Innovations in the early pregnancy diagnosis in cattle

Abstract

The identification of the pregnancy status earlier than the current methods done on about 30 days post-insemination allows a reduction in the economic gain. The main thesis is that biomarkers stimulated by conceptus in the blood are detectable at early pregnancy. This may allow the development of an early and innovator pregnancy diagnosis method in cattle. Therefore, we aimed to develop a diagnostic method through the quantification of the abundance of reported genes stimulated by the IFN-tau (ISGs) or new biomarkers coupled to the identification of the non-pregnant cows by the evaluation of the luteal function. Thus, in Study 1 new markers of pregnancy status may be identified by the transcriptome study of the immune cells and total peripheral blood on Days 14 and 18 post-insemination. The purpose is to characterize the abundance of the known ISGs and of new transcripts stimulated by the presence of the conceptus in the total blood, polymorphinuclear immune cells (PMNs) and immune cells of the milk between Days 12 and 20 post-insemination in dairy and beef cows. Together, the luteolysis will be detected by Doppler ultrasonography through the changes in the size and vascularization of the corpus luteum (CL) e by the circulating progesterone concentrations to detect cows with non-functional CL. For measurement of P4 concentrations, we aim to develop and validate an immunoenzymatic assay with high sensitivity and specificity to avoid the use of radioisotopes. In Study 2, the accuracy of the developed methods will be analyzed in a moment before Day 20 post-insemination based in the combined or the single use of the expression od ISGs or the new biomarkes, and the CL function (by the P4 concentration or by the Doppler ultrasonography). Based on these results, we will evaluate in Studies 3 and 4 the productive and economic of the use of the proposed methods to identify non-pregnant beef and dairy cows and to propose a protocol for earlier re-insemination. The new knowledge and the innovative methods here proposed will serve as basis for development of new technologies for meet and dairy systems. The practicability is guaranteed by the combined work of specialists in each analytical step and by the infrastructure of the institutions involved. (AU)