Thermotolerance in cows: cellular and physiological approaches

Abstract

This study aims to quantify the expression of HSP70 in lymphocytes and oocytes correlating with heat stores heat of cows of different origins, submitted to artificial insemination at fixed time. In grazing systems, the physiological and behavioral responses triggered by high temperatures in summer, determine effects on conception rate, so is necessary to study the underlying mechanisms and identify viable solutions for increase productivity. The experimental phase will be developed in Terceira Island and Alentejo (Portugal) and São Paulo (Brazil) with Holstein Frisian and Limousine breeds. Animals of the breeds Mertolenga and Brahman will be also evaluated in Alentejo and São Paulo, respectively. In each experimental place will be undertaken four steps to which the animals are subjected. In the first step will be performed thermolysis capacity test, which aims to assess the relationship between the physiological and behavioral parameters and physiological thermotolerance. Simultaneously, the blood samples will be collected in order to undertake an assessment of gene expression of HSP70 in lymphocytes (second step). In the third step the female will undergo estrus synchronization so that artificial insemination is performed at fixed time. 28 days after artificial insemination will take place the pregnancy diagnosis by ultrasonography. As a fourth step will be harvested oocytes from females of various breeds in order to study to evaluate the expression of HSP70. (AU)