Mastitis In Herds Research Articles

The Role of Women on Dairy Goat Farms in Southern Spain.

Simple SummaryThe involvement of women in livestock production is a tradition around the world, where women have been associated with small animal farming, mainly based on family production systems. They used to be responsible for animal care (feeding and milking) and family care (children and the elderly), with the working hours exceeding the daily working time defined in developed countries. Men are responsible for the farm’s management and finances. In Europe, small ruminants are mainly raised in adverse environments. Nevertheless, they contribute to maintaining an open environment and the prevention of fire damage in times of drought. On the farms studied, a lower incidence of mastitis in goats was found when a woman worked on the farm (they milk with more care and patience). In this study, there is a predominance of farms with women and men (a family unit), where the genders both equally participate when making decisions that involve household expenses; however, this shared control usually ends up being transferred to the man. In addition, very few women are the owners of farms or make binding decisions. Finally, the inclusion of women should be recommended throughout the small ruminant productive process: this would help improve farming results and provide an incentive to keep women in rural areas.One of the factors involved in goat milk production is the role of women as farmers. The aim of this study was to evaluate the role of women on dairy goat farms, considering: (1) the profile of women occupationally involved, (2) the organization of the women’s work, (3) the degree of involvement by women in the decision-making on these farms, and (4) the influence of women’s work on productive results. This study was conducted on 52 dairy goat farms in southern Spain. A descriptive analysis and means comparisons were performed to describe the farms where any women were involved or not. In 61.5% of the farms, at least one woman was involved, with an age of 42.2 ± 8.8 years. Very few women were farm owners, although women took binding decisions in 81.25% of these farms. Their work is dedicated to milking and caring for the kids. Women had a positive influence on the productive variables analysed, and for mastitis in herds, the incidence was lower in herds where women participated (p < 0.01). In conclusion, it is recommended to include women’s work as a factor when characterizing dairy goats farms’ systems to evaluate their positive effect on a farm’s performance.

Phenotypic and Genotypic Characteristics and Resistance Profile of Staphylococcus spp. from Bovine Mastitis

Background: Bovine mastitis remains one of the health problems that cause the most damage to milk producers. The negative impact of mastitis is due to reduced milk production, early slaughter of females, reduced commercial value of the affected animals, losses in the genetic potential of the herd, expenses with medicines and veterinary medical assistance. Staphylococcus spp. stands out as the cause of this disease and has been able to remain in the mammary gland, becoming resistant to several antimicrobials. The aims of the present study were to characterize the phenotypes, genotypes and resistance profiles of Staphylococcus spp. isolates from bovine mastitis cases in the state of Pernambuco, Brazil.Materials, Methods &amp; Results: These isolates were classified according to biochemical tests and the presence of the nuc gene. The polymerase chain reaction (PCR) for amplification of the mecA and blaZ genes was used to analyze the genetic potentials of antimicrobial resistance. Isolates were also phenotypically tested for resistance to nine antimicrobials (ampicillin, doxicillin, erythromycin, gentamicin, rifampicin, cephalothin, amoxicillin, nalidixic acid and oxacillin). The genetic potentials for biofilm production were evaluated by the amplifications of the icaD, icaA and bap genes. The phenotypic test of gentian violet was used for biofilm formation analyzes. Ninety-three (93.0%) of the isolates among the Staphylococcus spp. samples were classified as Staphylococcus aureus. The lowest percentage of sensitivity observed was for amoxicillin (28.0%). All of the isolates were sensitive to erythromycin and gentamicin, and 15 (15%) exhibited sensitivity to all of the drugs tested. All of the isolates were negative for the mecA gene, and 36 (36%) were positive for blaZ. In the adhesion microplate tests, 44 (44%) of the isolates were capable of biofilm formation. Of these, seven (15.9%) were strong formers, whereas 16 (36.3%) and 21 (47.8%) were moderate and weak formers, respectively. The icaD gene was confirmed in 89 (89%) of the isolates. The icaA gene was confirmed in 61 (61%) samples, and the bap gene in 52 (52%) samples. One of the samples did not possess icaA, icaD or bap and exhibited moderate biofilm formation according to the microplate adherence test. Sixteen isolates simultaneously exhibited the three genes tested for biofilm production (icaA, icaD and bap) and were negative according to the microplate adherence test.Discussion: The indiscriminate use of antibiotics to treat mastitis is a common practice in the study area, which may have contributed to the high proportion of herds (88.23%; 15/17) with multi-resistant isolates, constituting a selection factor for the dissemination of resistant bacteria among herds. The absence of the mecA gene in the present study may be associated with the development of resistant bacteria through another mechanism, such as the overproduction of beta-lactamases. The results demonstrate that antimicrobial resistance occurs in Staphylococcus spp. that cause bovine mastitis in herds of Pernambuco and that these isolates have the a great capacity for biofilm formation. It is necessary to sensitize the professionals involved in the milk production chain of Brazil regarding the importance of the adequate use of antimicrobials for the treatment and control of mastitis, since studies in the country indicate the dissemination of resistant bacterial strains.

