Detection of subclinical mastitis in ewes

Effects of management strategies during early lactation and weaning on etiological agents of ovine subclinical mastitis and antimicrobial susceptibility of milk-derived bacterial isolates

Subclinical mastitis is a common intramammary disease in sheep production systems. Expenses associated with compromised animal performance, therapeutic interventions, and decreased ewe longevity make efforts to minimize its prevalence worthwhile. The objectives of this study were to (i) quantify the prevalence of subclinical mastitis throughout lactation, (ii) evaluate the impact of bedding treatments on subclinical mastitis during early lactation, (iii) evaluate the efficacy of prophylaxis and feed restriction during weaning on subclinical mastitis cure rates, (iv) and identify levels and types of antimicrobial resistance in milk-derived bacteria. Ewe milk samples were collected at d 1, 2, and 28 post-partum, weaning, and 3-d post-weaning for bacterial identification via culture-based methods. Staphylococcus spp. and Streptococcus spp. isolates were subjected to in vitro antimicrobial susceptibility testing. The overall prevalence of subclinical mastitis defined by culture growth ranged between 22 and 66% and differences were observed between post-weaning and d 1 and 28 milk samples. Commonly isolated bacteria include coagulase-negative staphylococci (CoNS; 59%), Bacillus spp. (35%), Mannheimia haemolytica (10%), Staphylococcus aureus (8%), Streptococcus spp. (5%), and Corynebacterium spp. (5%). Early milk samples (d 1 and 2) were compared between jug bedding treatment: jugs were recently vacated, cleaned, and dusted with barn lime before adding fresh straw (CLEAN) or jugs were previously vacated and fresh straw was added atop soiled bedding (SOILED). Jug bedding treatment did not affect the prevalence of subclinical mastitis, though CoNS had greater sulfadimethoxine resistance in SOILED isolates than CLEAN isolates (P = 0.03). Three different weaning treatments were used: ewes were injected with penicillin at weaning (PENN), ewes had restricted feed access 48 h prior to and 72 h post-weaning (FAST), or a combination of these treatments (COMBO). Weaning treatment did not affect the prevalence of subclinical mastitis or cure rate from weaning to 3-d post-weaning, though all PENN and no FAST milk S. aureus isolates were resistant against tetracycline (P = 0.08). Subclinical mastitis prevalence tended to decrease from weaning to post-weaning (P = 0.08). These data show subclinical mastitis is common throughout lactation and the levels of antimicrobial resistance of bacteria isolated from ewe milk are generally low against commonly used antimicrobials.

Relationships among intramammary health, udder and teat characteristics, and productivity of extensively managed ewes

Mastitis is an economically important disease and its subclinical state is difficult to diagnose, which makes mitigation more challenging. The objectives of this study were to screen clinically healthy ewes in order to 1) identify cultivable microbial species in milk, 2) evaluate somatic cell count (SCC) thresholds associated with intramammary infection, and 3) estimate relationships between udder and teat morphometric traits, SCC, and ewe productivity. Milk was collected from two flocks in early (<5 d) and peak (30 to 45 d) lactation to quantify SCC (n = 530) and numerate cultivable microbial species by culture-based isolation followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS; n = 243) identification. Within flock and lactation stage, 11% to 74% (mean = 36%) of samples were culture positive. More than 50 unique identifications were classified by MALDI-TOF MS analysis, and Bacillus licheniformis (18% to 27%), Micrococcus flavus (25%), Bacillus amyloliquefaciens (7% to 18%), and Staphylococcus epidermidis (26%) were among the most common within flock and across lactation stage. Optimum SCC thresholds to identify culture-positive samples ranged from 175 × 103 to 1,675 × 103 cells/mL. Ewe productivity was assessed as total 120-d adjusted litter weight (LW120) and analyzed within flock with breed, parity, year, and the linear covariate of log10 SCC (LSCC) at early or peak lactation. Although dependent on lactation stage and year, each 1-unit increase in LSCC (e.g., an increase in SCC from 100 × 103 to 1,000 × 103 cells/mL) was predicted to decrease LW120 between 9.5 and 16.1 kg when significant. Udder and teat traits included udder circumference, teat length, teat placement, and degree of separation of the udder halves. Correlations between traits were generally low to moderate within and across lactation stage and most were not consistently predictive of ewe LSCC. Overall, the frequencies of bacteria-positive milk samples indicated that subclinical mastitis (SCM) is common in these flocks and can impact ewe productivity. Therefore, future research is warranted to investigate pathways and timing of microbial invasion, genomic regions associated with susceptibility, and husbandry to mitigate the impact of SCM in extensively managed ewes.

