Mule deer are Ruminants, meaning they employ a nutrient acquisition strategy of fermenting plant material before digesting it. Deer consuming high-fiber, low-starch diets require less food than those consuming high-starch, low-fiber diets. Rumination time also increases when deer consume high-fiber, low-starch diets which allows for increased nutrient acquisition due to greater length of fermentation[1]. Because some of the subspecies of mule deer are migratory, they encounter variable habitats and forage quality throughout the year (deCalesta). Forages consumed in the summer are higher in digestible components (i.e. proteins, starches, sugars, and hemicellulose) than those consumed in the winter. The average gross energy content of the consumed forage material is 4.5 kcal/g (Wallmo). Due to fluctuations in forage quality and availability, mule deer fat storage varies throughout the year, with the most fat stored in October, which is depleted throughout the winter to the lowest levels of fat storage in March (Bergman). Changes in hormone levels are indications of physiological adjustments to the changes in the habitat(Wallmo). Total body fat is a measure of the individual’s energy reserves while thyroid hormone concentrations are a metric to determine the deer’s ability to utilize the fat reserves. Triiodothryionine (T3) hormone is directly involved with basal metabolic rate and thermoregulation.
- ^ Mccusker, S (2011). "Effects of starch and fibre in pelleted diets on nutritional status of mule deer (odocoileus hemionus) fawns". Journal of Animal Nutrition.