Enzymic methods for estimation of the somatic cell count in bovine milk: 1. Development of assay techniques and a study of their usefulness in evaluating the somatic cell content of milk

Abstract

Summary: Assay procedures were developed for a number of enzymes in milk which apparently originate from leucocytes. The enzymes studied were acid phosphatase, N-acetyl-β-D-glucosaminidase, β-glucuronidase, arylsulphatase, α-mannosidase, and catalase. Quarter-milk samples were analysed for enzyme activity and results compared with the electronic cell count and the Wisconsin Mastitis Test. All enzymes measured except acid phosphatase and α-mannosidase showed good correlation with the electronic cell count. Of the other 4 enzymes tested, β-glucuronidase and arylsulphatase were unsuitable as diagnostic aids owing to the lengthy incubation periods required in their assay procedures. The assay of catalase, which involved the measurement of the initial rate of release of O₂ using an O₂ analyser apparatus, was rapid, sensitive and reasonably reliable, if fresh milk samples were used. The assay procedure for N-acetyl-β-D-glucosaminidase was considered to be the most reliable, simple and rapid enzymic method for estimating the number of somatic cells in milk.