75Pasture pests & weeds

Abstract Seeds of eight plant species were fed to four penned goats on three separate occasions. The faeces were collected over subsequent days, then seeds were recovered and tested for viability. Less than 10 % of the ingested seeds survived passage through the goats for five of the species, though 32.3 % of broad-leaved dock (Rumex obtusifolius) seeds and 19.2 % of gorse (Ulex europeaus) seeds were excreted undigested. The percentage of viable seeds ingested that remained viable when excreted ranged from 25.7 % for broad-leaved dock to 0.5 % for variegated thistle (Silybum marianum). A large proportion of recovered seeds was excreted within 24 h of ingestion, and all seeds had passed through the goats within 72 h. Grazing by goats of weed seed-heads is generally seen as beneficial due to large decreases in the number of viable seeds added to the soil. However, as all species established from intact goat dung, potential exists for dispersal of weeds to new areas, especially by feral goats