This in vitro study investigated the enhancement of rumen bacterial adhesion on a substrate to increase the digestibility of rice straw in Hanwoo cattle. The rice straw was pretreated with enzymes, probiotics, or ammonia, and the effects on the enhancement of bacterial adhesion and fiber degradation were analyzed using in vitro rumen fermentation. Enzyme treatment included spraying of cellulase and xylanase at 40 and 120 U per g of rice straw, respectively; Saccharomyces cerevisiae culture of 1.0×107 CFU was sprayed as a probiotic treatment per gram of rice straw; ammonia was sprayed at 0.3% per gram of rice straw. Following enzyme treatment, Fibrobacter succinogenes formed a higher adhesion colony than the control group (7.26±0.03 and 8.43±0.20) after 6h and 12h of in vitro culture (p<0.05), respectively. Attachment of Ruminococcus flavefaciens also increased following enzyme treatment (p<0.05) after 6 and 12 h compared to that of the control (5.18±0.06 and 6.60±0.15); and R. albus attachment showed a significant increase compared to that of the control (5.94±0.15) after 6 h of incubation (p<0.05). Probiotic treatment increased attachment of F. succinogenes in comparison with untreated rice straw after 6 h and 12 h of fermentation (p<0.05); R. flavefaciens attachment showed an increase only after 6 h of culture (p<0.05); R. albus was not affected. Attachment of F. succinogenes, R. flavefaciens, and R. albus increased with ammonia treatment after 6 h and 12 h (p<0.05). Dry matter digestibility was higher after the enzyme treatment (3.45±0.21 and 7.04±0.09) than in the control group(1.85±0.08 and 3.94±0.04) after 6 and 12 h of in vitro culture (p<0.05), respectively. It was also higher than that of untreated rice straw after probiotic and ammonia treatments (p<0.05). There was an increase in the enhancement levels of bacterial adhesion depending on the type of fibrolytic bacteria following enzyme, probiotic, and ammonia treatment. These treatments improved digestibility. This enhancement is considered to be greater following enzyme and ammonia treatments than with probiotics.

This study was conducted to research on the efficacy of chemical treatment as an effective method for reducing mycotoxin in rice straw silage. As a chemical treatment method, ammonia and sodium hydroxid were treated at 4% level of rice straws contaminated with mycotoxin, and the effects of silage storage on fungal toxin reduction, fermentation quality, and fiber digestion were evaluated. Aflatoxin B1, B2, G1, G2 and fumonisin B1, B2 as well as deoxynivalenol were not detected in all experimental groups, and ochratoxin A and zearalenone were detected. Ochratoxin A was detected lower in the chemical treatment than control (41.23 g / kg) (p<0.05). Zearalenone showed lower results in sodium hydroxide treatment (297.44 μg / kg) than control (600.33 μg / kg) and ammonia treatment (376.00 μg / kg) (p<0.05). The pH of rice straw silage was the lowest in ammonia treatment and the highest in sodium hydroxide treatment (p<0.05). The lactic acid contents of control and ammonia treatments were similar, but sodium hydroxide treatment was the lowest (p<0.05). Propionic acid was higher in the control than in the chemical treatments (p<0.05), and showed similar contents in the ammonia and sodium hydroxide treatment. Both the rumen microbial degradation rate of NDF and ADF showed the highest in sodium hydroxide treatment, followed by ammonia treatment, and the control showed the lowest level (p<0.05). Therefore, the results of this study are demonstrated to have a good effect on the treatment of ammonia and sodium hydroxide to reduce the mycotoxins and increase the rumen microbial degradation rate in the rice straw silage. Sodium hydroxide treatment was more effective in reducing mycotoxins and improving fiber degradation rate than ammonia treatment, but it is thought to have an inefficient effect on silage fermentation in rice straw silage.

This study was to research the relationships between rice straw degradation and changes of fibrolytic bacteria population during the in vitro rumen fermentation. Dry matter(DM) digestion of rice straw and population of fibrolytic bacteria were measured at the 0. 4, 8, 12 and 48 hours during the incubation. The populations of F. succinogenes. R. albus and R. flavefaciens were defined as log copy number of 16S rDNA by technical method of Quantitative real-time PCR. Total population of F. succinogenes, R. flavefaciens and R. albus was sum of bactera attached on rice straw and suspended in medium. It's population was increased with incubation, reached top level of 29.0 Log copy No at the 24 hour and then decreased. In the meantime, DM digestion of rice straw showed the higher increasement from the 8 hour to the 24 hour than from the 0 hour to the 8 hour, and then a slowdown in increasing trend of digestibility. Attachments of F. succinogenes, R. flavefaciens and R. albus were detected immediately after start of in vitro rumen incubation. At the same time, the colonized bacterial share were respectively 34.5%, 84.4% and 67.9% in total population. All of them was reached the highest colonized bacterial share above 94.7% at the 4 hour incubation. However population of attached bacteria was shown the highest level at the 12 hour or the 24 hour incubation. Kinetics of colonization were formed area of top speed from the 12 hour to the 24 hour and respectively reached 10.33, 9.28 및 8.30 Log copy No/h/g DM at the 24 hour by F. succinogenes, R. flavefaciens and R. albus. The kinetics of rice straw degradation was formed top level of 0.95% DM/h at the 24 hour. The present results gave clear evidence that degradation of rice straw was increased with the development of total fibrolytic bacteria in process of rumen fermentation. Also, their attachment was largely occurred immediately after insertion of rice straw, the colonized bacteria was actively proliferated, and then degradation of rice straw was maximized.