| Chicken necrotic enteritis caused by Clostridium perfringens is one of the important intestinal diseases of chickens.In the past,traditional methods of prevention and treatment were to add antibiotics and other additives to the feed,but the use of antibiotics would bring great side effects to chickens.At the same time,due to the spread of the food chain,it will also bring potential harm to human health.This study intends to screen the appropriate antibiotic substitute-plant essential oil,and develop a new dosage form of compound plant essential oil,which can overcome the shortcomings of the essential oil itself,such as large irritancy,volatile,poor stability,etc.,and this new dosage is used for preventing and treating chicken necrotic enteritis.So that it can be better invested in production practice,reduce production costs in the poultry breeding industry,and increase the income of farmers.The first part of the subject uses the checkerboard method for in vitro combined susceptibility testing.Two plant essential oils with additive effects were screened from a number of plant essential oils against Clostridium perfringens.Among them,thyme essential oil single medicine MIC=2.5mg/mL,nutmeg essential oil single medicine MIC=1.25mg/mL,thyme essential oil combined with MIC=0.625mg/mL,nutmeg essential oil combined with MIC=0.625mg/mL;FIC value is 0.75,It is determined that the combination of nutmeg essential oil and thyme essential oil has an additive effect,and the antibacterial effect is outstanding after compounding.In the second part of this project,the determination method of the content of nutmeg and thyme compound essential oil was established by GC/MS and UV spectrophotometry.The main components of the two essential oils were first analyzed by gas chromatography.The content of eugenol in the nutmeg oil was about 28%,and the eugenol content in the thyme oil was about 56.5%.Then the eugenol standard was used as the reference substance to determine the content of nutmeg and thyme essential oil by ultraviolet spectrophotometry.The standard curve was drawn.The regression equation of eugenol concentration and UV absorbance was y=0.01736x-0.00563,R~2=0.99997,indicating a linear relationship in the range of 10.630～37.205 ug/mL concentration;at the same time the results of the precision,stability,repeatability,sample recovery rate of the methodological study,the RSD is within the error tolerance.It is proved that the UV spectrophotometry established in this study is feasible for the determination of essential oils.The third part of this topic optimizes the preparation process of microcapsules.Firstly,the enteric wall materials were selected from many microcapsule wall materials:soy protein isolate and maltodextrin;then the emulsion stability was used as an indicator to determine the optimum emulsion formula.The experiment showed that the core-wall ratio was 1:2,the ratio of soy protein isolate and maltodextrin is 2:1,the amount of emulsifier added is 1%,the ratio of compound emulsifier is 1:1,the stability coefficient of emulsion is X=0.890,and the stability is good.Finally,the micro-encapsulation rate was used to determine the spray drying process conditions.The experiment showed that the inlet air temperature was 180℃,the feed amount was 25%,the air flow meter was 600nl/h,the needle frequency was 20 seconds/time,and the outlet temperature was 90℃.The microcapsules prepared under these conditions could have uniform color,uniform particle size,soft fragrance and an average embedding rate of 67.78%and the microcapsules have good intestinal solubility.The experiment showed that the nutmeg and thyme essential oil were used as the core material,soy protein isolate and maltodextrin were the wall materials.The microcapsules could be prepared by spray drying method,and the preparation process was scientific and reasonable. |
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