## 4 Discussion  
We examined healthy and diseased animals to see if there is a dependence between under surface skin temperature and milk yields for cows in general. However, the results showed that there is a dependence only for elevated temperatures (36 \({}^{\circ}\)C and above) and reduced milk yield of diseased animals. In a similar study, [PERSON] et al. have confirmed a significant relationship between under surface skin temperature (USST) and classes of somatic cell count in collected milk samples using similar equipment [25]. They confirmed the lesser accuracy of the method compared to the mastitis test, but at the same time they appreciated the huge potential of the method. The most interesting result for us was the sharp difference between the results in healthy and diseased animals. The absence of a significant dependence in healthy animals, in our opinion, indicates a large scatter of individual indicators of animal productivity. [PERSON] et al., in a study carried out on 62 dairy cows, found a positive correlation between under surface skin temperature values and somatic cell count [26]. When somatic cell count is increased, the values of udder surface skin temperature showed to increase logarithmically and the best linear model that fitted this relationship reached an R\({}^{2}\) value of 0.73.  
We concluded that for healthy animals it makes no sense to focus on the dependence between the values of the udder surface skin temperature and milk yield, and it is necessary to consider the temperature [32-35.9 \({}^{\circ}\)C] and milk yield [7.9-13 kg] ranges as normal values;  
Figure 8: Algorithm for contactless inflammation detection.  
48 unique measurements should be enough to determine if there is a dependency. The regression model (R\({}^{2}\) = 0.029) and [PERSON]'s correlation coefficient (0.16) showed the strongest scatter of values, confirming our conclusions.  
A completely different situation exists for elevated temperatures in diseased animals--after exceeding a certain threshold, the udder surface skin temperature and milk yield begin to correlate strongly. Temperature ranges [36-38.3 \({}^{\circ}\)C] defined as subclinical mastitis and [38.4-39 \({}^{\circ}\)C] defined as clinical mastitis follow the general trend. It is possible to distinguish them with high accuracy either by assessing the temperature characteristic of specific animals, or by tests for mastitis. The weak point of our study is the relatively small number of animals studied with clinical mastitis, but this is offset by the fact that clinical mastitis can be detected without special tests, simply by the very different behavior of the animal. Statistical processing of data, coefficient of determination (R\({}^{2}\) = 0.886) and [PERSON]'s correlation coefficient (\(-\)0.96) confirm the hypothesis about the dependence between udder surface temperature and milk yield.  
In previous studies authors have investigated which area of the cow udder should be more promising for the measurement of a correct and significant udder surface skin temperature. [PERSON] et al. used three areas, selected considering the udder' height in the dorsal-ventral direction, for the measurement of the udder surface skin temperature [27]. We formed reference images, helpful to use for making thermograms.  
Comparison of these values using thermography will allow you to quickly identify cows with onset of inflammation, as well as to determine the form of mastitis with a high degree of probability. [PERSON] et al. [28], in a study performed on 37 ewes, found that higher udder surface skin temperature were related to high somatic cell count, in addition to lower yield. Therefore, statistical results seem to confirm that USST could be a possible index for the detection of a not healthy state of cow udder.  
Figure 9 shows the result of using the algorithm for non-contact determination of the state of the animal.