Influence of intra-mammary ozone administration on udder health in herds with contagious mastitis in the context of management practices

This study investigates the effectiveness of intra-mammary ozone administration in the dry period and at the time of delivery for preventing against mastitis in herds with contagious mastitis. The cows were divided into five groups with 10 cows in each. Group 1 was administered an ozone-containing foam preparation via the teat canal into four udder quarters for 5 seconds at the beginning of the dry period; Group 2 was administered ozone at the beginning of the dry period and at the time of delivery; Group 3 was administered ozone at the time of delivery; Group 4 was administered a dry period udder preparation at the beginning of the dry period; and Group 5 was administered only teat seal at the beginning of the dry period. No statistically significant difference was found between the cows with regard to the SCC values at the beginning of the dry period and at the time of delivery (in cows without clinical mastitis, n=25). The SCC values were reported to decrease when the values at the beginning of the dry period and at the time of delivery were compared. All cows except two in Group 1 were detected to have clinical mastitis according to the frequency of microbial isolation in milk at the time of delivery. In conclusion, intra-mammary ozone administration did not prevent mastitis in the dry period or at the time of delivery in herds with contagious mastitis; moreover, it was determined to increase the rate of clinical mastitis in the postpartum period.

PREVENTIVE METHODS IN REDUCTION OF MASTITIS PATHOGENS IN DAIRY COWS

Mammary gland tissue inflammation (mastitis) is the most frequent disease in dairy cattle in the world, and negatively influences the milk quality having consequences for the dairy processing industry. The aim of the study was analyze designed preventive and control methods focused to reduction of mastitis in herd of Slovak pied cattle in the east of Slovakia during two years of experiment. From 180 cows at quarterly intervals in the 3rd, 6th, 9th and 12th month was performed a complex examination of health udder including an assessment clinical signs of mammary gland, abnormal udder secretions, Californian Mastitis Test (CMT) with subsequent collecting of milk samples for bacteriological examination. In the first year during the first two complex examinations, treatment of mastitis caused by coagulase positive staphylococci (S. aureus), coagulase negative staphylococci (S. haemolyticus, S. warneri, S. epidermidis) and Str. agalactiae, a reduction in prevalence from the original 41.3 % to 32.1 % was achieved. During the last two complex examinations in the first year the prevalence decreased to 25.2 % and then at the end to 21.1 %, respectively. The reduction of mastitis during the second year is characterized by a 22.1 %, 19.2 %, 12.2 % to 7.3 % mastitis, when the prevalence dropped by 5.5 %, respectively. Coagulase negative staphylococci and Str. agalactiae were the most numerous in each case during the second year and their occurrence subject to a proportional reduction. Proposed antimastitis methods and their implementation of continuous mastitis control system during two years, significantly reduced prevalence of mastitis by 34.0 % and influenced the occurrence of the most common pathogens of the mammary gland in monitored herd of dairy cows. Recorded reduction of mastitis in monitored dairy herd is an example of using available scientifically validated methods in a rationally compiled mastitis control program for the specific conditions of each dairy farm in the long period.

