Do Minerals Work for Improving Deer Health?
August 15, 2018
Last month, we discussed what's really in a bag of food-plot seed and how to make sense of that without getting caught up in the marketing. If you read that column, hopefully you are now wise enough to ignore the fancy graphics on the front of the bag (think 200-inch bucks) and instead flip the bag over to read the label.
This month, I'll take a similar approach to the topic of minerals. As any bowhunter knows, the same aisle stocked with food-plot seed also has a plethora of mineral supplements GUARANTEED to grow massive racks almost instantly. Lots of hunters use minerals, and if you are one of them, have you ever wondered if you are throwing your hard-earned cash in the dirt along with the pixie dust? And if you don't use minerals, have you ever wondered if you're missing out on something that can truly offer benefits to your local deer herd and boost your bowhunting success?
Wildlife biologists and researchers are known to avoid the topic of mineral supplementation — and you can count me among them! In fact, I was a bit hesitant when the editor asked me to address the topic in this column. That's because researching the benefits of mineral supplementation is extremely difficult in wild deer and questionable, at best, in captive deer. Although studies on captive whitetails have been conducted, researchers are quick to point out that captive deer don't live similar lives to free-range deer. These studies have included a relatively small number of deer that are typically stressed from being confined, often in overcrowded conditions.
When it comes to the impact mineral supplements have on wild deer, most of what you hear and read is based purely on anecdotal observation and not backed by any scientific research. If you don't believe me, simply call the manufacturer of your favorite supplement and ask for the research that backs up their claims. I've spent 15 years questioning claims and reading quality science, and I can assure you they won't be able to supply it. The fact is, the "experts" argue all the time over whether mineral supplementation in free-range whitetails actually provides benefits.
With that said, you might guess I am not a proponent of mineral use. However, nothing could be further from the truth! I believe in merging quality science with on-the-ground experience to grow larger, more mature bucks for bowhunters. And while there's no question the science on deer minerals is inconclusive, common sense suggests that offering minerals to improve the overall health and antler development of the deer you hunt makes perfect sense. In fact, I purchase mineral supplements in bulk every year and use them on my own farm and the properties I manage!
For Deer & Deer Hunters
German research in the 1950s found that soil fertility was a major factor in determining body and antler size in roe deer. Also in the 1950s, Pennsylvania scientists published landmark findings that biologists still reference today when discussing some potential benefits of mineral supplementation in deer. Research in the 70s and 80s documented peak mineral use by does during fawning and lactation, as well as by bucks during the "costly" antler-growing period.
In the early 80s, Dr. Harry Jacobson from Mississippi State University revealed some very interesting findings from 23 areas in Mississippi. He found a strong correlation between deer body weights and soil phosphorous levels. Again, we don't have a clear-cut cause and effect between higher mineral content in the soils and larger antlers; however, we can deduce this would be true. We know healthier, heavier bucks are able to express their full genetic antler potential and healthy does have more resources to commit to producing and raising fawns. Furthermore, phosphorous levels in soils across the whitetail's range tend to be low. So, it only makes sense that addressing that limiting
factor through supplementation would result in a healthier deer herd and larger antlers.
In 1990, a Louisiana study focused on the effects of supplemental mineral licks on deer and found no difference in growth rate, body size or antler quality. Armed with plenty of inconclusive research, I decided to narrow it down to what we do know. One thing is clear; deer are seeking sodium. Peak mineral use seems to follow spring green-up, and usage falls off rapidly in late summer as the growing season winds down and native plants mature. Researchers believe the higher potassium and water content in spring forages creates a sodium imbalance that causes deer to seek out salt.
While biologists commonly point out that commercial mineral offerings with high sodium (salt) levels do not grow antlers, sodium has been proven to play a role in antler development. Furthermore, the sodium needs of yearling bucks are even greater as they build their first antlers. A great start in life affords a buck the opportunity to maximize his antler potential instead of playing catch-up in subsequent years. Antler growth in bucks is extremely expensive physiologically. It's a little-known fact that bucks literally perform voluntary osteoporosis and mobilize mineral deposits from their skeletons to produce antlers. Their window of opportunity to maximize antler size before velvet sheds and antlers harden is very narrow. It only makes sense to assist them in this journey.
Equally important, research in 1987 found that milk production in does required 78 percent of their total sodium intake! These higher mineral demands are what drive pregnant and nursing does to mineral supplements from May-July. If you want to maximize the size of the bucks you bowhunt, don't ignore momma!
In addition to the physical benefits mineral supplements likely offer deer, the value minerals bring to bowhunters make them worth it. Because mineral sites are highly attractive to deer, they provide bowhunters with a prime opportunity to survey the local deer herd via trail cameras and obtain population characteristics such as buck age structure, adult sex ratios, fawn recruitment rate and overall deer numbers. In addition to being extremely useful information, getting a glimpse at all those deer really helps build excitement leading up to opening day!
Mineral Site Tips
In spite of the cloudy science regarding the tangible benefits of mineral supplementation, there are multiple studies that document whitetail deer eating soil to consume minerals that are in limited supply. It's hard to imagine there is no benefit to the whitetails that seek these minerals out during such critical times in their annual cycles.
Because of these observations, I've always felt it was more natural to develop a mineral site that mimics natural deposits. For this reason, I prefer granular minerals so I can dig up the soil and mix the supplement into the loose dirt. When possible, I also prefer to add a bucket of water before leaving the mineral site. This helps mix the nutrients into the soil, as you never know when the next rain is coming. I have also noted heavier deer utilization when minerals are supplied granularly and mixed into loose, moist soil.
Interestingly, many landowners have told me they avoid granular products because they don't "last as long." I think they are missing the boat here, because even the greatest mineral supplement in the world can't provide benefits if the deer don't consume enough of it! If deer are consuming the soil where minerals have been mixed in, and utilization is high, the ultimate benefits to the animal are greatest.
One word of caution here is the legality of mineral supplements where you hunt. Some states — such as Illinois — prohibit them altogether, and many states require removal of all mineral supplements (and residues) at least 30 days prior to hunting season. In such instances, you may prefer using mineral blocks or naturally sourced mineral rocks, as it makes removal much easier.