Abstract 282

Veiga,-JB-da; Mott,-GO; Rodrigues,-LR-de-A; Ocumpaugh,-WR

EMBRAPA/Cent. de Pesquisa Agropecuaria do Tropico Umido, 66.000 Belem, PA, Brazil.

Pesquisa-Agropecuaria-Brasileira. 1985, 20: 8, 937-944; 19 ref.

In grazing trials in Florida in 1982 Pennisetum purpureum cv. N-70 was grazed by heifers at intensities resulting in 0.5-2.5 t residual leaf DM/ha after grazing and either continuously grazed or with grazing cycle lengths of 14, 28, 42 or 56 days, 2 days of continuous grazing being followed by a rest period specific for each cycle length. Chemical composition and digestibility were analysed before each grazing period and every 28 days in continuously-grazed swards. Leaf and stem CP content increased as grazing intensity increased and grazing cycle decreased. In vitro digestibility was quadratically related to grazing cycle and higher levels of intensity tended to increase stem digestibility, whereas CP content of grazed forage was higher under shorter grazing cycles. Opt. digestibility of grazed forage occurred under 14-day grazing cycles with grazing intensity resulting in about 1.5 t residual leaf DM/ha. Nutritive value of leaves was higher than that of stems and it was concluded that P. purpureum was a very valuable grass sp. under grazing management.