Somatic Cell Count Values Research Articles

QUALIDADE FÍSICO-QUÍMICA E MICROBIOLÓGICA DO LEITE BOVINO EM DIFERENTES SISTEMAS DE PRODUÇÃO E ESTAÇÕES DO ANO

Resumo O objetivo deste trabalho foi avaliar a interação entre sistemas produtivos e estações do ano sobre a qualidade do leite bovino. Três propriedades foram avaliadas mensalmente, durante as estações, em quatro graus de especialização dos sistemas de produção: altamente especializado, especializado, semiespecializado e não especializado. Em termos de qualidade do leite, consideraram-se os teores de gordura, proteína, sólidos totais, contagem de células somáticas, contagem bacteriana total, acidez titulável em graus Dornic, densidade, índice crioscópico, estabilidade ao alizarol, potencial de hidrogênio (pH) e teste de redução do azul de metileno. Além destes, devido à sua importância para o rendimento industrial dos produtos lácteos de base proteica, foi realizado o fracionamento da proteína total do leite em equivalente proteico do nitrogênio não proteico, da proteína verdadeira e da caseína. A acidez Dornic foi maior na primavera e no inverno, enquanto os valores mais elevados de contagem de células somáticas foram no verão. Os teores de proteína total e proteína verdadeira foram menores durante o verão e elevaram-se os sólidos totais no outono. Com a diminuição dos níveis de especialização das propriedades rurais, observaram-se aumento na contagem bacteriana total e diminuição do nitrogênio não proteico. A densidade apresentou comportamento inverso ao da gordura, enquanto o potencial de hidrogênio (pH) se expressou de modo antagônico à acidez titulável. Na análise multivariada dos dados, foi possível identificar as combinações entre estratos produtivos e estações do ano que apresentavam a melhor qualidade da proteína do leite. Nesse sentido, todos os arranjos de sistemas de produção com o outono, o sistema altamente especializado no inverno, o semiespecializado no verão e o especializado na primavera tiveram qualidade proteica positiva, destacando-se pelas menores contagens de células somáticas a combinação entre a estação primavera e o sistema semiespecializado de produção.

Association between Somatic Cell Count, Electric Conductivity and pH in Diagnosis of Subclinical Mastitis in Crossbred Cows

The objective of the present study was to determine the relation between somatic cell count (SCC), Electrical conductivity (EC) and pH of milk for diagnosis of subclinical (SCM) and clinical mastitis (CM). For this a total of 120 samples were collected from crossbred cows of organised and norganised dairy farms for determination of EC, SCC and pH. On the basis of SCC, the cows were categorized as healthy(SCC below 2×105 per ml), subclinical mastitis (SCC in the range 2×105 - 3×105 per ml)and mastitis(SCC more than 3×105 per ml).The values of milk SCC and EC were significantly (P less than 0.05) higher in crossbred cows having subclinical and clinical mastitis. Milk pH ranged from 6.48 to 6.62 in healthy and subclinical cases,whereas pH 7.03 was observed in clinical mastitis cases. There was a significant positive correlation (P less than 0.05) between SCC, EC and milk pH.

CONFORMITY OF REFRIGERATED RAW MILK FROM FAMILY PRODUCTION UNITS OF SOUTHERN ESPÍRITO SANTO

Abstract Dairy farming is an important activity in Brazil and Espírito Santo state, with small properties accounting for 80% of production. Despite of this economic importance, data about quality of the milk produced and the hygienic-sanitary conditions are still scarce. Then, the objective of this study was to evaluate the characteristics of refrigerated raw milk produced in family production units in southern Espírito Santo to verify compliance with Brazilian legal standards. Three collections were carried out in 29 community expansion tanks, for a total of 87 samples of refrigerated raw milk. Analysis of standard plate count (SPC), psychrotrophic bacteria count (PBC), somatic cell count (SCC), titratable acidity, density, fat, total dry extract (TDE), non-fat dry extract (NFDE), residues of antibiotics (β-lactam and tetracycline), cadmium and lead levels were performed. Of the 87 samples, 66% presented non-standard values for SPC, and 38% had non-standard values for SCC. Eighty five percent of the samples presented non-standard results for NFDE, 10.3% for density and 2.3% for titratable acidity. All samples complied with the legislation regarding residues of antibiotics, Cd and Pb levels. These results indicated failures in the raw milk obtainment and storage chain from family production units of southern Espírito Santo, Brazil.

