Brazilian Dairy Research Articles

The potential use of probiotic and beneficial bacteria in the Brazilian dairy industry.

Scientific studies demonstrate the importance of intestinal microbiota to human health and how probiotic microorganisms can positively affect health when administered regularly and in adequate amounts. Probiotic bacteria can be part of fermented products and their functional importance is associated mainly with their metabolism. They are thought to benefit individuals to maintain their health and also to strengthen resistance against various types of diseases. The acceptance of probiotic cultures and products by consumers increased when these bacteria were marketed as natural cultures that help in digestion and health. Considering this, the food industry has an increasing demand for new candidates as probiotic cultures, and the dairy industry has a particular interest for fermented milks and other dairy products, since these are the most common food vehicles for probiotic cultures. Therefore, the dairy industries are increasingly seeking to improve their products with these beneficial bacteria. However, the legal peculiarities and excess of control agencies in Brazil makes the registration of these products and the collection of data very complex. Prospective analysis suggests that probiotic foods have the potential to effect a considerable expansion of the dairy industry, allowing the dairy sector to grow and for these products to be increasingly sought by consumers globally. For this, not only actions on research and innovation are necessary, but also official clarifications on the claims for considerations of microbiological security and functionality of these products. This review aims to elucidate important probiotic research regarding the isolation and characterization of beneficial cultures in Brazil, and to demonstrate the relevance of the dairy chain as a potential source of novel cultures for the development of new probiotic products to expand the Brazilian dairy industry.

Association of herd-level risk factors and incidence rate of clinical mastitis in 20 Brazilian dairy herds

The objectives of this study were to characterize the pathogen frequency and severity of clinical mastitis (CM) in 20 dairy herds of southeastern Brazil; and to determine the incidence rate of clinical mastitis (IRCM; overall and based on specific-pathogen groups) based on quarter time at risk and its association with risk factors at the herd-level. Data were recorded in each herd for a period of 8 to 15 months. The association between herd-level risk factors and IRCM were determined by two groups of mixed regression models: one based on the overall IRCM, and five based on the following specific-pathogen groups: contagious, other Gram-positive, Gram-negative, other, and negative culture. The following herd-level risk factors were evaluated: herd size, housing system, average daily milk yield per cow, bulk milk somatic cell count (BMSCC), and bulk milk total bacterial count (BMTBC). A total of 5957 quarter-cases of CM were recorded from 2637 cows, but only 4212 cases had milk samples collected for culture. The most frequently isolated pathogens were Escherichia coli (6.6% of total cultures), Streptococcus uberis (6.1%), and Streptococcus agalactiae (5.9%). The majority of CM cases were mild (60.3%), while 34.1% were moderate and 5.6% severe. The frequency of severe CM cases was lower for those with a Gram-positive result (4.6%) compared to a Gram-negative result (11.4%). Overall, monthly mean IRCM was 9.7 cases per 10,000 quarter-days at risk (QDAR). Herds with a geometric mean BMSCC ≥ 601 × 103 cell/mL had higher overall IRCM (16/10,000 QDAR) than those with BMSCC ≤ 600 × 103 cell/mL (≤7.7/10,000 QDAR). When the specific-pathogen groups were evaluated, for contagious pathogens, variables housing (free-stalls or compost-bedded pack barns), BMSCC (≥601 × 103 cells/mL), and average daily milk yield per cow (21 and 25 Kg/d) presented the highest IRCM. Furthermore, in Gram-negative group, herds with BMTBC ≥ 31 × 103 cfu/mL had higher IRCM compared with herds with BMTBC ≤ 30 × 103 cfu/mL. Although environmental pathogens were the most common cause of CM in this study, contagious pathogens (e.g., Strep. agalactiae and Staph. aureus) are still a concern in dairy herds of Brazil. Additionally, as there were some herd-level risk factors associated with the IRCM, there may be opportunity for management strategies aiming to improve the control of CM in dairy herds.

