The difficulties in reviewing ergovaline

Authors: NICOL, ALASTAIR - Lincoln University - New Zealand; Klotz, James

Submitted to: Proceedings New Zealand Society of Animal Production
Publication Type: Proceedings
Publication Acceptance Date: 4/21/2015
Publication Date: 6/28/2018
Citation: Nicol, A.M., Klotz, J.L. 2018. The difficulties in reviewing ergovaline. Proceedings New Zealand Society of Animal Production. pp. 18.

Interpretive Summary: In the process of reviewing the physiological responses and metabolism of ergovaline (a toxin produced in both perennial ryegrass and tall fescue) and the effect of its consumption on animal production we encountered problems which limited the completeness of the review and the robustness of the conclusions. The aim of this paper is to document these difficulties in the hope that future work on ergovaline may avoid some of the problems and address the unknowns thus better contribute to our understanding of its importance to New Zealand farmers. This paper, although geared towards New Zealand researchers, can be used by researchers in the U.S., as it identifies specific gaps in the research and inconsistencies across laboratories that prevent a robust recommendation on the threshold of ergovaline intake by livestock.

Technical Abstract: The endophytic alkaloid, ergovaline, is a secondary metabolite of a number of endophytes associated with perennial ryegrass. Ergovaline is known to protect ryegrass against attack by a range of insect pests but can also negatively affect domestic ruminants. We have recently reviewed the physiological responses and metabolism of ergovaline (Klotz & Nicol 2015) and the effect of its consumption on animal production (Nicol & Klotz 2015). A brief summary of the main points from these reviews will be included in this paper but the main thrust is on the difficulties encountered in preparing these reviews. These include: the lack of a cost-effective source of ergovaline to allow for robust dose dependent trials. This has resulted in ergovaline treatments based on seed sources presented in a range of processed forms, or as ryegrass pasture in which ergovaline is often associated with other alkaloids. Intake of ergovaline is often difficult to predict because ergovaline concentration of the diet on offer may not represent the concentration in the diet consumed. Furthermore the mean liveweight and level of production of the experimental animals is not always available to allow a prediction of ergovaline intake. Any change in gut-fill in response to ergovaline consumption needs to be accounted for in assessing any impact on body weight. Experimental objectives need to be clear as the effects of short-term effects of ergovaline exposure can be masked in a production system by subsequent compensatory growth/production. By identifying the difficulties, we hope that future work on ergovaline may be more consistent and of greater value to further reviews.