Fluxos de biomassa e padrões de desfolhação de azevém pastejado por bezerras de corte recebendo ou não suplemento

Abstract

Flows of leaf biomass, the intensity and frequency of defoliation were evaluated in Italian ryegrass (Lolium multiflorum Lam), by beef heifers that grazed exclusively on pasture or that grazed and received oat and corn grain as a supplement. We used the method of continuous grazing with variable number of animals. The corn grains and oat in the proportion of 0.93% of body weight, were administered from Monday to Saturday at 14 hours. The experimental design was completely randomized, with repeated measurements over time, with three food systems and three area replications. Flows of leaf biomass, the intensity and frequency of defoliation were calculated using the morphogenetic and structural characteristics of the pasture.The flows of growth, senescence and consumption of leaf blades were similar in the different food systems. The consumption of leaf blades in relation to body weight was lower when heifers received corn or oat grain as supplement. The intensity of grazing, independent of the leaf blade types (in expansion or expanded) was 54.4% and similar in the different food systems. The frequency of defoliation of Italian ryegrass increases when the heifers receive supplement. The increase in stocking rate occasioned by the use of grain, corn or oat, as a supplement did not alter the dynamics of the biomass flows of Italian ryegrass, but reduced the consumption of leaf blades in relation to body weight of heifers and occasioned increase in frequency defoliation of Italian ryegrass.