My hay baling career was last active quite a while ago, back in the era of old-fashioned sisal twine. That old twine seemed to do the job back when there were no other alternatives, but it certainly wasn’t perfect.

Broken twine and disintegrated, sloppy looking bales were not uncommon. But twine’s organic nature meant we weren’t concerned with any effect it might have on cattle consuming the hay.

Fast-forward to today, when net-wrapped bales are the norm. Just drive past a recently baled hayfield and you’ll see reasons why: tight, uniform bales with nary a broken one in the field. Talk to the farmer running the baler and they’ll tell you wrapping a bale in net wrap is a lot quicker than using twine. Moving and transporting those bales is more efficient when uneven or broken ones aren’t in the mix.

Net wrap’s advantages extend past the hayfield. Bales shed water better during their storage, reducing spoilage and translating into better nutrient value for the critters eating the hay.

It’s therefore understandable why using net wrap is so widely embraced by hay and cattle producers. However, there’s a potential dark side to consider.

My first inking of this came several years ago, when one of our diagnostic lab pathologists called me out of my office to look at a cow he had on the necropsy floor. A local producer had brought in a skinny cow that had recently died, looking for a reason for the cow’s illness.

When the pathologist opened up the cow’s rumen, he found a volleyball-sized wad of plastic strands lying within. Closer examination revealed the wad consisted of net wrap the cow had eaten.

When asked, the producer noted he’d been feeding his cows hay ground from round bales still wrapped with net wrap. No other disease problems were noted in the cow, so the net wrap wad was considered the main cause of the cow’s demise. It had blocked the outflow of feed from the rumen to cause severe digestive problems.

At the time, I thought the finding was a weird fluke. But this story has been repeated to me many times by veterinarians posting cattle in the field. SDSU Extension beef experts found when they surveyed producers using net wrap, about 15% of dead cows examined had net wrap in their systems.

Net wrap gets into cows by a couple different methods. Most producers (as shown by the SDSU survey) do not remove net wrap when they grind hay, relying on the screens to grind it up along with the hay. The problem here is that even small, ground-up strands of net wrap ball up in the animal’s rumen: it’s indigestible with very little coming out of the back end of the cow. Secondly, while more producers (about half) remove net wrap from bales being fed whole, if it’s left out on the feeding ground, many cows pick it up and chew on it when the hay is gone.

The need to prevent cattle from access to plastic net wrap is somewhat controversial among producers and veterinarians. Granted, many who have never removed net wrap from their bales don’t observe cow health problems or death losses. Additionally, removing net wrap is a pain. It takes time, more so in freezing weather. Since many producers are already stretched thin on time and labor, this extra work gets skipped.

However, the effects of accumulating net wrap in a bovine’s digestive tract aren’t often apparent. That cow that doesn’t put on any weight? That calf that bloated up in the feedlot? We often chalk these presumably sporadic and unrelated occurrences up to other reasons. How often does net wrap contributes to these illnesses?

Most producers – whether they’re net wrap removers or not – are advocates for preventive health: vaccinating the cow herd, for example. We don’t worry about how much time it takes to vaccinate cows – for germs they may or may not be exposed to – because it’s the right thing to do.

Why then, wouldn’t we spend time preventing our cows’ access to another potential health threat – that they’re exposed to every day we feed hay? In the spirit of the health and well-being of our cattle, whether it takes 30 seconds, 60 seconds or 15 minutes to take net wrap off a bale, wouldn’t it be worth it?

Russ Daly, DVM, is the Extension Veterinarian at South Dakota State University.  He can be reached via e-mail at russell.daly@sdstate.edu or at 605-688-5171.