Gas production and environmental impact indicators from in vitro fermentation of diets with nopal silage (Opuntia ficus-indica L.)

Abstract

Objective: To evaluate the global warming potential index (GWPI) and in vitro gas production (GP) of diets of fattening lambs fed with silage of agricultural by-products of cactus and prickly pear (Opuntia ficus-indica L.)-hibiscus grain (Hibiscus sabdariffa L.)-oats straw (Avena sativa L.)
 Design/methodology/approach: The PG technique was used to obtain the GWPI of isoproteic (crude protein (CP)) and isoenergetic diets 15%CP and 2.8 Mcal ME (metabolizable energy)): conventional diet (CD; control), with corn silage (CSD), and with 10 or 20% of cactus-prickly pear-hibiscus grain-oats straw silage (CHSD10, CHSD20), offered during 60 d to 24 fattening bighorn sheep.
 Results: Although in vitro dry matter digestibility at 72 h (IVDMD72) was better in CSD, it was similar for CHSD10, CHSD20, and CSD. CHSD10 and CHSD20 had the lowest CH4 production, GWPI, and environmental impact index (EII). The low fermentable fraction (LF; GP=24-72 h) was related to IVDMD72.
 Findings/conclusions: The cactus pear-hibiscus grain silages inclusion had the same IVDMD72 that conventional diets but decreased the CH4 emissions and the GWPI.