In May of 1994, Marine World Africa USA and New York's Aquarium for Wildlife Conservation successfully recovered seven orphaned walrus calves (Odobenus rosmarus divergers) from the Alaskan waters of the Bering Sea during the annual spring migration. Three animals (1.2) were transported to the New York facility and four (1.3) to Marine World in Vallejo, CA. The Marine World animals have adapted extremely well to their new environment and have had no significant health problems during this first year. The calves are very strong and active, their body weights have increased an average of more than 300% in the first 10 months, and their blood parameters are consistently within normal ranges. Factors that appear to be most significant to the animals' desirable state of health and well-being include facility design and maintenance, social and psychological management, staff training and involvement, and a well planned program of preventative veterinary care. Probably the single most important factor, however, has been nutritional management.

For the first 24-48 hrs only clear fluids (powdered electrolytes and water) were administered via stomach tube. A blended formula of Multi-milk and water (in a volume ratio of 1:2), cod liver oil, vitamins, minerals, and taurine was then utilized. Various types, sizes, and shapes of human and animal baby bottles and nipples were offered with results varying with each individual calf. After several days the animals began to accept water and then formula from the bottles. Daily body weights, appetite and activity levels, and fecal appearance were important in determining dietary changes. Volumes and caloric density of the formula were increased slowly and in small increments so as to allow the animals sufficient time to adapt to each successive change. Caloric density was controlled primarily by varying the ratios of Multimilk to water. Due to some concern that the calves may have trouble digesting large amounts of lactose and since they were gaining weight at desirable rates, no dairy products (e.g., whipping cream) were used. After 3 months ground clam meat was added to the formula which was then followed by ground herring at 6 months.

Each formula component and food item was analyzed for fat, protein, and carbohydrate composition utilizing the best available source (e.g., product labels, supplier's laboratory analysis, or literature search). Approximate caloric values were determined by multiplying each macronutrient by its average energy coefficient (e.g., fat x 9 kcals/g, protein and carbohydrate x 4 kcals/g.

During the first ten months the gross energy values for the formula ranged between 920 and 1370 kcals/liter, fat content varied between 7.9% and 11.9%, and protein composition rose from 4.3% to 8.2%. At their peak, the calves were gaining approximately 0.5-0.7 kg of total body weight (TBW) per day and were consuming about 125 kcals/kg (TBW) per day. Caloric consumption rates (koala/kg TBW) decreased substantially after the fourth month while total body weights continued to rise at desirable rates (see Figure 1). Solid food (clams, herring, squid, and white bait) was first introduced at 8 months and within several days became an increasingly important source of nutrition. At ten months of age the calves were consuming between 5 to 6 liters of formula and 2.5 to 6.5 kg of solid food per day. Even though the animals are eating solid food very well, bottles will continue to be offered for several more months. As with all previous changes to the dietary regime, the weaning process will proceed slowly and the animals will not be completely weaned until they are about 18 months of age.

Figure 1. Pacific Walrus Calves at Marine World Africa USA: Average Total Body Weights and Daily Caloric Intake

Reference

1.  Multi-milk Animal Milk Replacer Pet-Ag, Inc., 30W432 Route 20, Elgin, Il 60120, USA.