In vitro ruminal fermentation kinetics of alternative supplemental feeds formulated with by-products from food crops

Abstract

Commercial feed is an important component of ruminant production systems in Trinidad and Tobago. However, most farmers are unable to afford commercial feeds because of recent hike in prices and has resorted to available alternative feedstuffs. This study evaluated the in vitro ruminal fermentation kinetics and fermentation profile of two alternative supplemental feeds formulated from available agriculture by-products to determine their usefulness as alternatives to commercial feeds for small ruminants. Two iso-nitrogenous and iso-caloric alternative supplemental feeds were formulated with available agriculture by-products (cocoa hulls and shells, coconut meal, powdered bean, rice bran, rice hulls and corn stover). One was formulated without coconut meal (Supp.-CM) and the other without corn stover (Supp.-CS). In vitro ruminal gas production of the alternative supplemental feeds and a commercial feed was measured at 2, 4, 6, 8, 10, 12,18, 24, 36, 48, and 72 hours after incubation with buffered rumen inoculum. Gas production rate peaked 6-hours post incubation in the commercial feed and around 12–18-hours post incubation in the alternative supplemental feeds. The gas produced for the immediately soluble fraction (a) and potential degradability (PD) was highest in the commercial feed. However, gas production from the insoluble fraction (b) was similar for the commercial feed and Supp.-CS (246–262 g/kg^− 1). Gas production rate constant for insoluble fraction (c), the lag phase, ruminal pH and partitioning factor (PF) did not differ between feed types. The estimated amount of methane produced from the alternative supplemental feeds (49.1 ml/g DM^− 1) were significantly lower than the commercial feed (40.5–41.5 ml/g DM^− 1) while organic matter digestibility (iOMD) was highest in the commercial feed (586 g/kg). Supplemental feeds from available agriculture by-products has potential to be used as alternatives to commercial concentrate feeds for ruminants in Trinidad and Tobago due to comparable fermentation efficiency (PF), fermentation of insoluble fraction and reduced estimated methane production. However, potential deleterious effects of Supp.-CM and Supp.-CS at the on-set of ruminal fermentation is concerning and may require further investigation.