Effect of Different Levels of Irradiation of Soybean on In Sacco Degradability of Dry Matter and Crude Protein

Three crossbred calves fitted with rumen fistula, maintained on wheat straw and concentrate mixture (60:40) along with 5 kg green oats were used to study the in sacco ruminal degradability of soybean irradiated at 0, 1, 2, 5, 10 and 20 kGy levels. Samples (5g) in nylon bags were incubated in rumen for 4, 8, 12, 18, 24 and 36 h. NBDMD and NBCPD were reduced from 57.4 ± 1.6 and 57.9±1.8 to 52.8±2.1 and 51.9±2.5% at 4h, on increasing the levels of irradiation from 0 to 20 kGy, however significant differences were observed only at 10 and 20 kGy levels. The rate of DM and CP degradation was 0.068 and 0.074 in unirradiated soybean which was reduced to 0.054 and 0.066 in soybean irradiated at 20 kGy level. EDMD and ECPD values also declined gradually from 75.7 and 76.5 at 0 kGy level to 72.6 and 71.5% at 20 kGy dose level of irradiation. RDP values were lowered only by 5% in samples irradiated at 20 kGy. Thus irradiation did not to improve the UDP value to an appreciable extent which was expected from reduction in solubility 31.3–24.2 in Vansoest buffer and from 36.9 to 27.2 in McDougall's buffer respectively.