Chemical composition and fermentative characteristics of elephant grass (Pennisetum purpureum Schum.) cv. Roxo silages with increasing levels of Annato (Bixa orellana L.) seed by-product.

Abstract

This research aimed to evaluate the chemical composition and the fermentative characteristics of elephant grass (Pennisetum purpureum Schum.) silages with annatto (Bixa orellana L.) seed by-product (ASB) addition. Experimental silos of PVC pipe (340 x 100 mm) were used in a completely randomized design with five addition levels (0; 5; 10; 15 and 20%) of ASB and four replicates. After 64 days of ensiling, the silos were opened and samples were collected to determine dry matter (DM), ether extract (EE), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose, (HEM) amonnia nitrogen (N-NH3) levels and the pH values. The levels of DM were enhanced with the ASB addition, reaching 28.00% of DM with 18.95% of ASB addition, which is minimum for the predomination of lactic fermentation. The minimum CP level (6%) necessary for a satisfactory ruminal functioning was obtained with 4.04% of ABS addition. The levels of NDF and ADF were reduced in 0.64 and 0.81 percentual units, respectively, for each 1% of ASB addition. All silages presented N-NH3 levels below 12% and pH values below the critical limit (4.2), promoting the occurrence of a good fermentative process. It can be concluded that the annatto seeds by-product addition promotes appropriate fermentation and improves the chemical characteristics of elephant grass silages. Moreover, there is no restriction to its inclusion up to 20% of natural matter.