Etiologia e perfil de sensibilidade de bactérias isoladas de ovelhas com mastite na região nordeste do estado do Pará

Objetivou-se com este trabalho estudar a etiologia da mastite em ovelhas na região nordeste do Pará, além de estabelecer o perfil de sensibilidade das bactérias isoladas frente a antimicrobianos. Foram examinadas 176 ovelhas da raça Santa Inês, em lactação, mantidas em sistema semi-intensivo, pertencentes a sete propriedades especializadas na criação de ovinos. Foi realizado o exame clínico da glândula mamária, o exame macroscópico da secreção láctea por meio do Teste da Caneca Telada, o California Mastitis Test (CMT), o exame microbiológico do leite e o antibiograma. Das 352 metades mamárias estudadas (176 ovelhas), 21 (5,97%) apresentaram mastite clínica, 26 (7,39%) apresentaram mastite subclínica e 305 (86,64%) metades mamárias foram negativas. A maioria dos animais acometidos pela mastite estava no terço médio da lactação, com menor número de crias e maior número de lactações. Na mastite clínica (MC) as bactérias isoladas foram Staphylococcus spp. coagulase negativo (42,9%); Staphylococcus aureus (9,52%); Streptococcus spp. (4,76%) e Escherichia coli (4,76%). As associações observadas foram Staphylococcus aureus e Streptococcus spp. (4,76%); Staphylococcus spp. coagulase negativo não hemolítica, Staphylococcus spp. coagulase negativo hemolítica e Staphylococcus spp. coagulase negativo pigmento não hemolítica (4,76%). Já na mastite subclínica (MSC), as bactérias isoladas foram Staphylococcus spp. coagulase negativo (26,9%); Staphylococcus aureus (15,4%); Streptococcus spp. (7,69%); Escherichia coli (7,69%) e Citrobacter freundii (11,5%). A associação observada foi Staphylococcus spp. coagulase negativo não hemolítica e Staphylococcus spp. coagulase negativo hemolítica (3,85%). Os antimicrobianos com maior eficácia contra os agentes isolados Gram positivos foram penicilina/novobiocina (100%), cefalotina (100%) e florfenicol (100%) e contra o Citrobacter freundii foram a ampicilina (100%) e florfenicol (100%). Já em relação a Escherichia coli, 66,7% dos isolados mostraram-se resistentes à ampicilina, cefalotina, florfenicol e tetraciclina. A mastite está presente em ovelhas no estado do Pará, havendo a necessidade de estimar, em estudos futuros, as perdas econômicas causadas por essa enfermidade. O CMT apresentou resultados satisfatórios, podendo ser recomendado como teste de triagem para o diagnóstico de casos individuais de mastite subclínica em ovinos, uma vez que apresentou boa relação com o exame microbiológico. No antibiograma foi observado que a maioria dos agentes isolados apresenta-se sensível aos diferentes antimicrobianos testados, sendo os antibióticos com melhor eficiência o florfenicol e a cefoxitina.

Frequency of subclinical mastitis and observations on somatic cell counts in ewes' milk in northern Greece

Somatic cell counting by the Coulter Counter method, California mastitis test and bacteriological examination were performed on milk samples taken at fortnightly intervals throughout lactation from healthy primiparous and iniiltiparous ewes of the Chios and Karagouniki breeds and from healthy ewes in five grazing flocks in northern Greece.

