Surveillance Of Milk Quality And Pathogens Investigation Of Mastitis On A Dairy Farm In Nanning

Bovine mastitis in the dairy industry is one of the common diseases,which cause loss of milk yield and poor quality of raw milk,often lead to some problems of public health and food safety issues.The harm caused by mastitis arises a very heavy economic pressure to dairy farmers and dairy processing industry.In present study the milk samples were collected on a dairy farm in Nanning,and milk quality was evaluated by somatic cell count(SCC)detection.Then the major pathogens of mastitis were cultivated and identified by biochemical method and drug sensitivity test was conducted.The virulence genes of Staphylococcus aureus was detected by PCR method.The specific studies are as follows:Test 1:mastitis and milk quality monitoringIn October 2014 to October 2016,monthly(individual months missing)random collection of milk samples,the application of the Dutch production DEITA brand Somascope SmartTM somatic cell detector milk samples for milk somatic cell count,according to different SCC classification,SCC in 50 to 1 million/ml for recessive mastitis.SCC<500,000/ml for normal milk,the smaller the number of SCC,suggesting that the better the quality of milk.Statistical analysis of the occurrence of dairy cow mellitus in different periods and the quality of milk.The results showed that the changes of SCC in different dairy cows were different,and the individual milk SCC of lactation month showed fluctuating changes.On the whole,the change of SCC of different body milk in different lactation month was different,and the SCC of milk milk was fluctuating in lactation month.The fluctuation of SCC was the most obvious in summer,and the SCC was the least in winter.In the 20 months,the milk quality gradually improved,of which 2016 years of milk is the best.In summer and autumn,the number of somatic cells is higher than that of spring and winter.Qualified milk as a whole show the trend of rising,unqualified milk as a whole is also showing a downward trend.Test 2:isolation and identification of major pathogens of dairy cow mastitis and drug sensitivity testIsolation and identification of bacteria by biochemical identification,156 suspicious strains,biochemical identification identified 57 strains of Staphylococcus aureus,accounted for 36.5%,13 strains of Streptococcus agalactiae,dysgalactiae 7 strains,6 strains of Streptococcus pneumoniae breast,accounted for 16.7%,73 strains of Escherichia coli,which accounted for 46.8%.resistant Staphylococcus aureus is the rate of 33.7%,the drug resistance rate of Streptococcus was 31.1%,the resistant rate of Escherichia coli is 35.2%.streptomycin,penicillin,tetracycline in Escherichia coli has lost 100%;streptomycin,penicillin on Staphylococcus aureus was 100%lost,enrofloxacin is highly resistant to ampicillin,carbenicillin,doxycycline produced not sensitive to ampicillin;Streptococcus,streptomycin,penicillin,erythromycin resistance was 100%,but three kinds of bacteria to amikacin,carbenicillin,cefoperazone,ceftriaxone,levofloxacin has higher sensitivity to oxygen.Test 3:Staphylococcus aureus virulence gene test57 strains of Staphylococcus aureus on the biochemical identification,using PCR detection of its NUC,HLA,HLB,sea,SEB gene,the results show that the carrying NUC gene 57 strains(100%)carrying Hla gene,13 strains(22.8%)carrying Hlb gene 15 strains(23.6%)at the same time.There are two kinds of carrying accounted for 7.0%.carrying sea gene,12 strains(21.1%)carrying SEB gene 8 strains(14%),while carrying two genes accounted for 3.5%.on the issue of food safety,still need to pay attention to.Test 4:Staphylococcus aureus resistance gene detectionStaphylococcus aureus is one of the most important pathogens causing dairy cow mastitis,because of its high infection rate,and showed multiple drug resistance.The ermB,ermC and methicillin-resistant grapevine mecA gene primers were designed by online software using the PCR software,ermB and ermC virulence genes.The results showed that the ermB gene There were 10 strains(17.5%),16 strains(28.1%)of the ermC gene,and 57 strains of Staphylococcus aureus were detected by PCR.No mecA gene was detected.In the use of antibiotics,to try to avoid the emergence of drug-resistant strains.