HUSBANDRY

2.1 Housing

Dugongs are rare in managed care and at the time of writ­ing there were only four globally, with a male in Australia; this animal was an unreleasable rescue. Injured, diseased or orphaned dugongs are occasionally rescued and may require managed care.

There are no specific standards or guidelines for hous­ing and managed care of dugongs. However, some funda­mental requirements are important to ensure their health and welfare. Mature males may be aggressive towards females, particularly those in oestrus. It is important to have the ability to separate sexes to avoid injury to females from the male’s tusks. Equally important is physical sepa­ration of males and females to prevent breeding, as there are no proven means of either surgical or chemical con­traception in this species.

2.2 Nutrition

Dugongs feed almost exclusively on several tropical and temperate seagrasses. Managed care diets include seagrass (if available), cos lettuce, snow pea sprouts, cabbage, endive, wheat grass and spinach. Sourcing seagrass is time-consuming and requires a permit for collection in certain jurisdictions. Cos lettuce has been the predomi­nant diet in Australian facilities. Adult dugongs may con­sume up to 30 kg/d, making feeding time-consuming and costly (Walsh and Blyde 2017). Dugongs only feed from the seabed and this must be mimicked in managed care by anchoring the food into trays that can be lowered to the floor of tanks (Fig. 47.1). Additionally, they are notoriously inefficient eaters, wasting a great deal of what is fed.

Dugongs being fed cos lettuce alone suffer microcytic, hypochromic non-regenerative anaemia. This appears to be responsive to parenteral vitamin and mineral supple-

Fig. 47.1.

Fig. 47.2. A dugong (Dugong dugon) calf being bottle-fed.

mentation (Hemoplex, Troy Laboratories, Glendenning, NSW), administered via projectile dart q 3 mo, suggest­ing cos lettuce is deficient in some essential vitamins and/ or minerals. Dugongs housed in managed care have not lived as long as their wild counterparts (up 70 yr), dying at ages less than 20 yr. Many of these animals have not thrived and have remained in poor body condition. Necropsies have revealed conditions that may be associ­ated with inadequate nutrition. These conditions include excessive teeth wear, goitre, metastatic calcification and mild hyperplastic enterocolitis (Blyde 2023).

2.3 Hand-rearing

Rescued dugongs less than 1.5 m in length are likely to be milk dependent (Marsh 1997). Neonatal dugongs have been hand-reared on the milk formula Di-Vetelact (Nutri­tional Laboratories, St Ives Chase, NSW) with added Calogen (N.V. Nutricia, Zoelemeer, The Netherlands), a high-energy, long-chain triglyceride fat emulsion (W Blanshard pers. comm.). They can be bottle-fed and gen­erally nurse better while being cradled upside down in water (Fig. 47.2). Initially, if the neonate is not suckling well, they can be fed via a 12-16 Fr orogastric feeding tube. Volumes for tube feeding should be approximately 15-20 ml/kg bodyweight. Hand-rearing is extremely labour intensive and prolonged (up to 9 mo) until weaned. haematological and biochemical variables are poorly understood and extrapolation from the Florida manatee when interpreting results may be appropriate.

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