Abstract
The discrepancy in fatty acid (FA) status between a “natural” and a “civilized” environment, recognized as a major dietary phenomenon of clinical relevance in humans, was historically first described in the comparison of free-ranging and captive wild animals (CRAWFORD 1968). Compared to their free-ranging counterparts, captive specimens seemed to have a lower polyunsaturated FA (PUFA) status, and in particular a lower omega(n)3/n6 PUFA ratio. However, a comprehensive evaluation of the available data on free-ranging and captive wild animals was missing so far. We collated data on the FA status of free-ranging and captive wild animals, comparing only data for the same body tissues and lipid fractions. In general, zoo-kept wild animals had a lower n3/n6 PUFA status; in particular, birds and mammalian herbivore species for which data were available consistently showed lower proportions of n3 PUFA and total PUFA in captivity. In zoo animals, this discrepancy has been repeatedly suspected to contribute to clinical problems, although conclusive studies are lacking. Should an adjustment of the FA status in captivity to the one in the wild be an objective in the dietary management of zoo animals, several strategies could be adopted: the feeding of horse or rabbit instead of ruminant meat; the use of food insects that are raised on green produce instead of grain products; the feeding of marine non-vertebrates such as shrimp or squid to animals specialized on these items but conventionally fed fish. In particular, a higher proportion of forage in general, the use of fresh or ensilaged forage instead of hay, a reduction of the use of grain-based concentrates, and an increased use of forage products (grass or lucerne meal) and linseed products in pelleted feeds, are measures that have been demonstrated in domestic herbivores to increase the n3/n6 PUFA status.
Clauss, Marcus