The botanical species composition achieved in sown swards is largely a result of plant factors such as capacity for growth of the component species, their competitive interaction and sward canopy structure interacting with the different diet selection patterns of the grazing animals. These interactions not only control the subsequent development of plant species and their contribution to overall sward composition but also affect animal outputs.

Sown swards offer a simple model to test hypotheses for understanding diet selection and foraging strategy of novel farm animal species like goats (Gordon and lllius, 1992). Their apparent selection against legumes in temperate grasslands (Clark et al., 1982), as compared to sheep, may offer opportunities for differential niche use by sheep and goats on grass/clover pastures. This could lead to increase clover contents in grass/clover swards and enhanced animal production. Previous field studies indicate that lambs in particular gain more live-weight when grazing swards with a higher clover content (Vipond et al., 1993).