Somatic cell count in the diagnosis of subclinical mastitis in sheep of different breeds

The aims of this study were to determine the occurrence of subclinical mastitis in sheep of different breeds and the values for somatic cell count (SCC) in milk for the diagnosis of the disease at lactation and weaning, a fundamental prerequisite for identifying animals in need of control measures. Milk samples were obtained from 1,457 mammary halves of Santa Inês, Texel, Ile de France, and Dorper sheep at two different periods, during the second week of lactation and at weaning. After teats antisepsis, the samples were collected, and identification of the infectious etiology of mastitis and determination of SCC were performed. Microorganisms were identified in 117/762 (15.3%) mammary halves in the second week of lactation and in 86/694 (12.4%) at weaning. Coagulase-negative staphylococci (CoNS) were the etiological agents with the highest incidence alone and in association with other microorganisms, with percentages of 58.1% and 60.6%, respectively. The Santa Inês presented a higher incidence of subclinical mastitis when compared to the other breeds. The cut-off values of SCC for subclinical mastitis were determined at both sampling periods and varied according to stage of lactation, as well breed. These results illustrate the lack of a universal value that can be used for the diagnosis of mastitis and suggests the need for permanent follow-up in herds in order to control the disease.

Association of BoLA-DRB3 genotype with somatic cell count in milk of Polish Holstein cattle

ABSTRACT The objective of this study was to evaluate the suitability of the BoLA-DRB3 gene polymorphism to define the phenotypic value of somatic cell count of 808 Polish Holstein cows. The cows were fathered by 190 sires. The PCR-RFLP alleles were identified with the BstYI, HaeIII, and RsaI restriction enzymes. For statistical analysis, 17 alleles whose frequencies in the herds were equal to or higher than 2% were selected. Somatic cell count was analyzed based either on the lactation averages [...]

Molecular Detection and Antimicrobial Resistance Pattern of Staphylococci Isolated from Clinical and Subclinical Bovine Mastitis

The present study was carried out on bovine mastitis with an objective to screen bovine milk samples around Junagadh for status of subclinical mastitis (SCM) by somatic cell count (SCC), to reveal the prevalence of staphylococcal mastitis by conventional and molecular methods and to evaluate the antimicrobial resistance pattern of the isolated Staphylococci. Total 390 bovine milk samples (180 from clinical mastitis and 210 from apparently healthy animals) were collected. Among 210 milk samples from healthy bovine, 72 samples showed SCC value andgt; 5 lakhs/mL revealing 34.29% prevalence of SCM. A primary culture isolation of 252 milk samples (72 SCM and 180 clinical mastitis) showed 38.72% prevalence of Staphylococcal mastitis. The isolated Staphylococci were further characterized by biochemical tests which showed prevalence of coagulase negative Staphylococci and S. aureus 23.08% and 15.64%, respectively. The high resistance of Staphylococci was observed against ceftriaxone and amoxicillin-salbactum which displays antibiotic usage pattern in the region. Likewise bacterial isolates studied were highly sensitive to levofloxacin which suggest judicious use of this antibiotic in treatment of bovine mastitis. All the conventionally isolated Staphylococci and S. aurues were confirmed by polymerase chain reaction targeting 16S rRNA and nuc gene respectively in shorter period of time which signifies the superiority of molecular diagnostic tools.

Threshold somatic cell count for delineation of subclinical mastitis cases.

