Near Infrared Spectroscopy Using Short Wavelengths and Leave-One-Cow-Out Cross-Validation for Quantification of Somatic Cells in Milk

Abstract

A short wavelength near infrared (NIR) analysis method for somatic cell count (SCC) determination in unhomogenised raw milk was developed. NIR spectra (700–1100nm) of unhomogenised milk samples from 14 cows during days 7 to 36 of their lactation were measured for two consecutive years. Measurements from animals with different physiological conditions (healthy and mastitic)were included. A “leave-one-cow-out” cross-validation partial least square (PLS) regression model for SCC in the raw milk was developed. Good correlation ( R2=0.76) was observed between estimated and reference SCC levels in milk samples when the differential spectra and SCC reference values were used for developing the PLS model. The NIR estimation achieved a standard error of 0.3 LogSCC. The results were well within the range needed for real-time monitoring of milk on a daily basis. Thus, the NIR method may prove to be a valuable tool for monitoring somatic cells in routine milk samples analysed for dairy cow health management.