Effect of starch and fiber on the energy metabolism and growth of red-footed tortoise (Chelonoidis carbonaria)

Abstract

There is very little information on nutrient requirements and captive management of red-footed tortoise for its conservation. Carapace malformations is a major problem seen in many zoos and zoo farms around the world. The objective of the present study is to determine the effect of two feeds, one with high fiber content and another one with high starch content, on the energy metabolism, nutrients digestibility and growth of the red-footed tortoise (Chelonoidis carbonaria). The effect of food composition on energy metabolism will be additionally studied in two ambient temperatures. The study will follow a completely randomized design, with at least 14 newly hatched tortoises, randomly divided into two experimental diets, at least 7 animals per diet. The diets will be similar to each other about the ingredients and chemical composition, except for, one will have high crude fiber content and the other one less fiber and more starch. The study will last 18 months, during which period the tortoises will receive only their respective experimental diet ad libitum and water. Evaluations of the animals will include: determination of nutrients apparent digestibility and gastrointestinal transit time at 5 and 13 months-old; determination of the resting metabolic rate, caloric increment and postprandial period in respirometry chambers and under two temperatures at 6 and 12 months-old; determination of the growth curve and carapace characteristics, with special attention to pyramid formation; determination of body composition by dual energy X-ray absorptiometry (DXA) at 6, 12 and 18 months-old. Measurements of the resting metabolic rate and caloric increment will be performed individually in respirometry chambers, after 5 days fasting. A basal metabolic rate measurement will be performed for 2 days; the animals will be fed for the postprandial heat production measurement. These measures will be carried out under environmental conditions of species preference (27 ° C) and low temperature (21 ° C). The nutrient digestibility will be determined by means of the feces total collection method and the gastrointestinal transit time by the indicator method, with iron oxide. The growth of the animals will be evaluated by weigh of the body mass and several parameters of the carapace. Body composition, especially for bone mineral content, will be evaluated using DXA. (AU)