Aim:Somatic cell count (SCC) is the most widely used single reliable indicator of udder health. The present study was carried out with an objective to find the exact threshold of SCC.Materials and Methods:Milk samples collected from a total of 214 Holstein Friesian crossbred dairy animals were subjected to bacterial DNA extraction and SCC estimation by digital PortaCheck. California Mastitis Test and polymerase chain reaction based on amplification of organism using reported primers were performed to diagnose subclinical mastitis. Receiver’s operating characteristic (ROC) curve analysis and discriminate function analyses were performed using SPSS 18 software.Results:ROC curve analysis represented that the area under the curve was 0.930 with the standard error of 0.02. Results indicated that 93% of the case could be correctly predicted as mastitis infected using SCC as a marker (p<0.001). At cut score level of 282 000 cells/ml, 285,000 cells/ml and 288,000 cells/ml, sensitivity remained 92.6% and specificity augmented as 86.3%, 87.2%, and 88%, respectively. At SCC value of 310,000 cells/ml of milk, sensitivity and specificity were optimal, namely, 92.6% and 91.5%, respectively. The function fitted demonstrated 89.2% accuracy with p<0.001. The functions at group centroids were −0.982 and 1.209, respectively, for normal and mastitis-infected animals and log_SCC value was the most important factor contributing 38.30% of the total distance measured.Conclusion:Our study supports that the threshold value to delineate subclinical mastitis case from the normal is 310,000 somatic cells/ml of milk and a model so fitted using the variable SCC can be successfully used in field for the diagnosis of subclinical cases of mastitis which otherwise would be difficult to differentiate based on clinical signs.

Relationships Between Dye Reduction Test Scores and Somatic Cell Count in Bovine Raw Milk

The aim of this study was to reveal the relationships between dye reduction test scores and somatic cell count (SCC) in bovine raw milk. The SCC, methyelene blue reduction scores (MTS) and resazurin reduction test scores (RTS) were determined at biweekly intervals in four test days (TD) between March and April 2017 in a total of 89 raw milk samples sold in Samsun province as unpacked. While SCC values were recorded by an automatic counter, all SCC values were transformed to log10 base before statistical analysis. In MTS method, the time for the change of the color of milk from blue to white was noted and milk quality was assessed using a 1 to 4 point scale (1=&gt;5h-good/excellent; 2=2-5h-medium; 3=0.5-2h-bad and 4=

Milk hygiene in small ruminants: A review

Somatic cell count (SCC), mammary pathogens prevalence, total and specific bacterial counts, antimicrobial residues, macroscopic sediment, water addition, aflatoxins and other contaminants constitute the basis for milk payment-schemes, monitoring and improvement of flock hygiene and health management, and development of analytical surveillance programs in the dairy small ruminants. The present work reviews factors influencing the variation of these variables, including milk analytical methods, storage and preservation, along with management implications during the last two decades. Following farmer and cooperative educational programs, progressive reductions have been reported for total bacterial count and antimicrobial residue occurrence in bulk tank milk. These results were consistent, however, with high values for SCC and specific bacterial populations. Thus, mastitis control programs should be intensified to increase hygiene in milk and economic returns for producers and processors. In addition, the implementation of programs to reduce specific bacterial counts (i.e., psychrotrophs, coliforms, Clostridium spp. spores) and mammary pathogen prevalence (i.e., Staph. aureus, Mycoplasma spp.), as well as the use of combined screening methods for an increased rate of antimicrobial detection, are currently required strategies which are positively valuated by milk processors, industry and consumers. Other contaminants may also be present, but cost-effective screening and analytical systems have not yet been implemented. This review aims to be helpful for troubleshooting milk quality and safety, developing future premium payment systems and industry quality-standards, optimizing management, on-farm risk traceability systems and consumer acceptance.

Diagnostic evaluation of milk lactate dehydrogenase and alkaline phosphatase activities by receiver operating characteristic analysis curve in early lactation of ewes with subclinical mastitis.

