Ruminant-specific molecular and systemic adaptation of renal electrolyte handling to low N intake

For economical and ecological reasons precise protein rationing is essential in the nutrition of ruminant livestock. This dietary adjustment should consider the endogenous capacity to recycle urea-N for maintaining rumen microbial protein synthesis. However, results of our previous study showed that despite urea recycling, dietary intake of a low N diet affected not only N metabolism but also systemic and renal molecular electrolyte handling in growing male Saanen-type goats (Starke et al., unpublished data). We hypothesized that these changes were also reflected by changes in electrolyte excretion in vivo. Therefore, the main objective of the present study was to evaluate the impact of adaptive changes due to low crude protein (LCP) intake on electrolyte handling and excretion in vivo in growing goats. To examine whether this adaptation is ruminant-specific, a similar experiment was conducted on growing rats consuming a LCP diet in consideration of the specific differences in nutrition, digestive physiology and metabolism of rats and goats.