The prevalence of heifer mastitis and its associated risk factors in Huanggang, Central China

Esculetin improves murine mastitis induced by streptococcus isolated from bovine mammary glands by inhibiting NF-κB and MAPK signaling pathways

Cow mastitis, caused by Streptococcus infection of the mammary glands, is a common clinical disease that can lead to decreased milk quality and threaten animal welfare and performance. Esculetin (ESC) is a coumarin with anti-inflammatory and anti-asthmatic effects. However, whether ESC has therapeutic effects on mastitis remains unexplored. This study was conducted to investigate the protective effect of ESC against murine mastitis caused by Streptococcus isolated from bovine mammary glands and elucidate the underlying mechanisms. Streptococcus uberis was used to construct a mouse model of mastitis. The results showed that the mice exhibited edema and thickening of the acinar wall with inflammatory infiltration after S. uberis treatment. Intraperitoneal injection of ESC significantly reduced inflammatory cell infiltration, restored normal physiological function, and inhibited the production of the inflammatory cytokines interleukin-1β, interleukin-6, and tumor necrosis factor-α. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot analysis revealed that ESC reduced P38 phosphorylation, further inhibited the influence of mammary Streptococcus on cytoplasmic translocation of nuclear factor-κB (P65), and inhibited the transcriptional activation of P65, thus inhibiting the generation of inflammatory cells. Collectively, ESC may inhibit mitogen-activated protein kinase and nuclear factor-κB, thereby highlighting its potential for the treatment and prevention of mastitis.

Association of Mastitis and Farm Management with Contamination of Antibiotics in Bulk Tank Milk in Southwest, China

Bovine mastitis could reduce the milk production and the quality of the bulk tank milk (BTM). Antibiotic treatments through intramammary or parenteral methods are being widely used in dairy farms. A cross-sectional study to investigate for general farm management and pre-test the questionnaire was performed in Southwestern Yunnan province, China. A total of 134 dairy farms were included. Milking cows of each farm were determined for the presence of clinical (CM) and sub-clinical (SCM) mastitis using the California Mastitis Test (CMT). Rates of CM and SCM in studied farms ranged from 2-11%, and 24-69%, respectively. The incidence of antibiotic residues in BTM of all farms was very high (32%, 44/134). All antibiotic contaminated samples were from smallholder dairy farms. Factors significantly associated with the presence of antibiotic contamination included farm region, antibiotics usage, persons performing mastitis treatment, and rates of CM. Rates of CM were significantly associated with the farm region, cleanliness of udders before milking, and the number of milking cows. Our results emphasize that the risk factors of dairy farm management should be paid attention, which can reduce mastitis prevalence and antibiotic contamination in BTM in Southwestern China.

Taurine protects blood-milk barrier integrity via limiting inflammatory response in Streptococcus uberis infections

Streptococcus uberis (S. uberis) is an important causative agent of mastitis, leading to significant economic losses to dairy industry. This research used a mouse mastitis model to investigate the protective effects of taurine on mammary inflammatory response and blood-milk barrier integrity in S. uberis challenge. The results showed that taurine attenuated S. uberis-induced mammary histopathological changes, especially neutrophil infiltration. The S. uberis-induced expression of pro-inflammatory mediators were decreased significantly by taurine. Further, we demonstrated that taurine limited the S. uberis-induced inflammatory responses via inhibiting the activation of NF-κB and MAPK signaling pathways. Inflammation usually disrupts the mammary barrier system. The recovery of claudin-3 and occludin expressions indicated that attenuation of inflammatory response by taurine can protect the integrity of blood-milk barrier in S. uberis infection. Taken together, our results reveal that the development of taurine as an effective prevention and control strategy for S. uberis-induced mastitis.

