Studies on Various Treatment Conditions Affecting Urea-Ammoniated Rice Straw in Ghana

Abstract

Four experiments were undertaken to evaluate the effect of various treatment conditions on the nutritive value of urea-ammoniated rice straw. Experiment 1 was carried out to determine the optimum condtions necessary for ammoniating rice straw with urea. The factors investigated included urea concentration (3 .5 , 4.0, 6.5 and 8.0% W/w), treatment period (7, 14 and 21 days) and moisture le v e l (40, 50 and 60%), in a 4 x 3 x 3 factorial experiment. Samples were analysed for to ta l Nitrogen content, neutral detergent fib r e (NDF), acid detergent fibre (ADF) and in v it r o organic matter digestibility (IVOMD). Results showed that the optimum urea concentration, treatment period and moisture le v e l ware 6.5%, 21 days and 40% respectively. In Experiment 2, the optimum conditions obtained in Experiment 1 were used to treat rice straw which was then stored in different types of silo (earthern pit, cane basket and cement cu lv e r t) to determine the best silo to use. The earthern p it was found to be the best among the silo s with its contents having a N content of 1.75% and IVOMD 52.65. Straw from the basket and culvert had 1.55% and 1.10% N and 50.03 and 43.21 IVOMD respectively. The in situ rate of ruminal dry matter (DM) disappearance (DMD) (3-72h) and extent of DM disappearance (72h) investigated in Experiment 3 indicated that urea ammoniated straw was more fermentable in the rumen of sheep compared with untreated rice straw. The rate and extent of DMD was found to be 0.48%/hr and 44.64% for untreated rice straw and 0.74%/hr and 58.97% for ammoniated rice straw. Urea treatment significantly increased straw intake but did not prevent sheep freight los s in Experiment 4. Straw ensiled with urea for 21d and fed to sheep with little supplementation can supply maintenance needs of ruminants during the dry season.