## 3 Results and Discussion
### Signal Monitoring  
Figure 4a shows a head section of an adult bovine. This figure illustrates the distance from the brain to the frontal region of the bovine head. Finding the best position for signal acquisition involves locating the region where this distance is as short as possible. Figure 4b shows the layout of the monitoring electrodes at the three evaluated positions. Figure 5 depicts a disc electrode and electrode fixation with adhesive tape. The animal module consisted of a box measuring 2.5 \(\times\) 7.0 \(\times\) 11.0 cm\({}^{3}\) and weighing 180 g. To make it less uncomfortable for animals, the box was placed in a fabric bag, which was attached to the neck with a soft ribbon. Figure 6a presents the animal module placed at the animal's neck, whilst Figure 6b,c shows the halter that was used to protect the electrodes and the electrodes fixed with super glue. The adhesive tape failed to keep the electrodes rigidly attached to the animal, so they often came loose. The glue (Figure 6b,c) kept the electrodes in the right position for a whole day of acquisition. At the end of the day, the electrodes and the animal's forehead had to be cleaned for a new acquisition. Compared to the use of implanted electrodes, which can go on for a year [25], this was a short period. It is important to highlight the possibility of noninvasive monitoring here, though. Figure 4: (**a**) Head section from adult animal. POS2 corresponds to the region where the brain is closest to the surface. (**b**) Layout of monitoring electrodes in three positions. Numbers 1, 2, and 3 indicate POS1, POS2, and POS3, respectively. Figure 7 contains the signals acquired at the three selected positions for one of the two animals in this stage of the experiment, while Figure 8 corresponds to the artifact-free signal sections in Figure 7.  
Figure 5: Disc electrodes at POS2. Figure 6: (**a**) Animal module inside a fabric bag placed at animal’s neck. (**b**,**c**) Glue fixation of electrodes and protection with halter. Figure 9 contains the PSD for the signal sections in Figure 10.  
Figure 8: Artifact-free signal sections in (**a**) POS1, (**b**) POS2, and (**c**) POS3. Figure 7: Signals in (**a**) POS1; (**b**) POS2; (**c**) POS3. Original signal is in grey and selected signal epochs in black. Figure 10: Arrangement of the animals within the cages inside the climatic chamber. Figure 9: PSD for artifact-free signal sections in (**a**) POS1, (**b**) POS2, and (**c**) POS3. In Figure 7a, the signal at POS1 presented many artifacts, most of which were due to ear movement. POS2 provided longer artifact-free sections than POS1 and POS3 as a result of two main facts. First, POS3 was largely influenced by eye movement, whereas POS2 is the region where paranasal sinuses are smaller, and hence, the surface is closer to the cerebral cortex. This result was expected, given the analyzed anatomical head section (e.g., Figure 4). The three positions had similar PSD profiles, and the observed frequencies (2-10 Hz; 13-27 Hz) agreed with those obtained by [PERSON] et al. [31]. Therefore, the metric to choose the best electrode position was the length of the obtained artifact-free section, and POS2 was selected as the best one to acquire brain signals in cattle. Most studies in this area have been conducted in laboratory conditions [31] and used subdermal electrodes [31; 32] in animals that were subjected to some type of containment [24; 32]. The method presented herein allows brain signals to be recorded with surface electrodes in freely moving animals. Figure 10 shows the arrangement of the awake animals within the cages inside the climatic chamber, while Figure 11 illustrates their positioning within enclosed compartments within the experimental paddock. Figure 12 displays the enthalpy values for the animals in the climatic chamber or pasture during the first of the three days of experiment.