Genetic diversity of thermoduric spoilage microorganisms of milk from Brazilian dairy farms

When correctly pasteurized, packaged, and stored, milk with low total bacterial counts (TBC) has a longer shelf life. Therefore, microorganisms that resist heat treatments are especially important in the deterioration of pasteurized milk and in its shelf life. The aim of this work was to quantify the thermoduric microorganisms after the pasteurization of refrigerated raw milk samples with low TBC and to identify the diversity of these isolates with proteolytic or lipolytic potential by RFLP analysis. Twenty samples of raw milk were collected in bulk milk tanks shortly after milking in different Brazilian dairy farms and pasteurized. The mean thermoduric count was 3.2 (±4.7) × 102 cfu/mL (2.1% of the TBC). Of the 310 colonies obtained, 44.2% showed milk spoilage potential, 32.6% were proteolytic and lipolytic simultaneously, 31% were exclusively proteolytic, and 48 (36.4%) were only lipolytic. Regarding the diversity, 8 genera were observed (Bacillus, Brachybacterium, Enterococcus, Streptococcus, Micrococcus, Kocuria, Paenibacillus, and Macrococcus); there was a predominance of endospore-forming bacteria (50%), and Bacillus licheniformis was the most common (34.1%) species. Considering the RFLP types, it was observed that the possible clonal populations make up the microbiota of different milk samples, but the same milk samples contain microorganisms of a single species with different RFLP types. Thus, even in milk with a high microbiological quality, it is necessary to control the potential milk-deteriorating thermoduric microorganisms to avoid the risk of compromising the shelf life and technological potential of pasteurized milk.

The energy mix and energy efficiency analysis for Brazilian dairy industry

Abstract This paper focuses on an analysis of the energy mix profile and energy efficiency of the Brazilian dairy industry. It investigates dairies’ energy mix and energy efficiency and identifies some actions for a cleaner energy mix. Primary data from 37 dairy cheese-making establishments distributed among the Brazilian regions were obtained from online surveys. The results indicate that woodfuel plays a critical role, being the most used fuel in thermal energy generation, while diesel is dominant in electric generation. It also emphasizes that only 51% of the dairy establishments utilize electric energy generators. Other alternative biomass sources are still incipient in the sector, restricted to just 9.5% of the cases for thermal energy generation and no cases for electricity. Regarding the energy efficiency analysis, the results suggest dairies are more scale efficient than pure technical efficient. However, the dairies present a low energy efficiency level. There is no evidence that inefficiencies are differently distributed according to their size. These findings are important for government agencies, industry associations, scientists, universities and research institutes. High inefficiencies, regarding the use of electricity and thermal energy, are a key issue in sustainable bioenergy production.

Antimicrobial-Resistance Genetic Markers in Potentially Pathogenic Gram Positive Cocci Isolated from Brazilian Soft Cheese.

Although most Brazilian dairy products meet high technological standards, there are quality issues regarding milk production, which may reduce the final product quality. Several microbial species may contaminate milk during manufacture and handling. If antimicrobial usage remains uncontrolled in dairy cattle, the horizontal transfer of antimicrobial resistance genes in foodstuffs may be of particular concern for both food producers and dairy industry. This study focused on the evaluation of putative Gram positive cocci in Minas cheese and of antimicrobial and biocide resistance genes among the isolated bacteria. Representative samples of 7 different industrially trademarked Minas cheeses (n = 35) were processed for selective culture and isolation of Gram positive cocci. All isolated bacteria were identified by DNA sequencing of the 16S rRNA gene. Antimicrobial resistance genes were screened by PCR. Overall, 208 strains were isolated and identified as follows: Enterococcus faecalis (47.6%), Macrococcus caseolyticus (18.3%), Enterococcus faecium (11.5%), Enterococcus caseliflavus (7.7%), Staphylococcus haemolyticus (7.2%), Staphylococcus aureus (4.3%), Staphylococcus epidermidis (2.9%), and Enterococcus hirae (0.5%). The genetic markers mecA (78.0%) and smr (71.4%) were the most prevalent, but others were also detected, such as blaZ (65.2%), msrA (60.9%), msrB (46.6%), linA (54.7%), and aacA-aphD (47.6%). The occurrence of opportunist pathogenic bacteria harboring antimicrobial resistance markers in the cheese samples are of special concern, since these bacteria are not considered harmful contaminating agents according to the Brazilian sanitary regulations. However, they are potentially pathogenic bacteria and the cheese may be considered a reservoir for antimicrobial resistance genes available for horizontal transfer through the food chain, manufacturing personnel and consumers.

