Abstract

Rice straw was fermented by two strains of Aspergillus terreus (ATCC 74135 and ATCC 20542) to enhance the antioxidant content of this agro-biomass as ruminant feed. After 8 days of fermentation, antioxidant capacity of samples was determined using Ferric reducing antioxidant power (FRAP), 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) and 1,1-diphenyl-2-picryl- hydrazyl  (DPPH) methods. Results of all three methods showed that treatment by both strains of A. terreus significantly (P<0.01) improved the antioxidant capacity of rice straw with higher enhancement for A. terreusATCC 74135 than A. terreus ATCC 20542. In vitro gas production method was used to examine the stability of antioxidant components of the fermented samples under rumen microbial influence. Our results showed that rumen liquid sample containing fermented rice straw have higher antioxidant capacity than the control (untreated rice straw) after 48 h incubation, indicating that antioxidant capacity of the fermented rice straw remains stable during ruminal fermentation. These results show that biological treatment using A. terreus can be a practical method for production of high quality agro-biomass as ruminant feed with natural antioxidant capacity.

Key words: Antioxidant capacity, biological treatment, agro-biomass, Aspergillus terreus.

Abbreviation

FRAP, Ferric reducing antioxidant power;  ABTS, 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid; DPPH, 1,1-diphenyl-2-picryl- hydrazyl; methods;RS, rice straw; FRS, fermented rice straw.