Elephant grass [Cenchrus purpureus (Schum.) Morrone] is a tropical forage grass widely used in ruminant feeding in tropical and subtropical areas, mainly in cut-and-carry systems due to is high potential for herbage accumulation. However, most common genotypes (tall genotypes) generally show an early stem elongation, which contributes to a rapid decline in the forage nutritive value. Dwarf elephant grass types usually present less stem elongation and may be considered an option for the production of high nutritive value forage in cut-and-carry systems. The aims of this study were to evaluate and explain variations in herbage characteristics and kinetics of in vitro gas production of irrigated elephant grass genotypes (two tall-types – Elephant B and IRI-381 – and two dwarf-types genotypes – Mott and Taiwan A-146 2.37) under two harvest frequencies (60 and 90 days) in the dry and rainy seasons of two years. Herbage characteristics varied among genotypes, harvest frequency and seasons. Dwarf genotypes showed better in vitro fermentation parameters with the advancement of maturity compared to the tall size genotypes. Harvesting tall genotypes at a higher frequency (60-day) contributed to improving the fermentation, while dwarf elephant grass maintained greater fermentation when less frequent harvests were adopted (90-day).

The objective of this study was to describe and explain the effect of adding corn meal (CM) on losses, fermentation characteristics and nutritional value of silages from two elephant grass [Cenchrus purpureus (Schumach.) Morrone] genotypes (Taiwan A-146 2.37 and IRI-381) mixed with butterfly pea (Clitoria ternatea L.) legume. The forage was harvested at 75 days of regrowth from elephant grass plots intercropped with butterfly pea legume and ensiled with or without CM at 5% of dry matter (DM) content. Greater gas losses (12 g/kg) and pH (4.2) were observed in the Taiwan A-146 2.37 + butterfly pea silages. The greatest crude protein content was observed in the ‘Taiwan A-146 2.37’ + butterfly pea silage added with CM (116 g/kg). Silages with additive and those containing IRI-381 had a greater acid detergent fibre content (367 and 366 g/kg, respectively). CM increased the silage DM (221 g/kg), remaining water-soluble carbohydrates contents (26 g/kg) and in vitro digestibility of DM. The aerobic stability was maintained until 45 h after opening the silos. All silages presented a good fermentative profile and were not affected by the relatively large proportion of butterfly pea (>34%) in the ensiled mass as indicated by the reduced contents of butyric acid and ammonia nitrogen. CM reduces total losses, increases DM recovery and improves the nutritional value of silages from mixed elephant grass–butterfly pea legume.