The Effects of Fescue Toxicosis at Different Stages of Gestation on Fetal Development

The objective of this study was to determine the effects of ergot alkaloids fed to ewes during two gestational time periods on fetal growth and development. Suffolk ewes (n = 36) were synchronized and bred to a single ram. Ewes (BW 78.02 ± 9.53 kg) identified by ultrasound at d 35 to be pregnant with twin fetuses were fed endophyte-infected tall fescue seed (E+; 1772 µg/hd/d ergovaline+ergovalinine) or endophyte-free tall fescue seed (E-; 0 µg/hd/d ergovaline+ergovalinine) during the two gestational time periods (d 35-85 or d 86-133). This created four unique dietary treatments E+/E+, E+/E-, E-/E+, and E-/E-. Ewes were pair-fed to maintain similar DMI. Maternal and fetal necropsies were performed at d133 of gestation. Data was analyzed as a randomized block design with a 2x2 factorial with treatment (E+ or E-) , time of gestation (d 35-85 or d 86-133), and two-way interaction in the model. Feeding ergot alkaloids during early gestation did not alter (P > 0.05) fetal BW, muscle or organ weights. Feeding ergot alkaloids during late gestation reduced fetal BW at d 133 of gestation by 10% compared to E- treatment. Thoracic circumference was smaller (P < 0.05) for E+ fetuses than E-; crown-rump length and abdominal circumference also tended (P < 0.10) to be smaller for E+ fetuses. Total muscle weight was reduced (P < 0.05) by 13% in fetuses from ewes fed E+ seed during late gestation. Weights of the psoas major, semitendinosus, semimembranosus, and quadriceps femoris were lighter (P < 0.05) for fetuses from ewes fed E+ seed during late gestation. Weight of the heart and liver were lighter (P < 0.05) for fetuses from ewes fed E+ seed during late gestation. There were interactions (P < 0.10) between fescue treatment and time of gestation for kidney, pancreas, spleen, and brain weights. Brain weight expressed on a fetal BW basis was higher (P = 0.01) in fetuses from ewes fed E+ fescue seed indicating asymmetrical fetal growth. Feeding endophyte-infected seed containing ergovaline + ergovalinine during late gestation (d 86-133) reduces fetal growth and muscle mass.