Botanical composition of available forage selected by esophageal fistulated steers in a guineagrass-perennial soybean pasture

Abstract

The seasonal selectivity of grazing cattle was investigated in a Guineagrass (Panicum maximum) - perennial soybean (Neonotonia wightii) pasture. The purpose of this work was to determine the botanical composition of the available forage and of the forage selected by esophageal fistulated steers, during the period from January to November 1979. The components species of the green forage changed seasonally and differently, by the effects of climate and grazing. The occurrence of frost in the Fall decreased substantially the green forage, increasing the dead material to more than half of the total dry matter in the pasture. The associated effects of climate, pest defoliation and highl grazing pressure imposed at the beginning of the season led to a shortage of the available perennial soybean and its proportion in the pasture at Spring. From the samples collected by five esophageal fistulated steers, it was found that in March and April, when the available green forage was high (from Summer's end to Fall's beginning) the animals selected their diets refusing perennial soybean. The relative intake of perennial soybean increased linearly from May over, when the available green forage decreased. The Guineagrass was selectivelly grazed only in March (Summer). In the latter months its proportions in the diet did not differ from its proportions in the pasture. Common Bahiagrass (Paspalum notatum) showed a good acceptability when regrowth conditions were favorable. It contributed, in April, with 17.5%of the green forage consumed.