Characterization of Staphylococcus spp. strains in milk from buffaloes with mastitis in Brazil: the need to identify to species level to avoid misidentification

ABSTRACT Mastitis is an inflammation of the mammary gland that affects dairy cattle worldwide causing economic losses. Coagulase-negative staphylococci (CNS) are the predominant cause of this type of infection. We have recently showed that coagulase-positive staphylococci could be misidentified. So, the aim of this study was to characterize the Staphylococcus spp. strains initially classified as coagulase-negative Staphylococci, isolated from buffalo with subclinical mastitis. Milk of buffaloes with mastitis in herds was collected and 9 strains were identified as CNS by phenotypic tests. Molecular methodologies latter identified the strains as coagulase-negative Staphylococcus chromogenes (5), coagulase-positive Staphylococcus hyicus (2) and coagulase-positive Staphylococcus aureus (2). Our results strongly support the need to identify the isolates to a species level in order to avoid misidentification and to be aware of the classification using the coagulase test alone.

Prediction of Streptococcus uberis clinical mastitis risk using Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) in dairy herds

The purpose of this study was to evaluate whether the risk of Streptococcus uberis clinical mastitis at cow level could be predicted from the historical presence of specific strains of S. uberis on dairy farms. Matrix-assisted laser desorption ionization time of flight mass spectrometry was used to identify S. uberis isolates potentially capable of contagious transmission. Data were available from 10,652 cows from 52 English and Welsh dairy farms over a 14 month period, and 521 isolates of S. uberis from clinical mastitis cases were available for analysis. As well as the temporal herd history of clinical mastitis associated with particular S. uberis strains, other exposure variables included cow parity, stage of lactation, milk yield, and somatic cell count. Observations were structured longitudinally as repeated weekly measures through the study period for each cow. Data were analyzed in a Bayesian framework using multilevel logistic regression models. Similarity of mass spectral profiles between isolates of S. uberis from consecutive clinical cases of mastitis in herds was used to indicate potential for contagious phenotypic characteristics. Cross validation showed that new isolates with these characteristics could be identified with an accuracy of 90% based on bacterial protein mass spectral characteristics alone. The cow-level risk in any week of these S. uberis clinical mastitis cases increased with the presence of the same specific strains of S. uberis in other cows in the herd during the previous 2 weeks. The final statistical model indicated there would be a 2–3 fold increase in the risk of S. uberis clinical mastitis associated with particular strains if these occurred in the herd 1 and 2 weeks previously. The results suggest that specific strains of S. uberis may be involved with contagious transmission, and predictions based on their occurrence could be used as an early warning surveillance system to enhance the control of S. uberis mastitis.

Pharmacokinetics, milk penetration and PK/PD analysis by Monte Carlo simulation of marbofloxacin, after intravenous and intramuscular administration to lactating goats.

The main objectives of this study were (i) to evaluate the serum pharmacokinetic behaviour and milk penetration of marbofloxacin (MFX; 5mg/kg), after intravenous (IV) and intramuscular (IM) administration in lactating goats and simulate a multidose regimen on steady-state conditions, (ii) to determine the minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) of coagulase negative staphylococci (CNS) isolated from caprine mastitis in Córdoba, Argentina and (iii) to make a PK/PD analysis by Monte Carlo simulation from steady-state pharmacokinetic parameters of MFX by IV and IM routes to evaluate the efficacy and risk of the emergence of resistance. The study was carried out with six healthy, female, adult Anglo Nubian lactating goats. Marbofloxacin was administered at 5mg/kg bw by IV and IM route. Serum and milk concentrations of MFX were determined with HPLC/uv. From 106 regional strains of CNS isolated from caprine mastitis in herds from Córdoba, Argentina, MICs and MPCs were determined. MIC90 and MPC90 were 0.4 and 6.4μg/ml, respectively. MIC and MPC-based PK/PD analysis by Monte Carlo simulation indicates that IV and IM administration of MFX in lactating goats may not be adequate to recommend it as an empirical therapy against CNS, because the most exigent endpoints were not reached. Moreover, this dose regimen could increase the probability of selecting mutants and resulting in emergence of resistance. Based on the results of Monte Carlo simulation, the optimal dose of MFX to achieve an adequate antimicrobial efficacy should be 10mg/kg, but it is important take into account that fluoroquinolones are substrates of efflux pumps, and this fact may determine that assumption of linear pharmacokinetics at high doses of MFX may be incorrect.

