Association between days open and milk spectral data in dairy cows

Data on 19,489 Brown Swiss cows reared in northeastern Italy were used to associate absorbances of individual wavenumbers within the mid-infrared range with days open (DO). Different postcalving milk (DIM) intervals studied determine most informative sampling periods for predicting DO. Milk samples analyzed using a MilkoScan (Foss Electric, Hillerød, Denmark) Fourier-transform infrared (FTIR) spectrometer 1,060 (wn) ranging from 5,011 925 cm−1. To DO, we considered an insemination lead conception when there was no return heat (i.e., successive insemination) and cow had subsequent calving date whereby gestation length required be ±30 d 290 d. Only records first 90 DIM considered. Associations inferred by (1) fitting linear regression models between DO each wavenumber or component, (2) Bayesian model that included complete FTIR spectral data. The effects including systematic (parity number, year-season, herd) these associations also studied. These analyses performed data (5–90 DIM) stratified period (5 30, 31 60, 61 DIM). Overall, regions spectra associated wn 2,973 2,830 cm−1 [related fat-B (C-H stretch)], 2,217 1,769 fat-A (C = O 1,546 (related protein), 1,465 urea fat), 1,399 1,245 acetone), 1,110 lactose). Estimated depended period, drawn during 60 being strongly are typically negative energy balance peak lactation.