Rumen Fermentation Profile and Greenhouse Gas Mitigation of Three Forage Species from Agroforestry Systems in Dry and Rainy Seasons

The variability of climatic conditions throughout the year and the physiological maturity of plant material can have effects on the nutritional value of plants and the productive performance of animals. The aim was to determine the effect of three tropical forage species (Tithonia diversifolia, Erythrina poeppigiana and Cratylia argentea) harvested at four cutting ages (30, 45, 60 and 75 days), during the dry and rainy seasons on in vitro gas production, rumen pH, volatile fatty acids (VFA) and CH4 production. A completely randomized design in a factorial arrangement (three forage species, four cutting ages and two seasons) was used. Four Brahman bulls of 250.0 ± 20.5 kg of live weight were used, provided with a ruminal cannula for the extraction of ruminal fluid. The animals were kept separately in individual pens, where they were fed with P. maximum and water was provided ad libitum. Gas production among forage species was lower (p = 0.0001) in T. diversifolia and E. poeppigiana in the dry season. The cutting age had an influence on gas production, showing lower production (p = 0.0164) at 30 and 45 days in the dry season. The VFA production showed differences for the effect between forages in the rainy season, with higher values (p E. poeppigiana, C. argéntea and T. diversifolia respectively. CH4 production showed differences between forage species, showing the lowest (p = 0.0001) production of CH4 in T. diversifolia for the dry and rainy seasons. It is concluded that the use of shrubby species (T. diversifolia, E. poeppigiana and C. argéntea) in ruminant production systems in the rainy and dry seasons, with an early regrowth age (30 and 45 days), present a promising alternative on the reduction of CH4