Improvement in Subclinical Mastitic Milk Detection Methods PDF

Keywords

Mastitis, NAG-ase, SCC, milk, transparization

Abstract

Subclinical mastitic milk presents a composition sensitively different from normal milk which could be reflected in milk products. Among the diagnostic methods of subclinical mastitic milk proposed, the enzymatic method (NAG-ase determination) and somatic cell count (SCC) are the most utilized. According to several authors, NAG-ase determination could be considered as one of the best to detect mastitic milk. We present here a method for the determination of NAG-ase (N-Acetyl-B-D- glucosaminidase) activity in cow's milk. The analysis procedure was derived from that of Kitchen and Middleton (1976), where the precipitation, centrifugation and filtration steps were replaced by the transparization technique. A dissolving reagent was used at the end of the enzymatic reaction which rendered the medium transparent and thus could be directly read by spectrometer. The reproducibility of the procedure was satisfactory and good correlations with a fluorimetric enzymatic method and somatic cell count were observed. Our results show that it is possible to classify milk according to its degree of infection while being based only on the activity of NAG-ase