Evaluation of native plant seed for plant establishment from cattle dung

Background/Question/Methods

Invasive plant species have displaced native plants on grasslands of North American and this has significant consequences for native flora and fauna, soil ecology, and livestock production.  The introduced grasses smooth brome (Bromus inermis) and Kentucky bluegrass (Poa pratensis) are now abundant across large areas of the northern Great Plains and Lehmann lovegrass (Eragrostis lehmanniana) is locally abundant in the semi-desert grasslands of southern Arizona, southwestern New Mexico, and northwestern Mexico.  It may be possible to establish, in a cost-effective manner, native plants within stands of these invasive grasses by feeding their seed to cattle with new plants arising from their dung.  Since seed viability for some species may be seriously compromised by passing through the g-i tract of cattle, we fed 50,000 seeds per species of Canada milk-vetch (Astragalus canadensis), western wheatgrass (Pascopyrum smithii), green needlegrass (Stipa viridula) and Arizona cottontop (Digitaria californica) to two beef cows to determine the percentage of viable seed that passed through their g-i tracts for 4 days after ingestion.   

Results/Conclusions

For Canada milk-vetch, western wheatgrass, green needlegrass and Arizona cottontop, 7, 0.1, 2, and 1%, respectively, passed out of the cows and germinated.  In comparison, 21, 61, 72, and 73%, respectively, of non-fed Canada milk-vetch, western wheatgrass, green needlegrass and Arizona cottontop germinated.  For the northern Great Plains, Canada milk-vetch appears to be a potential candidate for fecal seeding, western wheatgrass does not, and green needlegrass may be if this species is particularly good at establishing from cow pies.  For the semi-desert grasslands, normal Arizona cottontop does not appear to be a good candidate for fecal seeding, but debearded seed should be evaluated before this species is eliminated because debearded seed may pass through cattle faster with less harm.