Recovery and Viability of Sulfur Cinquefoil Seeds From the Feces of Sheep and Goats

Abstract

Targeted grazing by sheep or goats is a potentially useful tool for suppressing the noxious weed sulfur cinquefoil (Potentilla recta
L.). However, possible transmission of weed seeds by grazing livestock is a serious ecological concern that must be addressed in
any targeted grazing prescription. We investigated the effect of sheep and goat digestion on the viability of sulfur cinquefoil
seeds collected from live plants growing on a foothill rangeland site in southwestern Montana. Eight sheep and eight goats (all
wethers) were each gavaged with 5 000 sulfur cinquefoil seeds. Four animals of each species received immature seeds, and four
animals received mature seeds. All animals were fed ground grass hay in excess daily, and intake averaged 2.0% body
weight d1. Total fecal collection began immediately after gavaging and continued for 7 consecutive days. Once each day, all
identifiable sulfur cinquefoil seeds were recovered and counted from fecal subsamples. Seed viability before gavaging averaged
36% for immature seeds and 76% for mature seeds. Sheep and goats excreted similar numbers of viable seeds. Almost all (98%)
of the viable seeds recovered from sheep and goats were excreted during Day 1 and Day 2 after gavaging. No viable seeds were
recovered from either sheep or goats after Day 3. Our estimates of sulfur cinquefoil seed excretion and viability in sheep and
goat feces are likely inflated compared with targeted grazing animals because gavaging with seeds bypassed mastication.
Grazing livestock that consume sulfur cinquefoil seeds should be kept in a corral for at least 3 d to prevent transferring viable
seeds to uninfested areas.

Key Words: endozoochory, Potentilla recta, prescribed grazing, targeted grazing, weed seeds