GRASSLAND SYSTEMS *

Reference is made to the contrast between actual and potential yields from grassland, to the main factors affecting the development of effective grassland systems for dairy cows and to the technical developments which are now available. The unrealized potential for simplification and increased output from grazing systems is stressed. The available information on the effect of mechanical grazing and storage feeding systems is reviewed and the practical advantages and problems of these systems summarized. Simple calculations are made of the capital involved in large herd organization and the increases in herbage yield or efficiency of use needed to justify this additional expenditure. For large herds a relatively small increase (10%) in output per acre would justify the annual capital charge and feed cost for mechanical harvesting or tower silage; greater increases would be needed for grass drying (22%) or for tower silos in smaller (100‐cow) herds (16%). Other important but less tangible factors influencing the choice of system are referred to. It is considered that unless herbage yields can be greatly increased by the use of mechanical grazing compared with normal grazing, the practical difficulties of this method outweigh its advantages. If tower silos allow more efficient conservation and easier feeding, they may be worthwhile, but the search should continue for cheaper alternatives. Only in very large‐scale enterprises can grass drying, solely to produce cattle feed, be justified, although this method offers the greatest potential. In view of the complexities, it is suggested that computer models may help to resolve such problems and one such study is briefly described.