GRAZING INTENSITY, YIELD AND GROWTH RATE OF RYE GRASS

Abstract

An experiment was established on marginal soils in Texcoco, México, in 1991, to evaluate the effects of four levels of forage allowance: 3, 5, 7 and 9% [kg of dry matter of ryegrass (Lolium perenne L.) for each 100 kg of alive .animal], on the biomass production and growth rates of this grass. Three cycles were studied, each consisting of 5 grazing days and 35 non-grazing (resting) days. In the recuperation period, forage was sampled on days 1, 16 and 31 after grazing, by hand clipping samples of .25 x
.25 m. No differences were found among cycles (P> .05), regarding dry matter production, but the residual forage decreased as the herbage allowance also decreased; that is, as the grazing pressure increased. Likewise, the growth rates (crop growth rate, relative growth rate and net asimilation rate) of ryegras were larger in the lower allowances (3 and 5%, i.e., higher grazing intensity) than at the higher allowance levels (7 and 9% ).