9th International Deer Biology Congress

AUTHORS: Santiago Gomez. Departamento de Anatomía Patológica, Universidad de Cádiz, Spain; Pablo Gambin and Jamil Cappelli, Animal Science Techniques Applied to Wildlife Management Research Group, Instituto Investigación en Recursos Cinegéticos (IREC), Universidad de Castilla-La Mancha, Albacete, Spain; Salvador Luna, Departamento de Enfermería y Fisioterapia, Universidad de Cádiz, Spain; Andrés Garcia, Martina Perez-Serrano, Laureano Gallego, and Tomás Landete-Castillejos – Animal Science Techniques Applied to Wildlife Management Research Group, Instituto Investigación en Recursos Cinegéticos (IREC), Universidad de Castilla-La Mancha, Albacete, Spain

ABSTRACT: Deer antler is an external cranial appendage constituted by a primary bone that is dead and dry [1]. As bone tissue, the antler has some outstanding mechanical properties. In fact, the antler has higher toughness and impact energy than other bones of skeleton (i.e., femur) that make it difficult to break and appropriate for fights among males [1]. The objective of this work was to evaluate the microhardness, the Calcium (Ca) content, and the mineralization sequence of antler compared with femur. Three antlers from adults and one femur from a yearling were used. Microhardness was determined by Vickers microindentation (IndentaMet 11100, Buehler) using a load of 25 g/10s applied on the polished surface of samples embedded in plastic. Microstructure was studied in mineralized sections, 100 μm-thick, by circularly polarization microscopy (maps of collagen orientation in false color) and in stained sections. The Ca content (g/100 g) was analysed by atomic emission spectrometry with inductively coupled plasma (ICP). Mineralization sequence was determined injecting 5 mg of calcein per kg of body weight at day 117 of the antler development, (following protocol as in [2]). Subsequently, growth marks present in the mineralized sections were examined by epifluorescence microscopy and the time elapsed between the beginning of primary osteons formation and the velvet shedding was calculated. The micro-hardness is much lower in the antlers compared to the femur (48%), and also the calcium content (70%). For the same antler, both values decreased in the proximal-distal direction according to the mineralization sequence [2]. The microarchitecture of antler differed markedly from that of the femur (fibrolamellar bone), it consists of two types of bone tissue (woven and lamellar bone) that link together to form a compact bone. It can be concluded that the microhardness of the antler is much lower than that of femur. Since the microhardness represents a mechanical property related to the maximum elastic load of a material and, in the bone, with the Ca content, it is noted that the exceptional mechanical properties of antler are based on its microstructure, its low mineralization, and its cement (non-collagenous organic matrix).