[Ingestive behavior nycterohemeral patterns of dairy cows, at the beginning and at the end of lactation, fed a corn silage based diet]

The effects of the stage of lactation upon the ingestive behavior nycterohemerat patterns were evaluated with eight dairy cows eating a corn silage based diet. Spectral analysis was performed through application of the finite Fourier transformation upon hourly duration of eating or ruminating time series. Variance analysis and inspection of phase diagrams and periodograms were done upon modified data. The mean meal duration and dry matter intake were larger while the unitary ruminating time was inferior at the beginning than at the end of the lactation. Nycterohemeral patterns of time spent eating or ruminating at the beginning and at the end of lactation followed mainly periodicities of, respectively, 24, 12, 8 and 4 hours and 24, 12 and 8 hours. A significant effect of stage of lactation was observed at the rhythm component 4 for both time spent eating and ruminating. Lactation stage affected some parameters of ingestive behavior and its rhythmicity patterns