The Efficiency of the Brazilian Dairy Sector: A productivity Analysis from 1974 to 2016

The Efficiency of the Brazilian Dairy Sector: A productivity Analysis from 1974 to 2016

Comparative genomic survey of Bacillus cereus sensu stricto isolates from the dairy production chain in Brazil.

The genomes of 262 Bacillus cereus isolates were analyzed including 69 isolates sampled from equipment, raw milk and dairy products from Brazil. The population structure of isolates showed strains belonging to known phylogenetic groups II, III, IV, V and VI. Almost all the isolates obtained from dairy products belonged to group III. Investigation of specific alleles revealed high numbers of isolates carrying toxin-associated genes including cytK (53.62%), hblA (59.42%), hblC (44.93%), hblD (53.62%), nheA (84.06%), nheB (89.86%) and nheC (84.06%) with isolates belonging to groups IV and V having significant higher prevalence of hblACD and group IV of CytK genes. Strains from dairy products had significantly lower prevalence of CytK and hblACD genes compared to isolates from equipment and raw milk/bulk tanks. Genes related to sucrose metabolism were detected at higher frequency in isolates obtained from raw milk compared to strains from equipment and utensils. The population genomic analysis demonstrated the diversity of strains and variability of putative function among B. cereus group isolates in Brazilian dairy production, with large numbers of strains potentially able to cause foodborne illness. This detailed information will contribute to targeted interventions to reduce milk contamination and spoilage associated with B. cereus in Brazil.

Transrectal ultrasound evaluation in tropical dairy goats: an indispensable tool for the diagnosis of reproductive disorders.

In Brazil, great milk productivity was achieved after the implementation of a genetic improvement program. However, reproductive efficiency is still far from optimal, possibly due to the high number of undiagnosed disorders that may affect fertility. The aim of this study was to evaluate occurrences of the main reproductive disorders in dairy goats in southeastern Brazil. Data were collected between January 2015 and May 2017 from 23 commercial herds of different breeds, with goats ranging from 8months to 12years of age. Transrectal ultrasound exams were performed in 2680 goats. A total of 14.8% of the does showed a disorder in the reproductive tract: hydrometra (10.0%), ovarian follicular cysts (2.3%), gestational loss (1.5%), and hydrosalpinx (1.1%). This was the first study evaluating reproductive disorders in live animals that used a high number of Brazilian dairy goats. Considering that all these diseases affect fertility to different degrees, the performance of transrectal ultrasonography exams twice a year is strongly suggested, in order to guide precocious treatment or discard the animal as soon as possible, thus reducing economic losses in dairy goat farming.

Virus neutralization technique as a tool to evaluate the virological profile for bovine viral diarrhea virus infection in dairy water buffalo (Bubalus bubalis) herds.

Serological evidence shows that the bovine viral diarrhea virus (BVDV) infections are present in Brazilian dairy and beef water buffalo herds. As few reports describe the BVDV infection profile the aim of this study was to evaluate the dynamics of BVDV circulation in Brazilian dairy water buffalo herds through analysis of the seropositivity rate and the titer range of anti-BVDV neutralizing antibodies in a group of animals that are considered sentinels. Blood samples (n = 305) were obtained from unvaccinated, asymptomatic young water buffalos from four dairy herds randomly identified as A (n = 106), B (n = 62), C (n = 119), and D (n = 18). The detection and titration of anti-BVDV neutralizing antibodies were evaluated by the virus neutralization test according to the World Organization for Animal Health. Analysis of the results revealed two distinct epidemiological conditions. The first is represented by herds A and C where high rates of seropositive animals (A = 39.6%; C = 51.3%) and high and very variable antibodies titers suggested active BVDV infection. The other condition is represented by herds B and D with low rates of seropositive animals (B = 8.1%; D = 11.1%) and low and little variable antibodies titers suggesting an epidemiological condition of infection stability. Some variables were observed in herds with a distinct BVDV infection profile. Herds with active infection were big, open herds, and had more management practices. In contrast, the herds with infection stability were small, closed herds with few management practices. These results highlight the importance of evaluation, monitoring, and control of BVDV infection also in dairy water buffalo herds.