The proportion of the bacteriologically positive milk samples was 0·22. The prevalence of subclinical mastitis ranged, between the flocks, from 29 to 43% of the ewes. Subclinical mastitis occurred more frequently in Karagouniki than in Chios eives and in multiparous than in primiparous ewes of both breeds. Coagulase-negative staphylococci and S. aureus were isolated in 44 and 33% of the bacteriologically postive samples, respectively. No parity, breed or flock differences in normal somatic cell count were noticed, but stage of lactation influenced normal somatic cell count both in primiparous and multiparous ewes. The results of this investigation also suggest that (a) ovine milk samples with somatic cell count more than 1000 × 103 cells per ml, should be tested bacteriologically, (b) somatic cell count values between 1000 and 2000 × 103 cells per ml should cause suspicion about the presence of coagulase-negative staphylococci in the milk, and (c) the presence of S. aureus in ewe's milk results in a significant increase in somatic cell count, but the wide range of the values does not permit us to suggest any threshold value. The significant correlation between the results of the Coulter Counter somatic cell count method and the Califortiia mastitis test, indicates that the latter can be used for the determination of somatic cell count in ewe's milk.

Etiologia e perfil de sensibilidade antimicrobiana dos isolados bacterianos da mastite em pequenos ruminantes e concordância de técnicas empregadas no diagnóstico

A mastite é a inflamação da glândula mamária que acomete raças de aptidão leiteira como também aquelas voltadas para produção de carne. Esta enfermidade ocasiona sérias alterações na produção de leite e na sua qualidade, redução no ganho de peso e mortalidade de cordeiros. O presente estudo teve por objetivo conhecer os principais agentes causadores de mastite em ovinos e caprinos, bem como a sua susceptibilidade aos agentes antimicrobianos, além de avaliar o grau de concordância entre testes diagnósticos. Foram visitadas 25 propriedades durante a realização do experimento, sendo criatórios de caprinos, ovinos e rebanhos mistos, nos estados de Pernambuco e Bahia. Coletou-se leite de 439 caprinos e 76 ovinos. Foi realizada lactocultura, o California Mastitis Test (CMT) e o teste de sensibilidade aos antimicrobianos. Além disso, determinou-se o grau de concordância entre os testes diagnósticos empregados. Foi constatada uma maior freqüência de Staphylococcus spp. nos casos de mastite em caprinos e ovinos, sendo observado ainda, isolados de Streptococcus spp., Corynebacterium spp. e bacilos gram negativos (BGN). Os isolados apresentaram alta sensibilidade aos antimicrobianos testados, sendo o menor percentual de sensibilidade observado para o ácido nalidíxico. Em relação ao diagnóstico da mastite caprina, a análise comparativa entre o exame microbiológico e o CMT demonstrou um grau de concordância igual a K=0,17, enquanto que para a espécie ovina, este valor foi de K=0,22. A utilização do CMT para o diagnóstico da mastite subclínica em cabras e ovelhas deverá ser associado à técnica da lactocultura.

Genetic parameters for somatic cell score according to udder infection status in Valle del Belice dairy sheep and impact of imperfect diagnosis of infection

Background

Somatic cell score (SCS) has been promoted as a selection criterion to improve mastitis resistance. However, SCS from healthy and infected animals may be considered as separate traits. Moreover, imperfect sensitivity and specificity could influence animals' classification and impact on estimated variance components. This study was aimed at: (1) estimating the heritability of bacteria negative SCS, bacteria positive SCS, and infection status, (2) estimating phenotypic and genetic correlations between bacteria negative and bacteria positive SCS, and the genetic correlation between bacteria negative SCS and infection status, and (3) evaluating the impact of imperfect diagnosis of infection on variance component estimates.

Methods

Data on SCS and udder infection status for 1,120 ewes were collected from four Valle del Belice flocks. The pedigree file included 1,603 animals. The SCS dataset was split according to whether animals were infected or not at the time of sampling. A repeatability test-day animal model was used to estimate genetic parameters for SCS traits and the heritability of infection status. The genetic correlation between bacteria negative SCS and infection status was estimated using an MCMC threshold model, implemented by Gibbs Sampling.

