Identification of differentially expressed genes for fescue toxicosis in high and low tolerant Angus cows

Abstract Background Fescue toxicosis (FT) is the multifaceted syndrome that causes the major loss of revenue in beef industry. Management of FT has been substantial challenge for the beef industry. Little research has been conducted to identify host genetic variation for FT response. Therefore, the objectives of this study were 1) to identify differentially expressed genes (DEG) in animals with contrasting response to fescue toxicosis, 2) to assess the biological relevance of DEG and 3) to investigate the relationships of DEG through gene networks in Angus cows. Results Genotype-by-location-by-time interaction was evident, with one location (2,296) having much greater number of DEG (q-value < 0.1) between HT and LT animals than the other (554). In addition, there was a greater number of DEG (q-value < 0.1) between HT and LT animals on week 5 (3,892) than on weeks 1(1,413), 9 (1,384), and 13 (573). So, further analyses focused on DEG between HT and LT animals on week 5 at the most toxic location. The most significant DEG between HT and LT animals had relevant functions associated with FT: cellular growth (SPDYC, HEYL, ANXA13), cardiovascular function (FGB, HBA, WNT11, BPIFB4, MESP2), protein metabolism (ENPP6, MMP8), and immune response (CTBS, SDC2, CXCL13, IL-13, JAKMIP2). The strongest positive partial correlation (0.99) was between CTBS and CXCL13, where CTBS is involved in carbohydrate metabolism and immune function, and CXCL13 is involved in immune, inflammatory, and defense response, and G-protein coupled pathway. The regulation of the most significant DEG between HT and LT animals on week 5 are highly correlated, indicating a complex interaction between. When all DEG were analyzed, the enriched biological processes associated with fescue toxicosis included immune response, cardiovascular function and development, metabolic, cellular and biological processes, and fertilization. Conclusions These findings provide potential biomarkers that should be evaluated for selection of cattle with greater tolerance to fescue toxicosis which will help to establish the herd with fescue tolerant cows in regions where high endophyte infected pasture is present.