Let’s assume that a deer on decent natural habitat will eat no more than 25 percent of its daily diet in supplemental feed (high-protein pellets, cottonseed, dried soybeans, etc.). The only time I’ve ever seen deer eat more than about 2 pounds of supplemental feed per day is when they have degraded the natural habitat to the point that browse plants (including not just “ice cream” plants but also “subsistence” species) are of limited availability and quality. In such cases, the deer have no choice but to utilize supplemental feed heavily to get adequate nutrients.
True, whitetails can do well enough on supplemental feed, as evidenced by captive deer with no other forage options; however, they will only become dependent on such feed when forced to because of severely degraded habitat nearly devoid of natural browse. Deer are browsers by nature. Standing in one place at a feeder and eating feed is an unnatural act, and they will only do it in excess if forced to by the elimination of good browse options.
Let’s assume that supplemental feed has 20 percent protein. With 25 percent daily consumption of supplemental feed and 75 percent of natural forage (at 11 percent protein), the average protein level increases from 11 percent to 13.5 percent. That’s nearly a 25 percent improvement: much better than the natural habitat alone, but still well below the 16 percent level reputed to be the desired minimum for full body and antler growth.
Assuming that supplemental feed replaces 25 percent of the natural browse in the diet, logic says that the herd density can increase by 25 percent — to a deer per 19.1 acres — without a significant increase in browsing pressure on the habitat. Or, to look at it another way, if the density stays at a deer per 25.6 acres, the increase in the nutritional plane (as reflected by the increased protein level) would result in an increase in body and antler size. How much? Perhaps something along the order of 25 percent of what would be possible with ideal nutrition.
So with supplemental feed in poor natural habitats, we see real gains in both deer numbers and size – without, in theory, necessarily impacting the habitat negatively. And my experience with supplemental feed supports this theory. It can elevate the nutritional plane enough to boost size and allow more deer to be carried. However, the degree of improvement is incremental and limited without damaging the natural habitat.
One of the great benefits of supplemental feed is that it tends to help level out year-to-year and season-to-season forage fluctuations, which can be a real challenge in some parts of North America. Also, it can give managers without an agricultural option a way to improve the herd.
The danger of too much long-term dependence on supplemental feed is the temptation to increase deer numbers to the point that the natural habitat is severely degraded. This creates a damaged ecosystem, a situation unacceptable to any responsible deer manager.