Variation in Rumen-Reticulum Fill in White-Tailed Deer (Odocoileus Virginianus)
Aiken, Meredith R.E.
Understanding variation in rumen-reticulum fill allows us to predict how ruminants will accommodate fluctuations in food supplies and animal production demands. Studies suggest rumen-reticulum fill increases with lower quality diets (low crude protein-CP, high acid detergent fiber-ADF) and browse diets compared to pelleted diets. In male white-tailed deer rumen-reticulum fill presumably fluctuates with the demands of antler growth and access to females during the mating season, and during late gestation and lactation in females. Previous research has mainly examined the relationship between rumen-reticulum fill and body mass. It is likely, however, that there are multiple influences on rumen-reticulum fill. Herein, I examined the influences of nutrition (ADF and CP), diet type (pelleted or browse), reproductive demands (males in rut vs. males outside of rut, lactating vs. non-lactating) as well as body mass, rump fat, age, and sex on wet and dry rumen-reticulum fill. I collected white-tailed deer (122 males, 152 females) from Kerr Wildlife Management Area, Texas (pen-raised, free ranging) and a private ranch in south Texas. I built models and used Akaike Information Criteria to select competing models to understand which hypotheses explain rumen-reticulum fill dynamics. The only prediction that was not falsified was that lactating females had greater fill. In regards to nutrition, wet fill decreased, as ADF increased. This is likely because of chemostatic factors that regulate food intake and diet quality when dietary fiber is 'low'. Deer consuming a pelleted diet had greater wet and dry rumen-reticulum fill than deer consuming a browse diet. Factors driving rumen-reticulum function were complex because wet and dry rumen-reticulum fill were influenced by differing factors. My findings indicate that scaling relationships between body mass and rumen-reticulum fill were allometric. Additionally, rumen-reticulum fill is influenced by a wide variety of factors.
white-tailed deer, nutrition, rumen, gastrointestinal system
Aiken, M.R.E. (2014). Variation in rumen-reticulum fill in white-tailed deer (odocoileus virginianus) (Unpublished thesis). Texas State University, San Marcos, Texas.