Sea otter milk is composed of 62% water and 38% solids. On average, the solids are composed of 31% protein, 65% fat, 2.5% carbohydrate, and 1.5% ash (Jenness et a1., 1981). Although it is not practical to duplicate the composition of sea otter milk in the rehabilitation center, the following formula has been used successfully to raise sea otter pups at the Monterey Bay Aquarium:
113.5 g (0.25 lbs) white meat of squid (Loligo spp.)
113.5 g (0.25 lbs) manila clam meat (Tapes spp.)
100 m1 (3.33 oz) 5% dextrose
200 m1 (6.33 oz) lactated Ringer’s solution
2 m1 (0.4 tsp) Hi-Vite(TM) drops
5 m1 (1 tsp) cod liver oil
5 m1 (1 tsp) D-Ca-Fos(TM)
Blend the ingredients for two to three minutes, then add 200 m1 (6.33 oz.) half-and-half (or whipping cream if greater caloric content is needed) and continue blending for one minute; avoid over blending or the mixture will clot. Keep the formula refrigerated and discard unused portions after twenty-four hours. If 5% dextrose and lactated Ringer’s solution are unavailable, substitute 300 ml Pedialyte(TM). Diarrhea can develop in pups placed on a formula diet. During the Exxon Valdez oil spill (EVOS), Kellogg’s All Bran (TM) cereal (28.3 gm) was added to the formula to mitigate this problem (Styers and McCormick, 1990). However, the cause of the diarrhea should be investigated before changing the formula. Eliminating stress often can mitigate this problem. Pups may refuse formula if the ingredients are suddenly altered. Pups less than one month old should be formula fed every two hours and receive 30% of their body weight daily. The formula should be warmed to 38 oC using warm tap water or a double boiler. Pups are sensitive to the temperature of the formula and may reject the bottle if it is too cool. Bottle feeding is relatively new and the preferred method for sea otter pups. Although syringe and tube feeding also work, they do not allow the pup to suckle. The only nipples that have been accepted by sea otter pups are manufactured by Wombaroo Food Products (Brisbane, Australia). Type LD and SD nipples, which are designed for small dogs, cats, and opossums, work best. The nipple is inserted carefully into the pup’s mouth and held in place until suckling is initiated. Several days may be necessary to habituate the pup to this method of feeding. If bottle feeding fails, the formula can be gently injected into the pup’s mouth with a syringe. Alternatively, pups can be fed through a stomach tube. This method ensures that the pup receives 30% of its body weight per day in formula, and prevents the fur from becoming soiled with formula leaking from the mouth. However, tube feeding can be dangerous if the pup accidentally aspirates formula. Only animal handlers experienced in tube feeding should attempt this method. When used properly, tube feeding is an acceptable alternative to bottle and syringe feeding.
Small pieces of local prey items (i.e. rockcod, Sebastes spp.; blackcod fillets, Peprilus spp.; and geoduck clams, Panope spp. for Alaskan sea otters) should be offered after the formula feeding beginning at the age of one month. The amount of solid food should be increased and the amount of formula decreased until the pup is weaned at the age three months. All solid food should be kept chilled and unused portions discarded after each feeding.
After weaning, all hand feeding should be eliminated. Food should be placed in the pen or pool every three hours to ensure that the pup eats 30% of its body weight daily. The diet should include a mixture of one-half whole food items such as rock crabs (Cancer spp.), mussels (Mytilus spp.), manila clams (Tapes spp.), cherry clams (Venus spp.), and one-half prepared foods (shells,carapace, and pens removed) such as geoduck clam (Panope spp.), squid (Loligo spp.), rockcod (Sebastes spp.), blackcod (Peprilus spp.), shrimp (Peneaus spp.), and abalone trimmings (Haliotis spp.). Pollock and scallops also have been used. All food debris and particles must be cleaned off the fur by bathing the pup in seawater.
The rate of weight gain in sea otter pups will vary between individuals, but on average, pups gain 0.6 kg every eight days. However, there seems to be a plateau in the 10 kg range when weight gain may slow. For some pups, this plateau may last for a month. Around this age, pups may experience teething problems that cause painful gums and decreased interest in food. Pups should be weighed when they arrive at the rehabilitation center, daily while in the nursery, and weekly when housed in outdoor pools.
