Influence of the phenological stage at harvest of sesame (Sesamum indicum) on silage quality

Abstract

The objective of this study was to evaluate the effect of harvesting the sesame plant at different phenological stages on silage quality. A completely randomized design with five replications was adopted. The treatments were different phenological stages of the plant at harvest (WOP = Without pod, WP = With pod, MG = Milky grain, MTG = Mature grain). The chemical composition was determined after opening the silos. Fermentation characteristics were evaluated by measuring pH, N-NH3 concentration, organic acid contents (acetic, butyric, propionic and lactic), quantification of losses through gases and effluents, dry matter recovery (DMR) and evaluation of the aerobic stability of the silage. Dry matter in situ degradability (DM) was evaluated using two rumen-cannulated sheep. All data were analyzed through mixed models. The means of chemical composition, fermentation characteristics and losses were compared by the Tukey's adjusted test and significant differences were declared when P ≤ 0.05. The chemical composition of the sesame silage was affected by the plant's phenological stage at harvest. There was significant effect (P < 0.05) on all chemical composition variables evaluated in this study. There was no effect (P > 0.05) on fermentative characteristics. Losses through gases and effluents reduced at older phenological stages of the sesame plant. The highest DMR (949.7 g/kg) was observed in the silage of plants harvested at the MTG stage. The most stable silages were those made with plants harvested at the WOP stage (64 h), followed by MG (48 h). The highest levels of degradation of the soluble fraction were found in the silage of plants harvested at WOP (366.3 g/kg) and MG (366.1 g/kg) stages, respectively. The highest potential degradability was found in the silage of plants harvested at the MTG stage (552.7 g/kg), which consequently had the shortest lag time (6.60 h). The effective degradability at different passage rates 20, 50, 80 g/ kg /h was higher in the silage of plants harvested at WOP and MG stages. The sesame plant can be harvested at the phenological stages with pod, milky grain and mature grain for silage making.