Epidemiological Survey Of Mastitis In Dairy Cows In Wuzhong Area And Study On The Application Of Teat Sealant During Dry Milking Period

Mastitis in dairy cows is a disease caused by a variety of non-specific pathogenic microorganisms infecting the udder.It mainly causes loss of mammary tissue in cows,changes milk quality,reduces milk production,increases treatment costs and causes significant economic losses to dairy production.The large use of antibiotics and the emergence of drug-resistant strains of bacteria in actual production pose a challenge to the prevention and control of the disease.Therefore,it is particularly important to find ways to better prevent mastitis in dairy cows.In this study,we investigated the incidence of clinical mastitis in dairy cows in four different sizes of farms in the Wuzhong area and investigated the prevalence of the main pathogens of clinical mastitis in dairy cows by PCR identification.A combination of teat sealant and antibiotics was also used during the dry milk period to investigate its effectiveness in preventing mastitis in postpartum cows.Firstly,this study investigated the incidence of clinical mastitis in dairy cows on four different scaled farms in the Wuzhong area and analysed the main causes and incidence patterns of clinical mastitis in dairy cows in the area.The results showed that the average incidence of clinical mastitis in cows in the Wuzhong area was 1.87%.The incidence of mastitis was higher in December,January and February,with the highest incidence in January and the lowest incidence in May.Winter had the highest incidence of 2.55%and spring had the lowest incidence of 1.42%,indicating that the incidence of mastitis in dairy cows is month and season related.The incidence of mastitis in cows at different litters increased with litter size and then decreased,with the highest incidence of mastitis in the 5th litter at 21.79%.The incidence of mastitis in the left hind and right hind teats was higher than that in the front teats,mainly because the hind teats have more exposure to contaminants and a higher chance of infection.The highest percentage of affected cows,22.95%,had the disease at 90-150 days of lactation.Secondly,this study investigated the main pathogenic bacteria in milk samples from clinical-type mastitis in dairy cows in the Wuzhong area.A total of 96 milk samples were collected from four farms in the area and the pathogenic bacteria were isolated and identified by PCR.The results showed that a total of 20 genera,42 species and 147 pathogenic bacteria were isolated,with high isolation rates of Staphylococcus spp,Escherichia spp,Streptococcus spp,Enterococcus spp,Uralia spp,Pseudomonas spp and Klebsiella spp.The detection rates of the main pathogens,Staphylococcus aureus,Escherichia coli and Streptococcus lactis,were the highest,with isolation rates of 13.61%,11.56%and 8.84%respectively,indicating that Staphylococcus aureus,Escherichia coli and Streptococcus lactis were the most common pathogens in the Wuzhong area.Finally,to further investigate the effectiveness of using teat sealants to prevent postpartum mastitis during the dry milk period,this study was conducted to determine the effectiveness of teat sealants in preventing postpartum mastitis by testing the somatic cell count in the milk of cows before and 30 days after dry milking in order to provide a reference for mastitis prevention on farms.The results showed that the use of teat closures in combination with antibiotics compared to antibiotics alone during the dry milking period reduced somatic cell counts in different milk zones postpartum,with a 71.76%reduction in somatic cell counts in cows 30 days after dry milking using intra-teat closures and antibiotic dry milking therapy,compared to a 16.93%increase in somatic cell counts in cows using dry milking therapy only.The trial showed that the use of teat closures during dry milking reduced somatic cell counts in postpartum cows and prevented the development of mastitis in cows.In summary,the prevalence of clinical mastitis in dairy cows in the Wuzhong area is closely linked to month,season,litter size,milking area and stage of lactation.The main pathogenic microorganisms causing clinical mastitis in dairy cows in Wuzhong are Staphylococcus aureus,Streptococcus lactis and Escherichia coli.By using teat milk sealants in combination with antibiotic dry milk therapy during the dry milk period,the number of somatic cells in the milk 30 days postpartum was significantly reduced and mastitis was prevented.