Comparative use of four different marker systems for the estimation of digestibility and low food intake in a group of captive giraffes (Giraffa camelopardalis)

In a feeding trial with four captive giraffes, nutrient digestibility was d eter-mined using four different marker systems. Although cobalt-ethylenedia minetetraacetic acid proved to have no utility as a digestibility marker in this study, reasonable values could be obtained using C-36 n-alkane, acid detergent lignin, and acid insoluble ash as markers. A comparison of method s and literature data suggests that the values derived from the C36 n-alkan e assay are the most reliable absolute values. Apparent digestibility range s thus determined were 63.5-74.3% for dry matter, 73.4-82.4% for crude prot ein, 49.9-62.2% for neutral detergent fiber, and 49.7-63.7% for acid deterg ent fiber. However, digestibility data gained by the ADL method provided th e most stringent inter-individual comparisons. It is concluded that both al kanes and lignin can be used for giraffe digestibility studies. These capti ve giraffes ingested a smaller quantity of food than has been reported for other giraffes from both the wild and other zoos. Energetic calculations sh owed that these animals might be on the brink of an energy deficit. A simil ar situation has been described at least once before in captive giraffes, a nd the results are of direct relevance to the peracute mortality syndrome, a condition of captive giraffes in which severe depletion of body fat store s occurs. Reasons for the seemingly low food intake could not be elucidated , but observations suggested that these giraffes were ready to ingest more if more palatable or suitable food was offered. Monitoring food intake in o ther giraffe groups and designing a diet that is both palatable and nutriti ous are important objectives of captive giraffe management. Zoo Biol 20:315 -329, 2001. (C) 2001 Wiley-Liss, Inc.