Global and countrywide prevalence of subclinical and clinical mastitis in dairy cattle and buffaloes by systematic review and meta-analysis

In the present study, subclinical mastitis (SCM) and clinical mastitis (CM) prevalence for various countries in the World were calculated by using online and offline databases. The SCM and CM prevalence studies reported during 1967-2019 were collected, reviewed, and a meta-analysis was done in R-Software. A total of 222 and 150 studies from the World and 103 and 37 studies from India on SCM and CM, respectively were included. The pooled prevalence of SCM and CM were 42% [Confidence Interval (CI) 38-45%, Prediction Interval (PI) 10-83%] and 15% [CI 12-19%, PI 1-81%] in the World respectively, 45% [CI 40-49%, PI 11-84%] and 18% [CI 14-23%, PI 3-60%] in India respectively. Continent-wise analysis indicated a higher prevalence of SCM in North America and CM in Europe and among the countries, a higher SCM prevalence in Uganda and CM in the United Kingdom was observed. Further, species-wise indicated a higher SCM and CM prevalence in buffaloes of the World than the cattle. Based on method-wise, SCM and CM prevalence were high in somatic cell count and clinical examination, respectively in the World. The SCM prevalence was higher than CM and indicated the importance of SCM in dairy cattle. This might result in low milk productivity in dairying and may set off losses to dairy farmers. Hence, there is an urgent need to reduce the SCM and CM prevalence by implementing scientific dairy management, good feeding practices, and timely therapeutic interventions for increasing the benefits from dairying to the farmers in the World.

Prevalence, Etiology, and Risk Factors of Mastitis in Dairy Cattle in Embu and Kajiado Counties, Kenya

Bovine mastitis continues to be a leading cause of heavy economic losses in the dairy industry and a public health hazard globally. This cross-sectional study investigated the prevalence, etiologies of clinical and subclinical mastitis, and associated predisposing factors in Embu and Kajiado counties in Kenya. A semistructured questionnaire was administered to 154 smallholder dairy farmers to collect data on management practices, animal factors, and disease history. A total of 395 dairy cows were initially screened for subclinical mastitis using the California mastitis test (CMT), and milk samples were aseptically collected. Both CMT positive and CMT negative samples were analyzed using conventional bacteriological isolation and identification procedures. In the present study, the overall prevalence of mastitis based on CMT and clinical examination was 80% (316/395), out of which 6.8% (27/395) was clinical mastitis, while 73.1% (289/395) was subclinical mastitis. Based on culture, the overall prevalence of clinical and subclinical mastitis was 51.6% (815/1580), 74.4% (294/395), and 76.6% (118/154) at the quarter, cow, and farm level, respectively. From the 1574 milk samples analyzed by cultured, 1016 bacteria were yielded. The predominant bacteria were coagulase-negative Staphylococcus (CNS), 42.8% (435/1016), and in decreasing order, Streptococcus species, 22.2% (226/1016), Staphylococcus aureus, 15.7% (160/1016), and Pseudomonas aeruginosa, 5.1% (52/1016), and the least was Enterobacter species, 0.7% (7/1016), while 23.7% of the sample yielded no bacterial growth. Risk factor analysis revealed that milking mastitic cows last (p=0.002), using a clean udder drying towel for each cow (p=0.033) and previous history of mastitis (p=0.046) were significantly associated with presence of mastitis. The current study has shown a relatively high prevalence of subclinical mastitis with CNS as predominant bacteria. Therefore, control measures are urgently warranted. Management factors such as milking mastitic cows last, using a clean towel for udder drying for each cow, and culling mastitic cows should be considered and included in the Kenyan mastitis control programs.

Occurrence of β-lactam-resistant Staphylococcus aureus in milk from primiparous dairy cows in the northeastern region of Brazil

