Effects of different regrowth ages and cutting heights on biomass production, bromatological composition and in vitro digestibility of Guazuma ulmifolia foliage

Abstract

Guazuma ulmifolia (G. ulmifolia) is a tropical tree species with potential in ruminant feeding. The objective of this study was to evaluate the biomass production, chemical composition and in vitro digestibility of G. ulmifolia foliage at different regrowth ages and cutting heights in two seasons. Sixty G. ulmifolia trees were selected and distributed in two heights (25 and 50 cm) and three regrowth ages (30, 60 and 90 days). A randomised design with a 2 × 3 × 2 factorial arrangement was used. In both seasons, the biomass production and the nutritional content increased (P < 0.05) with increasing regrowth age, except for crude protein (CP), which was decreased in the dry season (P < 0.05) at a cutting height of 25 cm. In the rainy season, the parameters, dry matter and CP were higher at a cutting height of 25 cm and at 60 and 90 days after regrowth (P < 0.05), while NDF, ADF and hemicellulose were lower (P < 0.05). There was a similar behaviour in the dry season, although at a cutting height of 50 cm. In-vitro digestibility was higher in the rainy period (P < 0.05), although in the dry season, digestibility at a cutting height of 25 cm was greater. In the rainy period, forage should be collected at a height of 25 cm and after a regrowth period of 60 days, while in the dry period, the ideal cutting height is 50 cm, at a regrowth age of 60 days.