Adição de celulase e período de fermentação na composição bromatológica e digestibilidade de silagens de capim mombaça

Abstract

The present study was carried out to determine the effect of cellulase added to the silage process of the Mombaça grass, on the bromatological composition, cell wall digestibility and the minimum fermentation period to open the silo. The experimental design was completely randomized, with four replicates, in a 3 x 3 factorial scheme, three cellulase weight / weight (0, 3 and 6%) and three fermentation periods (30, 60 and 120 days), totaling 36 experimental silos. For silage, the mombaça grass was cut at an approximate height of 80 cm, at 20 cm from the ground level. The addition of the enzyme was efficient in improving the fermentative and bromatological parameters of the silages of the cultivar in question. The addition of cellulase promoted a reduction of 5.7% in the NDF contents in relation to the control, but there was also a reduction in the fiber digestibility of 6.6% in relation to the control. However, the digestibility reduction was lower in proportion to the reduction of NDF, which allowed to increase net lactation energy by 15% and NDT by 11%. The enzyme use also resulted in lower pH (4.74 vs 3.73 control and with cellulase) and higher titratable acidity (5.86 and 12.77 control and with cellulase), indicating that the cellulase allowed a fermentative process within the recommended standards. After 30 days of silage, the silages had already completed the anaerobic fermentation cycle and would be fit for consumption. After the 60 day period, the silage had a reduction of the quality parameters indicating that tropical grass silages should be used with up to 60 days of fermentation.