Maintaining Forage Quality and Dry Matter in Large Square Bales

Mike Rankin
Crops and Soils Agent - Fond du Lac County
University of Wisconsin - Extension

        Large square bales (LSB) are increasing in popularity.  At several of the quality tested hay auctions during the past two years, the numbers of LSB lots have out-numbered those of small square bales.  Packaging hay into LSB’s certainly provides some labor and handling advantages over both small square and large round bales, however, they also offer some unique challenges in terms of long-term storage and maintaining initial forage quality.

        Large square balers typically have a pre-compression chamber and hydraulically loaded panels on three sides of the bale chamber.  The result is a much denser package than other bale types.  Wisconsin studies show that the density of an intermediate sized square bale (3 ft. by 4 ft.) is about 54 percent more dense than the average small square bale.  This higher density predisposes the large square bale to heating, dry matter loss, and forage quality deterioration during storage if harvest moisture is over 15 percent.

        Kevin Shinners, UW Ag Engineer, has studied the effects of using a ventilation hole (formed in the center of the bale as it passes through the chamber) and propionic acid (0.8% by weight) to preserve forage quality and dry matter when LSB’s are harvested between 16 and 24 percent moisture.  Here were his results:

• Ventilated bales did not heat any less in storage than non-ventilated control bales.

• Bales treated with propionic acid had less heating and less heat damage to proteins compared to control bales with no treatment.

• Neither treatment method produced a definitive trend toward reducing dry matter losses.

• Bales treated with propionic acid maintained a higher moisture during storage.  This potentially may cause microbial degradation in the long-term if bales are not fed-out in a reasonable amount of time.

• Moisture is the key.  To maintain forage quality and keep dry matter losses under 4 percent, bale below 16 percent moisture.

For more information contact Mike Rankin