Mario Herz Fig. 19.
Mario Herz Fig. 19. Juvenile Aldabrachelys gigantea in an outdoor pen: if enough feeder plants are cultivated, the animals will for some part cover their dietary needs all on their own. 12 RADIATA 22 (4), 2013
Aldabra Giant Tortoise, Aldabrachelys gigantea gigantea years. Coe et al. (1979) quantified the dry food mass as amounting to 380 g during the rainy season and 110 g during the dry season for specimens of 20–30 kg in body weight living in the wild. In Prague Zoo, adult giant tortoises are fed daily with hay mixed with 1.5 kg of germinated barley per specimen. They furthermore receive 500 g of vegetable matter per specimen twice a week (Velensky et al. 2006). Juveniles of the Galápagos Giant Tortoise kept in Zurich Zoo are fed a det that is composed for 90 % of hay and only for 10 % of herbs (Furrer 2006). According to Gisler (2003), the digestion rates of the food with regard to the raw protein content are about 63 % and ca. 55 % for raw fibres in Galápagos Giant Tortoises. The digestibility of raw protein is important for juveniles during their growth phase, whereas too much or too protein-rich food will compromise the health of adults. While water was available at all times during the first three years of raising, the giant tortoises in my care have been given water only occasionally both in their indoor and outdoor quarters since their fourth year of life. They exploit rains for drinking, however: To this end they will lift the posterior part of the body on stiffened hind legs to let rainwater run forward down the dorsal shell towards the head from where it will drip down on the ground, accumulate in front of it, and form a puddle to drink from. Heavy rains are used by the tortoises to dig out wallows in the soaked and therefore soft ground. They will then lie in the mud until the sun has dried out the wallows once more. If temperatures are low, I will intervene and put a stop to this occupation to prevent them from contracting colds. Right from the beginning I thought that feeding them calcium in the shape of cuttlefish shell was important: For one, to facilitate the hardening of the shell, and for the other, to ensure an adequate calcium supply for their rapid growth. Ebersbach (2001) recommended paying attention to maintaining a calcium/ phosphorus (Ca:P) ratio of 3–4:1 in their diet. In Zurich Zoo, however, juvenile Galápagos Giant Tortoises receive food at a Ca:P ratio of 14:1 (Furrer 2007)! Figs. 20. Juveniles in their outdoor enclosure. Figs. 21. Juveniles in their outdoor enclosure. Fig. 22. Willow makes a favourite food for giant tortoises. RADIATA 22 (4), 2013 13