Brazilian Citizens: Expectations Regarding Dairy Cattle Welfare and Awareness of Contentious Practices.

Simple SummaryAnimal welfare is an important issue for citizens in North America and Europe, but much less is known about how citizens from emergent countries, such as Brazil, view this topic. Our aim was to explore attitudes of urban Brazilian citizens about dairy production and, in particular, how they view four routine husbandry practices: early cow-calf separation; zero-grazing; culling of the newborn male calf; and dehorning without pain mitigation. Through in-depth interviews and a questionnaire using open-ended questions, we can conclude that animal welfare was a major issue for our participants, especially in terms of its perceived relation with milk quality. Although participants were initially unaware about any of the four management practices, they were all viewed as contentious and not supported. This study provides some insights that farmers and others working in the Brazilian dairy supply chain should take into consideration, particularly in terms of social sustainability.The primary aim of this study was to explore attitudes of urban Brazilian citizens about dairy production. A secondary aim was to determine their knowledge and attitudes about four potentially contentious routine dairy cattle management practices: early cow-calf separation; zero-grazing; culling of newborn male calves; and dehorning without pain mitigation. To address the first aim 40 participants were interviewed using open-ended semi-structured questions designed to probe their views and attitudes about dairy production in Brazil, and 300 participants answered a questionnaire that included an open-ended question about the welfare of dairy cattle. Primary concerns reported by the participants centered on milk quality, which included the rejection of any chemical additives, but also animal welfare, environmental and social issues. The interviewees rarely mentioned animal welfare directly but, when probed, expressed several concerns related to this topic. In particular, participants commented on factors that they perceived to influence milk quality, such as good animal health, feeding, clean facilities, and the need to avoid or reduce the use of drugs, hormones and pesticides, the avoidance of pain, frustration and suffering, and the ability of the animals to perform natural behaviors. To address our second aim, participants were asked questions about the four routine management practices. Although they self-reported being largely unaware of these practices, the majority of the participants rejected these practices outright. These data provide insight that animal welfare may be an important issue for members of the public. Failure to consider this information may increase the risk that certain dairy production practices may not be socially sustainable once lay citizens become aware of them.

Physical hazards in dairy products: Incidence in a consumer complaint website in Brazil

The incidence of physical hazards in dairy products (2012–2016) was investigated through a complaint website (Reclame Aqui) used by Brazilian consumers to report complaints. Among the complaints, 2% referred to the presence of physical hazards in the products. With regard to milk and dairy products, 515 complaints were reported, with the greatest percentage for yogurt/milk drink (37%) followed by UHT milk (14.6%) and milk powder (10.7%). The least cited products were Prato Cheese, Brie-type cheese, and Cottage cheese (0.3–0.4%). The most reported hazards were the presence of foreign objects (42.4%), followed by insects (23.3%), hair (15.2%), plastics (11.1%), metal (6.2%) and fabric (1.8%). The results showed failures in both Brazilian dairy foods processing and the public-sector inspection, and demonstrated that the Internet has proven to be an effective tool for spreading consumer dissatisfaction.

Impact of farm size on milk quality in the Brazilian dairy industry according to the seasons of the year

ABSTRACT: Milk produced in Brazil has been seen as having poor quality and is associated with a large number of small farms. However, there are few studies demonstrating lower quality of milk of small properties. Thus, this study aimed to evaluate the relationship between production scale on dairy farms and milk quality, how it behaviors throughout the year and set goals to improve quality according to each strata. A total of 21,917 analysis of 409 farmers conducted from January 2005 to December 2014 were used. To study the database, the properties were divided according to monthly average daily milk yield: 10 to 100; 100 to 200; 200 to 500; 500 to 1,000; and 1,000 to 5,000L of milk day-1. The data showed that dairy farming is predominantly carried out on small-scale production properties; however, the highest volumes are produced by a small number of producers. Additional data reveals that milk quality can vary because of distinct factors as nutritional condition and feed supply. Quality of the milk produced should be a matter of concern for the entire milk-production chain, because it still has problems such as high total bacterial count, high somatic cell count and low solids.

