Abstract: Formulated animal feeds having excellent digestibility with high energy and good protein content based on lactose-rich whey products are produced by supplementation with small quantities of water insoluble poly-N-acetyl-.beta.-D-glucosamine glycosides having a molecular weight of at least 5,000 and are fed to farm type animals. Most of the formulated feeds contain at least 7% lactose and up to 5% poly-N-acetyl-.beta.-D-glucosamine glycoside in addition to the usual protein, fat, carbohydrate, vitamin and mineral constitutents of the feed. For poultry, which are among the least efficient metabolizers of lactose, such feeds may contain 5-25% lactose.

Abstract: A process for detecting and visualizing enzymatically active xanthine oxidase which comprises first analysis by discontinuous polyarcylamide gel electrophoresis and then staining the polyacrylamide gel containing xanthine oxidase using neotetrazolium chloride.

Abstract: A milk xanthine oxidase active enzyme concentrate having an average protein to flavin ratio as measured by E.sub.280nm for protein and E.sub.450nm for flavin of 2.0 to 4.1, one symmetric peak by ion-exchange gel chromatography, and shows a single protein band by polyacrylamide disc gel electrophoresis. The xanthine oxidase is not denatured.

Abstract: Bovine milk xanthine oxidase, referred to herein as XO, is isolated and purified from raw whole milk by a streamline method without the use of proteolytic and lipolytic enzymes, butanol, or other organic solvents. Sodium salicylate, ethylenediaminetetraacetate (EDTA), and a 0.2 M phosphate buffer are added to fresh milk. After incubation at 40.degree.-45.degree. C. for 105 min., the mixture is adjusted to 1-2% with Triton X-100 and allowed to incubate for 15 min. The mixture is cooled to 4.degree. C., followed by a 2-step fractionation of the proteins with ammonium sulfate. The crude enzyme is isolated as a red-brown precipitate which is dissolved in 0.1 M Tris/CaCL.sub.2 buffer and stored for from 12 to 168 hours at -20.degree. C. The isolated enzyme is purified by column chromatography (Sephadex G-75, Sephacryl S-200, Sepharose 6B, and Sephadex G-75).