Results

The heritability was 0.10 for bacteria negative SCS, 0.03 for bacteria positive SCS, and 0.09 for infection status, on the liability scale. The genetic correlation between bacteria negative and bacteria positive SCS was 0.62, suggesting that they may be genetically different traits. The genetic correlation between bacteria negative SCS and infection status was 0.51. We demonstrate that imperfect diagnosis of infection leads to underestimation of differences between bacteria negative and bacteria positive SCS, and we derive formulae to predict impacts on estimated genetic parameters.

Conclusions

The results suggest that bacteria negative and bacteria positive SCS are genetically different traits. A positive genetic correlation between bacteria negative SCS and liability to infection was found, suggesting that the approach of selecting animals for decreased SCS should help to reduce mastitis prevalence. However, the results show that imperfect diagnosis of infection has an impact on estimated genetic parameters, which may reduce the efficiency of selection strategies aiming at distinguishing between bacteria negative and bacteria positive SCS.

Risk factors and impacts of clinical and subclinical mastitis in commercial meat-producing sheep flocks in Quebec, Canada

We conducted a prospective observational study on clinical and subclinical mastitis in 30 commercial meat-producing sheep flocks from 2 regions of the province of Quebec, Canada. A total of 2,792 ewes selected in late gestation were followed from lambing to weaning of lambs. The incidence of clinical mastitis for the total lactation period (average of 58 days) ranged among flocks from 0 to 6.6%, with a median of 1.2%. The most frequently isolated bacteria from the cases of clinical mastitis, in pure or mixed culture, were Mannheimia haemolytica (26%), Staphylococcus aureus (23%), and coagulase-negative staphylococci (17%). Incidence of clinical mastitis was higher in ewes that gave birth to 3 or more lambs and from the Estrie region, and was associated with an increase in ewe mortality, an increase in lamb mortality at the litter level, and a decrease in lamb's weaning weight for lambs born in multiple litter size or from ewes >or=4 years old. Among 354 selected ewes with clinically normal udder at the end of lactation, 28.8% had potentially pathogenic bacteria isolated from milk. The most prevalent bacteria were S. aureus (9.3%) and coagulase-negative staphylococci (9.3%). The risk of having a positive culture in at least one half was different between the two regions. Prevalence of ewes (n=261) with California Mastitis Test (CMT) positive result in at least one half was 24.1 and 14.9% using a cut-off of >or=1+ and >or=2+, respectively. Prevalence of culture-positive udder halves was 11.7% for CMT-negative compared with 53.6% for CMT 3+ halves. CMT status was positively associated with the isolation of coagulase-negative staphylococci, M. haemolytica, S. aureus, and various Streptococcus species, but not with other isolated bacteria. Additionally, prevalence of CMT-positive halves was higher in ewes from the Estrie region, aged of >or=4 years versus 1 year, having clinical mastitis previously detected in the lactation and/or with low body condition score. Lamb weaning weight was associated with CMT status of ewes, while weaning weight was not associated with milk culture results. More research is needed to understand the dynamic of milk SCC and IMI in ewes from meat-producing flocks, its economical impact and best ways to control it.

Changes in milk composition as affected by subclinical mastitis in goats

The mechanism of the effects of subclinical mastitis (SM) at the glandular level in dairy goats on milk yield and its composition as expressed in curd yield (Yc) was studied. Twenty-five Israeli goats of various crossbreeds were chosen; one udder half was naturally infected with identified coagulase-negative staphylococci, and the contralateral gland was free of bacteria. The milk yield of the infected halves was significantly lower than that of the uninfected ones. Somatic cell count and N-acetyl-beta-D-glucosaminidase activity were significantly higher in the infected halves. The lactose concentration in the infected glands was significantly lower than that in the uninfected ones, casein concentrations did not differ, and the whey protein and albumin concentrations were significantly higher in the infected glands. Plasmin activity was significantly higher in the infected glands, whereas plasminogen activity was undetectable. Concentrations of Ca2+ did not differ, whereas Ca2+ activity was significantly lower in the infected glands. The proteose peptone concentration was 1.5 times as great in the infected glands as in the uninfected ones. The Yc was significantly lower in the infected halves, and clotting time was significantly longer. The mechanisms of the effects of SM on milk yield and Yc in goats and sheep are discussed and compared.

