Effects of age, gut fill, and sex on dressed mass - whole mass relationships of white-tailed deer
Hunters and management agencies are often interested in whole mass of harvested whitetailed deer (Odocoileus virginianus) but measuring whole mass in the field is challenging, which is why hunters often dress deer. Dressed mass consists of the carcass mass minus organs in the abdominal, thoracic, pelvic cavities as well as any blood loss. Dressed mass is strongly related to whole mass but covariates of site where deer was harvested, age, sex, body fat, and lactation state of females might also improve predicting whole mass. Also, gut fill variation should help explain why some covariates are influential. Using data from three different sites, which contained deer of various ages, sexes, and lactation states of females, I analyzed the effects of site, age, sex, body fat, lactation state of females, and gut fill on relationships between dressed mass and whole mass (n = 432). Rumen-reticulum fill served as my surrogate of gut fill because these compartments comprise 50 – 70 percent of gut capacity. I analyzed linear regression models and compared them for fit and parsimony with a Bayesian Information Criterion model selection analysis. The selected model had statistically significant predictors of dressed mass, age, sex, lactation status of females, and site. Gut fill also influenced dressed mass – whole mass relationships. Variation in gut fill across sites and due to age, sex, and lactation status of females was consistent with effects of these covariates on dressed mass – whole mass relationships. Lastly, I standardized variables in the selected model to have a mean of zero and standard deviation of one to assess the extent of influence of dressed mass and covariates on whole mass. Dressed mass had a much larger influence on whole mass than covariates. Although site, age, sex, and lactation status of females are influential, the improvement in predicting whole mass is slight. First and foremost, to accurately predict the whole mass of small to large deer requires measuring animals that range widely in dressed body mass.
dressed mass, white-tailed deer
Maldonado, J. (2023). Effects of age, gut fill, and sex on dressed mass - whole mass relationships of white-tailed deer (Unpublished thesis). Texas State University, San Marcos, Texas.