Fermentability and Nutritive Value of Corn and Forage Sorghum Silage When in Mixture with Lablab Bean

Abstract

ABSTRACTIntercropping legumes with nonlegume crops has shown benefits in improving dry matter (DM) yield, but additional information is needed when crop mixtures are ensiled. This study assessed the fermentation characteristics of forage corn silage (Zea mays L.) (CS) and forage sorghum silage [Sorghum bicolor (L.) Moench] (FS) when mixed with different proportions of lablab bean [Lablab purpureus (L.) Sweet] (LB). Corn, FS, and LB were grown in separate fields at two locations in 2009. At each location, crops were cut and chopped separately and taken to the laboratory for ensiling. Six mixtures were handmade on a percentage fresh weight basis for each CS–LB and FS–LB combination, including (i) 100:0, (ii) 90:10, (iii) 75:25, (iv) 50:50, (v) 25:75, and (vi) 0:100. For each mixture, a 1‐L glass jar (mini‐silo) was filled with 500 g of fresh material, with four jars per treatment. Forage in mini‐silos was fermented for 60 d at room temperature (25°C). Analysis was conducted for nutritive value and fermentation characteristics. The greatest impact of mixing LB with CS or FS was on crude protein (CP) and acid detergent fiber (ADF) concentrations, with no significant impact on neutral detergent fiber (NDF). Averaging across CS and FS, CP concentration increased from 87 to 173 g kg−1 and ADF concentration from 253 to 306 g kg−1 as LB increased from 0 to 75% in the mixture. Increasing LB in the mixture also increased other constituents, such as pH and lactic and acetic acid concentrations. Adding LB to CS or FS for silage can have a positive effect on the final nutritive value, but additional research is needed to assess the impact in cattle.