The fate of legume seeds eaten by sheep from a Mediterranean grassland.
Abstract
The consumption of legume seed by grazing sheep was assessed in a Mediterranean grassland in NW Syria, during the summers of 1986 and 1987. Large paddocks were also surveyed for the amount of legume seed in sheep faeces. The seed recovery of the most common legumes (Trifolium stellatum, T. tomentosum and T. campestre) was also investigated in a pen-feeding experiment, by feeding 150-200 g of clover pods to each of 10 sheep in a single meal. The percentage of hard seeds was assessed before and after passage of seeds through the alimentary tract. When large numbers of legume seeds were present in the grassland, seed consumption was proportional to the stocking rates, but when small numbers were present (<2000-3000 seeds/m2) sheep ate proportionately fewer seeds, because they were difficult to gather. Sheep faeces collected from the grassland contained an average of 9.5 legume seeds/pellet. Seed recovery after controlled ingestion was 23, 36 and 59% of the number eaten, for T. stellatum, T. tomentosum and T. campestre, respectively; recovery was inversely proportional to seed size. Ingestion reduced hardseededness and increased germination after 20 d from 22.4 to 46.5% for T. stellatum, from 0.8 to 5.6% for T. tomentosum and from 6.6 to 11.6% for T. campestre.