Microbiological quality and somatic cell count of ewe milk with special reference to staphylococci

A total 1502 useful half udders of 762 Churra ewes from eight herds were aseptically sampled in midlactation to study both the bacteriological isolates and the SCC of milk. Corynebacteria, enterococci, micrococci, staphylococci, and streptococci represented 11.2, 2.9, 1.4, 78.9, and 3.1% of all isolates, respectively. Within staphylococci, novobiocin-sensitive species (71.1%) were much more frequently isolated than novobiocin-resistant ones (7.8%). Staphylococcus epidermidis was the most prevalent species (53.2% of the isolates). Log SCC of uninfected half udder milk was 4.86. Isolates of novobiocin-resistant coagulase-negative staphylococci, micrococci, and corynebacteria were associated to low values of log SCC (4.85 to 5.20). In contrast, infection by novobiocin-sensitive coagulase-negative staphylococci, streptococci, and enterococci organisms was related to a sharp inflammatory response with log SCC means between 5.92 and 6.32. The species that showed the highest log SCC were Pasteurella haemolytica (7.62), Streptococcus agalactiae (7.28), and Staphylococcus aureus (6.68). High prevalence of infections by novobiocin-sensitive staphylococci together with high SCC related to such infections show a relevant role of these organisms in ewe mastitis. Consequently, implementation of staphylococcal mastitis control programs would be of great interest in dairy ewe herds to improve microbiological and hygienic quality of milk.

Detection of subclinical mastitis in dromedary camels (Camelus dromedarius) using somatic cell counts and the N-acetyl-beta-D-glucosaminidase test

Somatic cell counts, N-acetyl-beta-D-glucosaminidase (NAGase) activity and the infection status of the udder were determined in quarter milk samples (n = 86) from 22 multiparous, clinically healthy camels, traditionally managed by Bedouin nomads in the Negev desert, Israel. Seventy (81.4%) of the 86 samples examined contained bacteria, of which 35 (40.7%) gave mixed isolations of two or more bacteria, suggesting the existence of subclinical mastitis in the camel herds studied. Sixteen samples (18.6%) yielded no growth of bacteria. Staphylococcus aureus, Micrococcus spp., Bacillus spp., Streptococcus dysgalactiae and Escherichia coli were the main organisms isolated. The somatic cell count (SCC) ranged from 1.01 x 105 to 11.78 x 106 cells/ml. NAGase values were between 41.4 and 372 NAGase units. Quarter milk samples that contained bacteria had significantly (p < 0.01) higher mean values for SCC but the mean NAGase levels were not significantly different for the bacteriologically negative and positive samples. There was a low correlation coefficient (r2 = 0.097) between the SCC and NAGase in the quarter milk samples from which bacteria were not isolated (n = 16) and a low negative correlation (r2 = -0.038) with the samples that contained bacteria (n = 70). The type of bacteria had a significant effect (p < 0.01) on the SCC but not on the NAGase activity. Quarter samples from which Staphylococcus aureus (coagulase positive) was isolated showed the highest mean SCC and this organism is therefore suspected to be the underlying cause of the subclinical mastitis. The SCC gave a better indication of the presence of pathogenic microorganisms in milk samples than did NAGase.

Mastitis of sheep and goats

This article presents an overview of the recent research into ovine and caprine mastitis. The common clinical presentations of mastitis in these species are reviewed, as are the important etiologic agents and their significance. The interpretation of somatic cell counts and surrogate tests, factors that affect somatic cell count levels, and association of somatic cell count levels with productivity are reviewed. Investigations into the treatment and prevention of mastitis and milking equipment function are discussed, and comments are made on the public health implications of extra label drug use and the consumption of unpasteurized milk.

