NUTRITIONAL INVESTIGATIONS AND MANAGEMENT OF CAPTIVE MOOSE

Historically, moose have been difficult to maintain in captivity when on diets of grass or legume hays and grain due to enteritis that frequ ently leads to chronic diarrhea/wasting disease. The development of wo od-fiber diets has increased the lifespan of moose in captivity, but t hese diets do not completely prevent chronic wasting. Purina Mills (St . Louis, MO) hypothesized that captive moose are unable to digest star ch that escapes the rumen, and therefore abnormal bacterial fermentati on in the hindgut causes chronic diarrhea. An earlier study found no e vidence of a digestive problem, so we tested the hypothesis that moose have difficulty metabolizing excess propionate produced from the ferm entation of starch found in traditional cervid rations and high-grain wood-fiber diets. When challenged with an i.v. propionate load, moose metabolized propionate similar to healthy mule deer and domestic lives tock. We then tested the hypothesis that grass forage is an initiating factor to chronic diarrhea/wasting and further hypothesized that gras s, alfalfa, and other agriculture-based forages in association with an anaerobic bacteria produce inflammatory bowel disease (IBD) in moose. Captive moose that had ad libitum access to a wood-fiber pelleted moo se diet and grazed in grass pastures developed chronic wasting symptom s at 2-4 years of age and died at 4.7 +/- 0.3 years unless restricted from grass before the development of advanced symptoms. We isolated Ba cteroides vulgatus in the feces and successfully treated a moose with chronic diarrhea/wasting disease with longterm metronidazole therapy, suggesting that the chronic enteritis causing wasting disease arises f rom a bacteria-associated defective immunosuppressive response similar to IBD in other species. Further support for the IBD cause of wasting in moose is that this animal will relapse within hours if the metroni dazole treatment is discontinued even after many months. We developed a highly palatable high-fiber, low-starch moose ration that can he fed as the sole source of nourishment, although additional research and d ietary improvements are required. (C) 1997 Wiley-Liss, Inc.