The aim of the present study was to investigate the diagnostic evaluation of milk lactate dehydrogenase (mLDH) and alkaline phosphatase (mALP) activities by receiver operating characteristic (ROC) analysis curve in early lactation of ewes with subclinical mastitis (SCM) and determine the correlation between number of somatic cell count (SCC) and mLDH and mALP activities. A total of 196 udder half milk samples were collected within the first 6 weeks of lambing. The SCM was determined by positive milk bacterial culture and positive California mastitis test (CMT); SCC was determined by fossomatic method and enzyme activities were determined spectrophotometrically. The mLDH and mALP of SCM cases were positively correlated with SCC values. Values of mLDH, mALP and SCC were significantly higher in SCM than non-SCM udder halves. The optimum cut-off points of mLDH and mALP activities for SCM diagnosis were determined at 203.61 (U L-1) and 329.84 (U L-1), respectively. In conclusion, SCC has positive correlation with mALP and mLDH activities in SCM ewes and mLDH and mALP activities could be considered as reliable indicators for intra-mammary inflammation diagnosis.

Factors affecting milk quality of crossbred dairy cows in automated Herringbone milking system

The aim of the study was to investigate the effect of factors affecting milk quality of crossbred dairy cows milked in automated Herringbone milking system. The study was conducted on 37 crossbred Karan Fries cows of different parities, stages of lactation and udder types for 3 months. The milk quality was assessed based on milk composition, on-line electrical conductivity (EC) and peak conductivity, somatic cell count (SCC) and standard plate count (SPC) of milk samples. The results showed that there was no change in milk composition in terms of fat and SNF except in different parity groups. The milk conductivity was significantly higher in the late stage of lactation. However, no change in SCC values was observed. The udder types showed significant increase in EC values in udders with poor structure and loose attachment. The SCC values were also significantly higher for such udder types. The SPC was significantly higher when the number of milkings on each liner exceeded 2000 milkings/liner. The SCC was had a positive correlation with EC and SPC. The correlation between SPC and SCC was highly significant whereas, EC was moderately correlated with SPC. It can be concluded that the milk quality of crossbred dairy cows was significantly affected by parity, stages of lactation, udder type and liner usage in automated parlours. Therefore, effective management strategy needs to be taken to improve the quality of milk taking into consideration on-line EC, SCC and SPC.

Detection and characterization of pathogenic Pseudomonas aeruginosa from bovine subclinical mastitis in West Bengal, India.

Aim:Subclinical mastitis in bovines is mainly responsible for the huge economic loss of the dairy farmers, of which Pseudomonas aeruginosa is one of the causative agents. The study was aimed at a screening of suspected milk samples from different cattle farms of West Bengal for detection and confirmation of P. aeruginosa strains followed by their characterization.Materials and Methods:Around 422 milk samples were screened from different dairy farms primarily by on-spot bromothymol blue (BTB) test and then in the lab by somatic cell counts (SCC) to finally consider 352 samples for detection of P. aeruginosa. Selective isolation and confirmation of the isolates were done using selective media, viz., cetrimide and Pseudomonas agar followed by confirmation by fluorescent technique. Molecular characterization of the strains was done by polymerase chain reaction for the presence of toxA (enterotoxin A, 352 bp) and exoS (exoenzyme S, 504 bp) genes.Results:Approximately, 371 (87.9%) samples were positive in on-spot BTB test among which 352 (94.8%) samples revealed high SCC values (more than 3 lakh cells/ml) showing infection when screened. Among these, 23 (6.5%) samples yielded typical Pseudomonas sp. isolates out of which only 19 (5.4%) isolates were confirmed to be P. aeruginosa which showed characteristic blue-green fluorescence due to the presence of pigment pyoverdin under ultraviolet light. Out of these 19 isolates, 11 isolates were positive for toxA, 6 isolates for exoS, and 2 for both these pathogenic genes.Conclusion:Approximately, 5.4% cases of bovine subclinical mastitis infections in South Bengal were associated with P. aeruginosa which possess pathogenic genes such as toxA (63.2%) and exoS (36.8%).

