Ergot alkaloid induced changes during late gestation in ewes

Pregnant Suffolk ewes (n = 19; 81.2kg ± 7.7) estimated to be carrying twins were assigned to endophyte-infected tall fescue seed (E+; 4.14 µg ergovaline + ergovalinine/g seed) or a control diet (CON; 0 µg ergovaline + ergovalinine) and evaluated at different stages of gestation (gd85 [pre-treatment, n = 3], gd110 [n = 4/treatment] or gd133 [n = 4/treatment). Ewes were individually fed a basal diet with (E+) or without (CON) endophyte-infected tall fescue seed from gd86 to gd110 or gd133. A terminal necropsy was performed, and uterine components were evaluated for size, weight, and type. Data were analyzed using a priori contrasts to test effects of stage of gestation (gd85 vs. gd110 or gd110 vs. gd133) and adaptive responses to feeding E+ fescue seed versus CON at gd110 and gd133. Serum prolactin concentrations were greater (P < 0.05) at gd110 than gd85, and then remained constant to gd133. Feeding E+ tall fescue seed reduced (P < 0.05) serum prolactin concentrations compared to CON at both gd110 and gd133. From gd85 to gd110, placentome type and number changed from type A to type B (P < 0.05) but did not change (P > 0.05) after gd110. Total fetal weight per ewe increased 2977 g from gd85 to gd110 (P = 0.011) and then 3151 g from gd110 to 133 (P = 0.012). Brain weight as a percentage of fetal body weight was higher (P = 0.029) for E+ fetuses on gd110 compared to CON, which demonstrates asymmetrical growth and intrauterine growth restriction (IUGR). In total, 15,961 genes were identified in the cotyledon through mapping to the ovine genome across all samples. There were 136 genes differentially expressed (FDR < 0.05; log2foldchange < -1 and > 1) from gd85 to gd110 with ovarian steroidogenesis and steroid biosynthesis pathways enriched and 469 genes differentially expressed from gd110 to gd133 with ribosome and oxidative phosphorylation pathways enriched. Exposure to E+ fescue resulted in differential expression of 22 genes at gd110 but only one gene at gd133 compared to CON. These results show that there are major changes in fetal growth and placental remodeling during the late gestation period that are influenced by exposure to ergot alkaloids from endophyte-infected tall fescue seed; however, major changes in the transcriptome of the cotyledon tissue in response to E+ fescue were not observed and other factors must be involved in the reduction of placental efficiency and fetal growth observed with E+ fescue exposure. Overall design: For this study, the 15 samples are divided into five groups of 3 replicates each. Three of the groups are control groups at gestation date 85, 110, and 133. Two groups are experimental at gestation date 110 and 133.