Produção vegetal e animal e composição química do solo em pastos de capim-massai manejado sob alturas de pré-pastejo

Abstract

The objective of this study was to evaluate the effect of pre-grazed sward heights of Massai-grass, Panicum maximum, over forage productive characteristics, structural and qualitative pasture under animal productivity and soil fertility. . Four grass canopy heights were evaluated in the pre-grazing: 35, 40, 45 and 50 cm. The pastures were managed by intermittent grazing method with 32 St. Agnes wethers. The interaction among heights and grazing cycles was significant for pre-grazing light interception (LI) and leaf area index . LI had linear and positive effect to the pre-grazing heights only in the one and three grazing cycles, with a proportional increase of 1% for each centimeter in the sward. The total forage mass had a linear regression, every centimeter in canopy height increased the forage mass dry materin 187 kg ha-1. The masses of leaf blades and dead materials also linearly increased with the canopy heights. The leaf blades and thatches offered to the animals were not affected by the canopy heights in the pre-grazing, the average values were 23.29 and 10.95 kg of DM 100 kg BW-1, respectively. There was no effect of the grass canopy heights in the chemical composition of the stem and the leaf blades, except for the crude protein of the leaf blade, which was affected linear and negatively. The average daily gain (ADG) and the stocking rate (SR) had linear response to the pre-grazing heights, with positive effect on the SR and negative on the ADG. The weight gain per hectare was not affected by the pre-grazing canopy heights. The grazing time had quadratic response to the canopy height where the minimum point was 502.9 min.day-1 at 42.57 cm. The dry matter intake relative to body weight increased linearly with the growth of the grass sward. The organic carbon stocked in the soil did not differ on the sward height targets. The definition of proper management of time for this grass will depend on the production targets. Can be used 50 cm when you want greater crop production and maintain more animals in maintenance area or by 35 cm when most individual performance.