Acta Scientiarum: Animal Sciences (Apr 2008)
Degradabilidade in situ da matéria seca e da fração fibra da cana-deaçúcar fresca ou ensilada e da silagem de milho em diferentes ambientes ruminais = In situ degradability of dry matter and fiber fraction of fresh or ensiled sugar cane and corn silage under different ruminal conditions
Abstract
O presente trabalho teve como objetivo determinar degradabilidades in situ da matéria seca (MS), fibra em detergente neutro (FDN) e ácido (FDA) da cana-de-açúcar in natura (CF) ou ensilada (SC) e da silagem de milho (SM) em diferentes ambientes ruminais, utilizando a técnica in situ macro-bag. Foram utilizadas duas vacas canuladas, alimentadas com rações formuladas de maneira a serem obtidos diferentes ambientesruminais, de acordo com os volumosos: CF ou SC. A degradabilidade in situ dos volumosos foi avaliada utilizando-se sacos com poros de 50 μm, medindo 20 x 40 cm, sendo os volumosos incubados in natura nos horários 0, 12, 24, 48, 72 e 96h. Os ambientes ruminais consistiram de um arranjo hierárquico 3 x 2 (3 forragens x 2 ambientes ruminais). Amostras de fluido ruminal foram colhidas para a determinação do pH e nitrogênio amoniacal. O horário de colheita afetou significativamente o pH ruminal. Foram observadas diferenças significativas (p The objectives of this study were the in situ dry degradability (ISD) determination of dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF) of fresh (FSC) or ensiled sugar cane (SCS), as well as corn silage (CS), under different ruminal conditions. Two Holstein cows fitted with ruminal canulas were utilized (live weight of 450 kg) and fed diets formulated to obtain different ruminal conditions by the inclusion of two forage sources: FSC or SCS. The ISD nutrients were evaluated by the use of 20 x 40 cm nylon bags, with 50 mm porosity, beingthe different forages incubated in natura at 0, 12, 24, 48, 72 and 96 hours. Treatments consisted of a 3 x 2 hierarchy design (3 forages x 2 ruminal conditions). Rumen fluid samples were taken for the evaluation of rumen pH and ammonia-N. Sampling time significantly affected ruminal pH (p < 0.05). Differences were observed (p < 0.05) for the soluble fraction (a), potentially degradable fraction, undegradable fraction and potential degradability of the DM of the forages. As for degradation of NDF and ADF of forages incubated under different ruminal conditions, differences (p < 0.05) were observed only for the “a” fraction. The ruminal condition resulting from ensiled sugar cane was favorable for the degradability of the evaluated forages.
