Fiber Content and Relative Feed Value Estimation of Gamma Irradiated Rice Straw

Abstract

Ionizing irradiation is an alternative treatment to reduce the cell wall constituents and improve the nutritional value of substrates. The purpose of this research was to evaluate the fiber content and relative feed value of rice straw after gamma irradiation treatment. Rice straw was obtained from Sidenuk rice variety. Two polyethylene packages of samples were irradiated in Iradiator Karet Alam (IRKA), Indonesia at doses of 5 and 10 kGy in the presence of air. Treatments includes untreated/unirradiated, 5 kGy and 10 kGy irradiated rice straw. The observed parameters were neutral detergent fiber (NDF), acid detergent fiber (ADF), dry matter digestibility (DMD), dry matter intake (DMI) and relative feed value (RFV) estimation. The change of fiber content was also qualitatively observed by Fourier Transform Mid-Infrared (FTIR). This research was arranged into a completely randomized block design with five replications. The results showed that there was no difference in NDF and ADF content between all treatments. There was also no difference in RFV due to the results of NDF and ADF measurements. Interestengly, there was a strong absorption with a wide and strong band centred at 3331 cm−1 (O-H stretch) only observed in the untreated sample. Meanwhile, a peak signal was observed at 1722 cm−1 only in 5 kGy and 10 kGy irradiated rice straw spectra. This could affect in the increased of hemicellulose compounds after irradiated treatments. It can be concluded that gamma irradiation treatment at doses of 5 and 10 kGy has not been able to influence the fiber content and relative feed value of rice straw. However, there was a tendency for hemicellulose compounds increasingly due to irradiation treatment.