Forage yield and quality of Leucaena leucocephala and Guazuma ulmifolia in mixed and pure fodder banks systems in Yucatan, Mexico

In tropical areas of Mexico, Leucaena leucocephala is widely used in silvopastoral systems. However, little information exists on other native woody species of high forage potential, such as Guazuma ulmifolia. The aim of this study was to evaluate the components of biomass, forage yield and quality, and availability of N in fodder banks of L. leucocephala, G. ulmifolia, and a mixture of both species during dry and rainy seasons, under sub-humid tropical conditions. The research areas were established using 30 plants in total per species, 15 in pure fodder banks and 15 in mixed forage banks, in a randomized complete block design. In both seasons, there were a significantly greater proportion of leaves in the G. ulmifolia fodder banks (71%) and in mixed fodder banks (69%) than in L. leucocephala fodder banks (64%). Consequently, these systems had leaf-to-stem ratios of 2.4, 2.2 and 1.9, respectively. The forage yield of fodder banks was not influenced by season. The mixed fodder bank had greater forage yield (5.1 t DM ha^-1) than the L. leucocephala fodder bank (3.4 t DM ha^-1) in each season. Additionally, the mixed fodder bank accumulated more forage yield during the experimental period (10.2 t DM ha^-1 year^-1) than G. ulmifolia (9.0 t DM ha^-1 year^-1) or L. leucocephala (6.9 t DM ha^-1 year^-1). The concentrations of CP, C and C:N were not influenced by season. Forage NDF and ADF concentrations were greater in the rainy season (476 g kg^-1 DM) compared with the dry season (325 g kg^-1 DM). Mixed fodder banks had the greatest N yield (185.9 kg ha^-1) and consequently the greatest availability of N (371.8 kg N ha^-1 year^-1). We conclude that, mixed fodder banks of L. leucocephala and G. ulmifolia are a better option for improving productivity and forage quality in comparison with pure fodder banks in the sub-humid tropics.