Determination On The Effective Temperature For Simmental Beef Cattle By Its Seasonal Thermoregulation

Along with the rapid development of animal husbandry and market of the market growing demand for beef, beef cattle breeding tend to scale, industrialized, intensive. In the process of confinedness, thermal environment affects the normal growth and energy metabolism of beef cattle and the quality of animal products. Analyzes the effect of thermal environment on physiological indexes of beef cattle, it can further improve the effect of environment and the production performance.Part1:In order to understand the effect of DBT, WBT, V on mTs and RR of beef cattle, the indexes of thermal environment in the beef cattle shed and physiological indexes of beef cattle were carried out. The results were as follows:Through factor analysis, it was found that the variations of DBT and WBT were larger. The highest value of mTs was25～35℃higher than the lowest one. The mTs was positively correlated with DBT when wind velocity below1.0m/s; There was a significant negative correlation between WBT and mTs. The influence of DBT on mTs was about65%. The wind velocity in beef cattle sheds was from0.094～1.437m/s. The mTs was negatively correlated with V when DBT below5℃; It was positively correlated with V when DBT above5℃. The wind velocity had cooperative effects on mTs with ambient temperature. The wind velocity was associated with RR when DBT was fixed, coefficient of regression was0.034. Sensible heat loss for beef cattle was mainly at lower temperatures, RR did not change obviously. Thermal environment mainly affects mTs.Part2:The relations and regressions of RR, mTs and DBT、WBT、V were analyzed respectively. The result indicated:DBT and WBT were positively correlated with RR, coefficients of regression were0.81times/mi、1.89times/min respectively. Regressions of RR on V were40.03times/min (V<1m/s) and-4.37times/min(V>1m/s). According to the regression equations of DBT and WBT on RR, coefficients of regression were0.45and1.26, and the influences were27%and73%respectively; V is from0.42m/s～2.73m/s, according to the regression equations of DBT, WBT and V on RR, coefficients of regression were0.39,1.94and-2.64. The RR was negatively correlated with V, and the influences of V on RR were larger than DBT and WBT, which is53%.Part3:Effect of thermal environment in spring and autumn on respiration rate (RR) and mean skin temperature (mTs), respectively, were analyzed, and through the Regression analysis to analyze thermoregulation of beef cattle. The results were as follows:In April, DBT is from11.2℃～19.4℃, Relative Humidity(RH) is from23.29%-83.23%. The influences of WBT on RR were32.1%, and the influences of V on RR were37.6%; In September, DBT is from17.0℃～24.4℃,Relative Humidity(RH) is from45.96%～96.91%. The influences of WBT on RR were35.2%, and the influences of V on RR were37.8%. It showed that the influences of WBT on RR in September were larger than those in April, and the influences of V on RR in September were less than those in April.