Identification of possible nutritional and stress risk factors in the development of marmoset wasting syndrome.

Marmoset wasting syndrome (MWS) describes a series of symptoms in callitrichids that lead to general weakness and a failure to thrive in captive conditions such as zoological institutions. Though the cause of MWS has not been identified, the majority of hypotheses are linked to deficiencies of specific nutrients and increased stress levels. Questionnaires were sent to zoos requesting information on diets and housing of currently living and dead callitrichids before their deaths, as well as their postmortem reports. Risk factors for development and occurrence of MWS include close proximity of predator enclosures and high levels of dietary magnesium and zinc. Variables with effects which may protect against the development of MWS included provision of a nest box, natural trees within enclosure, reduced visibility to visitors, as well as dietary factors such as higher concentrations of potassium and fiber fractions. The protective effects of limited concentrate feeds and increased total dietary fiber may help reduce the risks of developing MWS. The minerals may not have biological implications in MWS per se, however, they may be reflective of diets too high in concentrates and too low in plant matter. Habitat designs that are less naturalistic and those which provide insufficient privacy or hide areas may increase chronic stress for callitrichid species, possibly because of visitor-related stress. Other causes of chronic stress in captive zoo populations should be the topic of further research to reduce occurrence of MWS.