Contagious mastitis part 1: herd diagnosis

Historically much emphasis has been placed on the control of ‘contagious’ mastitis in dairy herds and the importance of preventing spread of infection between and one or more infected cows to uninfected cows in the herd, typically during the milking process. The pathogens implicated in contagious mastitis include Staphylococcus aureus, Streptococcus agalactiae and Mycoplasma spp. but ultimately all pathogens responsible for intra-mammary infection have the potential to be transmitted from one cow to another. The ability to transmit will depend on characteristics that allow them to do so (e.g. persistence in the mammary gland) and this will vary between pathogens and importantly between strains of pathogens, a good example of the latter is Streptococcus uberis. As discussed in the previous article, the analysis of somatic cell count and clinical mastitis data is essential to understand the ‘pattern’ of mastitis in a herd — and this includes patterns which would indicate that significant contagious spread may be occurring.

Clinical forum: the role of dry cow therapy in the modern dairy herd

Antibiotic dry cow therapy (ADCT) is a crucial component for the control of contagious mastitis pathogens as part of a herd's mastitis control policy and recent research has again highlighted the excellent cure rates achieved with ADCT, despite ‘apparent’ cure rates across the dry period averaging much lower than those published. However, following the control of the classic contagious mastitis pathogens, environmental pathogens such as Escherichia coli and Streptococcus uberis have become significantly more important and have resulted in a shift in emphasis at drying off, away from identifying those cows with a persistent infection towards protecting those without. This means there are two clear roles for any dry cow therapy, i.e. the cure of existing infections and the prevention of new ones, giving rise to a challenge for veterinary herd health advisors. This should lead to an increased awareness of the importance of taking an individual cow approach to dry cow therapy — moving away from ‘blanket’ ADCT approaches, using internal teat sealants and products with extended Gram-negative activity to protect against new infections and regularly reviewing the use of ADCT in herds as part of prescribing antimicrobials responsibly.

Biofilm formation on biotic and abiotic surfaces in the presence of antimicrobials by Escherichia coli Isolates from cases of bovine mastitis.

Escherichia coli is a highly adaptive microorganism, and its ability to form biofilms under certain conditions can be critical for antimicrobial resistance. The adhesion of four E. coli isolates from bovine mastitis to bovine mammary alveolar (MAC-T) cells, biofilm production on a polystyrene surface, and the expression profiles of the genes fliC, csgA, fimA, and luxS in the presence of enrofloxacin, gentamicin, co-trimoxazole, and ampicillin at half of the MIC were investigated. Increased adhesion of E. coli isolates in the presence of antimicrobials was not observed; however, increased internalization of some isolates was observed by confocal microscopy. All of the antimicrobials induced the formation of biofilms by at least one isolate, whereas enrofloxacin and co-trimoxazole decreased biofilm formation by at least one isolate. Quantitative PCR analysis revealed that all four genes were differentially expressed when bacteria were exposed to subinhibitory concentrations of antimicrobials, with expression altered on the order of 1.5- to 22-fold. However, it was not possible to associate gene expression with induction or reduction of biofilm formation in the presence of the antimicrobials. Taken together, the results demonstrate that antimicrobials could induce biofilm formation by some isolates, in addition to inducing MAC-T cell invasion, a situation that might occur in vivo, potentially resulting in a bacterial reservoir in the udder, which might explain some cases of persistent mastitis in herds.

Production of enterotoxins of Staphylococcus spp. isolated from samples of sheep milk

In our study was followed occurrence of mastitis in herd of 430 sheep of breed zoslachtena valaska with hand milking technology examined two times during one lactation season. Individual examination consisted from clinical examination of udder and microbiological examination of milk samples. By PCR was determined presence of genes coding production of enterotoxins, and by ELISA methods production individual types of enterotoxins. From individual forms of mastitis were frequently detected subacute (6.7%), subclinical (5.7%) and acute (2.9%). The coagulase-negative staphylococci (CNS) were identified in 102 (65.4%) from all 156 positive isolates. The CNS and S. aureus caused subacute (5.1%), subclinical (3.9%) and acute (2.4%) forms of mastitis. The most frequently isolated were S. epidermidis, followed by S. chromogenes and S. xylosus from ewes with subacute and subclinical mastitis. From acute and chronical forms of mastitis were predominantly isolated S. aureus, S. uberis and S. epidermidis. The production of staphylococcal enterotoxins (SE) - SEA, SEB, SEC, SED and the presence of genes sec (3), sea (2), seb (2) and sed (2) were determined in S. aureus, S. epidermidis, S. schleiferi and S. chromogenes, respectively. The results suggested on the high occurrence (12.4%) of subacute and subclinical forms. Confirmed production of enterotoxins and presence of genes coding their production present a risk for human health and decreased a quality of milk and products from sheep´s milk.

