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The present study evaluated the feed value of a new forage resource, kenaf, for the ruminant animal. Rumen fermentation characteristics and digestibilities of kenaf (K) and its silage (KS) were compared with those of rice straw (RS) and ryegrass (RG) in an in vitro study. The effects of KS feeding on growth performance of Hanwoo steer were also investigated. In vitro rumen fermentation using 0.5 g of dried and ground forage and 50 mL of rumen inoculum was performed for 72 hours. For rumen fermentation characteristics, total gas production of KS was significantly higher than that of others at 48 h. Gas productions of RG and K were significantly higher than others at 72 h. Ammonia nitrogen did not differ among groups at both of 48 and 72 h. For IVDMD, K showed significantly higher values than others at 48 h (P < 0.05). At 72 h, RG and K showed significantly greater IVDMD than the others treatments (P < 0.05). No difference between RG and K for IVDMD was found. Total volatile fatty acid and acetate production were significantly higher in the order of K > RG > KS > RS, regardless of incubation time (P < 0.05). In propionate production, RG was significantly higher than others at 48 and 72 h (P < 0.05). Thirty-six Hanwoo steers were assigned into three groups (RS, RG, and KS) based on a complete randomized design for a feeding trial. Growth performances were measured for 172 days. During the early period (0 ~ 43 days), average daily gain (ADG) of K was significantly lower than that of other treatments (P < 0.05). However, during the following days, no significant differences in ADG between groups were detected. At the end of trial, a significantly decreased feed requirement (feed/gain) was found in the KS group (P < 0.05). In conclusion, results of ruminal fermentation characteristics and feeding trial showed that kenaf and its silage can be used as forage resource for ruminants, and these resources could be beneficial for farm in terms of nutrition for animal and economics for farm. [ABSTRACT FROM AUTHOR]

The present study investigated the relationship between organic acid contents in total mixed ration (TMR) and rumen volatile fatty acid production. TMR for lactating dairy cow was used. Organic acid production in TMR was modified by inoculation of different starter cultures. Five lactic acid bacteria (LAB) were used as a starter culture, and 12 different blends of those strains were designed based on Plackett-Burman experimental design. TMRs with different inoculants were fermented for 3 days at room temperature, and organic acid profiles (lactate, acetate, propionate, butyrate, and valerate) were examined. Fermented TMR was then air-dried at 60°C and ground for in vitro rumen fermentation. Rumen fluid from a cannulated Holstein cow was mixed with McDoughal solution. In vitro rumen fermentation with TMR was performed for 24 hours, and volatile fatty acid (VFA) production was measured. Significant effects of LAB were found for lactate, propionate, and butyrate of TMR (P < 0.05). On lactate, L. paracasei HNB34 showed a significant positive effect (PE) (P < 0.05). A significant PE on propionate was detected for L. paracasei HNB31 (P < 0.05). On butyrate, HNB34 and L. parabuchneri HNB35 showed a significant PE (P < 0.05). Significant alterations of nutrients (DM, CP, EE, NDF, and ADF) in TMR by LAB were not found. Then, the correlation between volatile fatty acid profiles from in vitro rumen fermentation with TMRs and organic acids used in TMR was investigated. Lactate in TMR showed a significant positive correlation (PC) with propionate in the rumen fluid (P < 0.05). Ruminal propionate was found to be negatively correlated with acetic acid in TMR, significantly (P < 0.05). Propionate in TMR showed significant correlation with all ruminal VFAs (P < 0.05). All ruminal VFAs, except valerate, showed PC with propionate in TMR. Butyrate in TMR showed a significant PC with valerate (P < 0.05) and significant negative correlations with acetate and propionate (P < 0.05). In conclusion, propionate and butyrate were detected as influencing factors toward rumen VFAs profiles. More propionate and less butyrate production in TMR could be beneficial in terms of more propionate production in the rumen. [ABSTRACT FROM AUTHOR]