Effects of different Lactobacillus combinations on fermentation quality and in vitro rumen fermentation characteristics of rape straw
This experiment was designed to investigate the effects of Lactobacillus plantarum and Lactobacillus brucei on the conventional nutrient composition and protein fraction of rape(Brassia campestris)straw,and in vitro rumen fermentation parameters in yaks.Four treatment groups with five replicates in each group were set up,including a control group(CON;without any bacterial preparation),an LP group(with 1.0 g·kg-1 L.plantarum),an LB group(with 1.0 g·kg-1 L.brucei),and an LPB group(with 1.0 g·kg-1 L.plantarum+1.0 g·kg-1 L.brucei).Rape straw was used as fermentation substrate.The rape straw was cut to 2 cm lengths and mixed well with the bacterial preparation,then packed into polyethylene bags.The bags were evacuated and anaerobically fermented at room temperature for 45 days.Samples were taken to determine the nutrient composition,Cornell net carbohydrate and protein(CNCPS)system data,and yak in vitro rumen fermentation parameters of the straws.The results showed that:1)Compared with the CON group,the pH values of the LP,LB,and LPB groups were decreased(P<0.05),and lactic acid content was increased(P<0.05),with the highest values recorded in the LPB group.2)Compared with the CON group,the neutral detergent fiber(NDF),acid detergent fiber(ADF),and cellulose content of the LP,LB,and LPB groups were decreased,and the ether extract content was increased(P<0.05).Furthermore,the NDF,ADF,and acid detergent lignin levels(ADL)in the LPB group were lower than those in the other two treatment groups(P<0.05).3)Compared with the CON group,the rapidly degraded protein(PB1)and moderately degraded protein(PB2)in each treatment group did not change significantly(P>0.05).The content of non-protein nitrogen(PA1)in the LPB group increased(P<0.05),and the content of unavailable protein(PC)decreased(P<0.05).The content of unavailable fiber(CC)in each treatment group decreased(P<0.05),and the content of available fiber(CB2)and non-structural carbohydrates(NSC)increased(P<0.05),compared to CON.The content of CC in the LPB group was lower than that in CON,LP and LB groups(P<0.05).4)After 72 hours in vitro gas production of rape straw,there was no significant difference in rumen fluid pH among the groups(P>0.05).The NH3-N content in each group was lower than that in the CON group(P<0.05).The dry matter degradation rate(DMD)and volatile fatty acid(VFA)content in the LPB group were higher than those in the CON group(P<0.05).In conclusion,the anaerobic fermentation of rape straws inoculated with bacterial preparations improved the nutritional value of the rape straws,and different bacterial preparations differed in their efficacy.On a multivariate comparative score,the treatments ranked:L.plantarum+L.brucei>L.plantarum>L.brucei.
rape strawCornell net carbohydrate and protein systembacterial preparationin vitro fermentation
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