Relationships among somatic cell count, California mastitis test, impedance and bacteriological status of milk in goats and sheep in early lactation

The objectives of this trial were to evaluate and compare the test characteristics of a number of indirect tests of bacteriological status of the milk from goats and sheep and to assess the affect of varying levels of prevalence of infection on the performance of those tests.The somatic cell count, California mastitis test (CMT) score, electrical impedance and the bacteriological status of 220 and 262 milk samples from the glands of lactating dairy goats and sheep, respectively, were determined. The sensitivity and specificity of indirect tests in predicting the bacteriological status were compared by analyzing the areas under the receiver operating characteristic curve and calculating the likelihood ratio at various cut-off values.Bacteria were isolated from 17.7 and 4.6% of glands from goats and sheep, respectively. Somatic cell count was a better predictor of bacteriological status than either the CMT score or impedance in both goats and sheep. However, knowledge of the CMT score in both sheep and goats and the impedance in goats increases the likelihood of predicting the presence of a bacterial pathogen compared to no testing at all (P<0.05). Knowledge of the age and days postpartum of the animals at the time of testing did not increase the probability that infection status could be predicted. Variation in cut-off levels to predict infection status reported in the literature may be due to variation in the prevalence of infection in the populations studied. Use of likelihood ratio allows comparison of tests over a range of prevalence's as likelihood ratios are independent of prevalence. The prevalence of infection within a herd should be considered when selecting a cut-off value for indirect testing for the presence of bacteria in milk of small ruminants.

The role of coagulase-negative Staphylococcus spp. and associated somatic cell counts in the ovine mammary gland

The somatic cell count (SCC) of ewes' milk was determined by the Fossomatic method and compared with the bacteriological status of the mammary gland. Of 366 samples from uninfected udder halves, 64.5% had SCC less than 50 x 10(3) cells/ml, 81.9% had SCC less than 250 x 10(3), and 92.4% had less than 500 x 10(3) cells/ml. Of 130 bacteriologically positive samples, 91.1% had SCC more than 500 x 10(3) cells/ml and 98.8% more than 250 x 10(3). Of the examined milk samples 26.2% showed positive bacteriology during the single sampling. The most frequent pathogens isolated from the milk samples were coagulase-negative staphylococci. Considering our results, 250 x 10(3) cells/ml should be the threshold value, which could be regarded as the upper limit for normal SCC of ewes' milk.

Udder disease etiology, milk somatic cell counts and NAGase activity in Israeli Assaf sheep throughout lactation

Bacterial pathogens causing udder infections in Israeli Assaf dairy sheep were identified and changes occurring throughout lactation were monitored to study the correlation between the contaminant and the severity of the infection, as measured by somatic cell count (SCC) and NAGase tests. A total of 159 Israeli Assaf dairy sheep on one farm, in their first (69), second (13) or third and more (77) lactations were included in this study. Udder halves were tested for bacterial condition, SCC and NAGase activity 2-3 weeks post lambing and every 4 weeks after until drying-off. At first sampling, in 60.7% (193/318 quarters) of the halves no bacterial growth (NBG) was detected. Different species of coagulase negative staphylococci (CNS) were the main pathogen group in infected udders. Streptococci were isolated from 14 halves, most of them in the two udder halves. The percent of udder infection in sheep in their third or further lactations was 2.8 greater (P<0.05) than in that of sheep in their first lactation. During the lactation, 90.6% of the halves did not change their classification status, suggesting that most infections occur before lambing and/or during the following first few days. The arithmetic mean of SCC and NAGase of total half udder milk and samplings (during the lactation) were 1144+/-48x10(3)cells/ml and 49.4+/-2.5, respectively. The average SCC in the milk of halves classified as NBG was 321+/-35x10(3)cells/ml and was not significantly changed during the lactation period. In halves infected with CNS, average SCC was 1371+/-150x10(3)cells/ml at the first testing and increased to 2129+/-347x10(3)cells/ml at drying-off. No significant differences were found in SCC and NAGase activity between the different species of the CNS. The mean SCC over the types of bacteria isolated, lactation number and days in lactation was significantly different (P<0.0001). In 4% of the halves, from all samples, SCC was above 5000x10(3)cells/ml although no bacteria were detected in their milk. The higher SCC in the CNS infected halves contrasted with the more moderate SCC found in dairy cows similarly infected, suggesting that the sheep udder has a lower resistance and an augmented immunological response against this group of bacteria. Thus, this should be considered accordingly in schemes for sheep's milk quality payment.

