The Massese is an autochthonous Italian sheep breed, used for meat and mainly milk production and thermoregulatory variations can directly affect the performance of these animals. We evaluated the thermoregulatory patterns of Massese ewes and identified the changes due to environmental variations. Data was collected from 159 healthy ewes from herds of four farms/institutions. For thermal environmental characterization, air temperature (AT), relative humidity (RH) and wind speed were measured, and Black Globe Temperature, Humidity Index (BGHI) and Radiant Heat Load (RHL) were calculated. The thermoregulatory responses evaluated were: respiratory (RR), heart rate (HR), rectal temperature (RT) and coat surface temperature (ST). All variables were subjected to analysis of variance with repeated measures over time. A factor analysis was conducted to determine the relationship between environmental and thermoregulatory variables. Multiple regression analyses were also examined using General Linear Models, and Variance Inflation Factors were calculated. Logistic and Broken line non-linear regressions for RR, HR and RT were analyzed. The RR and HR values were outside reference values and associated with normal values of RT. In the factor analysis, most environmental variables were seen to affect the thermoregulation pattern of the ewes, except for RH. In the logistic regression analysis, RT was not affected by any of the variables studied, maybe because BGHI and RHL were not sufficiently high enough. Nevertheless, BGHI and RHL affected RR and HR. The study shows a divergence for Massese ewes from reference thermoregulatory values for sheep.
Keywords: Animal health; Broken line analysis; Heart rate; Logistic regression; Respiratory rate.
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