Feeding Tall Fescue Seed Reduces Ewe Milk Production, Lamb Birth Weight and Pre-Weaning Growth Rate

Abstract

Endophyte-infected tall fescue (E+) produces ergovaline and ergovalinine, which are mycotoxins that act as dopamine agonists to suppress prolactin and induce vasoconstriction. The experiment was designed as a 3 × 2 × 2 factorial with DRD2 genotype (AA, AG, GG), fescue seed (endophyte-free, E− or endophyte-infected, E+), stage of gestation (MID, d (day) 35–85; LATE, d 86–parturition) and all interactions in the model. Pregnant Suffolk ewes (n = 60) were stratified by genotype and fed E+ or E− seed in a total mixed ration according to treatment assignment. Serum prolactin concentrations were lower (p < 0.05) in ewes fed E+ seed but did not differ by maternal DRD2 genotype or two-way interaction. Lamb birth weight was lower (p < 0.05) in ewes fed E+ seed in last trimester. Pre-weaning growth rate, milk production and total weaning weight was reduced (p < 0.05) in ewes fed E+ fescue seed during MID and LATE gestation. Ingestion of ergovaline/ergovalinine in last trimester reduces lamb birth weight; however, lamb growth rate, milk production and total weaning weight are reduced in all ewes fed E+ during mid and last trimester.

Mycotoxin ingestion during late gestation alters placentome structure, cotyledon transcriptome, and fetal development in pregnant sheep

“…38,47 Previous research found that exposure to E+ fescue during late gestation reduced fetal BW at gd133 by 15% 11 and birth weight by 10.2%. 31 Brain to fetal body weight was increased with exposure to mycotoxins in this study, which is an indicator of asymmetrical growth and IUGR. [15][16][17] This agrees with our earlier work that showed asymmetrical growth in lambs at gd133 10 after exposure to mycotoxins during late gestation that altered growth of the offspring and delayed puberty in females.…”

“…Reductions in serum prolactin levels are commonly reported in sheep grazing endophyte-infected tall fescue pastures [33][34][35] or fed E+ tall fescue seed containing ergot alkaloids. 11,31,36 The reductions in prolactin concentrations are caused by the structural similarity of the ergoline ring of ergot alkaloids to dopamine, which allows them to interact with D2 dopamine receptors. 7 During late gestation, placenta growth plateaus around gd80 37 to gd90 38 and then remodeling of the placenta occurs.…”

“…7 Limited research has examined how these mycotoxins alter placental and fetal development during gestation. Previous research found that exposure to ergot alkaloids during late gestation (gd86 to gd133) had the greatest impact on placental remodeling, 13,29,31 fetal development 10 and subsequent postnatal growth 32 ; however, how these changes occur within this stage of gestation have not been examined. In this study, ergot alkaloid intake for E+ ewes was maintained by feeding tall fescue seed with known levels throughout late gestation.…”

Effects of Tall Fescue Endophyte Type and Dopamine Receptor D2 Genotype on Cow-Calf Performance during Late Gestation and Early Lactation

“…Similarly, others have also reported no change in calf birth weight when cows grazed E+ fescue prior to calving [ 19 , 48 , 49 ]. In contrast, others have shown that calves or lambs born to dams exposed to endophyte-infected tall fescue during gestation have reduced birthweights by 5% [ 18 ], 15% [ 50 , 51 ] or 36% [ 52 ]. Britt et al [ 50 ] found that exposure to ergot alkaloids during late gestation had the greatest impact on fetal development with little to no effect when fed during mid-gestation in sheep.…”

“…Calf gains during this first 30 days period were lower for E+ than NOV. Feeding toxic endophyte-infected seed to ewes during mid and late gestation reduced milk production by 59 to 82% and reduced pre-weaning growth rates [ 51 ], which altered subsequent puberty development and post-natal growth [ 64 ]. In addition, cow calving rate was lower in cows that grazed E+ fescue during late gestation and early lactation.…”