ABSTRACT
Summary Grazing experiments were conducted to implement and improve animal-grazing-management systems. The primary objectives were (experiment 1) to investigate animal production with fixed and controlled stocking and (experiment 2) to study animal production and canopy characteristics with three managed stocking rates. Live-weight gains/head for the grazing season were similar for fixed and controlled stocking; during a summer period, gains/head were higher for controlled stocking. Gains/head were not associated with available herbage. The canopies with fixed stocking had 28% to 82% more forage than those with controlled stocking, the former being high in dead tissues and stems. Controlled stocking gave 61% more live weight/ha than fixed stocking because more of the flush high-quality forage was consumed. Live-weight gains/head for the grazing season were higher for the low than for the two higher stocking rates. Gains/head during the summer-autumn season were similar for the three stocking rates even though available pasture varied, dry matter averaging 2,001, 880, and 369 kg/ha for low, medium, and high stocking. During spring, when canopies were similar in leafiness, live-weight gains/animal were allied with available pasture. Double stocking rates during the spring season caused high gains/ha. Values were lower for low than for medium and high stocking. The findings imply that pastures and animals should be managed concurrently to supply the different nutritional needs for classes of ruminants by controlled grazing to maintain high yields of canopies of suitable structure and leafiness. Data suggest that farms should be stocked at high levels, but stocking rate within a farm should vary to control the quality, yield, and available growth for high productivity of responsive animals. Constant or fixed stocking ignores nutritional needs of ruminants and the dynamic characteristics of canopies during growth and grazing.
