Body Weight and Age Influences on Liver Weight in White-Tailed Deer (Odocoileus virginianus): Implications for Reproductive Effort
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The mammalian liver is integral to homeostasis, metabolism, and reproduction. Previous research into the liver has mainly examined liver function; there have been far fewer investigations into how liver weight is coupled to body weight, age, and reproductive events like lactation. Understanding how these variables are coupled to liver weight may be useful to understanding reproductive effort as animal age. I examined the scaling relationship between body weight and liver weight and the influences of age, sex, body condition (back fat), tooth wear, and lactation on liver weight to shed insight into the reproductive effort of aging white-tailed deer. White-tailed deer (62 males, 71 females) from Kerr Wildlife Management Area, Texas, and a private ranch near Hebbronville, Texas, were measured. There was an allometric relationship between body weight and liver weight. Sex and age were predictors of liver weight at Kerr WMA and sex, back fat, and lactation were significant predictors at the private ranch. Controlling for body weight, males had heavier livers than females and age was positively related to liver weight. My findings indicate that liver weight reflects metabolic and reproductive demands and that older animals can potentially invest more effort in reproduction because of larger livers. These findings might be useful to understanding senescence and terminal investment on reproduction in older deer.