Quantifying ruminal fermentation and methane production using the in vitro gas technique in the forages of a sheep silvopastoral system in Chiapas, Mexico

Abstract

Ruminal fermentation and methane production in a sheep silvopastoral system were quantified with the in vitro gas production technique. Evaluations were done of local energy sources (molasses, Zea mays L. and Musa paradisiaca L.), of the base forage (Panicum maximum cv. Tanzania), of forage tree foliage (Gliricidia sepium (Jacq.) and Leucaena leucocephala cv. Cunningham), and diets combining these elements. Ruminal fluid was collected from five sheep (Pelibuey x Katahdin; 40 ± 3 kg). Five treatments (diets) containing different mixtures of forage tree foliage, energy sources and the base forage were analyzed in a completely random experimental design. Maximum gas volume production (V) was observed in M. paradisiaca (544 ml/g-1 DM) and Z. mays (467 ml/g-1 DM) (P≤0.05). The lowest V values were for the foliage of G. sepium (253 ml/g-1 DM) and L. leucocephala (180 ml/g-1 DM) (P≤0.05). Of the diets, D4GMP (48% P. maximum, 30% G. sepium, 7% Z. mays, 15% M. paradisiaca) had the highest V value. Methane production ranged from 6.31 to 9.60 L/Kg digested DM, and did not differ between treatments (P>0.05). Data were used to generate a potential fermentable gases emission index, which suggested that the diets containing slow fermenting carbohydrates resulted in higher gas emission rates. Inclusion of forage trees and local energy sources in sheep silvopastoral management systems can improve diet quality and contribute to reducing CH4 emissions.