Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 24051, U.S.A.
Low conversion efficiencies of forage to animal products are associated with low digestibility and intake and result in low production per animal. Energy intake and production per ruminant is higher with temperate than with tropical species. Dense-leafy as compared to mature-stemmy sward structures improve energy intake by increasing size and frequency of biting. The high temperatures during high summer rainfall stimulate growth, but depress digestibility and intake because of leaf senescence and increased cell wall constituent.
Animal performance may be highest with either continuous or rotational grazing depending on available pasture. In special rotational grazing, first grazers produced from 25 to 54% more milk and 65% more liveweight than last grazers.
Constant stocking rates ignore the nutritional needs of ruminants and management requirements of pasture plants associated with morphological and physiological characteristics. Constant stocking without conservation causes extreme differences in pasture quality and availability during the year. With integrated management, pastures and animals are managed concurrently to supply the nutritional needs of the various classes of ruminants and to maintain desirable yields and quality of swards. Systems with pastures differing in seasonal growth can be stocked at constant rates, but variable stocking rates within a system provide opportunity for the control and allocation of pasture to different classes of ruminant. Managed, rather than set, variables can improve the efficiency of animal production.
The generally low energy intake and performance per animal grazing tropical pastures can be improved by integrated pasture and animal management.