| In tropical and subtropical areas grasses grow rapidly and matured quickly following the onset of rain,however the standing forages are high in structural carbohydrates and low in water soluble carbohydrate,protein and minerals during the dry season.The reductions in nutritive value of forages are the major limiting factors in animal production in such environments.Conservation through ensiling is one approach to effectively preserve forages at their optimum stage of growth.However,ensiling of tropical and subtropical grasses are very difficult given to their low water soluble carbohydrate and high accumulation of cellulose,hemicelluloses and lignin compared to the temperate grasses.Even though,many studies are conducted to preserve grasses using additive,much emphases has been placed on assessing the fermentation quality apparently,little information was available on structural and water soluble carbohydrate compositions.Furthermore,there is limited information on the release of monomeric carbohydrates from silage after treated with enzymatic or acid.Then this research examined the effect of chemicals and biological additives on dynamic changes in fermentation quality,structural carbohydrate,water soluble carbohydrate and in vitro digestibility.1.Effects of additives on fermentation quality,carbohydrate compositions and enzymatic digestibility of napier grassThe first study was conducted to examine the effects of additives on the fermentation quality,carbohydrate compositions,and enzymatic digestibility of napier grass.Napier grass was ensiled with:no additive control(C),0.2%formic acid(F),4%molasses(M),and 0.3%fibrolytic enzyme(E)in triplicate for 7,30,60 and 90 days of ensiling.Additives increased significantly(P<0.05)the contents of water soluble carbohydrates and lactic acid,and ratio of lactic acid to acidic acid,while decreased significantly(P<0.05)pH,ammonia nitrogen,dry matter loss and all structural carbohydrate compositions except acid detergent lignin as compared with control.Enzyme reduced significantly(P<0.05)structural carbohydrates,while significant(P<0.05)highest reserves of water soluble carbohydrates were recorded in formic acid silage compared to other silages.Ensiling days reduced the compositions of all measured structural carbohydrates and water soluble carbohydrates.Treatment of silages with 0.2%cellulase of 100FPU/g increased(P<0.05)the release of glucose in formic acid and molasses silage compared to other in all examined ensiling days.In summary,the additives improved nutrient available for livestock and bioproduct production by reducing conservation loss,structural carbohydrate and enhancing enzymatic digestibility.2.Effects of cellulase and xylanase enzyme on fermentation quality,carbohydrate compositions and in vitro digestibility of napier grass and rice straw.The second experiment was conducted to examine the effects of cellulase and xylanase on the fermentation quality,carbohydrate compositions and in vitro gas production and digestibility of napier grass and rice straw.Napier grass and rice straw were treated with no additive(CO),0.3%cellulase(CE),0.3%xylanase(XE),0.3%combined enzymes(CX)(a mix of 0.15%CE and 0.15%XE)based on ensilage material weight,respectively.Triplicate silos were open after 7,30,60 and 90 days of ensiling for napier grass silage and after 3,7,14 and 30 days of ensiling for rice straw silage.Enzymes significantly(P<0.05)increased the contents of lactic acid and water soluble carbohydrates,while decreased significantly(P<0.05)the contents of volatile fatty acids and ammonia nitrogen,dry matter loss and pH compared to control during ensiling.The structural carbohydrates composition of enzymes silages were significantly(P<0.05)lower than control during ensiling.Combined enzyme further improved fermentation quality,increased water soluble carbohydrates reserve and reduced structural carbohydrates than either of the additives and control during ensiling.In vitro gas production and digestibility of napier grass and rice straw silage was determined after 90 and 30 days of ensiling,respectively,and Enzymes showed higher in vitro gas production and digestibility than control.Ensiling days significantly(P<0.05)decreased the contents of lactic acid,water soluble carbohydrates and structural carbohydrates,and increased VFA in all silages..In summary,even though all enzymes improved fermentation quality and reduced structural carbohydrate compositions of napier grass and rice straw,the effect was more significant in CX silage than CE and XE)3.Effect of cellulose or/and lactic acid bacteria on fermentation quality,carbohydrates compositions and their response to dilute acid treatment of napier grass silageThe third experiment examined the effect of cellulase and/or Lactobacillus plantarum on fermentation quality,carbohydrates compositions of napier grass silage and their response on the release of monomeric sugar after dilute acid treatment.Napier grass was ensiled with no additive