Expression data from Day 15 bovine conceptuses. Bos taurus

The majority of pregnancy loss in cattle occurs between days 8 and 16 of gestation coincident with the initiation of conceptus elongation and the onset of maternal recognition of pregnancy. Differences in conceptus lengths on the same day of gestation may be related to an inherent lack of developmental competency or may simply be a consequence of asynchrony with the maternal environment. The primary objective of this work was to characterize differential patterns of mRNA expression between short and long bovine conceptuses recovered on Day 15 of gestation. Embryo selection is an important factor that contributes to pregnancy success following transfer of embryos produced in vivo or in vitro. Morphological evaluation of embryos for stage of development and quality grade is the most widely used method for predicting embryo viability in cattle. Multiple studies have demonstrated that there are significant differences in pregnancy rates across different morphological grades. However, morphological evaluation is not always the best predictor of pregnancy success. Therefore, it is of interest to develop an objective and highly predictive method of pre-transfer embryo screening. A secondary objective of this experiment was to characterize differential patterns of mRNA expression between Day 15 bovine conceptuses derived from Grade 1 (excellent) and Grade 3 (poor) embryos. Overall design: In Experiment 1, gene expression was compared between Day 15 conceptuses derived from the transfer of Grade 1 (n=4) versus Grade 3 (n=3) embryos. In Experiment 2, gene expression was compared between Grade 1-derived Day 15 conceptuses classified as either short (n=5) or long (n=5) in length.