Antimicrobial residues in milk and occurrence of clinical and subclinical mastitis in herds in the region of Campinas, São Paulo

The aim of this study was to evaluate the occurrence of clinical and subclinical mastitis and antimicrobial residues in milk samples from mammary quarters of 259 lactating cows of five properties in the region of Campinas-SP, Brazil. The Tamis test and the California Mastitis Test (CMT) were used to diagnose clinical and subclinical mastitis, respectively. The somatic cells count (SCC) was done in milk samples of weigh jars and cooling tanks. The presence of antimicrobial residues was analyzed in milk samples of the mammary quarters, weigh jars and cooling tanks, with a microbiological test (Delvotest SP). Milk samples were collected for microbiological isolation of mastitis-causing agents. Clinical and subclinical mastitis occurred in 2.32% to 16.66% and 21.00% to 69.1% of the mammary quarters, respectively. The SCC in the cooling tanks ranged between 221 and 1,124 x 103 cells/mL. Coagulase-negative Staphylococci were isolated in 45.93% of the milk samples. The analysis of the antimicrobial residues in the weigh jars and in mammary quarters showed 8.33% and 4.30% of samples testing positive, respectively. The presence of antimicrobial residues was detected in 5% of the cooling tanks. The findings point to the need to implement practices that focus on milk quality.

Cost-effectiveness of diagnostic strategies using quantitative real-time PCR and bacterial culture to identify contagious mastitis cases in large dairy herds

Diagnostic strategies to detect contagious mastitis caused by Mycoplasma bovis, Staphylococcus aureus, and Streptococcus agalactiae in dairy herds during an outbreak have been minimally studied with regard to cost and diagnostic sensitivity. The objective of this cross-sectional study was to compare the cost-effectiveness of diagnostic strategies for identification of infected cows in two California dairy herds during contagious mastitis outbreaks.M. bovis was investigated in a subset of a herd (n=1210 cows) with an estimated prevalence of 2.8% (95% CI=1.9, 3.7), whereas Staph. aureus and Strep. agalactiae were studied in a second herd (n=351 cows) with an estimated prevalence of 3.4% (95% CI=1.5, 5.3) and 16.8% (95% CI=12.9, 20.7), respectively. Diagnostic strategies involved a combination of testing stages that utilized bacterial culture, quantitative real-time PCR (qPCR), or both. Strategies were applied to individual or pooled samples of 5, 10, 50 or 100 samples. Culture was considered the gold standard for sensitivity estimation of each strategy. The reference strategy was the strategy with the lowest cost per culture-positive cow which for both M. bovis and Strep. agalactiae consisted of 2 stages, culture of samples in pools of 5 followed by culture of individual samples in positive pools with a sensitivity of 73.5% (95% CI: 55.6, 87.1) and 96.6% (95% CI: 27.7, 84.8), respectively. The reference strategy for Staph. aureus consisted of 3 stages, culture of individual samples in pools of 100 (stage 1), culture constituents of those positive from stage 1 in pools of 5 (stage 2), culture constituents of those positive from stage 2 individually (stage 3) which resulted in a sensitivity of 58.3% (95% CI: 88.3, 99.6). The most cost-effective alternative to the reference strategy was whole herd milk culture for all 3 pathogens. QPCR testing was a component of the second most cost-effective alternative for M. bovis and the third most cost-effective alternatives for the 3 pathogens.A stochastic model was used to assess the effect of prevalence or herd size on the cost-effectiveness of diagnostic strategies. In the current study, increasing the prevalence of mastitis did not alter the ranking of strategies by cost-effectiveness. However, larger herds could benefit from testing larger pools such as 50 or 100 samples to improve cost-effectiveness. Several diagnostic strategy options exist to identify contagious mastitis in herds, decisions should be based on cost and sensitivity of the strategies available.

