Comparative analyses of tooth wear in free-ranging and captive wild equids.

REASONS FOR PERFORMING STUDY: Captive breeding has played a crucial role in the conservation of threatened equid species. Grazing ruminants and rhinoceros in captivity have less abrasion-dominated tooth wear than their free-ranging conspecifics, with potential negative consequences for their health. However, a similar study on wild equids in captivity is missing. OBJECTIVES: The aim was to establish if different tooth wear patterns are exhibited by free-ranging and captive equids. STUDY DESIGN: Cross-sectional study of museum specimens comparing free-ranging and captive equids. METHODS: Dental casts of maxillary cheek teeth of 228 museum specimens (122 from free-ranging and 106 from captive individuals) of 7 wild equid species were analysed using the extended mesowear method. Although teeth showing specific abnormalities were not scored, the presence of focal overgrowths (hooks) of the rostral premolars (106, 206) was recorded. RESULTS: Captive Equus ferus przewalskii, E. grevyi, E. hemionus, E. quagga boehmi and E. zebra hartmannae have less abrasion-dominated tooth wear on their premolars than their free-ranging conspecifics (P<0.001). Fewer differences were exhibited between populations in the molars. No differences were exhibited in the distal cusp of the molars (110, 210) between populations, except in a small sample of E. kiang. Captive equids exhibited more homogeneous wear along the tooth row whereas free-ranging equids exhibited a tooth wear gradient, with more abrasion on premolars than molars. There were more rostral hooks on the premolars (106, 206) in the captive than the free-ranging population (P = 0.02). CONCLUSIONS: Captive equids did experience less abrasion-dominated tooth wear than their free-ranging conspecifics, but the differences in tooth wear were less pronounced than those between captive and free-ranging wild ruminant and rhinoceros species. This indicates that feeding regimes for captive equids deviate less from natural diets than those for captive ruminants and rhinoceros but that factors leading to hook formation, in particular feeding height, should receive special attention. The Summary is available in Chinese - see Supporting information.

Gastrointestinal morphology of the crowned lemur (Eulemur coronatus).

I provide measurements of the gastrointestinal tract of a captive female Eulemur coronatus, obtained at necropsy, and describe its morphology. The small intestine, caecum and colon were short when compared with those of other lemur species. The ratio of intestine length to body length was low. Distinct sacculations were present in the caecum, but not in the colon. The results suggest that E. coronatus is able to digest a certain amount of structural polysaccharides as contained in plant cell wall. The main fermentation chamber seems to be the caecum. Its digestive morphology implies that E. coronatus relies on a diet higher in energy-rich cell contents than those of other lemur species of similar body size.