Sheep preference for leafy spurge from Idaho and North Dakota

Published source details Kronberg S.L. & Walker J.W. (1999) Sheep preference for leafy spurge from Idaho and North Dakota. Journal of Range Management, 52, 39-44.
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Summary

Leafy spurge Euphorbia esula (native to Europe) was accidentally introduced to the USA in the early 1800s. It is now a serious invasive weed over large areas including within a number of national parks and reserves, and it displaces native vegetation in prairie habitats and fields. Three trials were conducted in Idaho and North Dakota (northern USA) to determine if low ingestion of some leafy spurge by domestic sheep Ovis aries is primarily due to differences in sheep or in leafy spurge edibility.

Trial 1 - Pastures in Idaho and North Dakota were grazed by sheep originating from both states.

Trial 2 - Ingestion of air-dried leafy spurge was compared by simultaneously offering samples to penned sheep from the two states.

Trial 3 - To assess potential effects of fertilizer addition, penned sheep were simultaneously offered leafy spurge (Idaho origin) harvested from fertilized and non-fertilized sites.

Trial 1 - Generally, sheep from both states reluctantly grazed leafy spurge growing in the Idaho pastures but grazed the spurge in proportion to its availability in the North Dakota pastures.

Trial 2 - Sheep consumed more leafy spurge originating from North Dakota than from Idaho.

Trial 3 - Sheep initially ate equal amounts of fertilized and unfertilized leafy spurge but by day four, had developed an obvious preference for leafy spurge from the fertilized site.

These trials indicate that sheep preference for leafy spurge differs depending on site, and that using sheep grazing to control leafy spurge may be more successful on soils of relatively high fertility.

Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://uvalde.tamu.edu/jrm/jan99/kronberg.htm