Diurnal variation of milk somatic and differential leukocyte counts of Murrah buffaloes as influenced by different milk fractions, seasons and parities

Milk cell counts are good indicators of a mammary infection and milk quality. The present study was done to record diurnal rhythmicity in the milk somatic and differential cell counts during different seasons, milk strips and parity in Murrah buffaloes. Milk somatic cell counts (SCC) were measured by SCC counter and milk differential cell counts were measured microscopically after making a milk smear and staining it to identify neutrophils, lymphocytes and macrophages. Maximum milk SCC was observed in the summer season. Milk neutrophils were lowest during thermoneutral (TN), intermediate during the winter season and highest during the summer season. Milk lymphocytes were highest during the winter season, intermediate in the TN and lowest in the summer season. Diurnal rhythm in the milk SCC and neutrophil percentage is noticed in the summer season only. Maximum milk SCC values were observed in the late strip but neutrophils were highest in the early strip. Diurnal rhythm was observed in the late strip for neutrophils and in mid strip for the lymphocytes. Milk SCC and milk neutrophils were found to be the highest in the multiparous buffaloes and diurnal rhythm was observed only in the lymphocytes of primiparous buffaloes. Milk macrophages were higher in the morning samples of primiparous as compared to the multiparous buffaloes. In this pioneer study, diurnal rhythms in the milk cell counts of buffaloes have been studied extensively. This will help in maintaining low milk cell counts in buffalo and thus help in getting more milk per buffalo during stress periods.

Subclinical mastitis in dairy camels in Algeria: Comparison of screening tests

The aim of the present study was to determine a threshold values and to assess the effectiveness of four indirect tests for the diagnosis of subclinical mastitis in dairy camels comparing with bacteriological culture. One hundred fifty three milk samples from 17 lactating camels were subjected to bacteriological culture, where 84 milk samples were positive, 47 were negative and 22 samples were considered as contaminated. A total of 131 milk samples were screened by pH, electrical conductivity (EC), California mastitis test (CMT) and somatic cell count (SCC). The good combination of sensitivity and specificity were obtained with a threshold of 6.55, 7.2 mS/cm, score trace was considered as CMT (+) and 240 000 cells/ml for the four tests, respectively. The sensitivity of the SCC, pH, EC and CMT was 72.61, 66.66, 47.61 and 39.28 %; the specificity 70.21, 38.02, 59.57 and 72.34 %; percentage accuracy 71.75, 51.14, 51.90 and 51.14 %; and positive predictive value 81.33, 47.61, 67.79 and 71.73 %, respectively. The SCC was significantly correlated with bacteriological culture (r = 0.415, p &amp;lt; 0.05). Kappa value of SCC was higher than that of other tests (SCC &amp;gt; CMT &amp;gt; EC &amp;gt; pH). In conclusion, the results suggest that the SCC was the most accurate, reliable, diagnostic method compared to other tests used in this study after cultural isolation for the detection of subclinical mastitis in dairy camel under field conditions.

Evaluation of microbiological, cellular and risk factors associated with subclinical mastitis in female buffaloes

ObjectiveThis study aimed to evaluate the microbiological and cellular milk profile for the diagnosis of subclinical mastitis in female buffaloes and to assess risk factors for predisposition of the disease.MethodsAnalyses were carried out by standard plate count (SPC), identification of species and antibiotic resistance, somatic cell count (SCC), electrical electrical conductivity of milk (ECM), and lactoferrin content in milk. Teat cups were swabbed to evaluate risk factors, observing hyperkeratosis, milking vacuum pressure and cleanliness of the site. Hence, 30 female buffaloes were randomly selected (15 from a group in early lactation and 15 in late lactation).ResultsThe most common bacteria in the microbiological examination were Staphylococcus spp., Streptococcus spp. and Corynebacterium sp. In the antibiotic sensitivity test, 10 (58.82%) of the 17 antibiotics tested were sensitive to all isolates, and resistant bacteria were Streptococcus uberis, Streptococcus dysgalactiae, Streptococcus haemolyticus, and Escherichia coli. It was observed that positive samples in the microbiological examination showed total bacterial count between 9.10×103 to 6.94×106 colony forming units/mL, SCC between 42,000 to 4,320,000 cells/mL and ECM ranging from 1.85 to 7.40 mS/cm. It was also found that the teat cups had high microbial counts indicating poor hygiene, and even faults in the cleanliness of the animals’ waiting room were observed. It is concluded that values of SCC above 537,000 cells/mL and ECM above 3.0 mS/mL are indications of mammary gland infection for this herd; however, the association of these values with a microbiological analysis is necessary to more accurately evaluate the health status of mammary glands with subclinical mastitis.ConclusionThrough phenotypic characterization of bacteria involved in the samples, the genera Staphylococcus spp., Streptococcus spp., and Corynebacterimum bovis were the most prevalent in this study. Faults in environment and equipment hygienization are factors that are directly associated with mastitis.

