Dietary Lysine: Calorie Ratios and Their Influence on Nitrogen Metabolism and Digestibility in Moderately Obese Mature Dogs

Reeder Reeder

doi:10.3844/ajavsp.2011.45.54

Abstract

Problem statement: A goal during weight loss is to reduce body fat while maintaining body protein. We hypothesized that an increased dietary lysine: calorie might be beneficial during periods of caloric restriction. Approach: Two experiments were conducted to determine if changing the ratio of lysine: calories (lysine g/kg: Mcal ME/kg) while maintaining an ideal profile of amino acids will change nitrogen metabolism and weight loss in obese mature dogs. Results: The results of these experiments imply that if all essential amino acids are in adequate supply in the food, foods with an optimal balance of nutrients can reduce muscle degradation during periods of caloric restriction. Conclusion: Our optimum food for decreasing protein degradation was the food containing 3.0 lysine: calorie. However, the present experiments were relatively short and these results may not be sustained over longer periods of restriction.

Highlights

Nutritional formulation of foods based on essential and non-essential amino acid concentrations instead of total protein is standard for most species
We hypothesized that an increased lysine: calorie in the dry canine food might be beneficial during periods of caloric restriction
We proposed that by varying dietary lysine: calorie in mature overweight dogs, differences in nitrogen and protein metabolism might be detected

Summary

Introduction

Nutritional formulation of foods based on essential and non-essential amino acid concentrations instead of total protein is standard for most species. Lysine is often the essential amino acid found in lowest proportion to the animal’s requirement and is often considered the first limiting amino acid Because of this lysine is the primary essential amino acid to which all other dietary amino acids are compared when formulating foods. We hypothesized that an increased lysine: calorie in the dry canine food might be beneficial during periods of caloric restriction. The present studies were designed to determine how altering lysine: calorie of canine foods impact nitrogen and protein metabolism during periods of caloric restriction. This concept was investigated by two means; (1) while maintaining an ideal profile of amino acids (Baker and Czarnecki, 1991) and (2) by increasing only lysine while maintaining isonitrogenous intakes

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