Preliminary Research And Application Of Compound Plant Oils On Promoting Growth Performance And Disease Resistance Of Broilers

It has been a long time,antibiotics as a growth promoting agent widely used in livestock and poultry diets in the low dose and long-term,was used as preventive medicine at practice situation.In recent years,because of the risk of drug resistance and public safety awareness,and the situation appears to be better.Now,the leading target is searching for a safe and effective application and put it into use.Plant essential oil originates which has the characteristics of volatile and special smell,has many pharmacological activities,and appliated in many fields,but it was rarely used in animal feeding field.This study chose thymol,carvacrol,eugenol,limonene and citral,cinnamaldehyde,garlicin 7 essential oil monomers as the research objects,using the orthogonal experiment design,factorial experiment design,drug sensitivity test for the best antimicrobial prescription screening;through animal feeding test on growth and slaughter of broilers,also measuring the content of albumin and other biochemical parameters,at last to determine the optimum adding amount;using MTT method,ELISA method,immune organ index to study its influence on immune function of broilers;In broilers are challenged with Escherichia coli O78,by microbial culture method,fluorescence quantitative PCR method and the pathological sections of heart,liver,spleen and kidney et al,to study its effect on broiler disease resistance and its immunological mechanism,to provide reference basis for production and practice.The field feeding experiment is carried out to determine its economic practicability.The results showed that eugenol,thymol and carvacrol as prescription composition,specific prescription for eugenol 3mg,thymol 3mg,carvacrol 2mg.MIC of Escherichia coli is 625μg/m L,Staphylococcus aureus 39μg/m L,Salmonella 19.5μg/m L;MBC of Escherichia coli is 1250μg/m L,Staphylococcus aureus 78μg/m L,Salmonella 39μg/m L.In broilers: 42 days feeding,treatments with 80mg/kg and 160mg/kg broilers’ average daily gain was significantly higher than the control group(P<0.01),but the feed :gain ratio in group 80mg/kg was significantly lower than the control group(P<0.05),the feed intake and feed :gain ratio in group 160mg/kg group was significantly higher than that of control group(P<0.05),and slaughter performance had also been improved(P<0.05);serum total protein,albumin,urea nitrogen,triglyceride,total cholesterol content had insignificant difference(P>0.05),but the serum urea nitrogen,triglyceride,total cholesterol content all tend to decrease;the compound plant essential oils can make the white blood cells and red blood cells increased,promoting lymphocyte proliferation and increasing serum complement.After vaccination analysis,Newcastle disease antibody titer and lysozyme in serum were significantly increased(P<0.05),and the secretion of immunoglobulin and cytokines IL-2,TNF-alpha,IFN-gamma were higher(P<0.01),SOD and T-AOC in serum increased(P <0.05),immune organ index improved(P <0.01);and challenged with Escherichia coli O78,essential oils could decrease the mortality of broilers(P<0.05),that was better on loss the body weight gain and higher feed conversion ratio(P<0.01),at the same time,the T2(add essential oil)broilers significantly reduced organ carrying bacteria volume(P<0.01),the degree of visceral lesions was reduced,Escherichia coli challenge significantly increased the level of IL-6 and s TLR4 in serum of broilers(P<0.01),spleen TLR4 and NF-κBm RNA expression was significantly increased(P<0.01),while the T2(add essential oils)than T1(no essential oil)broilers significantly reduced the expression of genes related with virus attack(P<0.05);application in field farming proved that the plant essential oils can save feed,reduce mortality,create economic benefits.Follows from the experimental results that the formulation for plant essential oils thymol 3mg,eugenol 3mg,carvacrol 2mg,has certain bactericidal effect on Escherichia coli,Salmonella,Staphylococcus aureus;the optimum adding amount of 80mg/kg in feed;can increase the immune function of broilers,improve the level of anti-infection of pathogenic microorganisms;the anti-inflammatory process that is relates to the inhibition of TLR4/NF-κB pathway transduction then to inhibit the secretion of inflammatory cytokines.The essential oil is well to use.