Because you asked, Douglas, and because it’s a fine winter blog topic, I shot an email over to wildlife biologist, QDMA Programs Manager, and friend Matt Ross, regarding winter deer feeding on hay and grains.
For anyone who didn’t see the comments on the last post, Douglas asked:
Biologists have stated that it is wrong to feed deer hay and grain during the hard winter months because they are in browsing mode and do not have the correct bacteria in their digestive tracts to digest the grain and hay. Apparently, deer can starve with full stomachs of hay. However, during mid-winter thaws hereabouts, I constantly observe deer foraging in meadows for hay and waste corn. What’s the deal?
Here’s the deal, according to Ross, whose Masters degree just so happened to focus on winter deer feeding in northern New Hampshire:
When people feed hay or grain, winter deer tend to pseudo-gorge themselves on the new food source. This is a shock to their digestive system, and, as the reader says, they don’t have the living bacteria to digest it. People usually feed deer at a time when snow is deep and there aren’t many other foods available. So the deer fill their stomach on the hay or grain alone and can get sick or die from it (rumenitis).
_The reader asks why this doesn’t happen during those brief periods when the snow melts and deer regain access to pasture or waste corn. It’s because in this case the deer are not eating those things only. With the snow gone, they also re-gain access to hardwood browse, leftover acorns, dead dry leaves, etc.–which allows them to build up the necessary bacteria to digest the hay and corn. For related scientific papers, click here or here.
The reason I said “pseudo-gorge” earlier is because deer have evolved to eat very little this time of year. Whatever they eat, it’s a break-even proposition at best in terms of the energy they expend to stay warm and survive. For the most part, northern deer are in a negative energy balance all winter long. Those in our research pens at college would voluntarily reduce their intake and lose weight, even though we offered them food ad libitum (like a buffet bar always available). They had no predators and ideal shelter. Why wouldn’t they eat? It’s because they’re built to live off the fat supply they worked so hard all fall to build. This is Nature’s way.
The best thing people can do to help deer through the winter is manage their property the rest of the year to provide suitable wintering habitat (that means areas that offer shelter from snow, cold, and wind) and preferred winter food sources (basically low hardwood and shrub browse that is less than 5 years old). Then stay out of it: Going out there and doing anything that stresses or moves deer is making them use valuable resources that they need to make it through the winter.