Study On The Factors Affecting The Content Of α-Tocopherol In Rice Straw Silage And Its Regulation

Rice（Oryza sativa L.）straw resources are very rich in China,but rice straw in most areas is not used rationally and is often discarded in the fields.This not only causes a waste of resources but also causes environmental pollution.At present,under the background of the local government’s financial subsidies for the collection and processing of rice straw,it will not cause environmental pollution,otherwise,it will easily cause waste of rice straw resources.Therefore,there is an urgent need for innovative technologies to improve the value of rice straw and utilize rice straw rational.In this research,rice straw was used as the material.The purpose was to clarify the factors that affected the content ofα-tocopherol in rice straw silage,and to screen out additives that improved the quality and content ofα-tocopherol in rice straw silage via studying the effects of vacuum time,storage time,additives,and exogenousα-tocopherol-producing bacteria on the fermentation quality,nutritional quality,andα-tocopherol content of rice straw silages.The results of this research were to provide new ideas for effective utilizing rice straw and provide technical support for the production of high-quality rice straw silage.1 The effect of vacuum and storage time on the quality of rice straw silage andα-tocopherol contentTwo-factor randomized block trials with vacuum time（A,14 seconds;B,11 seconds;C,8 seconds;D,5 seconds）and storage time（42 days and 77 days）were designed,with 4replicates for each treatment.The results showed that each treatment group showed high p H（4.86～5.27）,low lactic acid content（15.4～24.6 g/kg DM）,and LA/AA（0.89～1.12）.On the same storage time,there was no significant difference in p H（P>0.05）;compared with 42days,the p H of all treatment groups after 77 days of silage decreased（P<0.05）.In contrast to p H changes,the contents of lactic acid and acetic acid showed an upward trend with prolonging storage time.Vacuum time B treated silage ensiling for 77 d had the highest contents of lactic acid and acetic acid（P<0.05）.Vacuum time A,B,and D treated silage ensiling for 42 d had the lowest content of lactic acid and acetic acid（P<0.05）.Vacuum time B and D treated silage ensiling for 77 d had the highest and the lowest LA/AA,respectively（P<0.05）.Vacuum time D treated silage ensiling for 42 d had the NH₃-N content（P<0.05）.Besides,compared with other treatments,vacuum time silage treated silage ensiling for 42 d had the highestα-tocopherol content（P<0.05）,whereas vacuum time B and C treated silage ensiling for 77 d had the lowestα-tocopherol content（P<0.05）.2 Effect of vacuum time and additives on rice straw silage quality andα-tocopherol contentTwo-factor randomized block trials with additive treatment{1 blank control group（CK）and 4 additive treatment groups[sodium benzoate（BA）,Lactobacillus plantarum（LP）,cellulose-degrading enzyme（EN）,and L.plantarum and cellulose-degrading enzymes Combination（LPEN）]}and vacuum time（A,14 seconds;B,11 seconds;C,8 seconds;D,5seconds）were designed,with 4 replicates for each treatment.After ensiling for 42 d,the results were as followed.Compared with the control group,the BA,LP,EN,and LPEN treatment groups reduced p H and NH₃-N content（P<0.05）,and increased lactic acid content and LA/AA（P<0.05）.Among the additive treatments,the LPEN treatment group had the lowest p H,NH₃-N content,and the number of aerobic bacteria at each vacuum time（P<0.05）,and the highest lactic acid content（P<0.05）.Besides,compared with other treatment groups,the EN treatment group has a higherα-tocopherol content（P<0.05）;vacuum time C and D treated silage with EN and vacuum time D treated silage with LP had the highestα-tocopherol content（P<0.05）.Compared with other treatment groups,the BA treatment group had a lowerα-tocopherol content（P<0.05）,and vacuum time C treated silage with BA had the lowestα-tocopherol content（P<0.05）.3 Effect of adding exogenousα-tocopherol-producing bacteria on rice straw silage quality andα-tocopherol contentFour strains ofα-tocopherol-producing bacteria were isolated and their yields ofα-tocopherol were 43.65,44.66,46.49,and 50.72 mg/L,separately.They were identified as Bacillus safensis,B.tequilensis,Pantoea agglomerans,and B.circulans.One-factor randomized block trials with additive treatments:the control group（CK）and the above-mentioned 4α-tocopherol-producing bacteria addition groups,were designed,with 4replicates for each treatment.After ensiling for 42 d,the results were as followed.Compared with the control group,the addition of each bacteria reduced the p H（P<0.05）,and increased the lactic acid content and LA/AA（P<0.05）.Among the bacteria strain addition groups,the lactic acid content and LA/AA of the B.safensis and P.agglomerans addition groups were significantly higher than that of the B.tequilensis and B.circulans addition groups,and the p H of the B.safensis and P.agglomerans addition groups was significantly lower than the B.tequilensis and B.circulans addition groups（P<0.05）;B.circulans treatment group had the highest acetic acid content（P<0.05）;B.tequilensis treatment group had the highest propionic acid content（P<0.05）.The numbers of aerobic bacteria and lactic acid bacteria of the B.tequilensis treatment group were significantly higher than that of the B.safensis addition group.Neutral detergent fiber and acid detergent fiber of the B.tequilensis treatment group were significantly less than that of the B.safensis treatment group,and the B.tequilensis treatment group had the lowest butyric acid content（P<0.05）.Theα-tocopherol content in all bacterial treatment groups was significantly higher than that in the control group（P<0.05）.B.circulans treatment group had the highestα-tocopherol content（P<0.05）,followed by the B.safensis and B.tequilensis treatments group（P<0.05）.P.agglomerans treatment group had the lowestα-tocopherol content（P<0.05）.In summary,neither the vacuuming time nor the storage time can improve the fermentation quality of rice straw silage.The short vacuuming time（5 seconds）treated rice straw silage ensiling for 42 d and 77 d considerably increased theα-tocopherol content.After ensiling for 42 d,the addition of sodium benzoate,L.plantarum,cellulose-degrading enzyme,and the combination of L.plantarum and cellulose-degrading enzyme could improve the fermentation quality and nutritional quality,regardless of the vacuuming time.The combination of L.plantarum and cellulose-degrading enzymes had the best effect on improving fermentation quality and nutritional quality and could increase the content ofα-tocopherol in rice straw silage.Under the condition of 14 seconds vacuum time and ensiling for 77 days,the addition of theseα-tocopherol-producing bacteria all improved the fermentation quality of rice straw silage,but only the B.circulans treatment group had few the structural carbohydrates of rice straw silage,and considerably increased theα-tocopherol content.