Efficacy of a polyvalent mastitis vaccine against Staphylococcus aureus on a dairy Mediterranean buffalo farm: results of two clinical field trials.

BackgroundIn the last years the knowledges on Mediterranean Buffalo (MB) mastitis is remarkably improving, nevertheless the attention has been never focused on vaccination as preventive strategy for the control of mastitis in these ruminates. The aim of the current study was to assess clinical efficacy over time of two different preventive vaccination protocols against S. aureus mastitis, in primiparous MB.Vaccinated (VG) and not-vaccinated (N-VG) groups, of 30 MB each one, were selected from two different herds (herd A: VG1 and N-VG1; herd B: VG2 and N-VG2) of the same farm. Herd A received a double vaccination (Startvac®, 45 and 10 days before calving, protocol A), while in herd B an additional administration was performed (52 days after calving, protocol B). Bacteriological milk culture and assessment of somatic cell count (SCC) were performed at 10, 30, 60 and 90 days in milk (DIM) from composite milk samples. After 90 DIM, daily milk yields and SCC values were monthly detected until dry-off.ResultsThe overall incidence of positive MB for S. aureus was 40.8% (49/120) in VG1 and 43.3% (52/120) in N-VG1 (Protocol A), while 45.8% (55/120) and 50.8% (61/120) in VG2 and N-VG2 (Protocol B). The latter was associated with a significant decreased in prevalence (at 90 DIM) and incidence of mastitis (animals positive for S. aureus, SCC > 200^103, with or without clinical signs) in the vaccinated MB, while no difference occurred in protocol A. Moreover, herd B showed a significant reduction in prevalence of intramammary infection (animals positive for S. aureus, SCC < 200^103, no clinical signs) in the vaccinated MB at 60 DIM while no differences were detected in herd A, at any sampling time; N-VG2 had significantly higher overall SCC values than VG2 (4.97 ± 4.75 and 4.84 ± 4.60 Log10 cells/mL ± standard deviation, respectively), while no differences were recorded in herd A.ConclusionsThe current investigation explores for the first time the clinical efficacy of vaccinations against S. aureus infections in MB, showing encouraging results regarding reduction in mastitis and somatic cell count; the polyvalent mastitis vaccine may be considered an additional tool for in-herd S aureus infection and should be associated to other control procedures to maximize its properties.

P6022 Transcriptomic study of bovine macrophages infected in vitro with Streptococcus agalactiae

