If you don’t want to lose forage quality once a bale is made, consider using plastic net wrap rather than twine. That's according to a two year University of Wisconsin study that found three reasons net wrap out performs twine.
Reason #1: Net wrapping is faster than twine wrapping, which leads to greater productivity. Thirty-two percent more bales were formed per hour with net wrap compared to twine.
Reason #2: Harvest losses (hay dropping out of the bottom of the baler) are lower when using net wrap because of the shorter time needed for wrapping.
Reason #3: Net wrapped bales also have lower storage losses during outdoor storage compared to twine wrapped bales (7% vs. 11% respectively.) Researchers say this is because net-wrapped bales shed water better – if they are stored on well-drained areas.
Any round baler can be equipped with net wrap. The equipment costs $3,000 to $4,000, and plastic net is $.75-$1/bale more expensive than twine, but these University of Wisconsin researchers concluded it is worth it in forage quality and efficiency.
Another note: this study found that sisal twine rots, thus if you’re going to use twine, use the plastic type.