Sistema silvipastoril e monocultivo de braquiária para recria de novilhas mestiças: disponibilidade e consumo de forragem, ganho de peso e validação do CNCPS.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Four trials were caried out to evaluate growing crossbred holstein x zebu heifers on silvopastoral system (SPS) and signalgrass (Brachiaria decumbens Stapf.) monoculture (SGM). On the first trial were evaluated dry matter avalability and chemical composition and crossbred heifers performance on silvopastoral system and signalgrass monoculture, in rainy season. Sixteen heifers with 340 kg live weight were managed on rotational stocking rate system with seven days of ocupation and 35 days of resting period. The design randomized blocks was used. There was no difference (P>0,05) between treatments on total forage dry matter (TFDM) availability and green forage dry matter (GFDM) availability, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin and in vitro dry matter digestibility (IVDMD) of green forrage available. However there was (P<0.05) reduction on the nutritive value with advance of rainy season. There was no difference (P>0.05) between treatments on the daily weight gain. The silvopastoral system showed more efficiency considering the wood production and animal production simultaneously. On the second trial was evaluated the voluntary dry matter intake (DMI) of crossbred heifers on SPS and SGM using n-alcanes technique. Twelve heifers received controled released capsules containing C32 and C36 n-alcanes. Using chromatografic analysis were determinated the n-alcanes C27 to C35 in the samples. The C33 and C31 n-alcanes showed higher concentrations.The odd n-alcanes showed higher concentrations than the even n-alcanes as was expected. The voluntay DMI, as body weight (BW) percentage, were estimated utilizing C33:C32 n-alcanes pair. There was no diference (P>0.05) in the voluntary DMI on SPS and SGM treatments. The pasture DMI was 2,36% BW and 2,22% BW in the SPS and SGM respectively. On the third trial were evaluated the chemical composition and ruminal degradability parameters of available green forage in the SPS and SGM using in vitro semi-automated gas production technique. There was no diference between SPS and SGM considering chemical composition and ruminal DM degradability, however the maximum gas production potential, ruminal fermentation rates and ruminal DM degradability declined (P<0.05) with the advance of rainy season reflecting the progressive maturation of forage along grazing cycles. On the fourth trial the CNCPS model version 5.0 was used to predict the average daily gain of crossbred heifers managed on signalgrass (Brachiaria decumbens Stapf.) pasture. Sixteen crossbred heifers with 340 kg live weight and 23 months age were used. The levels of CP, ash, NDF, ADF, lignin and nitrogenous and carbohydrate fractions of thr green forage available were analised. Data concerning to the animal, the environment and the forage chemical composition were used as inputs of the CNCPS program to estimate the crossbred heifers performance. The observed average daily gain was 623 g, while the CNCPS estimated value was 226 g, underestimating the observed values in 63.7%. The CNCPS was not efficient in the prediction of the average daily gain of crossbred heifers under grazing on signalgrass pasture

ASSUNTO(S)

degradabilidade capim-braquiária teses novilha alimentação e rações teses pastejo teses

ACESSO AO ARTIGO

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