Toxicity of endophyte-infected ryegrass hay containing high ergovaline level in lactating ewes1

Abstract

The symbiotic association of var. (formerly named ) with perennial ryegrass () leads to the production of ergovaline (EV) and lolitrem B (LB) that are toxic for livestock. The objectives of this study were to determine the effects of feeding endophyte-infected ryegrass (SE+) hay on 16 lactating ewes (BW 80 ± 10 kg) in comparison with endophyte-free ryegrass (SE-) hay to investigate the putative mechanisms of action of EV and LB and to evaluate their persistence in milk and animal tissues. The mean EV and LB concentrations in SE+ hay were 851 and 884 μg/kg DM, respectively, whereas these alkaloids were below the limit of detection in SE- hay. No effect of SE+ was observed on animal health and skin temperature whereas prolactin decreased and significant differences between hays were observed from d 7 to 28 of the study ( < 0.03) but had no effect on milk production. Hematocrit and biochemical analyses of plasma revealed no significant difference between SE+ and SE-, whereas cortisol concentration differed significantly on d 28 ( = 0.001). Measurement of oxidative damage and antioxidant enzyme activities in plasma, liver, and kidneys revealed a slight increase in some enzyme activities involved in defense against oxidative damage in the SE+ fed ewes. Slight variations in the activities of hepatic and kidney flavin monooxygenase enzymes were observed, whereas in the kidney, glutathione -transferase activity decreased significantly ( = 0.002) in the SE+ fed ewes, whereas uridine diphosphate glucuronosyltransferase activity increased ( = 0.001). After 28 d of exposure of ewes to the SE+ hay, low EV and LB concentrations were measured in tissues. The highest concentration of EV was observed in the liver (0.68 μg/kg) whereas fat contained the highest concentration of LB (2.39 μg/kg). Both toxins were also identified at the trace level in milk.

Metabolomics of fescue toxicosis in grazing beef steers

“…Decreased plasma melatonin in E+, which would be consistent with the findings here, has been reported (Porter et al, 1993). AFMK is the product of the reaction between melatonin and reactive oxygen species (ROS; de Almeida et al, 2003;Hardeland et al, 1995;Tan et al, 2000), and previous reports found widespread decreased antioxidant defense mechanisms due to E+ (Lakritz et al, 2002;Settivari et al, 2008;Zbib et al, 2014Zbib et al, , 2015. Thus, increased AFMK may indicate early compensatory mechanism utilizing melatonin for the mitigation of E+-induced oxidative stress.…”

“…Plant ergot alkaloid levels are influenced by numerous abiotic factors (Guerre, 2015), and E+ EA levels here were slightly lower than previous summer studies (Hill et al, 2000). This is expected, however, as warming increases E+ alkaloid content (McCulley et al, 2014).…”

“…Vasoconstrictive responses (Klotz et al, 2008;Oliver et al, 1993;Oliver et al, 1998;Rhodes et al, 1991) inducing perturbed nutrient absorption and metabolism (Egert et al, 2014a;Pesqueira et al, 2014) occur concurrently with altered circulating prolactin and cholesterol levels, which together with and intra-and extrahepatic enzyme activity changes, may play a role in the etiology of FT (Bacon, 1995;Rosenkrans and Ezell, 2015;Settivari et al, 2008;Thompson and Stuedemann, 1993;Zbib et al, 2014Zbib et al, , 2015. Foote et al (2013) suggested impaired weight gain might be attributed to a decrease in volatile fatty acid (VFA) absorption or production caused by increased ruminal EA concentration.…”

“…A C C E P T E D ACCEPTED MANUSCRIPT 5 soil erosion, and impairs pasture sustainability (Bouton et al, 2002;Guerre, 2015;Gunter and Beck, 2004;Hancock and Andrae, 2012;Hoveland, 1993;Parish et al, 2003;Pimentel and Burgess, 2013).…”

Ergovaline, an endophytic alkaloid. 1. Animal physiology and metabolism

“…These authors concluded that milk is a minor route of excretion for intact ergovaline. In a separate study, ergovaline-containing perennial ryegrass hay (0.851 mg/g) was fed to lactating ewes for 28 days and ergovaline was detected in milk collected from some (but not all) of the exposed ewes, but all detectable concentrations were below the concentrations of quantitation (Zbib et al 2015). Schumann et al (2009) fed cows an ergot alkaloidcontaminated diet and did not detect any ergot alkaloids in the subsequent milk samples evaluated.…”