Horses\u2019 rejection behaviour towards the presence of Senecio jacobaea L. in hay

Louisa Sroka,Marie-Lena Hass,Anja These,Clara Müller,Sabine Aboling,Ingrid Vervuert

doi:10.1186/s12917-021-03124-0

Abstract

BackgroundSenecio jacobaea contains pyrrolizidine alkaloids that can induce severe hepatic intoxication in horses, either acute when ingested in high amounts or chronic when consumed over a long period. The aim of this study was to determine horses’ rejection behaviour towards the presence of Senecio jacobaea in hay when fed ad libitum. We hypothesized that adult horses can sort Senecio jacobaea out of the contaminated hay when hay is fed ad libitum. Six warmblood geldings with a mean (±SD) age of 15 ± 2 years were included. In a randomized study, Senecio jacobaea contaminated hay (5% or 10% contamination level) was provided at several timepoints over the day for 1 hour to six. Hay was provided ad libitum for the rest of the day. The horses’ rejection behaviour towards Senecio jacobaea was observed. If a horse ingested two Senecio jacobaea plants twice at different timepoints, then the horse was excluded from the experiment.ResultsTwo out of six horses had to be excluded from the study after three out of 12 observation periods due to repeated Senecio jacobaea intake. Two other horses had to be excluded after nine and 11 out of 12 observation periods. Only two horses were able to sort out the various amounts (5 and 10% contamination level) of Senecio jacobaea during the whole experiment.ConclusionsHorses’ intake of Senecio jacobaea cannot be avoided despite being fed with hay ad libitum. Due to the risk of chronic intoxication by pyrrolizidine alkaloids intake, feeding Senecio jacobaea contaminated hay must be avoided, and pastures with Senecio jacobaea growth are considered inappropriate for feed production.

Highlights

Senecio jacobaea contains pyrrolizidine alkaloids that can induce severe hepatic intoxication in horses, either acute when ingested in high amounts or chronic when consumed over a long period
The horses ingested stems of variable size, while on other days, the horses were able to sort out Senecio jacobaea L (SJ) independently of the size of the stems
Two horses were able to reject the various amounts of SJ (5 and 10% contamination level) throughout the whole feeding period (Fig. 1)

Summary

Introduction

Senecio jacobaea contains pyrrolizidine alkaloids that can induce severe hepatic intoxication in horses, either acute when ingested in high amounts or chronic when consumed over a long period. The aim of this study was to determine horses’ rejection behaviour towards the presence of Senecio jacobaea in hay when fed ad libitum. We hypothesized that adult horses can sort Senecio jacobaea out of the contaminated hay when hay is fed ad libitum. Senecio jacobaea contaminated hay (5% or 10% contamination level) was provided at several timepoints over the day for 1 hour to six. If a horse ingested two Senecio jacobaea plants twice at different timepoints, the horse was excluded from the experiment. SJ contains pyrrolizidine alkaloids (PAs), which are secondary plant metabolites [5] that can lead to severe intoxication in horses and other. To the best of our knowledge no clinical studies to this topic were performed in horses

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