Mastitis is a costly disease in dairy cattle, impairing animal welfare and increasing the use of antibiotics. It is a multi-factorial disease, affected by the load and virulence of the infecting pathogen, the milking hygiene, and the immune status and genetics of the host. Streptococcus agalactiae has re-emerged as a potential threat to udder health in Norway, especially in large herds and herds using automatic milking systems. Some cows develop chronic subclinical mastitis with high somatic cell count (SCC). Such animals shed the bacteria and contribute to spreading the infection to other cows and herds. Hence, investigation of why these become chronically infected is important. Macrophages are critical effectors and regulators of inflammation serving as the first line of defense against invading pathogens. Intramammary infections will activate macrophages to produce proinflammatory cytokines required to kill intracellular pathogens, however the balance between pro- and antiinflammatory signals is crucial for immune regulation of inflammation and preventing chronic conditions. The objective of this study is to increase the understanding of the host genetics and immune response to Streptococcus agalactiae causing chronic subclinical mastitis in Norwegian Red (NRF) dairy herds. In genotyped cows we will examine the transcriptomic responses of macrophages infected with high and low virulent strains of Streptococcus agalactiae. Seven animals were selected for a pilot study of in vitro challenge of blood monocyte-derived macrophages with two strains of Streptococcus agalactiae differing in virulence. Transcript analyses of several selected cytokines and chemokines were performed by qPCR. Four thousand NRF cows is currently genotyped using a customized 55K bovine SNP-chip (a typing tool for 55 000 Single Nucleotide Polymorphism markers) and genomic breeding values (GEBVs) for SCC will be estimated to evaluate the contrasts between the groups. Based on this genotyping cows with long duration of high SCC (= chronically infected animals) and unfavorable GEBV for SCC, and cows with very low SCC (= control) and favorable GEBV for SCC will be selected for in vitro challenge of blood monocyte-derived macrophages with the two bacterial strains. For each selected individual transcriptome analyses, i.e., mRNA sequencing, will be performed to identify the macrophage response to the infections in challenged and control sets of cells. This will generate information on genes and splice variants involved in immune responses during the infection with high and low virulent strains of Streptococcus agalactiae.

Evaluation of milk cathelicidin for detection of bovine mastitis.

Mastitis due to intramammary infection is one of the most economically relevant diseases in dairy cows, causing reductions in milk quality and quantity. Currently, mastitis monitoring is based on somatic cell count (SCC) and bacteriologic culture (BC) of milk. Nevertheless, inflammation-specific protein markers might provide more sensitive and reliable assays, enabling immunoassay-based screening strategies. Cathelicidin is an inflammatory protein released in milk that has recently demonstrated fair reliability and diagnostic potential for ewe mastitis. To assess its performance in cows, 531 quarter milk samples from 2 herds were tested using cathelicidin ELISA, SCC, and BC. We found that 29.0% of samples were positive for cathelicidin, 18.8% had SCC >200,000 cells/mL, and 13.7% were BC-positive. Cathelicidin showed a strong positive correlation with SCC as demonstrated by receiver operating characteristics curve analysis and by the clustering of cathelicidin-negative and cathelicidin-positive samples in association with low and high SCC values, respectively. For evaluating the diagnostic performance of a novel test, BC cannot be considered a reliable gold standard for true disease status because of its known limitations. Therefore, we assessed the sensitivity (Se) and specificity (Sp) of the milk cathelicidin ELISA using a latent class analysis approach together with BC and SCC by considering different diagnostic thresholds to identify the preferred Se/Sp combination. We modeled conditional dependence of cathelicidin and SCC to account for their close association. The cathelicidin ELISA showed higher Se than SCC and BC for almost all threshold combinations. In fact, at the best-performing threshold combination, the Se of cathelicidin was 80.6%, 6.2 percentage points higher than that of SCC >200,000 cells/mL (74.4%) and similar to that of SCC >100,000 cells/mL (80.2%). Most importantly, this Se was obtained with a loss in Sp of only 1.4 percentage points compared with SCC >200,000 cells/mL (94.9% Sp for cathelicidin vs. 96.3% for SCC >200,000). The limited Se of BC (38.8%) was also confirmed in this study, and BC showed a slightly lower Sp than both cathelicidin and SCC for most of threshold combinations. This study confirmed that cathelicidin is released in the milk of cows with mastitis and that its presence is highly correlated with SCC. The measurement of cathelicidin by ELISA may hold significant potential for improving the sensitivity of mastitis detection in dairy cows while maintaining high specificity.

