pasco, Washington, site, we tested the effect of various PTO rpm speeds on forage quality. Across all PTO rpm speeds, there was no more than a 1.5% difference in TDN.

Table 4. Total digestible nutrients (TDN) of forage raked by center-delivery MF 802 double rotary rake at various PTO rpm speeds.

Table 5. Ash content of forage raked by center-delivery MF 802 double rotary rake at various PTO rpm speeds.

What’s the Best Hay Rake for Your Operation?

Just as hay producers must consider many variables in the pursuit of high-quality hay, selecting the right hay-gathering equipment relies on many operation-specific questions. Our field studies demonstrated that rotary rakes produce uniform, easy-to-bale windrows with reduced ash contamination. However, cost and equipment requirements must be considered when making the switch to a rotary rake system. Connect with your local Massey Ferguson dealer to discuss the rotary rake options available for your specific needs.