Relationship between tympanic temperature and climatic variables in steers finished in Biobío region during the wintertime

Abstract

A total of 20 crossbreed steers received an electronic device in the tympanic canal to collect tympanic temperatures (TT). Simultaneously, climatic variables including air temperature, wind speed, solar radiation, relative humidity, and rainfall were collected by using a weather station located at the feedyard, and used to estimate the comprehensive climate index (CCI). Statistical analysis of data included descriptive, ANOVA, simple and multiple lineal regressions with a level of significance of 5 %. Climate variables and the CCI were the predictors variables, whereas TT was the response variable. Mean TT of steers was 37.59 ± 0.02 and 37.16 ± 0.03 °C for years 2010 and 2011, respectively. Climatic conditions during the collecting periods were considered as normal and not challenging for the animals from a thermal balance standpoint. The previous is reflected in the mean values of the CCI, 7.30 ±0.11 and 6.27 ±0.12 °C for years 2010 and 2011, respectively. Linear regression analyses showed that most of the observed variables were significant but none of them explains in good shape the observed variability (r2 < 0.10). Multiple regression analyses improved the value of the coefficients of determination (R2 ), but they still were lower than 0.50. Finally, we conclude that for the periods of study, TT did not undergo major changes due to environmental conditions of factors assessed. Similarly, the steers showed no signs of environmental stress. Nevertheless, days of data collection were not representative of uncomfortable winter conditions.