There is considerable controversy regarding the percentage of dietary protein that deer require.
There are many people believe that deer cannot tolerate more than 16 percent dietary protein, and that high-protein diets are wasteful or even toxic. This simply is not true.
High protein in wild deer diets
Research in South Texas has shown that wild deer diets at certain times of the year can be more than 25 percent protein. Many forbs highly utilized by deer are more than 30 percent protein. Obviously, the wild deer are unharmed by consuming these high-protein plants. Indeed, excellent antler growth years were those with superb spring forage conditions. The resulting antler growth suggests that not only were the deer not harmed by their high-protein diet, they actually utilized the protein to grow bigger antlers, indicating that higher protein is necessary for a buck to achieve his genetic potential for antler growth.
Protein supplementation for wild deer
Deer protein pellets designed to supplement natural forage need to be greater than 16 percent protein because the forage portion of the diet is often inadequate in protein content. Even in a good year, the digestible protein content of major deer browse species often falls well below 10 percent by late summer and will likely remain there until the spring green-up. In a tough year (late winter, drought, etc.), the nutrition supplied by natural forages can be inadequate even in the spring. Without supplemental protein, deer cannot maintain optimal body condition, which is essential for maximum antler growth.
Deer in confinement being fed complete diets should have at least 16-17 percent dietary protein in order to try to maximize health, growth and antler development. Today's high scoring bucks are sometimes fed diets containing 20 percent protein. Some people even feed diets containing as much as 24 percent protein with no adverse effects. Although if deer are being fed the majority of their diet from prepared feed, 16-17 percent protein is adequate.
Physiological benefits of protein for deer
Protein is needed for maintenance and growth of all organs in the body as well as for many physiological functions. The individual needs for protein are affected by many factors such as genetics, environment, disease and parasite challenges.
Antler growth, while desirable and important for social hierarchy, is not necessary for life and appears at the bottom of the priority of nutrient use list from the buck’s viewpoint. Therefore, unless there is enough protein in the diet to meet all the priority needs and have enough left over for optimal antler growth, trophy racks will not happen, no matter what the genetic potential of the buck. If you want to see giant antlers, you will need to provide the necessary protein with products such as deer protein pellets.