| China produces about 6 million tons of sugarcane tail leaves every year,but the utilization rate is less than 30%.One of the reasons is that the quality of sugarcane tail silage is affected by the lack of special strains.There are many kinds and quantities of silage agents on the market,and their quality and composition are not stable,which affects the stable development of sugarcane tail silage.Therefore,eight kinds of silage additives from different sources were selected for identification in this study.Subsequently,sugarcane tail silage tests were carried out to screen out silage additives with different qualities,which were verified by animal tests in order to clarify the quality status of commercially available silage additives and screen out high-qualitysilage additives for sugarcane tail silage.Experiment 1: To identify the bacterial community composition of silage additive,and to clarify the difference of bacterial species composition and quality status.Eight silage additives were purchased from markets in different regions.Agent 1(labeled as yeast + Lactic acid bacteria + cellulase),agent2(labeled as lactic acid bacteria + Bacillus subtilis + Candida perenne),Bacteria agent 3 + yeast cultures of lactic acid bacteria(tag),bacteria agent 4(labels for lactic acid bacteria,bacillus subtilis and yeast + filamentous fungi),bacteria agent 5(labeled + photosynthetic bacteria,yeast and lactic acid bacteria actinomyces + filamentous fungi),bacteria agent 6(labeled + yeast,lactic acid bacteria cellulose enzyme + vitamin + carbohydrates metabolites),bacteria agent7(labeled lactic acid Bacteria + bifidobacterium)and agent 8(labeled As Lactobacillus brinii + Coccus pentosus + glucose).The bacterial composition of eight silage additives was determined by 16 s RNA gene sequencing technology.The results showed that the bacterial composition of eight commercial silage additives was inconsistent.Among them,agent 2 and agent 3 were dominated by lactic acid bacteria,accounting for 98% in Agent 2,while the other additives contained less lactic acid bacteria,and agent 4,5 and 8 contained less lactic acid bacteria or even less than 1%.The microbial composition of the eight silage additives was not completely consistent with the instructions,but the dominant bacteria were different.Some additives were mainly lactobacillus,some were mainly enterococcus,and some were mainly Prevotella or Bacillus.However,the instructions of the eight additives did not indicate the dominant bacteria.It can be seen thatthe quality of commercially available silage additives is not stable.Experiment 2: In order to screen and verify the effects of eight commercially available silage additives on dry matter loss of sugarcane tail silage,eight additives were inoculated into sugarcane tail to carry out silage experiment,and the changes of dry matter loss in each group during silage were compared through 70-day silage experiment.The results showed that the loss of dry matter in the form of gas in silage was high in the early stage and tended to be stable in the later stage.The dry matter loss of sugarcane tail leaf was mainly concentrated in the first 3 days of silage,and the dry matter loss was above4g/kg of silage,and gradually decreased after 3 days.The amount of dry matter loss in silage was different in each group,and the dry matter loss of agent 3 was the least,which was 1.15 g.Dry matter loss of agent 1 was medium,2.38g;The dry matter loss of agent 2 was 2.93 g.It can be seen that although agent 3 and agent 1 contain less lactic acid bacteria,their effect is better than agent 2,which contains the most lactic acid bacteria,indicating that in addition to the lactic acid bacteria community in commercial silage additives,other compound components also have an important effect on their application effect.Experiment 3: To further verify the practical application effect of the three silage additives screened out in experiment 2,the effects of silage additive quality on animal growth performance were clarified.In this study,chemical composition analysis and sensory evaluation of wrapped sugarcane tail silage made with three silage additives were carried out.On this basis,40 dairy bulls were selected for a 60-day feeding experiment,during which they were fed with basal concentrate and silage with different treatments,respectively as control group(no silage additive group),test group 1(agent 1),test group 2(agent 2)and test group 3(agent 3).Growth performance,blood biochemical indices and nutrient apparent digestibility indices were measured during the experiment.The results showed that agent 3 was the best silage additive for improving silage quality,followed by agent 1 and agent 2,which were completely consistent with the results of laboratory verification and screening in the previous section.Compared with the control group,the silage made with high quality silage additive Agent 3 and medium silage additive agent 2 increased the apparent digestibility,decreased the ratio of feed to gain,and tended to increase the daily gain of dairy bulls.However,the daily gain and nutrient digestibility of dairy bulls were decreased after feeding the silage made with inferior silage additives,and the feeding effect was consistent with the quality evaluation results of silage.The reason why silage made with high quality additives can improve the growth performance of animals is related to the increase of nutrient apparent digestibility,but the specific mechanism needs to be further studied.In order to explore the mechanism that the growth performance and nutrient digestibility of experimental group 3 were significantly improved compared with control group and experimental group 2,rumen fluid of 6 dairy bulls in each group was collected in this study,and the bacterial community in the rumen of each group was sequenced and analyzed by 16 s RNA gene sequencing method.The results showed that the dominant flora in phylum,family and genus levels of the four test groups were not consistent,and Bacteroidetes and Firmicutes were the dominant flora in phylum level.At family level,Prevotellaceae and Ruminococcaceae were the dominant flora,while at genus level,unclassified and some other colonies were the dominant flora.To sum up,the quality of silage additives on the market is unstable,which mainly reflects that their labels cannot reflect the composition and dominant bacterial community,which can easily lead to the selection of additives unsuitable for silage.The advantages and disadvantages of the special strains of silage sugarcane tail must be related to the high content of lactic acid bacteria,reasonable combination of other components can improve the silage effect of lactic acid bacteria;The reason why high quality silage additive can improve silage quality and animal growth performance is related to the improvement of animal apparent digestibility of feed nutrients. |
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