Extracted Saponin from Sapindus rarak and Hibiscus sp. as an Additive in Cassava Leaf Silage: Effects on Chemical Composition, Rumen Fermentation and Microbial Population

This study aimed to evaluate the addition of saponin extracts from lerak fruit (Sapindus rarak) or hibiscus leaf (Hibiscus sp.) on chemical composition, in vitro rumen fermentation and microbial population of cassava leaf silage. Lerak and hibiscus extracts were added to cassava leaf by following a factorial design 2 × 3, in which the first factor was saponin source (Sapindus rarak or Hibiscus sp.) and the second factor was addition level (0, 2 or 4% of cassava leaf dry matter). Cassava leaf was then ensiled in a lab-scale silo (1 L capacity) for 30 d under room temperature. The silage was subjected to further chemical composition determination and in vitro rumen fermentation analysis, including rumen microbial population by using real-time PCR. Results showed thatthe chemical composition of cassava leaf silage added with various levels of lerak and hibiscus extracts showed significant differences (P<0.05) for a number of variables such as crude protein, ether extract and saponin. The addition of 4% lerak extract on cassava leaf increased significantly gas production after 24 and 48 h, and organic matter digestibility than that of control. The addition of lerak extract at 2% or 4% hibiscus extract in cassava silage significantly decreased (P<0.05) ruminal ammonia concentration. However, the addition of lerak or hibiscus extract to cassava leaf silage did not alter rumen microbial population. It is concluded that the addition of lerak extract at a level 4% to cassava leaf silage increases gas production, organic matter digestibility, and decrease ruminal ammonia concentration.