Weight gain and morphogenic characteristics of forage plants on Cameroon grass and braquiarÃo grass pastures under different stocking rates / Ganho de peso e caracterÃsticas morfogÃnicas das forrageiras em pastagens de capim-cameroon e capim-branquiarÃo sob diferentes taxas de lotaÃÃo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

The scope of this work was to evaluate on pastures formed of P. purpureum cv. Cameroon and B. brizantha cv. Marandu submitted to four stocking rates, the population dynamics of tillers and tissue turnover, aiming at increased availability of forage and animal yield. Two experiments were conducted at the Experiment Station of Animal Science of the Extreme South of CEPLAC, situated in the town of Itabela â BA, with an annual rainfall of 1,311 mm and average temperature of 25ÂC without a definite dry season. The soil is an Ultisol whose average chemical characteristics at 20 cm deep presented the following values: pH in H2O= 6.2; Al = 0.1 cmolc/dm3; Ca=2.6 cmolc/ dm3, Mg=0.4 cmolc/dm3; K= 0.2 cmolc/dm3; available P = 2.9mg/dm3. The experimental area comprehended 52 paddocks of P. purpureum and 52 paddocks of B. brizantha, with an unit area of 720 m2, amounting to 74,880 m2. Liming and establishment fertilization were performed at the basis of 1,000 kg/ha of dolomitic limestone and 80 kg/ha of P2O5 and maintenance fertilization at the basis of 160 kg/ha of N, 60 kg/ha of P205 and 120 kg/ha of K20. Each grass was submitted to four stocking rates in a rotated grazing system with three daysâ occupation and 36 daysâ rest, resulting into a grazing cycle of 39 days. An experiment was undertaken over the period of most intense rainfall (Experiment 1) and another over the period of poorest rainfall (Experiment 2). In Experiment 1, the stocking rates were 3, 4, 5 and 6 steers/ha and in Experiment 2 the rates were 2, 3, 4 and 5 steers/ha. In Experiment 1, the stocking rate of 5 steers/ha was the one which enabled the best combination between weight gains per animal and per area with daily average of 0.560 kg/animal and 2.995 kg/ha on P. purpureum and of 0.505 kg/animal and 2.797 kg/ha for B. brizantha cv. Marandu. However, in Experiment 2, the stocking of 4 steers/ha was the one which allowed the highest animal yield with mean daily gains of 0.670 kg/animal and 2.86 kg/ha on P. purpureum and 0.503 kg/animal and 2.10 kg/ha on B. brizantha. On P. purpureum, the numbers of basal tillers ranged from 59.02 to 57.75 and 64.64 to 81.36 tillers/m2 for the stocking rates of 5 to 6, and 4 to 5 steers/ha, in Experiment 1 and 2, respectively. On B. brizantha, the numbers of basal tillers were greater, lying between 437.75 to 547.08 and 447.56 to 467.42 tillers/m2 for Experiments 1 and 2, respectively. As regards aerial tillers, P. purpureum afforded 350.83 and 278.05 tillers/m2 for the stocking rates of 5 to 6 steers/ha in Experiment 1, respectively. In the second experiment, the stocking rate of 4 steers/ha afforded 470.20 aerial tillers/m2. The rate of leaf appearance (TApF) and lengthening (TAIF) did not differ as to stocking rates, neither differed in the two experiments, the TApF lying at 0.10 and 0.13 leaves/day and the TAIF between 0.82 and 1.36 cm/leaf/day. The average numbers of live leaves/tiller were of 8.04 and 9.51 for Experiment 1 and 2, respectively.

ASSUNTO(S)

morfogÃnese brachiaria brizantha zootecnia pennisetum purpureum morphogenesis pennisetum purpureum tillers perfilhamento pasture pastejo brachiaria brizantha

ACESSO AO ARTIGO

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