Microbial and fermentative characteristics and rumen degradation kinetics of saboya grass (Megathyrsus maximus) silage with increasing levels of passion fruit (Passiflora edulis) by-product

The knowledge of agro by-products and their inclusion in animal feeding offers new strategies for a sustainable livestock development in tropical areas. The aim of this study was to contribute to the knowledge in microbiology and aerobic stability of the Saboya grass silages with increasing levels of inclusion of passion fruit rind, and their in situ rumen degradation kinetics. Four levels of passion fruit rind were added (10, 20, 30 y 40% on fresh basis) into Saboya grass grown for 45 days (d). The silage of chopped and homogenized products was achieved in experimental micro-silos (five replicates per treatment). After 21 d, the micro-silos were opened and the chemical composition, microbial counts, the aerobic stability temperature (T) and pH for 6 d-,and the degradation of dry matter (DM) -0, 3, 6, 12, 24, 48 y 72 hours-were determined. No important effects were found on the microbiology in the combinations between 10 and 40% of passion fruit hulls and Saboya grass. All the treatments showed a low aerobic stability with an increase of T-a over 1 degrees C after 6 d and more than 0.5 units of pH after 2 d. The DM degradation was higher in the silages with 30 and 40% of passion fruit rind, which might indicate a higher nutritive value. The silage of Saboya grass added with passion fruit rind could be an efficient and environmental acceptable way to preserve feeds in order to sustain the productivity of the herds during the dry season. However, the higher aerobic instability should be considered in the silage management to avoid nutritive and material losses.