The Effects Of Moisture, Urea Level And Method Of Application On The Chemical Composition And Digestibility Of Native Grass Hay In The Caribbean

Ruminant livestock production in the Caribbean is sev erely hampered by seasonal deficiencies in the quality and quantity of forage and recurrent body weight losses. A series of experiments were conducted on St. Croix to evaluate the use of urea-ammoniation for improving the quality of locally produced guineagrass (Panicum maximum) hay. Initially, 5-kg samples of hay were reconstituted to 25 or 40% final moisture concentration and treated with urea at 0, 4, 6 or 8% of forage dry matter (DM), with or without urease addition. Urease application had no influence (P > 0.10) on any forage quality measure and there were no interactions between urease and moisture or urea treatments. However, increasing urea treatment level resulted in linear (P = 0.0001) increases in crude protein (CP) (4.2 to 18.4%) and in vitro organic matter digestion (IVOMD) (30.7 to 42.0%) of the hay. The quality improvement was greater at the 25% than at the 40% moisture concentrations. Subsequently, round bales (322 + 25 kg) of guineagrass hay were reconstituted to 25 or 40% final moisture concentration and treated with urea (0,4 or 6% of forage DM) by cither spraying the urea solution on both fiat surfaces of bales or by low pressure (10 psi) injection at five sites on each fiat surface. Urea treatment increased CP and IVOMD when the urea solution was sprayed-on rather than injected into bales. Neutral detergent fiber (NDF) concentration in hay was also rcduccd (74.3 to 72.5%) when solution was sprayed onto the hay. A lower ammoniation effectiveness was observed at the 40% moisture concentration because of greater urea seepage losses. From these preliminary results, diets based on 25% moisture, sprayed-on, urea treated hay described above, were selected for sheep feeding trial.