Study On The Prevention And Treatment Of Invisible Mastitis In Dairy Goats By Lactobacillus Salivarius Derived From Goat

Dairy goat invisible mastitis is a relatively high proportion of dairy goat mastitis,and it is not easy to be found,which brings serious economic loss to the dairy goat breeding industry.Antibiotics are the main drugs in the treatment of mastitis in dairy goats,but the long-term unreasonable use of antibiotics leads to the production of resistant bacteria and the risk of milk quality safety.Therefore,it is particularly urgent to find safe and effective prevention and treatment methods.The in-depth study of probiotics shows that Lactobacillus salivarius in lactobacillus has the functions of regulating intestinal flora and inhibiting the growth of pathogens,and is expected to become a probiotics replacing antibiotics to prevent and treatment mastitis.In order to obtain the prevention and treatment effect of Lactobacillus salivarius on mastitis and provide theoretical guidance and technical support for the prevention and treatment of recessive mastitis in milk goats.In this study,the epidemiological investigation of invisible mastitis in dairy goats on two large-scale farms.The invisible mastitis milk was collected by the isolation and purification of bacteria,morphological observation and PCR detection methods for the isolation and identification of the main pathogenic bacteria.Then,L.salivarius from the feces of healthy dairy goats.Seed identification by morphological observation and 16 S r DNA sequence detection.And to study its biological characteristics and safety in vitro.Finally,isolated L.salivarius were fed to goats and mice.By using the California mastitis assay,real-time PCR,histopathological observations and 16 S r RNA sequencing.To study the effectiveness of L.salivarius on the prevention and treatment of invisible mastitis.The main results were obtained as follows:1.Epidemiological investigation of invisible mastitis in milk goats and the isolation and identification of pathogens.The incidence of invisible mastitis in the two dairy goat farms was36.46% and 15.67% respectively;their main pathogenic bacteria were Staphylococcus aureus and Escherichia coli,and they were resistant to many antibiotics.2.Isolation and identification of Lactobacillus salivarius.An L.salivarius strain was isolated from the feces of healthy milk goats,which showed good tolerance to the gastrointestinal environment and inhibited the main pathogenic bacteria of invisible mastitis,and had a high safety profile.3.Prevention and treatment effect of Lactobacillus salivarius on invisible mastitis in dairy goats.Feeding the isolated and identified L.salivarius into invisible mastitis milk goats can significantly reduce the relative expression level of inflammatory factors such as IL-17,IL-6,IL-1β,IL-23,and TNF-α in the blood(P<0.05),increase the diversity of intestinal and milk microflora,and significantly reduce the positive detection rate of cryptic mastitis.4.Efficacy of L.salivarius on invisible mastitis in mice.Successful construction of a mouse model of S.aureus mastitis.After the mice fed L.salivarius,the pathological changes in the prevention and treatment group decreased;the relative expression of inflammatory factors such as IL-17,IL-6,IL-1β,IL-23,and TNF-α decreased significantly compared with the mastitis model group(P<0.05),and the relative expression of the tight junction proteins Claudin-1,Claudin-3 and Claudin-7 increased in the breast tissue(P<0.05),indicating that L.salivarius had a good protective effect and effective treatment effect on invisible mastitis.The above results show that the main pathogenic bacteria of invisible mastitis in the investigated farms are Staphylococcus aureus and Escherichia coli,and are resistant to various antibiotics.L.salivarius isolated from healthy goats has good growth characteristics in vitro,good tolerance to gastrointestinal environment,antibacterial and safe effect.L.salivarius can change the structure of goat gut and milk flora,reduce the expression of related inflammatory factors,and have preventive and therapeutic effect on model mice,improve the expression of tight junction proteins in breast tissue,and reduce the damage of pathogenic bacteria to breast tissue.In conclusion,L.salivarius has a good prevention effect against invisible mastitis and has a clinical prospect for the prevention and treatment of invisible mastitis.