Effects of microwave irradiation on nutritional value of native rapeseed meal

In this research, effect of treating native rapeseed meal (NRSM) with microwave irradiation on chemical composition, glucosinolate, phytic acid, ruminal dry matter (DM) and crude protein (CP) degradability, metabolizable protein (MP) and in vitro CP digestibility of before and after irradiation were investigated. At first, moisture content of samples (three sample of 500 g) were increased to 250 g/kg. Then, were subjected to microwave irradiation at a power of 800 W for 2, 4 or 6 min. Chemical composition, phytic acid and glucosinolate contents of untreated and irradiated samples were determined by standard methods. Degradation kinetics of CP were determined according to in situ procedure. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used to monitor protein subfractions and the fate of true proteins of untreated and irradiated feed samples in the rumen. The results of experience showed that irradiation decreased the total glucosinolate and phytic acid content of NRSM (p < 0.001). Ruminal disappearance of DM and CP in different incubation times linearly increased (p < 0.05) as irradiation time increased. Based on results of this study, microwave irradiation more than 2 min decreased glucosinolate and phytic acid content and ruminal degradability of CP and increased by pass protein, in vitro CP digestibility and MP of NRSM and eventually, microwave irradiation was effective in improving nutritional value of NRSM for using in ruminant diet.