Staphylococcus aureus in Some Brazilian Dairy Industries: Changes of Contamination and Diversity.

Staphylococcus aureus, a major food-poisoning pathogen, is a common contaminant in dairy industries worldwide, including in Brazil. We determined the occurrence of S. aureus in five dairies in Brazil over 8 months. Of 421 samples, 31 (7.4%) were positive for S. aureus and prevalence varied from 0 to 63.3% between dairies. Sixty-six isolates from the 31 samples were typed by Multi-Locus Sequence Typing to determine if these isolates were persistent or continuously reintroduced. Seven known sequence types (STs), ST1, ST5, ST30, ST97, ST126, ST188 and ST398, and four new ST were identified, ST3531, ST3540, ST3562 and ST3534. Clonal complex (CC) 1 (including the four new ST), known as an epidemic clone, was the dominant CC. However, there were no indications of persistence of particular ST. The resistance toward 11 antibiotic compounds was assessed. Twelve profiles were generated with 75.8% of strains being sensitive to all antibiotic classes and no Methicillin-resistant S. aureus (MRSA) strains were found. The enterotoxin-encoding genes involved in food-poisoning, e.g., sea, sed, see, and seg were targeted by PCR. The two toxin-encoding genes, sed and see, were not detected. Only three strains (4.5%) harbored seg and two of these also harbored sea. Despite the isolates being Methicillin-sensitive S. aureus (MSSA), the presence of CC1 clones in the processing environment, including some harboring enterotoxin encoding genes, is of concern and hygiene must have high priority to reduce contamination.

Buffalo milk composition, processing factors, whey constituents recovery and yield in manufacturing Mozzarella cheese

Abstract Mozzarella cheese is typically from Italy and consumed in the whole world. The aim of this study was to characterize the manufacture of Mozzarella produced similarly to Italian in a Brazilian dairy industry regarding the milk composition usage, factors involved in the production process, use of raw materials and cheese yield. Was monitored the Mozzarella yield (MY), milk composition, manufacturing of Mozzarella cheese and recovery of whey constituents of 30 lots of Mozzarella cheese in a dairy brazilian industry. Overall, processing reached an adequate MY for this type of cheese, being below 5.0 L kg-1. We find values of 5.93 ± 1.87; 34.97 ± 2.70; 33.39 ± 2.85; 95.04 ± 4.18; 44.02 ± 2.00; and 66.82 ± 3.36 respectively for recovery of fat, protein, casein, lactose, total solids and solids-not-fat in whey. The milk used by the dairy industry had satisfactory physicochemical characteristics. The manufacturing of Mozzarella cheese was efficient.

Social Networks, Social Capital and Performance: a study with brazilian Dairy cooperatives

This study aimed to evaluate if social network and social capital theories are enough do encompass the complexity of management of cooperatives works in order to get superior performance. The subject of this study arises on the relationship of inter-organizational social networks in managerial capabilities of Brazilian cooperatives operating in the dairy segment. We utilized a structured questionnaire to collect quantitative data. The questionnaire was sent by email and by mail to the leaders of 414 cooperatives. We obtained 348 responses and, after treatment of missing data, 331 of them were analyzed. A theoretical model based on the theoretical framework was proposed and then validated by analysis of Structural Equation Modeling (SEM). Thus, it was established that inter-organizational social networks generate capital and that the cooperatives make use of networks, albeit incipiently. It was noted, too, that inter-organizational social networks can benefit cooperatives’ performance.

Phylogenetic analysis of VP1 and RdRP genes of Brazilian aichivirus B strains involved in a diarrhea outbreak in dairy calves.