Questionnaire-based study to assess the association between management practices and mastitis within tie-stall and free-stall dairy housing systems in Switzerland

BackgroundProphylactic measures are key components of dairy herd mastitis control programs, but some are only relevant in specific housing systems. To assess the association between management practices and mastitis incidence, data collected in 2011 by a survey among 979 randomly selected Swiss dairy farms, and information from the regular test day recordings from 680 of these farms was analyzed.ResultsThe median incidence of farmer-reported clinical mastitis (ICM) was 11.6 (mean 14.7) cases per 100 cows per year. The median annual proportion of milk samples with a composite somatic cell count (PSCC) above 200,000 cells/ml was 16.1 (mean 17.3) %. A multivariable negative binomial regression model was fitted for each of the mastitis indicators for farms with tie-stall and free-stall housing systems separately to study the effect of other (than housing system) management practices on the ICM and PSCC events (above 200,000 cells/ml). The results differed substantially by housing system and outcome. In tie-stall systems, clinical mastitis incidence was mainly affected by region (mountainous production zone; incidence rate ratio (IRR) = 0.73), the dairy herd replacement system (1.27) and farmers age (0.81). The proportion of high SCC was mainly associated with dry cow udder controls (IRR = 0.67), clean bedding material at calving (IRR = 1.72), using total merit values to select bulls (IRR = 1.57) and body condition scoring (IRR = 0.74). In free-stall systems, the IRR for clinical mastitis was mainly associated with stall climate/temperature (IRR = 1.65), comfort mats as resting surface (IRR = 0.75) and when no feed analysis was carried out (IRR = 1.18). The proportion of high SSC was only associated with hand and arm cleaning after calving (IRR = 0.81) and beef producing value to select bulls (IRR = 0.66).ConclusionsThere were substantial differences in identified risk factors in the four models. Some of the factors were in agreement with the reported literature while others were not. This highlights the multifactorial nature of the disease and the differences in the risks for both mastitis manifestations. Attempting to understand these multifactorial associations for mastitis within larger management groups continues to play an important role in mastitis control programs.

A structural equation model to evaluate direct and indirect factors associated with a latent measure of mastitis in Belgian dairy herds

In dairy cattle, many farming practices have been associated with occurrence of mastitis but it is often difficult to disentangle the causal threads. Structural equation models may reduce the complexity of such situations. Here, we applied the method to examine the links between mastitis (subclinical and clinical) and risk factors such as herd demographics, housing conditions, feeding procedures, milking practices, and strategies of mastitis prevention and treatment in 345 dairy herds from the Walloon region of Belgium. During the period January 2006 to October 2007, up to 110 different herd management variables were recorded by two surveyors using a questionnaire for the farm managers and during a farm visit. Monthly somatic cell counts of all lactating cows were collected by the local dairy herd improvement association. Structural equation models were created to obtain a latent measure of mastitis and to reduce the complexity of the relationships between farming practices, between indicators of herd mastitis and between both. Robust maximum likelihood estimates were obtained for the effects of the herd management variables on the latent measure of herd mastitis. Variables associated directly (p<0.05) with the latent measure of herd mastitis were the addition of urea in the rations; the practices of machine stripping, of pre-and post-milking teat disinfection; the presence of cows with hyperkeratotic teats, of cubicles for housing and of dirty liners before milking; the treatment of subclinical cases of mastitis; and the age of the herd (latent variable for average age and parity of cows, and percentage of heifers in the herd). Treatment of subclinical mastitis was also an intermediate in the association between herd mastitis and post-milking teat disinfection. The study illustrates how structural equation model provides information regarding the linear relationships between risk factors and a latent measure of mastitis, distinguishes between direct relationships and relationships mediated through intermediate risk factors, allows the construction of latent variables and tests the directional hypotheses proposed in the model.

Mastitis investigation using the DairyCo mastitis plan on a Yorkshire dairy farm

The article describes the use of the DairyCo Mastitis plan in the investigation of high mastitis incidence in a dairy herd. The DairyCo mastitis plan uses software to analyse the herd's mastitis and cell count data in order to enable the mastitis problem to be categorised as predominantly dry period origin or lactation period origin and either environmental or contagious origin. A thorough farm visit and completion of a questionnaire will then allow areas for improvement to be selected which will be most likely to have the greatest benefit in reducing mastitis incidence in the herd in question.