control(C),6 log colony-forming units/g L.plantarum(Lp);0.3%cellulase(E),0.3%cellulose?6 log colony-forming units/g L.plantarum(E+Lp)calculated based on the fresh weight.Triplicate silos for each treatment were opened after 3,7,14,30,60 and 90 days of ensiling,respectively.Addition of cellulase or/and L.plantarum improved fermentation quality of napier grass silage by decreasing pH,the contents of ammonia nitrogen,acetic acid and butyric acid and increasing lactic acid and ratio of lactic acid/acetic acidas compared to control.The structural carbohydrate composition reduced significantly(P<0.05)in E and E+Lp silages as compared to control except for acid detergent lignin.The L.plantarum and its combination with cellulase improved the fermentation quality as compared to E and C silage.Additives increased(P<0.05)water soluble carbohydrates as compared to control.The water soluble carbohydratesreduced(P<0.05)rapidly during the first 7 days of ensiling,the reduction was very fast for control silage than additive.Treatment of napier grass silage with 0.5,1 and 1.5%sulfuric acid for 60 and 90 minute in 120? temperature significant(P<0.05)increased the contents of xylose and glucose release from additive silage.In summary combined addition of cellulase and L.plantarum reduced the structural carbohydrate,improved fermentation quality,water soluble carbohydrates availability,andproduced higher xylose and glucose after dilute acid treatment than individual additives and control silages.4.Isolation of cellulolytic bacteria from rumen and their effect on fermentation quality and carbohydrates compositions of napier grass and rice strawThe fourth experiment was to isolate and characterized cellulolytic bacteria from rumen and examined their effect on fermentation quality and carbohydrate compositions of napier grass and rice straw.A total of 23 bacteria were screened on CMC-Na media,and three of these bacteria were isolated based on their cellulolytic activities and growth as silage inoculants.These bacteria were identified as Klebsiella pneumonia,Enterobacter asburiae,Escherichia marmotae by biochemical and morphological characteristics and 16S rDNA sequences.Enzyme activity of the isolated bacteria was determined using DNS method.The isolated cellulolytic bacteria showed 0.25 to 0.32 U/ml CMCase and 0.19 to 0.27 U/ml filter paper enzymatic activities.To study the effect of isolated cellulolytic bacteria on fermentation quality and carbohydrate compositions,Napier grass and rice straw were ensiled with no additive control(CO),E.marmotae ST 401(ISO 401),K.pneumonia ST 83(ISO 83)and E.asburiae ST 56(ISO 56)for 3,7,14 and 30 days in triplicate at 6 log colony-forming units/g of ensilage material application rate.The isolated cellulolytic bacteria increased(P<0.05)the contents of water soluble carbohydrates and lactic acid,and ration of lactic acid to acetic acid,while decreased the contents of volatile fatty acids(P<0.05)and ammonia nitrogen,pH,and dry matter loss as compared with control during ensiling.Isolated cellulolytic bacteria reduced the structural carbohydrates compositions of all silage as compared with control,the ISO 83 had higher effect than others.Ensilage days influenced silage quality by reducing the LA,structural and water soluble carbohydrates and increasing total volatile fatty acid in all silages.In summary,cellulolytic isolated bacteria improved fermentation quality and reduced structural carbohydrate compositions of napier grass and rice straw silages.These results could provide insight and initiate the development of new silage additive from microbes.5.Effect of celluloytic fungi on fermentation quality,carbohydrate compositions and in vitro gas production and digestibility of rice straw silageThe fifth experiment examined the effect of direct inoculation cellulolytic fungi on fermentation quality,carbohydrate composition and in vitro gas production and digestibility of rice straw.Rice straw was ensiled with no additive(C),Trichderma reesei(F1),Thrichoderma harzianum(F2)for 3,7,14 and 30 days of ensiling,in triplicate.The addition of cellulolytic fungi increased the contents of water soluble carbohydrates and lactic acid,and ration of lactic acid to acetic acid,while decreased the contents of volatile fatty acids(P<0.05)and ammonia nitrogen,pH,and dry matter loss as compared to control during ensiling.Cellulolytic fungi decreased the structural carbohydrates compositions of rice straw silage as compared to control and ensilage material.Ensiling days decreased contents of water soluble carbohydrates,lactic acid and structural carbohydrates.However,the in vitro gas production and digestibility was higher in cellulolytic fungi silage compared to control after 30 days of ensiling.In summary,the cellulolytic fungi silage improved fermentation quality and nutritional content,and could open a new approach for the development silage additive for lignocellulosic biomass. |
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