Relations between udder infection and somatic cells in camel (camelus dromedarius) milk

Quarter milk samples (n = 391) from 101 camels were examined to study the occurrence and causes of mastitis in traditionally managed camels in eastern Sudan and to evaluate the value of the California Mastitis Test (CMT), somatic cell count (SCC) and adenosine triphosphate (ATP) in the detection of subclinical mastitis in the camel. One hundred and seventy (43.5%) of the quarter milk samples yielded pathogenic bacteria. Streptococcus agalactiae, other Streptococcus spp., Staphylococcus aureus, coagulase-negative staphylococci, and Escherichia coli were isolated from milk. Thirty-two (8.2%) quarter milk samples yielded mixed cultures, and 189 (48.3%) yielded no growth. Mean values for CMT, SCC and ATP were higher for quarters infected with major pathogens. However, a significant number of quarter milk samples had elevated values in these tests but were from quarters from which no bacteria were isolated. The ability of the tests to predict a positive bacteriology increased slightly when 2 or 3 tests were combined.

The detection of subclinical mastitis in the bactrian camel (Camelus bactrianus) by somatic cell count and California mastitis test

Milk samples (n = 160) from 7 clinically healthy bactrian camels were cultured to detect subclinical udder infection. The samples were assessed by the Californian mastitis test (CMT) and somatic cell count (SCC). Bacteria were recovered from 36 (22.5%) of the milk samples. Staphylococcus aureus and coagulase-negative staphylococci (CNS) were the main organisms found. Infected quarters had significantly higher mean values for the SCC (p < 0.01) and CMT (p < 0.001) than non-infected quarters. All 7 camels were infected with CNS but only 4 with S. aureus. CMT values for S. aureus-infected camels were significantly higher than for those only infected with CNS. The values for SCC and CMT were significantly influenced by the stage of lactation (p < 0.05). No significant difference was found from the effect of the quarters. Both SCC and CMT were of value in predicting the infection status of the udder.

Milk N-acetyl-beta-D-glucosaminidase and serum albumin as indicators of subclinical mastitis in the camel

NAGase activity (NAGase) and serum albumin concentrations were determined in milk from 101 traditionally managed camels in the Sudan. NAGase, a lysosomal enzyme released from damaged epithelial cells as well as other somatic cells in milk, was recorded for quarter milk samples from camels (n = 353) using the fluoroscan method. NAGase activity in major pathogen-infected quarters was significantly (P < 0.05) higher than in minor pathogen-infected and non-infected quarters. Means for minor pathogen-infected quarters were also significantly higher than non-infected quarters. Concentrations of serum albumin, resulting from increased vascular permeability, in quarter milk samples (n = 320) were measured by the radial immunodiffusion test. Serum albumin content in milk was not affected by infection status of the quarter. There were, however, large variations in serum albumin levels and, to a lesser extent, NAGase values between samples in both infected and non-infected quarters. NAGase was more effective in predicting bacteriological status of the quarter than serum albumin.

