Milk of northern fur seal: composition, especially carbohydrate and protein

The milk of northern fur seal was analyzed with special interest in carbohydrate and protein. High solids (61%) and fat (45.6%) were characteristics of its gross composition. Fatty acid distribution showed that more than 22% of the fatty acids had carbon chains longer than 20 and that approximately 70% contained one or more double bonds. Analysis of free sugars showed no lactose but 123 mg/100 ml of myo-inositol. In carbohydrates bound to casein, .99% of sialic acid and .2% of glucosamine were determined. The amino acid composition of casein showed higher tryptophan, lysine, serine, and glycine than bovine casein, and lower arginine, proline, and leucine. In whey, arginine, threonine, and valine were higher, whereas lysine, aspartic acid, isoleucine, and leucine were lower than in bovine whey. Amino acid patterns in casein and whey were similar to those of cat milk. The appearance of casein micelles was similar to bovine casein micelles. The mean diameter, however, was larger (approximately 330 nm). Electrophoretic pattern of casein showed five major bands in addition to minor components. One of the minor components was a glycoprotein, probably kappa-casein-like protein. The major whey protein had a mobility similar to that of bovine beta-lactoglobulin. No alpha-lactalbumin-like protein was observed.