Detection And Prevention And Control Of Mastitis In 16 Large-scale Dairy Farms In Xinjiang

Objective: Cow mastitis is a common disease in modern large-scale dairy farms.Chronic clinical mastitis and occult mastitis can have a serious impact on the pasture.This results in a series of problems,such as increasing pasture elimination rate,decreasing economic benefit and dairy quality safety.In order to understand the epidemic characteristics of mastitis in 16 large-scale dairy farms in four regions of Xinjiang and the characteristics of drug resistance and virulence gene carrying of main pathogenic bacteria.At the same time,combined with the clinical treatment results of mastitis and the effect of different dry milk schemes on controlling the incidence of mastitis in new cows,the current prevention and control schemes of mastitis in pasture cows were further optimized.Methods: Firstly,16 large-scale dairy farms in Kuitun,Tacheng,Changji and Aksu were selected as the research object.According to the "Afijin" software management system,the prevalence of dairy cow mastitis in each pasture was statistically analyzed.Secondly,the milk samples of some cows in each pasture and the environmental samples of pens and dairy halls were collected aseptically.The main pathogenic bacteria in the milk samples were isolated and identified by combining laboratory routine microbiology and molecular biology,and the sources of similar bacteria in the milk samples and environmental samples were compared and analyzed.Drug resistance phenotypes of main pathogenic bacteria in milk samples were detected and analyzed by K-B drug sensitive disk diffusion method,and drug resistance genes and virulence genes of main pathogenic bacteria in milk samples were detected by PCR method.Finally,combined with the results of drug sensitivity test and the epidemic characteristics of drug resistance genes,different clinical treatment schemes were designed to analyze the effects of different treatment schemes before and after treatment,and to evaluate the effects of different dry milk schemes on controlling the incidence of mastitis in newborn cattle.Results:1.Epidemiological survey results of 16 large-scale dairy farms in Xinjiang in 2021 showed that the average incidence of clinical mastitis was 2.60%;The average positive rate of recessive mastitis was31.03 %.The incidence of clinical mastitis was the highest in winter and the lowest in spring,while the positive rate of recessive mastitis was the highest in winter and the lowest in summer.The proportion of mixed infection of multiple pathogenic bacteria was the highest,and the proportion of single pathogenic bacteria infection of Enterobacter was higher than other bacteria.The positive rate of recessive mastitis increased with the increase of age and parity.2.Through the separation and identification of the main pathogenic bacteria in the milk samples,the separation rate of Staphylococcus aureus was 21.60%(398/1843),Escherichia coli was 32.30%(595/1843)and Streptococcus agalactiae was 14.70%(271/1843).The isolation rates of Staphylococcus aureus,Escherichia coli and Streptococcus agalactiae in environmental samples were 13.70%(59/432),42.60%(184/432)and 9.70%(42/432)respectively.Homology analysis of the same pathogenic bacteria in milk samples and environmental samples showed that the main pathogenic bacteria in some milk samples came from some environmental samples.3.After drug resistance analysis of the three pathogenic bacteria isolated from the milk samples,it was found that the drug resistance phenotype and genotype of the isolates were basically the same,and there was a high drug resistance rate to some antibiotics.The detection rates of drug resistance genes in Staphylococcus aureus,Escherichia coli and Streptococcus agalactiae were 50%(5/10),72.7%(8/11)and50%(4/8),respectively.The virulence gene detection rates were 30%(3/10),44.4%(4/9)and 50%(5/10),respectively.4.Clinical treatment of 124 clinical mastitis cattle showed that: The cure rate and effective rate of eusporin + medajia were the highest,83.33% and 90.00 %,respectively.Meanwhile,the mean value of SCC before treatment decreased by about 80% year-on-year,and the mean value of SCC before treatment decreased by about 25% year-on-year compared with that of cefotioproxme + medajia alone.Among the different dry milk regimens,the combination of "abenin + umechin" showed the highest cure rate of82.98% in the milk area in terms of clinical symptoms before and after dry milk,while the combination of "abenin + umechin" also showed the lowest proportion of uncured and newly infected milk area 10.10%.Moreover,the dry milk program of "Abenin + Eumexin" reduced the mean value of SCC before dry milk by 36% year-on-year.Conclusion: The main pathogenic bacteria of mastitis of dairy cows in 16 large-scale pastures in Xinjiang are Staphylococcus aureus,Escherichia coli and Streptococcus agalactiae.It is suggested that the pasture should effectively reduce the threat of environmental pathogenic bacteria and rationally use therapeutic drugs.Meanwhile,in order to reduce the incidence of mastitis in the pasture as much as possible,It is suggested that the comprehensive program of "euxine + medajia" treatment combined with "abenin + eumexin" dry milk should be adopted to prevent and control mastitis of dairy cows,and the comprehensive prevention and control program suitable for the pasture itself should be formulated.