Water hyacinth (Eichhornia crassipes) : biomass production, ensilability and feeding value to growing cattle

Water hyacinth has now spread to all tropical and subtropical countries and is regarded as one of the world's most invasive aquatic plants. Water hyacinth (WH) is also known to have significant ecological and socio-economic effects. A potential of WH as feed for ruminants was evaluated through four studies with respect to: a) biomass yield and nutritive value of WH grown in two different habitats (pond and river), harvested in three cuts at four cutting intervals; b) fermentation quality of WH with and without additives; c) feeding value to growing cattle of ensiled; or d) fresh WH at four different levels of inclusion in a rice straw based diet. Compositional changes as an effect of cut were generally small in the pond or negligible in the river habitat. Cutting interval had some minor effects on WH composition. The most obvious changes across habitats were an increase in neutral detergent fibre (NDFom) content from approximately 510 to 550 g/kg dry matter (DM) and a decrease in crude protein (CP) from approximately 210 to 170 g/kg DM when cutting interval was increased from 4 to 7 weeks. Water hyacinth has a potential as livestock feed. Results showed high CP contents (176 to 195 g/kg DM) and high DM yields for the two habitats of approximately 400 kg/ha/week. Application of sugars in the form of molasses or rice bran as a water absorbent resulted in a rapid decrease of pH to approximately 4.0. This level was maintained until at least day 14 and then gradually increased to approximately 4.8 at day 56. Ammonia nitrogen and fermentation end-product concentrations were within acceptable limits. The best fermentation quality was achieved in the silages with added molasses, absorbent or with a combination of the two and an inoculant. At the highest WH level, cattle consumed >50% ensiled WH which provided nearly three times as much metabolisable energy as when none was fed. These results were mainly due to an increasing digestibility with increasing level of ensiled WH. Cattle fed fresh WH showed abnormal rumen distension and a gradual increase of rice straw intakes over time. A long adaptation period to fresh WH is recommended and an inclusion level of not more than 30% of diet dry matter.