Effects Of Lycium Barbarum By-product And Lactobacillus On The Quality And In Vitro Fermentation Of Alfalfa Silage

The lack of green high-protein forage resources is a key reason to develop animal husbandry.It is of great importance to process and utilize high-quality forage grasses and to broaden their sources.Alfalfa is usually not easy to ensile due to its high buffering capacity and low water-soluble carbohydrates content.The effects of Lycium barbarum by-product(LBB)with different application rates(40 g·kg-1,T1;60 g·kg1,T2;and 80 g·kg-1,T3)on the quality,bacterial community structure and in vitro fermentation characteristics of alfalfa silage were investigated.This study confirmed the optimum addition amount of LBB to alfalfa silage,and further investigated the effects of the combination of LBB and Lactobacillus plantarum(LP)on quality,in vitro fermentation characteristics of alfalfa silage,providing supportive data for rational exploitation of LBB resources and production of high-quality alfalfa silage.The main results are as follows:(1)The application of LBB significantly increased the contents of total polysaccharide(TP)of alfalfa silages when compared the control treatment(P<0.05),but no significant difference was observed among the T1,T2 and T3 treatments(P>0.05).The lactic acid(LA)concentration significantly increased as the proportion of LBB increased in the alfalfa silage(P<0.05).The LBB significantly decreased the pH value and ammonia nitrogen(NH3-N)concentration of alfalfa silages when compared with control treatment(P<0.05).The NH3-N concentration of T3 treatment was significantly lower than that in T1 and T2 treatments(P<0.05).The T3 treatment presented lower aerobic stability than T1 and T2 treatments(P<0.05).Besides,the dominant alfalfa silage bacterial were Lactobacillus,Weissella and Pediococcus.The treatments of T1,T2 and T3 decreased the relative abundance of Lactobacillus and increased Weissella and Pediococcus.The relative abundance of Pediococcus in T2 and T3 treatments was significantly higher than that in control treatment(P<0.05).At the later stage of in vitro fermentation,the in vitro dry matter digestibility(IVDMD)and neutral detergent fiber digestibility(IVNDFD)of T2 and T3 treatments were significantly higher than those in control treatment(P<0.05),but no significant difference was observed among the T2 and T3 treatments(P>0.05).Compared with the control treatment,the concentration of propionic acid(PA)and total volatile fatty acids(TVFAs)of in vitro culture solution in T2 and T3 treatments were significantly increased(P<0.05).(2)The application of LP,LBB and LP+LBB significantly reduced the contents of neutral detergent fiber and acid detergent fiber of alfalfa silages when compared the control treatment(P<0.05),but no significant difference was observed among the three treatments(P>0.05).LBB significantly increased water-soluble carbohydrates and TP contents of alfalfa silage(P<0.05).LP,LBB and LP+LBB significantly decreased NH3-N concentration(P<0.05).The NH3-N concentration of LBB and LP+LBB treatments were significantly lower than LP treatment(P<0.05).The pH and acetic acid(AA)concentration of LP,LBB and LP+LBB treatments were significantly lower than control treatment,while LA concentration was higher than control treatment(P<0.05),but no significant difference among three treatments(P>0.05).At the early stage of in vitro fermentation,the IVDMD and IVNDFD in LP,LBB and LP+LBB treatments were significantly higher than those in control treatment(P<0.05).At the late stage of in vitro fermentation,the IVDMD and IVNDFD in LBB and LP+LBB treatments were significantly higher than those in LP and control treatment(P<0.05).LBB and LP+LBB significantly increased gas production,organic digestibility and metabolizable energy of alfalfa silage(P<0.05),but there were no significant differences between the two treatments(P>0.05).The treatments of LP,LBB and LP+LBB decreased AA and increased PA concentration of in vitro culture solution,significantly(P<0.05).The treatments of LBB and LP+LBB decreased the ratio of AA to PA of in vitro culture solution(P<0.05).The iso-valeric acid concentration in LP+LBB treatment was significantly lower than that in other treatments(P<0.05).In conclusion,the optimal supplemental level of LBB for alfalfa is 60 g·kg-1,additional application of Lactobacillus plantarum would not further enhance the alfalfa silage quality and in vitro rumen fermentation characteristics.