Nutritive value and herbage mass of Pueraria phaseoloides (tropical kudzu) in un-utilized open grasslands in north-eastern and central Trinidad and Tobago

Abstract

Pueraria phaseoloides is an important forage for ruminants in the tropics. However, its nutritive value and availability in areas easily accessed by ruminants and ruminant farmers in Trinidad and Tobago is unknown. This study, therefore, evaluated the effects of harvest date and location on the nutritive value, herbage mass and crude protein yield of P. phaseoloides in un-utilized open grasslands in three locations with high livestock density in Trinidad. Pueraria phaseoloides herbage (whole fraction and leaf) trailing on the upper canopy of open un-utilized grasslands were harvested in the late wet season of 2019 (October - November), early dry (January - February) and early wet (July - August) seasons of 2020 following a stratified random sampling scheme. The crude protein (CP) concentrations of P. phaseoloides leaves (235 g/kg DM) and whole fraction (217 g/kg DM) were highest in Wallerfield during the early wet season. Neutral detergent fibre (NDF), acid detergent fibre (ADF) and lignin were lowest in the early dry season (P < 0.01). Crude protein yield (376–478 kg CP ha−1) and herbage mass (1,742–2,654 kg DM ha−1) were highest during the late wet and early dry season, respectively. In vitro organic matter digestibility (IVOMD) of P. phaseoloides leaf (548–598 g/kg) and whole fraction (549 –580 g/kg) were highest in the late wet season. It was, therefore concluded that open un-utilized grasslands in Trinidad and Tobago produced significant amount of P. phaseoloides herbage year-round to support ruminant livestock production. However, the nutritive value, herbage mass and CP yield of P. phaseoloides herbage were highest during the late wet and early dry seasons.