Characterization of Prototheca zopfii Associated with Outbreak of Bovine Clinical Mastitis in Herd of Beijing, China

Prototheca zopfii (P. zopfii) has become an important cause of bovine mastitis in many countries. In the present study, to better understand the occurrence of one clinical mastitis (CM) outbreak due to P. zopfii, the molecular characterization and resistance patterns of the microalga were described. P. zopfii strains were isolated from 17 of 23 quarters, which suffered CM in the outbreak, and 7 of 46 CM recovered quarters before the outbreak, as well as 2 of 75 environmental samples in the dairy farm. All strains were identified as genotype 2 by genotype-specific PCR analysis. Results of in vitro antimicrobial and antifungal susceptibility tests indicated that these strains were resistant to majority of tested drugs, with the only exception of amphotericin B, nystatin, streptomycin, gentamicin, and amikacin. This is the first report about CM outbreak caused by P. zopfii in China. These data suggest that P. zopfii may represent a serious risk in the studied herd, and this microalga could be an important potential pathogen causing mastitis in dairy herds of Beijing.

Bacteria Staphylococcus spp. izolated from mastitis of sheep and their enterotoxigenic properties

In our study was followed occurrence of staphylococcal mastitis in herd of 350 sheep during one lactation season. We found, the bacteria S. schleiferi was identified in 88 from all 204 isolates. In high number were identified also S. caprae (33), S. chromogenes (21), S. aureus (19), S. epidermidis (17), respectively. Important was occurrence S. intermedius, S. simulans, S. xylosus a S. warneri, too. The Staphylococcuss spp. caused latent and subclinical forms of mastitis predominantly, showed into subacute mastitis (26.5%). Acute mastitis was determined in 7.8 %. Eight bacteria S. aureus, two S. chromogenes, and two S. epidermidis produced staphylococcal enterotoxins.

Molecular types and antibiotic resistance of Staphylococcus aureus isolates from bovine mastitis in a single herd in China

The molecular diversity, antibiotic resistance patterns and presence of resistance genes were determined in Staphylococcus aureus isolates from cases of bovine mastitis in a dairy cattle herd in China. Multiple locus variable number tandem repeat analysis was used for molecular typing. Resistance was determined through minimum inhibitory concentrations and resistance genes were detected by PCR. There was low molecular diversity; one predominant strain (type I) accounted for the majority of cases of S. aureus mastitis in the herd and this strain had a high frequency of resistance to penicillin and tetracycline. The most prevalent resistance genes were blaZ, ermC and tetM.

Mastitis and the shape of the lactation curve in Norwegian dairy cows

An investigation of the shape of the lactation curve and the mastitis incidence was conducted to identify whether management interventions of the lactation curve constitute a potential for reducing incidence of mastitis at herd level. Lactation curves were estimated to describe the variation of daily milk yield during the 305-d lactation period in Norwegian Red cows. Associations between mastitis incidence at herd level and lactation curve characteristics such as production level at onset of lactation, magnitude and time of peak milk yield, and increase and decrease of milk yield rates were studied. Data from 250,303 lactations occurring during 2005 and 2006 from 14,766 herds were obtained from the Norwegian Dairy Herd Recording System. Besides veterinary treatments, the records included information on monthly test-day milk yields. The shapes of the lactation curves at herd level were parameterized using a modified Wilmink model in two separate mixed model analyses. In the first analysis a subset of lactations with no records of veterinary treatments was used. Lactation curves from herds with high (>0·31 cases/305-d lactation) and low (<0·07 cases/305-d lactation) herd mastitis incidence rate were parameterized and compared for three separate strata of parity. The result showed that high herd mastitis incidence rate was associated with a low intercept (P<0·05), a steep slope before peak milk yield (P<0·01) and a rapid decline after peak milk yield (P<0·01). In the second analysis a subset of high-yielding lactations with veterinary treatments of mastitis only and lactations with no records of veterinary treatment were compared. This was done to investigate whether the findings at herd level were also reflected at cow level. These results showed that lactation curves from lactations with mastitis cases were associated with a steep slope before peak milk yield (P<0·05) in second and later parities and a rapid decline after peak milk yield (P<0·01) in all three parity groups.