Aichivirus B has been reported worldwide in calves and adult cattle with and without diarrhea. The aim of this study was to describe the molecular characteristics of the RdRP and VP1 genes of aichivirus B strains identified as the most frequent etiologic agent in a neonatal diarrhea outbreak in a high-production Brazilian dairy cattle herd. Preliminary laboratory analysis ruled out important enteropathogens (Cryptosporidium spp; Eimeria spp., E. coli F5, and bovine coronavirus). Fecal samples from diarrheic (n = 24) and asymptomatic (n = 5) calves up to 30 days old were collected for virological analysis. RT-PCR assays were performed for the detection of aichivirus B RdRP and VP1 genes and for rotavirus A VP7 and VP4 genes in fecal samples. Asymptomatic calves (control group) were negative for both viruses. Aichivirus B and rotavirus A G10P[11] genotypes were found in 54.2% (13/24) and 25% (6/24) of the diarrheic fecal samples, respectively. Aichivirus B was only identified (83.3%, 10/12) in calves up to two weeks old. Phylogenetic analysis based on the RdRP gene grouped the Brazilian strains in a new branch within the aichivirus B group. Comparative analysis of the nucleotide sequence of the VP1 gene of Brazilian and Chinese aichivirus B strains allowed the strains identified in this study to be classified in the putative lineage 1. This is the first description of a high rate of aichivirus B detection in a diarrhea outbreak in dairy calves, and the first phylogenetic study of the VP1 gene of aichivirus B wild-type strains performed in South America.

In vitro antimicrobial susceptibility and genetic resistance determinants of Streptococcus agalactiae isolated from mastitic cows in Brazilian dairy herds

Streptococcus agalactiae is one of the main causative agents of bovine mastitis and is associated with several economic losses for producers. Few studies have evaluated antimicrobial susceptibility and the prevalence of genetic resistance determinants among isolates of this bacterium from Brazilian dairy cattle. This work aimed to evaluate the frequency of the antimicrobial resistance genes ermA, ermB, mefA, tetO, tetM, aphA3, and aad-6, and in vitro susceptibility to the antimicrobials amikacin, erythromycin, clindamycin, tetracycline, gentamicin, penicillin, ceftiofur, and cefalotin, and the associations between resistance genotypes and phenotypes among 118 S. agalactiae isolates obtained from mastitic cows in Brazilian dairy herds. Of the resistance genes examined, ermB was found in 19 isolates (16.1%), tetO in 23 (19.5%), and tetM in 24 (20.3%). The genes ermA, mefA, aphA3, and aad-6 were not identified. There was an association between the presence of genes ermB, tetM, and tetO and phenotypic resistance to erythromycin, clindamycin, and tetracycline. Rates of resistance to the tested antibiotics varied, as follows: erythromycin (19.5%), tetracycline (35.6%), gentamicin (9.3%), clindamycin (20.3%), penicillin (3.4%), and amikacin (38.1%); conversely, all isolates were susceptible to ceftiofur and cefalotin. Antimicrobial resistance testing facilitates the treatment decision process, allowing the most judicious choice of antibiotics. Moreover, it enables regional and temporal monitoring of the resistance dynamics of this pathogen of high importance to human and animal health.

In vitro antimicrobial susceptibility and genetic resistance determinants of Streptococcus agalactiae isolated from mastitic cows in Brazilian dairy herds

Streptococcus agalactiae is one of the main causative agents of bovine mastitis and is associated with several economic losses for producers. Few studies have evaluated antimicrobial susceptibility and the prevalence of genetic resistance determinants among isolates of this bacterium from Brazilian dairy cattle. This work aimed to evaluate the frequency of the antimicrobial resistance genes ermA, ermB, mefA, tetO, tetM, aphA3, and aad-6, and in vitro susceptibility to the antimicrobials amikacin, erythromycin, clindamycin, tetracycline, gentamicin, penicillin, ceftiofur, and cefalotin, and the associations between resistance genotypes and phenotypes among 118 S. agalactiae isolates obtained from mastitic cows in Brazilian dairy herds. Of the resistance genes examined, ermB was found in 19 isolates (16.1%), tetO in 23 (19.5%), and tetM in 24 (20.3%). The genes ermA, mefA, aphA3, and aad-6 were not identified. There was an association between the presence of genes ermB, tetM, and tetO and phenotypic resistance to erythromycin, clindamycin, and tetracycline. Rates of resistance to the tested antibiotics varied, as follows: erythromycin (19.5%), tetracycline (35.6%), gentamicin (9.3%), clindamycin (20.3%), penicillin (3.4%), and amikacin (38.1%); conversely, all isolates were susceptible to ceftiofur and cefalotin. Antimicrobial resistance testing facilitates the treatment decision process, allowing the most judicious choice of antibiotics. Moreover, it enables regional and temporal monitoring of the resistance dynamics of this pathogen of high importance to human and animal health.

