An attempt to detect oestrus from changes in Fourier transform infrared spectra of milk from dairy heifers

This study was carried out to investigate if there were systematic changes in milk Fourier transform infrared (FT-IR) spectra relative to stage of the oestrous cycle in cattle. Oestrous cycles of 22 lactating heifers were syn chronized with two injections of prostaglandin F2 alpha (PGF) administered 11 days apart. The heifers were milked twice daily, and milk samples were c ollected from each heifer at each milking for a period of 70 days, starting on the day of the second PGF injection. Oestrus was diagnosed by visual de tection in conjunction with monitoring rectal temperature. Milk samples wer e analyzed by FT-IR spectroscopy and the spectra data were analyzed using p artial least squares (PLS) methods in relation to time of observed oestrus in heifers. In this investigation, it was not possible to identify reliable changes in milk FT-IR spectra in relation to oestrus on a single heifer ba sis, though there was a weak correlation between FT IR spectra and expected time of oestrus when the analysis was carried out across all the heifers. (C) 2001 Elsevier Science B.V. All rights reserved.