Investigation On Influencing Factors Of Clinical Cow Mastitis In Large-Scale Breeding Farm And Pathogen Isolation And Identification

Cow mastitis is one of the main diseases in large-scale breeding farms,which causes serious economic losses.The causes of cow mastitis are complex and related to farm management closely.In order to analyze the influencing factors,main pathogens and drug resistance of clinical cow mastitis in large-scale dairy farms,and to provide experimental basis for the prevention and treatment of mastitis in large-scale farms,this study collected the information related to the fetal number,month,season,incidence area and incidence frequency of 1164 cows with clinical mastitis from a large-scale dairy farm in Ling Wu,Ning Xia and analyzed its correlation in recent one year.The bacteria were isolated and identified from 118 lactoid pathogens of clinical mastitis and 46 environmental samples of milking hall and cattle house collected from the farm.The incidence regularity and main influencing factors of clinical mastitis were analyzed,and the sensitivity of antibiotics commonly used in the farm was detected and analyzed for 160 isolated strains.Further,the management details of the milking hall of the farm were evaluated to explore the influence of the limit of low flow rate of dewatering of milking equipment on the therapeutic effect of clinical mastitis in cattle.Achieve the following results:1.The average incidence of clinical mastitis was 3.42% in 2021,and the incidence was higher from January to March,with the highest incidence in March(10.15%).The incidence was the lowest(0.68%)in May.There was a negative correlation between temperature and the incidence of clinical mastitis(P=0.05)when the average temperature ranged from-7℃ to 27 ℃.The incidence rate of first-born calves was low(1.96%),and increased gradually with the increase of parity,with the highest incidence rate of 6 parity(15.55%).The lowest morbidity was found in the early lactation period(0.82%),and the morbidity increased with the increase of lactation days.The highest morbidity was found in the late lactation period(5.52%).There was a significant difference between the anterior and posterior mammary regions(P=0.023).Among the cattle with clinical mastitis,the number of cattle with an average yield of less than 15 kg accounted for the lowest proportion(1.14%),and the number of cattle with an average yield of more than 35 kg accounted for the highest proportion(58.43%).2.According to the hygiene scores of milk area and hind limbs and hoof,66.52% of dairy cows with 1-2 points of milk area cleanliness accounted for 28.81% of dairy cows with 1-2 points of hind limbs and hoof cleanliness in the whole herd.In 60 cows with clinical mastitis,the proportion of cows with 1-2 min cleanliness in milk area was 34.34%,and the proportion of cows with 1-2 min cleanliness in hind limbs and hoof was 8.33%.The keratinization scores at the end of the nipple of lactating cows in the whole herd showed that the ratio of 3-4 points of cows in 11 months was lower than 20%,with the lowest in October 2021(13.9%)and the highest in July 2022(20.64%).The results of normative evaluation on milking operation of staff in dairy hall showed that the milking operation of staff was basically within a reasonable range,but the area covered by the medicated bath was less than 100%.The wiping score in the anterior and posterior breast areas was higher(83.65%,71.67%)with 3-4 points.The proportion of cured cattle in test groups(cupping threshold 0.4kg/min)for 3-5 days was higher than that in control group(cupping threshold0.2kg/min),and the proportion of cured cattle in test groups with somatic cell count below 1million /m L on the 7th and 14 th day was 26.67% and 16.66% higher than that in control group.3.From 118 clinical mastitis samples,17 species of 164 pathogens of 7 genera were isolated and identified,the isolation rate was 99.15%,among which the main pathogens were Streptococcus(46.34%),Staphylococcus(34.76%),Eschella(11.59%),Klebsiella(5.49%).From 46 environmental samples and milk samples,127 strains of 53 species of pathogens belonging to 14 genera were isolated and identified,among which the bacteria with a relatively high proportion were mainly: Bacillus(37.82%),Streptococcus(13.38%),Escherichia Bacillus(10.24%),Enterococcus(8.67%),Proteus(6.3%),Staphylococcus(3.93%)and Lactococcus(4.20%).4.A total of 7 classes and 9 kinds of antibiotics were selected to test the drug sensitivity of pathogenic bacteria isolated from milk samples of clinical cases.The results showed that the 76 streptococcus strains had the highest sensitivity to ofloxacin(92.11%),and the highest resistance to tetracycline(48.68%),followed by ampicillin(46.05%)and lincomycin(39.47%).The 57 strains of Staphylococcus had the highest drug resistance to ampicillin,with a drug resistance rate of 24.56%,followed by cefotaxime and lincomycin,with a drug resistance rate of 22.80% and 19.30%,and the highest sensitivity to ofloxacin,with a sensitivity rate of 92.98%,followed by vancomycin and gentamicin.The sensitivity rates were 91.22% and 85.96%.The 28 Enterobacteriaceae strains were most sensitive to ofloxacin(100%),followed by gentamicin(75%),amoxicillin(64.29%),and cefotaxime(53.57%).In conclusion,the incidence of clinical cow mastitis in this farm is significantly correlated with month,temperature,parity,lactation stage,milk yield and milk area.The main pathogenic bacteria were Streptococcus,Staphylococcus,Eschella and Klebsiella,which were closely related to the types of bacteria in the dairy environment.By evaluating the management of dairy office,optimizing the milking parameters of clinically infected cows and carrying out drug sensitivity test of common antibiotics,this study provided experimental basis for the prevention and control measures of clinical dairy mastitis in livestock farms.