Evaluation of milk cathelicidin for detection of dairy sheep mastitis

Mastitis due to intramammary infections is one of the most detrimental diseases in dairy sheep farming, representing a major cause of reduced milk productions and quality losses. In particular, subclinical mastitis presents significant detection and control problems, and the availability of tools enabling its timely, sensitive, and specific detection is therefore crucial. We have previously demonstrated that cathelicidins, small proteins implicated in the innate immune defense of the host, are specifically released in milk of mastitic animals by both epithelial cells and neutrophils. Here, we describe the development of an ELISA for milk cathelicidin and assess its value against somatic cell counts (SCC) and bacteriological culture for detection of ewe mastitis. Evaluation of the cathelicidin ELISA was carried out on 705 half-udder milk samples from 3 sheep flocks enrolled in a project for improvement of mammary health. Cathelicidin was detected in 35.3% of milk samples (249/705), and its amount increased with rising SCC values. The cathelicidin-negative (n=456) and cathelicidin-positive (n=249) sample groups showed a clear separation in relation to SCC, with median values of 149,500 and 3,300,000 cells/mL, respectively. Upon bacteriological culture, 20.6% (145/705) of the milk samples showed microbial growth, with coagulase-negative staphylococci being by far the most frequent finding. A significant proportion of all bacteriologically positive milk samples were positive for cathelicidin (110/145, 75.9%). Given the lack of a reliable gold standard for defining the true disease status, sensitivity (Se) and specificity (Sp) of the cathelicidin ELISA were assessed by latent class analysis against 2 SCC thresholds and against bacteriological culture results. At an SCC threshold of 500,000 cells/mL, Se and Sp were 92.3 and 92.3% for cathelicidin ELISA, 89.0 and 94.9% for SCC, and 39.4 and 93.6% for bacteriological culture, respectively. At an SCC threshold of 1,000,000 cells/mL, Se and Sp were 93.3 and 91.9% for cathelicidin ELISA, 80.0 and 97.1% for SCC, and 39.4 and 93.5% for bacteriology, respectively. In view of the results obtained in this study, the measurement of cathelicidin in milk by ELISA can provide added Se while maintaining a high Sp and may therefore improve detection of subclinical mastitis.

SUBCLINICAL MASTITIS IN LACTATING COWS: COMPARISON OF FOUR SCREENING TESTS AND EFFECT OF ANIMAL FACTORS ON ITS OCCURRENCE

A total of 444 quarter milk samples from 111 crossbred dairy cows were subjected to California mastitis test (CMT), somatic cell count (SCC) test, white side test (WST) and surf field mastitis (SFMT) test to quantify their efficacy in detecting sub clinical mastitis in dairy cows of Bangladesh during the period from 2010 to 2011.Milk samples positive by CMT, SCC, WST and SFMT were 265,230, 225 and 222 respectively. All samples were subjected to cultural isolation (gold standard test for comparison of indirect mastitis tests). Of these, 261 samples were positive by cultural isolation. The sensitivity of the CMT, SCC, WST and SFMT were 80.08%, 86.60%, 60.54% and 57.47%; specificity 69.40%, 97.81%, 63.38% and 60.66%; percentage accuracy 75.68%,91.22%, 61.71% and 58.78%; positive predictive value 78.87%, 98.26%, 70.22% and 67.57%; and negative predictive value 70.95%, 83.64%, 52.97% and 50%respectively. Quarter-wise sub clinical mastitis (SCM) was detected in 59.68%, 51.80%, 50.68% and 50% samples by CMT, SCC, WST and SFMT, respectively, while animal-wise SCM was recorded in 72.07%, 66.67%, 64.86% and 61.26% samples by CMT, SCC, WST and SFMT, respectively. The right hind quarters were most significantly (p&lt;0.001) susceptible to SCM than other quarters. Cows with 3rd and 4th parity and at their early lactation stage had significantly higher (p&lt;0.001) SCM than others. Kappa value of SCC was higher than that of CMT. CMT was concluded to be the most accurate test after cultural isolation and SCC. Unlike laboratory tests as cultural isolation and SCC that require adequate laboratory facilities and skilled personnel, CMT is a reliable diagnostic method in field conditions.