## 2 Application of Thermography in Pig Breeding
### Meat Quality Prediction  
Several studies have been conducted on the use of infrared thermography to predict the final quality of pork meat. Postmortem, [PERSON] [20] assessed the quality of pork meat in pigs having high temperature values collected by thermography before stunning. Based on color and water retention, the assessed pork meat was classified as PSE (pale, soft, and  
Figure 4: Monitoring the skin temperatures of pigs as they arrive at the slaughterhouse. exuding), normal, or DFD (dark, firm, and dry). The thermographic values collected in vivo did not allow the prediction of PSE or DFD meat, but as the surface temperature of the back of the examined pigs increased, so did the frequency of flaws related to meat quality. [PERSON] et al. [21] carried out the following experiment: They classified animals as \"warm\" or \"normal\" based on the temperature of their lumbar region, measured with a thermographic camera, after having kept pigs at the slaughterhouse for some variable time span. The group of pigs kept in the rest area for a time span of 1 to 4 h, the \"warm\" ones, had a lighter muscle color, while no difference in pH and water retention rates had been detected. In the group of pigs kept in the rest area for one night (12 to 16 h), any difference in meat quality, both for \"warm\" and \"normal\" pigs, had disappeared. The pigs' recovery from previous stress, before stunning, had reduced any difference among the animals, and consequently, the effectiveness of thermography in predicting meat quality. [PERSON] [22] studied the use of thermography in measuring the surface temperature of those pigs that were exempt, heterozygous and homozygous for the recessive allele of the halothane gene. Images have framed the back and side surfaces of pigs kept in the rest area and on the outer and inner median of the midsection, 45 min after their deaths. Although the thermographic analysis showed no differences between genotypes, small, localized areas with higher temperatures were observed on the dorsal surface of homozygous pigs for the recessive allele of the halothane gene. Regardless of the genotype, pigs that had lower average temperatures on the side tended to have meats with worse retention and a lighter color. From this test, a need emerged for the identification of the most important anatomical parts of the animal's body, the most useful temperature ranges for thermal imaging, and the most appropriate environment and handling conditions suitable for a more effective use of infrared thermography in predicting pork meat quality. Due to the complexity of conditions where a thermographic shooting can be carried out, its definition is still undergoing some evaluations. Lately, [PERSON] et al. [23] have tried to single out the best spots on a pig body for the thermographic shootings that aim at identifying the widest temperature variations on the skin surface, as a result of two different handling ways from stable to ramp (calm or rude), and consequent upon a 40 min transportation. During this test, besides the use of the thermal camera, some stress indicators, such as salivary cortisol rate, heart rate and rectal temperature, had been used. The temperature measured in the orbital region is more sensitive to physical activity than the rectal one because of the different dissipation rate between internal and surface temperatures. The parasympathetic system reduces the gastrointestinal activity by decreasing the blood flow toward the intestinal tract, probably because of the vasoconstriction of the rectal wall in contrast to the orbital region. The orbital regions, and the one located at the posterior base of the ear, have shown the best correlation coefficients with the salivary cortisol (r = +0.49 e r = +0.50, respectively), proving to be the most reliable spots to measure body surface temperature.