Dietary protein supplementation and its consequences for intake, digestion, and physical activity of a carnivorous marsupial, Sminthopsis crassicaudata.

Lihong Yuan,Stephen J Simpson,Bronwyn M Mcallan,Shawn Wilder,David Raubenheimer,Michelle Shaw

doi:10.1002/ece3.3843

Abstract

Diet regulation behavior can mediate the consequences of imbalanced diets for animal well‐being, particularly for captive species that have little dietary choice. Dasyurids (carnivorous marsupials) are of conservation concern in Australia, and many species are in captive breeding programmes. However, their nutrient targets and dietary regulation behaviors are poorly understood, a limitation that may decrease the breeding success and well‐being of captive animals. We tested how dietary protein content influenced the intake and utilization of nutrients, physical activity, and body mass of fat‐tailed dunnarts Sminthopsis crassicaudata. Twelve adult dunnarts from six sibling pairs (one female and one male per pair) were provided ad libitum access to three diets in a repeated measures design: cat food, cat food supplemented with raw lean beef (1:1), and cat food supplemented with cooked lean beef (1:1). Food intake, activity level, and fecal output were measured daily. Dunnarts significantly decreased food intake, increased protein digestion, and physical activity, but body mass was unchanged when on the high‐protein diet compared to the normal cat food diet. These observations suggest a capacity of dunnarts to maintain constant body mass using a dynamic balance of feeding, digestion, and activity. We also found a significant effect of family, with differences between families as large as the difference between the diet treatments, suggesting a genetic component to diet selection. The nutrient regulation responses of dunnarts to high‐protein diets and the strong family effects provide important messages for the management of populations of small carnivores, including the aspects of dietary manipulation and conservation of genetic diversity.

Highlights

Dietary nutrient balance has been shown to strongly influence many life history traits of animals, including growth, reproduction, and lifespan (Koch, Ganzhorn, Rothman, Chapman, & Fichtel, 2017; López-Alfaro, Coogan, Robbins, Fortin, & Nielsen, 2015; Simpson & Raubenheimer, 2012)
Treatment, sex, and family had no significant effects on the change in body mass comparing cat food versus high- protein diets (Table 1)
Our results show that dietary protein supplementation had significant effects on the food intake, fecal production, and activity level of fat-tailed dunnarts

Summary

| INTRODUCTION

Dietary nutrient balance has been shown to strongly influence many life history traits of animals, including growth, reproduction, and lifespan (Koch, Ganzhorn, Rothman, Chapman, & Fichtel, 2017; López-Alfaro, Coogan, Robbins, Fortin, & Nielsen, 2015; Simpson & Raubenheimer, 2012). Recent examination of the diets of wild animals has demonstrated that they will modify seasonal intake of available foods or modify activity to accommodate nutrient shortcomings (Coogan, Raubenheimer, Stenhouse, & Nielsen, 2014; Irwin et al, 2014; Nie et al, 2015; Rothman, Raubenheimer, & Chapman, 2011). There is little analysis of nutrient content and selected preferences based on nutritional optimization in carnivores, circumstantial evidence suggests that in the wild carnivores do feed by selecting different food items to balance their macronutrient intake (Kohl et al, 2015). Our aims were to determine whether dunnarts preferred high-protein diets over the control diets and whether the extra protein in the diet affected behavioral outcomes These outcomes have important implications for the management of captive carnivores. Does this extend the integrated processing response paradigm to predators, but it builds on that paradigm through applying it to a species with discrete nutrient selection, energy storage, energy conservation, and energy expenditure mechanisms

| MATERIALS AND METHODS

Findings

| DISCUSSION