Storing large round bales of hay can be challenging, and storage conditions and type of bale wrap can affect dry matter losses and nutrient values significantly.
Amanda Reiter, a graduate student at the University of Minnesota’s Department of Animal Science, in Falcon Heights, recently compared types of bale wrap and their effects on alfalfa baling time, dry matter losses, nutrient values, moisture levels, cost, and bale value. She shared her findings at the 2019 Equine Science Society Symposium, held June 3-6 in Asheville, North Carolina.
“Ideally, you would store bales inside, away from moisture, snow, etc.,” Reiter said. “However, not everyone has that luxury, so we commonly store outside, which leads to 7-35% dry matter losses vs. 2-7% inside.”
She focused her study specifically on bales stored outside over a 12-month period. Reiter evaluated three wrap types: plastic twine, net wrap, and B-Wrap, “which is like Tyvek paper used in home building,” she said. “It’s advertised to shed precipitation without trapping moisture in the bale.”
First, Reiter calculated how long it took to wrap an alfalfa bale in each type during harvest. Twine took approximately 56 seconds per bale (3 hours and 55 minutes to bind 250 bales), net wrap 20 seconds (1 hour 15 minutes), and B-Wrap 28 seconds (1 hour 57 minutes).
She also noted each type’s cost. Twine cost $1 per bale, net $1.17 per bale, and B-Wrap $8.33 per bale. She then stored eight bales of each wrap type outside on pallets for one year, analyzing their nutrient content and dry matter losses every 90 days. At the end of the study period, she found:
- No differences in protein or fiber content between bales.
- A 2-3% decrease in nonstructural carbohydrates (NSC) in twine and net-wrapped bales but not B-Wrap.
- Dry matter losses of 0% for B-Wrap, 4.9% for net, and 5.3% for twine.
- The lowest moisture levels with the B-Wrap and the highest with the twine.
- The post-storage value of twine-wrapped bales was $55, net wrap $58, and B-Wrap $65.
B-Wrap proved to be the superior wrap type in nearly every category except initial cost.
“These results indicate that B-Wrap has the potential to mitigate dry matter and NSC losses in alfalfa round bales in long-term outdoor storage,” said Reiter.
“However, hay loss doesn’t end at storage,” she added. “Some occurs during feeding, as well.”