Comparing the effects of gamma ray and alkaline treatments of sodium hydroxide and calcium oxide on chemical composition, ruminal degradation kinetics and crystallinity degree of soybean straw

This research was conducted to compare the effects of gamma ray (GR) at doses of 100 and 150 kGy, alkaline treatments of sodium hydroxide (NaOH) and calcium oxide (CaO) at concentrations of 50 and 160 g/kg of dry matter (DM) respectively, and their combined use on chemical composition, ruminal degradation kinetics and crystallinity degree of soybean straw (SBS). After processing, the chemical composition of the samples was determined using the AOAC standard methods. Ruminal degradability trial was carried out by the nylon bag technique. Crystallinity degree of the samples was investigated through X-ray diffraction (XRD) technique. Using alkaline compounds in processing of SBS significantly increased the Ash amount (P < 0.0001). The greatest value was observed in CaO and CaO + GR treatments (100 and 150 kGy). The crude fiber (CF) of samples was reduced due to the effect of gamma irradiation, alkaline compounds, and their combination (P < 0.0001). Samples irradiated with 150 kGy dose of GR had the least amount of CF. The processing increased the effective rumen degradability (ERD) of DM for SBS at rumen outflow rates of 0.02, 0.05, and 0.08/h (P < 0.0001). The greatest amounts at the mentioned outflow rates were observed in GR (100, and 150 kGy), and NaOH + GR (100 and 150 kGy) treatments. Different treatments reduced the crystallinity degree of SBS compared to the control group. The least crystallinity percentage was observed in GR (150 kGy) treated samples. Totally, gamma irradiation, alkaline treatments and their combined use improved the nutritional value of SBS. In this respect, gamma irradiation was more effective than alkaline compounds.