There remain many options available to producers when it comes to mowing and conditioning forage.  Given that the mower-conditioner is one of the most highly used pieces of machinery on many dairy farms, when it comes time for a replacement there are several decisions that must be made relative to the purchase.  They are: cost, manufacturer, size, pull type vs. self-propelled, sickle vs. rotary disc, and conditioner type.  It is the final two considerations which we will deal with in this article 

Sickle vs. Rotary Disc 

Nationwide sales of disc mower-conditioners exceed that of sickle mower-conditioners.  Disc mowers do offer some advantages to the more conventional sickle types.  They perform more dependably where forage is lodged or in thick grass stands and can be operated at higher mowing speeds.  The primary disadvantage is a higher initial price.  Pull-types will range 20 to 30 percent higher in price while self-propelled units may approach 50 percent more.  Some producers don’t like the more “ragged” look of a field left by the disc mower compared to the sickle mower.  This is more of an aesthetical disadvantage rather than a practical one.   Further, some company manufacturers don’t sell a sickle type mower conditioner anymore and have moved exclusively to the disc types.  Others offer both, but total sales of each type vary between companies. 

         There may be no right or wrong answer as to which type to purchase.  Disc mowers shine the most in tough mowing conditions.  If your typical situation is a pure stand of alfalfa that isn’t excessively wet or lodged, the advantages of a disc mower may not be warranted relative to the additional cost.  However, if this is not the case, or if you have large acreages of hay to cut, disc mower-conditioners may be worth the added investment. If you’re still undecided, field test both types of units and evaluate performance first-hand before making an investment you won’t be happy with. 

Conditioner types 

Conditioner type options have really increased in the past ten years.  Here’s a brief look at the options: 

Molded Rubber:  Rubber is the most common type of conditioner roll. They are relatively inexpensive and gentle on the hay crop from a leaf loss standpoint.  The disadvantages of rubber rolls are that they wear more quickly and, because they are molded, may not mesh perfectly.  Proper adjustment is important. 

Tire Cord:  Rolls made from tire cord are similar in performance to the molded rubber with one primary advantage:  they are machined rather than molded.  This makes for a more perfect "mesh".  They are also less prone to wear compared to molded rubber. 

Metal:   Metal rolls are less vulnerable to wear compared to rubber or tire cord.  This is a popular choice in the western U.S. where large acreages of hay are cut and sandy soils tend to wear-out the rubber types in a relatively short amount of time.  Metal rolls are more aggressive and may result in slightly higher leaf loss than rubber rolls (Table 1). 

 Impeller/Flail:  Impeller-type conditioners have been popular in Europe for many years (mostly grass-based systems) and are becoming more widely used in the U.S. in recent years.  It is the lowest cost type of conditioning system.  On a disk-type mower, they allow for better air and crop flow through the machine compared to roll conditioners.  Unlike rolls, impeller conditioners work by stripping the crop rather than breaking the stem at 3 to 4-inch intervals.  They create a more "fluffy" windrow compared to rolls.  Proper adjustment of flails is critical to prevent extensive leaf loss on alfalfa. 

         Super Conditioner:  This is a specialty roll-type conditioner manufactured by Circle C Equipment, LLC in Hermiston, Oregon.  These zero-clearance rolls crush the stem along its entire length.  Research has shown a decrease in drying time compared to conventional rolls.  However, the cost of this system is economically prohibitive unless large acreages of baled hay are harvested. 

         Macerator:  The macerator is a separate pull-type conditioner marketed by AgLand Industries that consists of two sets of rolls, one rubber and one metal.  Maceration takes place between the two metal rolls, which cracks the stem and removes some of the waxy cuticle. 

        Although conditioner type is an important decision when purchasing a new or used mower-conditioner, of greater importance is the proper adjustment and maintenance of the hay conditioning system irrespective of type.  Research comparing the various conditioning methods does not flush-out big differences in performance relative to dry matter losses or drying time (Table 1).  However, when roll gap clearances are wider than 0.09 inches or impeller conditioners are set too aggressively, significant performance changes relative to drying time and leaf loss can occur. 

       Forage producers need to also keep in mind that swath width has more of an impact  on drying time than conditioner type.   Adjusting swath width is a key strategy to either delay or speed drying time depending on the situation.