Objective: The effects of Pleurotus ostreatus on the feed utilization improvement of broad bean stalks (BBS), rape straw (RS), paddy straw (PS) and corn stalk (CS) was examined.
Methods: The four roughages were co-cultured with Pleurotus ostreatus. The chemical composition; enzyme activities of laccase, carboxymethylcellulase (CMCase) and xylanase; carbohydrate and protein fractions (based on CNCPS) were assessed at different days after inoculation (7, 14, 21, 28 d) and un-inoculated roughages (control, 0 d). The digestibility of nutrient compenentscomponents and the gas production of roughage with various incubation times were monitored at 0, 2, 4, 6, 9, 12, 24, 36, 48, 60 and 72 h using an in vitro ruminal fermentation method.
Results: A higher CMCase activity (0.1039 U/mL) and earlier time to peak (14 d) were detected in Pleurotus ostreatus cultured with CS (P < 0.05). Significantly, the incubation length-dependent responses of cumulative gas production were observed from 24 to 72 hours post fermentation (P < 0.05), and these incubation length-dependent effects on cumulative gas production of PS and CS were appeared earlier (24 h) for PS and CS than those (48 h) for BBS and RS (P < 0.05). The fast-degradable carbohydrate (CA) content for all four roughages significantly increased over time (P < 0.05). Nonetheless, increased degradation efficiency for CA treated with Pleurotus ostreatus was detected at both 21 and 28 days of incubation (P < 0.05). With the exception of PS (P < 0.05), there were no significant difference among the roughages (P > 0.05) in slowly-degradable carbohydrate (CB2) at different incubation times (P < 0.05).
Conclusion: Assessment of the alterations in chemical composition, CNCPS system fractions, and the fermentation kinetics after biological pretreatment may yield valuable database for evaluating the biological pretreatment of Pleurotus ostreatus in ruminants feed.
Keywords: Biodegradation; Crop residues; Goats; In vitro digestibility; Nutrient availability; Pleurotus ostreatus.