Moen, R.A. and J. Pastor. 1998. Simulating antler growth and energy, nitrogen, calcium, and phosphorus metabolism in caribou. Rangifer Special Issue Number 10:85-97. Click here for 211K pdf.
We use a simulation model to predict energy, protein, and mineral requirements of moose. Body water, fat, protein, and ash are monitored on a daily time step, and energy requirements for reproduction and body mass changes are accounted for. We had to estimate energy requirements for antler growth because experimental data is not available. Antler growth in males increased energy requirements during the antler growth period by 12 to 22%, depending on the efficiency with which energy was used for antler growth. Energy requirements for the latter part of gestation and milk production by females were less than requirements for antler growth in males. Protein requirements for antler growth and lactation were met by forage intake. The simulation model predicts that calcium and phosphorus must be resorbed from bone during peak antler growth. For moose growing antlers which weigh 30 kg at the end of the velvet shedding, > 60 g / day of calcium and > 30 g / day of phosphorus are deposited in the antlers for 40 days when mineralization rate is highest. After energy, phosphorus was most likely to limit growth of antlers. Input parameters to the model can be easily changed to represent moose from other geographic regions and other cervid species. The model can be used to understand energy and mineral metabolism requirements for antler growth, and to understand the relationship between body mass and antler size in the Cervidae
Moen, R.A. and J. Pastor. 1998. A model to predict nutritional requirements for antler growth in moose. Alces 34:59-74. Click here for 241K pdf.
We added antler growth and mineral metabolism modules to a previously developed energetics model for ruminants to simulate energy and mineral balance of male and female caribou throughout an annual cycle. Body water, fat, protein, and ash are monitored on a daily time step, and energy costs associated with reproduction and body mass changes are accounted for. In order to simulate antler growth, we were required to predict calcium and phosphorus metabolism as it is affected by antler growth, gestation, and lactation. We used input data on dietary digestibility, protein, calcium and phosphorus content, and seasonal patterns in body mass to predict the energy, nitrogen, calcium, and phosphorus balances of a "generic" male and female caribou. Antler growth in males increased energy requirements during the antler growth period by 8 to 16%, depending on the efficiency with which energy was used for antler growth. Female energy requirements were proportionately much smaller because of the smaller size of female antlers and additional energy requirements for lactation. Protein requirements for antler growth in both males and females were met by forage intake. Calcium and phosphorus must be resorbed from bone during peak antler growth in males, when > 25 g / day of calcium and > 12 g / day of phosphorus are being deposited in antlers. Females are capable of meeting calcium needs during antler growth without bone resorption, but phosphorus was resorbed from bone during the final stages of antler mineralization. After energy, phosphorus was most likely to limit growth of antlers for both males and females in our simulations. Input parameters can be easily changed to represent caribou from specific geographic regions in which dietary nutrient content or body mass patterns differ from those in our "generic" caribou. The model has important implications for understanding the evolutionary basis for development of antlers in female caribou, and the relationship between body mass and antler size in the Cervidae.