Yellow snow and red deer: Do urinary metabolites reflect anthropogenic influences?

Abstract

:The effects of nutritional restriction on protein metabolism in non-supplemented alpine red deer (Cervus elaphus hippelaphus) were monitored during winter by snow-urine analysis. Forage was barely restricted in availability, but of low quality. Urinary urea:creatinine ratios (U:C) suggested that in non-supplemented red deer endogenous protein reserves were progressively depleted during the course of the winter and that the animals catabolized body protein to meet N demands already in early winter. However, potassium:creatinine ratios (K:C) reflected that the animals presumably satisfied energy demands by increasing intake. In a supplemented herd studied in comparison, urinary metabolites showed the same seasonal trend, despite constant and unlimited feed supply. Red deer are known to decrease activity, metabolic rate and voluntary feed intake in November or December as an adaptation to reduced forage quality and availability. However, U:C ratios, as an index of protein metabolism, showed a significant decline only in late January in both herds. Intensive hunting pressure may have caused energetically costly predator-avoidance strategies thus extending the period of tissue protein catabolism in non-supplemented red deer and the period of high feed protein intake in supplemented red deer.