Calcium (Ca) and phosphorus (P) are very important minerals in reptile nutrition, but many diets still are not balanced. To achieve optimal growth, including a healthy skeleton and a strong shell, a well-balanced supply with these minerals is prerequisite. The purpose of this study was to evaluate the digestibility of diets with different calcium levels, with special emphasis on the digestibility of minerals. Fourteen captive-born juvenile Galapagos giant tortoises of the Zurich and Rotterdam Zoos were used. The animals were housed indoors at a mean temperature of 23°C and 25°C, and at 65% and 60% humidity, respectively. The animals from the same zoo were fed the same diet, which consisted of vegetables, herbs, and a mixture of different Ca sources. Daily mixed fecal samples of all tortoises were collected from day 8 to day 18. A Weender analysis was performed and the HCl-insoluble ash was used as an indigestible indicator (marker) for the determination of the apparent digestibility. The Ca content of the mixed feedstuffs of diet I was 1.43% on a dry matter basis, and the Ca:P ratio in the food was 3.9:1. In diet II, the Ca content was 2.06% on a dry matter basis, and the Ca:P ratio in the food was 4.8:1. Diet III contained 7.33% of Ca on a dry matter basis, and the Ca:P ratio in the food was 6.7:1. The digestibility of Ca in diet I was 42%. The other examined minerals, Mg and P, had a digestibility of 54% and 84%, respectively. In diet II, the digestibility of Ca was 63%, of Mg 76%, and of P 88%, and in diet III the digestibility of Ca was 82%, of Mg 92%, and of P 91%. The results of this study indicated that higher Ca concentra- tions in the diet led to an increased apparent digestibility of Ca, Mg, and P. The influence of an increased fat and decreased fiber content in diet III concerning digestibility is discussed.
A high intake of easily fermentable carbohydrates and a low intake of fiber material are generally regarded as major factors affecting the health of captive langurs. The effect on fecal consistency of excluding fruits and vegetables from the diet was evaluated in Javan langurs (Trachypithecus auratus auratus). Cross-over trials were carried out at Rotterdam Zoo and at the Apenheul Zoo, The Netherlands. During the first and third dietary period, the langurs were fed their usual diet, which contained fruits, vegetables, langur pellets, and browse. During the second period, the vegetables and fruits were excluded from the diet and the diet essentially consisted of pellets and browse. Feces consistency was scored using a fecal score chart developed for langurs. During the second feeding period the feces consistency improved significantly in animals at both zoos. Across all trials, a firmer feces consistency was correlated with an increase in dietary cell wall (measured as neutral detergent fiber) and a decrease in dietary water. It is suggested that the combined decrease in the intake of soluble sugars, the increase of fiber intake, and a lower amount of dietary water in the diet resulted in more solid stools. The results indicate that a dietary neutral detergent fiber content of approximately 46% in dry matter will result in a feces consistency indicative of undisturbed gut function.
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