Biochemical evaluation of autoclaved and solid state fermented tropical pasture grasses

Abstract

Grass constitutes the nutritional basis for most livestock, whether domesticated or wildlife. The present study evaluates the enhancement of the nutritional value of five different pasture grasses: Palisade grass (Urochloa brizantha), Biscuit grass (Paspalum vaginatum), Giant star grass (Cynodon plectostachyus), Goose grass (Eleusine indica), and Stubborn grass (Sida acuta) for use as animal feeds and xylanase production. The grasses received two different treatments: Autoclaving and solid state fermentation. Analysis carried out on untreated, autoclaved and solid state fermented grasses showed an increase in pH for all autoclaved grasses and solid state fermented grasses when compared to the control. The total flavonoid content was significantly improved in the solid state fermented grasses (116.7 ±1.4 μg/ml for palisade grass). There was a significant increase (p<0.05) in soluble protein content from 21.86 ± 1.7 to 44.06 ± 1.3 mg g -1 of palisade grass fermented with Rhizopus oligosporus. Similarly, there was a substantial rise (p < 0.05) in glucose concentration of solid state fermented biscuit grass (54.6 ± 3.3 mg g -1 ) when compared to the control (32.4±1.6 mg g -1 ). The total flavonoid content was improved in the solid state fermented (73.53 ± 0.35 μg/ml for biscuit grass) compared to the control (64.6±3.35μg/ml). Biscuit grass subjected to solid state fermentation was more potentially active (62.4±1.3μg/ml) when compared to the control (42.2 ± 0.9 μg/ml). For xylanase production, solid state fermented goose grass showed the highest enzymatic activity. These results indicate that solid state fermentation enhanced the nutritional value and antioxidant profile of grasses, which can also be used in livestock feeding and as a substrate for the production of xylanase.