Meeting Abstract

58.4  Jan. 6  Lactating hares are limited by the capacity of the alimentary tract VALENCAK, T.G.**; RUF, T.; Veterinary Univ. Vienna; Veterinary Univ. Vienna Teresa.valencak@vu-wien.ac.at

Traditionally, animals were considered to be mainly limited by food availability in their environment. However, studies on mammals and birds over the past two decades have clearly demonstrated that, even when food is abundant, animals may encounter endogenous physiological limitations of energy turnover during periods of high nutrient demands, such as lactation. It is still not fully understood whether these metabolic constraints are imposed �peripherally�, by the capacity of energy expending organs (skeletal muscles, mammary glands) or �centrally�, by the capacity of the alimentary tract. We investigated sustainable energy turnover in a herbivorous mammal, the European brown hare to address the question of central vs. peripheral limitation during lactation in this species. During lactation, our experimental animals were fed two diets of different energy content. We found that lactating females were unable to fully compensate for a low energy content of their diet by increasing their food intake and/or gastrointestinal tract. Specifically, time courses of food intake, assimilated energy, and milk transfer to young were significantly different between the two feeding groups. We conclude that, limits to energy turnover may have different reasons in different mammalian species, and central limits may play an important role for herbivorous animals, such as hares. This study was funded by the Austrian Science Fund (P17794-B06).