Effects of chemical processing on the nutritional value of green pea (Pisum sativum) residues

This study was conducted to investigate the effects of processing with water (H2O, 2.5 l/kg), calcium oxide (CaO, 160 g/kg), hydrogen peroxide (H2O2, 57 mL/kg), and sodium hydroxide (NaOH, 50 g/kg) on the nutritional value of green pea (Pisum sativum) residues (GPR). Chemical composition of GPR samples was determined using the standard methods of AOAC. Ruminal degradability trial was carried out using nylon bag technique. Gas production test was performed to estimate in vitro fermentation parameters. In vitro digestibility of the samples was determined by batch culture method. Results demonstrated that the chemical composition of GPR was affected by the processing method (P<0.05). Ash content was increased by CaO, H2O2, and NaOH treatments compared to the control treatment. All treatments led to a decrement in crude protein (CP) content with the least CP amount in CaO treatment. Acid detergent fiber (ADF) content of CaO treated samples was also lower than other treatments. The treatments, except CaO, caused an increase in effective rumen degradability (ERD) of dry matter (DM) at rumen outflow rates of 0.02, 0.05, and 0.08 h-1 (P<0.05). The greatest ERD was observed in H2O2 treatment. The potential of gas production (b fraction) was increased by processing with H2O2 and NaOH as compared to the control (P<0.05). Processing with NaOH and H2O2 increased (P<0.05) the concentration of short chain fatty acids (SCFAs) and metabolizable energy (ME) content. The DM digestibility (DMD) and organic matter digestibility (OMD) rates were greater in H2O2, NaOH, and CaO treatments as compared to the control (P<0.05). All treatments, except H2O, increased the partitioning factor (PF) and efficiency of microbial biomass (EMB) of GPR samples (P<0.05). In conclusion, considering nutritional value and in vitro degradability parameters, processing GPR with NaOH and H2O2 was more beneficial compared to the CaO and control treatments.