Ten Years of Evaluating Natural Grassland in Southern Brazil Under Intermittent Stocking by an Ecophysiological Approach

The natural grasslands of southern Brazil are heterogeneous environments that exhibit strong seasonal variability in forage production. The absence of adequate management practices leads to low productivity and the degradation of desirable species. This work analyzed the results of 10 yr of evaluations in a natural grassland managed under intermittent stocking (i.e., method that imposes grazing on a particular management unit or area of land for indefinite periods at irregular intervals). An ecophysiological approach used frequencies of defoliation considering the duration of leaf elongation of grasses representative of resource conservation or capture functional groups. This approach can be a tool to maximize production per unit area and reduce the age of the first mating of beef heifers. Data were compiled from 12 experiments conducted from 2010 to 2020 in a natural grassland with 22.5 ha during spring/summer (September 23–March 21) and autumn/winter (March 21–September 23). This natural grassland in southern Brazil is composed with a predominance of species C 4 . The animals used were heifers of crossbreed Red Angus or Bradford, with initial ages that varied from 7 to 20 mo. Different types of supplements were used in the autumn-winter such as ground corn (0.5% body weight) + mineral supplement (45% crude protein; free access); wheat bran + glycerol (0.5% body weight); rice bran (1% body weight); energy protein salt + corn (salt ad libitum and corn 0.7% body weight). The productive, structural, and nutritional characteristics of pasture and animal performance were evaluated. The defoliation frequencies resulted in different pasture structures, in which the highest forage heights and masses occurred in the lowest frequency treatment. The average daily gain (ADG) was similar between treatments in both seasons. The ADG was 0.270 and 0.280 kg · an −1 · d −1 on spring-summer and autumn-winter, respectively. However, in autumn-winter, ADG was not influenced by the type of supplement used. In spring-summer, the live weight gains per hectare were 24% higher in the treatment of a higher defoliation frequency due to the 9% higher stocking rate. The ecophysiological approach in intermittent stocking and strategic supplementation in the autumn-winter enabled average gains close to 340 kg · ha −1 · yr −1 , which represents more than five times the production of traditional management in natural grasslands of southern Brazil.