Effect of Urea Level, Moisture Content and Incubation Period on Nitrogen Fractions and In Vitro Evaluation of Mustard Straw

Ground mustard straw (MS 5 mm) in the lots of 100 g was treated with four levels of urea (0, Ul; 3, U2; 4, U3 and 5, U4; per cent w/w) each at three moisture levels (55, Ml; 65 M2 and 75 M3; per cent) and kept at 40°C for three incubation periods (7, PI; 14, P2 and 21, P3 days) under air tight conditions using 4x3x3 factorial experiment with three replications. After the stipulated period of incubation, DM, total nitrogen (N), ammonia nitrogen (NH -N) and in vitro dry matter digestibility (IVDMD) were determined. Urea levels increased (P<0.01) the N content of MS from 1.9 (U2) to 3.0 (U4) times the initial value. However on increasing the treatment period N content of decreased (P<0.01). The NH -N concentration increased (P<0.01) due to increase in urea level moisture content and treatment period. The increase in IVDMD values (P<0.01) due to urea treatment was upto 28.6% (U3) in comparison with untreated MS and the values were reduced (P<0.01) when moisture content was raised beyond 65 per cent. IVDMD was progressively declined (P<0.01) with increase in incubation period. It is concluded that urea treatment (4% urea 55% moisture and 7 days incubation) was effective in improving the N content and the digestibility of mustard straw.