Improving behavior monitoring of free moving dairy cows using noninvasive wireless EEG approach and digital signal processing techniques.
BackgroundElectroencephalography (EEG) is the most common method to access brain information. Techniques to monitor and to extract brain signal characteristics in farm animals are not as developed as in humans and laboratory animals. New methodThe method comprised two steps. In the first step, the signals were acquired after the telemetric equipment was developed, the electrodes were positioned and fixed, the sample frequency was defined, the equipment was positioned, and artifacts and other acquisition problems were dealt with. Brain signals from six Holstein heifers that could move freely in free stalls were acquired. The control group consisted in the same number of bovines, contained in a climatic chamber (restrained group). In the second step, the signals were characterized by Power Spectral Density, Short-Time Fourier Transform, and Lempel-Ziv complexity. ResultsThe results indicated that there was an ideal position to attach the electrodes to the front of the bovines head, so that longer artifact-free signal sections were acquired. The signals showed typical EEG frequency bands, like the bands found in humans. The Lempel-Ziv complexity values indicated that the bovine brain signals contained random and chaotic components. As expected, the signals acquired from the retained bovine group displayed sections with a larger number of artifacts. Comparison with existing methodsWe present the first method that helps to monitor and to extract brain signal features in unrestrained bovines. ConclusionsThe method could be applied to investigate changes in brain electrical activity during animal farming, to monitor brain activity related with animal behavior. HighlightsO_LIA method that allows brain signals to be monitored in freely moving dairy cows is described C_LIO_LIThe method uses noninvasive electrodes to minimize stress during EEG monitoring and allows bovines to behave normally during the process C_LIO_LIThe method establishes the frequency sampling rate, electrodes positioning and fixation, equipment holding, artifact extraction, and signal characterization C_LIO_LIThe brain signals are characterized by PSD, STFT, and Lempel-Ziv normalized complexity C_LIO_LIThe method can be applied to relate EEG to animal behavior under normal handling conditions C_LI