The objective of the current study was to isolate and identify Staphylococcus (S.) aureus strains resistant to beta-lactam antibiotics from primiparous cows' milk. A total of 432 milk samples were collected from all primiparous dairy cows in early lactation that originated from 9 dairy properties. All samples were cultured in Mannitol salt agar enriched with egg yolk emulsion. Determination of genotypic resistance of S. aureus was achieved by polymerase chain reaction (PCR) for amplification of the blaZ, mecA, and mecC genes. Phenotypic resistance of S. aureus strains was evaluated by minimal inhibitory concentration (MIC) technique using broth microdilutions of penicillin G and oxacillin. From all the mammary quarters examined, S. aureus strains were detected in 27 out of 432 (6.25%) milk samples (CI_95%, 4.33-8.84). From all dairy properties visited, only two out of 9 were found to have S. aureus. Hence, it was possible to evaluate genotypic and phenotypic resistance in 27 samples from two dairy farms. The isolates of S. aureus had a frequency of (20/27) 74.07% to blaZ gene (CI_95%, 57.5-90.6), whereas mecA and mecC genes were not observed. According to MIC results, penicillin G had a 74.07% (20/27) resistance rate (CI_95%, 57.5-90.6) and oxacillin had a 14.81% (4/27) resistance rate (CI_95%, 1.4-28.2). Thus, the circulation of S. aureus strains resistant to beta-lactams has been confirmed in primiparous dairy cows in the northeastern region of Brazil, indicating the need for new management strategies involving the use of beta-lactam drugs to treat mastitis, discouraging and/or limiting their use. Also, it is important to highlight the need for further studies on epidemiology and traceability of the pathogen.

Bacteriological survey of bulk tank milk from dairy farms in Montero, Santa Cruz, Bolivia

Background and Aim:

Recently, bacterial surveys for mastitis-causing pathogens in bulk tank milk (BTM) have been conducted in several countries worldwide. However, no such surveys have been reported from Bolivia. Therefore, the present study aimed to estimate the prevalence of mastitis pathogens in BTM from dairy farms in Montero, Santa Cruz, Bolivia.

Materials and Methods:

Between July 2016 and August 2017, a total of 43 BTM samples were collected from 3264 cows to determine bulk tank somatic cell counts (BTSCC) and identify mastitis-causing bacteria. BTSCC was classified as follows: <100×10³, 100-500×10³, 500-1000×10³, and >1000×10³ cells/mL.

Results:

Mastitis-causing pathogens identified by agar medium cultures included Bacillus spp., coagulase-negative staphylococci (CNS), coliforms, Staphylococcus aureus (SA), streptococci, and other species. The proportions of BTSCC of <100×10³, 200-500×10³, 500-1000×10³, and >1000×10³ cells/ml were 0%, 37%, 51%, and 12%, respectively. The proportions of coliforms, streptococci, CNS, Bacillus spp., SA, and others detected in BTM were 33%, 30%, 16%, 7%, 2%, and 16%, respectively.

Conclusion:

Although the herd prevalence of contagious mastitis-causing pathogens, such as SA, in BTM was low, increased BTSCC were identified in Montero, Santa Cruz, Bolivia.

Prevalence and etiology of mastitis in dairy cattle in El Oro Province, Ecuador

This study described the occurrence of clinical and subclinical forms of mastitis in 250 cattle from 5 dairy farms around the cities of Santa Rosa and Machala, El Oro Province, Ecuador. Clinical mastitis (CM) was determined based on obvious changes in milk (mild), signs of inflammation in the udder (moderate), and/or generalized clinical symptoms (severe). Subclinical mastitis (SCM) was assessed using the California mastitis test. CM and SCM were detected in 30 (12.0%) and 150 (60%) of the 250 tested cattle, respectively. Prevalence at the udder quarter level was 57.7% (577/1,000), which was higher among forequarters (369/577; 63.9%) than hindquarters. Of the 577 mastitic milk samples subjected to microbiological analysis, 35 were excluded due to contamination and 20 tested negative. Identification of bacterial isolates revealed that 33.3% of the 93 CM samples contained coliforms, 25.8% coagulase-positive staphylococci, 20.4% coagulase-negative staphylococci (CNS), 9.7% streptococci, 7.5% Bacillus spp., and 3.2% Klebsiella spp. Bacterial profiling of the 429 SCM milk samples showed that 55.4% contained CNS, 22.1% Bacillus spp., 9.3% streptococci, and 6.1% coagulase-positive staphylococci. In vitro antibiotic susceptibility testing of the obtained isolates indicated that all were susceptible to amoxicillin, ampicillin, cefotaxime, enrofloxacin, sulfamethoxazole-trimethoprim, gentamicin, and neomycin. No multidrug-resistant strains were observed.

