Manganese supplementation improves antlers of adult deer even under a balanced diet

Trabajo presentado a The International Scientific Conference on Deer Genetics and Management, celebrada en Sigulda (Latvia) el 6 y 7 de agosto de 2014.Mechanical properties, and in general, growth of antlers, has been thought to be mainly depending on Ca and P input. However, many other minerals can influence growth and mechanical performance in bones. Our research group examines mineral composition of antlers as a diagnostic tool to detect nutrition deficiencies, and also their effect in mechanical quality of the antler material, internal structure, density of cortical wall, and other antler characteristics. One of the most interesting minerals, although not the only one, seems to be manganese. In this presentation we remind early studies where a deficiency in manganese (and also phosphorus) detected in broken antlers naturally occurring in 2005, produced as a result a 30% reduction in antler weight, and a similar reduction in resistance to impact (impact energy), other mechanical properties, and thinner cortical wall. As a result of this experiment, we decided to examine the effects of manganese supplementation in spikers and adults of red deer under a balanced diet. Subjects were 29 deer of different classes of age (adult n=16, subadult n=3 , spiker n=10) that were divided into a control group (n=15) and a group subjected to injection (n=14). Antler mineral content (ashes, micro and macro minerals), mechanical properties (Work to peak force, Bending strength, Young's Modulus of elasticity) and structure (average cortical thickness, cortical bone's specific gravity, cortical bone ratio) were examined in to 4 different test points along the antler beam. Each variable has been related to treatment, class of age, weight and year of growth of the antlers in a statistical test based on General Linear Model. The results show that manganese supplementation did not produce any effects in spiker antlers beyond an increase in manganese content. However, in adults results on the overall mean of the antler show a clear effect of manganese supplementation increasing the content of Ca, Na, P, B, Co, Cu, K, Mn, Ni, Se, Si, but no effect on mechanical properties. An analysis on the top portion of the antlers, where the effects are shown more clearly, showed the same effect in mineral composition, but also a 16% increase in work to fracture, much greater than in the mentioned study in wild deer. Thus, manganese supplementation can improve mineral composition of antlers, structure and some mechanical properties despite animals having a balance diet. The results are important for mineral and feed supplements in deer, but they may also have implications for human health and bone biology.Peer Reviewe