Mad_ hunter, It says
Therefore, supplementation of these minerals prior to and during antler growth MAY BE ( THE AUTHOR' S OPINION) beneficial
THERE IS NO SCIENTIFIC DATA EVER WRITTEN TO SUPPORT THAT STATMENT, NOR HAS ANY STUDY BEEN CONDUCTED THAT SHOWED ANY INCREASE IN ANTLER SIZE.
If you read down farther you will see the results of actual studies down on this subject
A classic study on the mineral needs of deer was conducted at Penn State University in the 1950s (French et al. 1956). In this study, researchers did detect a difference in yearling buck antler development between supplemented and unsupplemented groups. However, these herds were fed a nutritionally deficient diet below what most whitetails would have access to in the wild.Furthermore, when the same deer were examined the following year as 2.5–year–olds, no differences were detected between the two groups.
In a similar study conducted at Auburn University (Causey 1993), researchers tried to detect differences in body and antler size between an unsupplemented and supplemented group. The difference in this study and the Penn State study was that both herds were fed a nutritionally complete diet. In addition, one group was provided a commercial mineral supplement. Over a 4–year period the researchers were unable to detect any differences between the two deer herds.
A Louisiana study (Schultz and Johnson 1991) compared supplemented and unsupplemented wild herds in similar habitats. Although problems always arise when studying wild populations, they were unable to show any differences in body size or antler development using mineral supplementation.