Abstract

Barley Grain (BG) was sprouted using agricultural by-products such as Rice Straw (RS), Wheat Straw (WS), and Bean Straw (BS) as bedding media. The sprouted barley treatments were Sprouted Barley on Rice Straw (SBRS), Sprouted Barley on Wheat Straw (SBWS) and Sprouted Barley on Bean Straw (SBBS). Irrigation was carried out with a 0.5% urea aqueous solution via an automated fogging system using a digital timer. The Dry Matter (DM) content was almost similar for the different ingredients. While BG recorded the highest contents of Organic Matter (OM), Crude Protein (CP), Either Extractable (EE) and Nitrogen-Free Extract (NFE), whereas, RS, WS, and BS had the higher contents of Crude Fiber (CF), Fiber Fractions (NDF, ADF, ADL, cellulose and hemicellulose) and ash. Comparison of the proximate composition of different straw types showed that WS had higher contents of OM, NFE, CF, NDF, ADF, cellulose, and hemicellulose, RS had higher ash content and BS had higher contents of CP and ADL. Both fresh and dry crop biomass were significantly higher (P<0.05) in SBBS compared to SBWS, with slight differences with SBRS. Furthermore, SBBS had significantly (P<0.05) higher contents of DM and ADL, SBWS had higher contents of OM, NFE, CF, NDF, ADF and cellulose, and SBRS had higher contents of ash and hemicellulose. Meanwhile, CP and EE contents were almost similar for different sprouted barley grains. Also, Total Digestible Nutrients (TDN) and Digestible Crude Protein (DCP) contents tended to increase in SBWS, with slight differences (P>0.05) with both SBRS and SBBS. Accumulative gas production during the different incubation times was significantly higher (P<0.05) in SBRS followed by SBWS, but SBBS values were lower. Gas production also increased sharply in the first 12 hours of incubation, then increased steadily from 12 to 24 hours, and then increased slightly to 96 hours. The gas production kinetic parameters of the rapidly degradable fraction
a. The potentially degradable fraction
b. And the gas production rate
c. Were significantly higher (P<0.05) in SBRS followed by SBWS, but SBBS had the lowest values.

Gas Production from Fermentation of the Soluble Fraction (GPSF) and insoluble fraction (GPNSF) were significantly higher (P<0.05) in SBRS followed by SBWS and lower values were in SBBS. Methane production during the different incubation times was significantly lower (P<0.05) in SBRS, followed by SBWS, but SBBS had higher values. Furthermore, methane production increased sharply during the first 12 hours of incubation, then steadily increased during the period from 12 to 24 hours and increased slightly as the incubation period extended to 96 hours. Short Chain Fatty Acids (SCFA) concentration and Protein Production (MCP) were significantly higher (P<0.05) in SBRS followed by SBWS, while it was lower in SBBS. Predicted Dry Matter Intake (DMI) expressed in kg/day or kg/kg metabolic Live Body Weight (LBW0.75), Effective Dry Matter Degradability (EDMD) and Organic Matter Digestibility (OMD) were significantly higher (P<0.05) in SBRS followed by SBWS, but SBBS recorded the lowest values. Gross Energy (GE) was significantly (P<0.05) higher in SBWS and SBBS than that of SBRS. Metabolizable Energy (ME) and Net Energy (NE) were significantly higher (P<0.05) in SBRS followed by SBWS, while SBBS recorded the lowest values. Whereas Digestible Energy (DE) contents tended to increase in SBWS with insignificant (P>0.05) with both SBRS and SBBS. From these results, it can be concluded that sprouting barley grains on rice, wheat, and bean straws is a good source of green fodder and contributes to the utilization of poor-quality agricultural wastes in ruminant nutrition. Sprouting barley grains on straws increased biomass production, improved proximate composition and nutritional values and energy contents, increased feed intake, rumen fermentation, and microbial protein production, in addition to reduced methane emissions, with the best results achieved with rice straw.

Keywords:Sprouted barley grain; Rice; Wheat and bean straws; Composition; Biomass yield; Nutritional values; In Vitro gas production