Genetic diversity and virulence genes in Streptococcus uberis strains isolated from bovine mastitis

Mastitis is one of the most common and costly infectious diseases in dairy cattle worldwide. This is a multifactorial illness caused by different microorganisms, including virus, yeasts, algae, parasites, and several species of bacteria. Among these bacteria, Streptococcus uberis is an important environmental pathogen that is responsible for a large range of clinical and subclinical mammary infections, especially in intensively managed herds. Despite the increasing importance of this pathogen in the etiology of bovine mastitis, data on its virulence and diversity in Brazilian dairy herds are scarce. The aims of the present study were to investigate the virulence characteristics of S. uberis isolated from bovine mastitis and to assess the molecular epidemiology of the Brazilian isolates using pulsed-field gel electrophoresis (PFGE). In this work, 46 strains of S. uberis isolated from bovine mastitis from 26 Brazilian dairy herds were evaluated regarding their genetic diversity by PFGE using with the SmaI enzyme. Additionally, the presence of the virulence genes skc and pauA, which encode plasminogen activators, and the gene sua, which encodes an adhesion molecule in mammary epithelial cells, were assessed by PCR. Our results showed a high genetic diversity in the population, displaying many different patterns in the PFGE analysis. A high proportion of strains was positive for virulence genes in the sampled population (sua [100%], pauA [91%], and skc [91%]). The high frequency of skc, pauA, and sua genes among the studied strains suggests the importance of these virulence factors, possibly helping S. uberis in the colonization of the bovine mammary gland. Surveys of the genetic and molecular characteristics of this pathogen can improve our knowledge of bacterial activity and identify molecules that have roles in the establishment of the infection. This might help in the development of more effective measures to control and prevent bovine mastitis.

Genetic diversity and virulence genes in Streptococcus uberis strains isolated from bovine mastitis

Mastitis is one of the most common and costly infectious diseases in dairy cattle worldwide. This is a multifactorial illness caused by different microorganisms, including virus, yeasts, algae, parasites, and several species of bacteria. Among these bacteria, Streptococcus uberis is an important environmental pathogen that is responsible for a large range of clinical and subclinical mammary infections, especially in intensively managed herds. Despite the increasing importance of this pathogen in the etiology of bovine mastitis, data on its virulence and diversity in Brazilian dairy herds are scarce. The aims of the present study were to investigate the virulence characteristics of S. uberis isolated from bovine mastitis and to assess the molecular epidemiology of the Brazilian isolates using pulsed-field gel electrophoresis (PFGE). In this work, 46 strains of S. uberis isolated from bovine mastitis from 26 Brazilian dairy herds were evaluated regarding their genetic diversity by PFGE using with the SmaI enzyme. Additionally, the presence of the virulence genes skc and pauA, which encode plasminogen activators, and the gene sua, which encodes an adhesion molecule in mammary epithelial cells, were assessed by PCR. Our results showed a high genetic diversity in the population, displaying many different patterns in the PFGE analysis. A high proportion of strains was positive for virulence genes in the sampled population (sua [100%], pauA [91%], and skc [91%]). The high frequency of skc, pauA, and sua genes among the studied strains suggests the importance of these virulence factors, possibly helping S. uberis in the colonization of the bovine mammary gland. Surveys of the genetic and molecular characteristics of this pathogen can improve our knowledge of bacterial activity and identify molecules that have roles in the establishment of the infection. This might help in the development of more effective measures to control and prevent bovine mastitis.