Reisolation of Staphylococcus aureus from bovine milk following experimental inoculation is influenced by fat percentage and specific immunoglobulin G1 titer in milk

The associations of management parameters, herd characteristics, and individual cow factors with bovine mastitis have been subject of many studies. The present study aimed to evaluate the association between milk composition parameters, including fat, protein, lactose, urea, and specific immunoglobulin levels, at the time of experimental bacterial inoculation of the mammary gland and subsequent shedding dynamics of Staphylococcus aureus. Sixty-eight cows were experimentally infected with S. aureus and closely monitored for 3 wk. Mixed model analyses were used to determine the influence of management and herd characteristics (farm and experimental group), individual cow factors (days in milk, milk yield, and quarter position), and a challenge-related parameter (inoculation dose) in combination with either the milk components fat, protein, lactose and urea, or the S. aureus-specific antibody isotype titers at the time of bacterial inoculation, on the number of S. aureus reisolated from milk after inoculation. A positive association was observed between the milk fat percentage and the number of S. aureus reisolated from quarter milk, and a negative relationship between the S. aureus-specific IgG1 titer in milk and the number of S. aureus. These findings should be considered in the development of a vaccine against S. aureus-induced bovine mastitis.

Polymorphisms in the promoter region of the bovine lactoferrin gene influence milk somatic cell score and milk production traits in Chinese Holstein cows

Lactoferrin is an iron-binding protein found in cow's milk that plays an important role in preventing mastitis caused by intramammary infection. In this study, 20 Chinese Holstein cows were selected randomly for PCR amplification and sequencing of the bovine lactoferrin gene promoter region and used for SNP discovery in the region between nucleotide positions -461 to -132. Three SNPs (-270T>C, -190G>A and -156A>G) were identified in bovine lactoferrin, then Chinese Holstein cows (n=866) were genotyped using Sequenom MassARRAY (Sequenom Inc., San Diego, CA) based on the previous SNP information in this study, and the associations between SNPs or haplotype and milk somatic cell score (SCS) and production traits were analyzed by the least squares method in the GLM procedure of SAS. SNPs -270T>C and -156A>G showed close linkage disequilibrium (r(2)=0.76). The SNP -190G>A showed a significant association with SCS, and individuals with genotype GG had higher SCS than genotypes AG and AA. Associations were found between the SNPs -270T>C and -190G>A with SCS and the milk composition. The software MatInspector revealed that these SNPs were located within several potential transcription factor binding sites, including NF-κB p50, KLF7 and SP1, and may alter gene expression, but further investigation will be required to elucidate the biological and practical relevance of these SNPs.

Prevalence and patterns of antimicrobial resistance among Escherichia coli isolated from Zambian dairy cattle across different production systems

This study focused on the use of antibiotics on small, medium and commercial-sized dairy farms in the central region of Zambia and its relationship to antibiotic resistance in Escherichia coli. A stratified random sample of 104 farms was studied, representing approximately 20% of all dairy farms in the region. On each farm, faecal samples were collected from a random sample of animals and a standardised questionnaire on the usage of antibiotics was completed. An E. coli isolate was obtained from 98.67% (371/376) of the sampled animals and tested for resistance to six classes of antibiotics. The estimated prevalence of resistance across the different farming systems was: tetracycline (10.61; 95%CI: 7.40–13.82), ampicillin (6.02; 95%CI: 3.31–8.73), sulfamethoxazole/ trimethoprim (4.49; 95%CI: 2.42–6.56), cefpodoxime (1.91; 95%CI: 0.46–3.36), gentamicin (0.89; 95%CI: 0.06–1.84) and ciprofloxacin (0%). Univariate analyses indicated certain diseases, exotic breeds, location, farm size and certain management practices as risk factors for detection of resistance, whereas multivariate analyses showed an association with lumpy skin disease and a protective effect for older animals (>25 months). This study has provided novel insights into the drivers of antibiotic use and their association with antibiotic resistance in an under-studied region of Southern Africa.