Relationship between somatic cell count and intramammary infection of the half udder in dairy ewes

A total of 1382 milk samples from half udders of three breeds of ewes (686 Assaf, 422 Churra, and 274 Castellana) were collected aseptically at midlactation from 18 flocks in the Castile-León region of Spain. Bacteriological tests were carried out on the samples to ascertain the status and type of IMI. Somatic cell counts were determined for all samples after bacteriological analysis. Analysis of variance showed significant effects of breed, IMI status, flock nested within breed by milking type, organism within IMI status, and interactions of breed by milking type and of breed by organism. The most frequent bacterial groups were staphylococci, especially coagulase-negative staphylococci, followed by streptococci, micrococci, and yeasts. The SCC response was related to the bacterial group involved in the IMI; coagulase-negative staphylococci showed significantly lower SCC values than those for coagulase-positive staphylococci and streptococci. Highest percentages of IMI by major pathogens and highest SCC, both in the absence of IMI and in staphylococcal IMI, were in Assaf ewes. The threshold of 300,000 cells/ml allowed 81% of the half udders to be correctly classified according to IMI status. However, the existence of breed differences in SCC response and IMI type could make the use of specific SCC thresholds for each breed advisable.

Variation in somatic cell count, California mastitis test, and electrical conductivity among various fractions of ewe's milk

Variation of three estimates of udder inflammation (SCC, California mastitis test, and electrical conductivity) among the foremilk, machine milk, and hand stripping samples were studied. Foremilk and hand stripping milks were taken from each individual teat; machine milk was taken from the entire udder. For this experiment a total of 30 Manchega ewes were subjected to machine milking during the 9th wk of lactation. Samples were taken in duplicate during two milkings on consecutive mornings. Significant differences were observed in the SCC and electrical conductivity, but not in California mastitis test, between foremilk and stripping milk. The stripping fraction had higher SCC (70 +/- 12%) and lower electrical conductivity (difference = .52 +/- .03 mS/cm) than did the foremilk fraction in both healthy and mastitic udders. Machine milk, foremilk, and stripping milk fractions in udders where both halves were healthy were compared. The electrical conductivity values for the machine milk were intermediate and significantly different from conductivity of foremilk and stripping fractions. The log SCC of the machine milk did not differ from that of the foremilk fraction but was significantly less than the stripping milk.

Milk whey induction of agglutination in ovine and bovine mastitis Staphylococcus aureus

A total of 59 mastitis staphylococcic strains were tested for growth agglutination upon supplementation of growth media with ovine and bovine milk whey and mammary secretions from dry cows. Differences were observed when comparing bacterial species or origins (ovine vs. bovine) of bacteria and whey. All of the ovine and bovine S. aureus strains tested, but only 4 among 22 other ovine mastitis staphylococcic strains, showed growth agglutination in Todd Hewitt broth (THB) supplemented with greater than or equal to 30% (v/v) ovine milk whey. None of the strains agglutinated during growth in regular THB medium. Ovine whey had an agglutination induction capacity higher than bovine whey (P less than 0.005), concerning the number of responsive ovine and bovine S. aureus strains. There were no differences between whey samples from different ewes with regard to their capacity to induce agglutination. Ovine S. aureus strains were more responsive than bovine strains of this bacterial species, concerning the number of responsive strains (P less than 0.001) to bovine whey (greater than or equal to 30% in THB), the proportion of responsive strains at low (10%) ovine whey concentration (P less than 0.001), and the strength of reaction (precipitation timing and clump size). Secretions from dry cows systematically induced agglutination in all of the bovine and ovine S. aureus strains tested.

Use of California Mastitis Test, N-acetyl-beta-glucosaminidase, and antitrypsin to diagnose caprine subclinical mastitis

Analysis of 448 milk samples (11 herds) from caprine udder halves showed that microorganisms were isolated from 21.8% of the samples. California Mastitis Test (CMT) and N-acetyl-beta-glucosaminidase (NAGase) were superior to antitrypsin in detecting subclinical infections. Coagulase-negative staphylococci and micrococci were the main species isolated from halves showing no clinical disease. Coagulase-positive staphylococcal infections were associated with a significant increase of all inflammatory parameters. Significantly increased CMT and NAGase occurred when streptococci, other staphylococci or micrococci were present. Infection within one half was reflected as an increase in the inflammatory parameters in the milk of the infected half as well as a slight increase in the inflammation parameters in the adjoining half.