Determination Of Somatic Cell Count Research Articles

Clinical and histopathological aspects of naturally occurring mastitis caused by Listeria monocytogenes in cattle and ewes.

Listeria monocytogenes was isolated from the milk of two cows and two sheep with mastitis in one quarter and one udder half. The animals were observed over a period of 2-12 months. Clinical examination of the udder, bacteriological examinations and determination of somatic cell counts of milk samples were performed monthly. All four cases suffered from a subclinical mastitis characterized by an elevated somatic cell count (0.8-10.1 x 10(6) cells/ml), a persistent shedding of Listeria and by a normal appearance of the milk. The animals did not show any systemic reaction, but all animals developed an atrophy of the infected mammary gland. Histological examinations revealed a chronic interstitial mastitis with diffuse infiltration of lymphocytes, plasma cells and macrophages. All internal organs showed no abnormalities, no Listeria could be isolated. Listeria could however be isolated from the affected mammary parenchyma and from the mammary lymph node. The results of the bacteriological examination could be confirmed by means of PCR. Using PFGE, all the isolates from the same animal were identical. Immunohistochemical examination of the ovine mammary glands achieved a very strong immunoreactivity for CD5 cells. The mode of infection and the reaction of the immune system's defense of the ovine udders are discussed.

Quarter milk flow patterns in dairy cows: factors involved and repeatability

The objectives of our study were to describe the variation of quarter milk flow parameters and to determine the factors that affect these parameters the most. Additionally, repeatabilities (r<sub>2</sub>) of the quarter milk flow traits (duration of milk flow, time to reach peak flow, peak flow rate, and duration of milk flow in single phases – increase, plateau, decline and blind phase) were calculated. Repeatability of total milk yield and milk yield in single phases was calculated, too. The data from 39 Holstein cows, in their first to third lactation and free of clinical mastitis, were used for statistical analysis. A total of 1 656 curves of quarter milk flows were recorded during six consecutive days. At the last evening and morning milking samples of milk from each quarter were collected for determination of somatic cell count (SCC). Peak flow rate, quarter position, time of milking (morning and evening) and SCC significantly affected most of the measured traits. The highest r2 were for total milk yield and yield of plateau phase 0.53 and 0.50, resp. The lowest r2 were calculated for the duration of increase phase, and milk yield of the increase and blind phase 0.26, 0.12 and 0.21, resp. Peak flow rate, SCC, time of milking and front-rear position influenced the values of r2 of traits to various extent.

Concentrations of triiodothyronine (T3), tumour necrosis factor-α (TNF -α) and interleukin-6 (IL -6) in milk from healthy and naturally infected quarters of cows

The effect of naturally acquired bacterial infection of the bovine udder on the activity of 5′-thyroxine monodeiodinase (5′- MD), and on the concentrations of the pro-inflammatory cytokines interleukin(IL) -6 and tumour necrosis factor (TNF) -α in milk, from healthy (control) and inflamed quarters, was determined. The diagnostic procedure included history and clinical examination of the udder, macroscopic evaluation of secretions, the Californian Mastitis Test, determination of somatic cell counts and bacteriological examination of milk. It has been found that the milk triiodothyronine (T3) content and the 5′- MD activity from inflamed quarters were decreased when compared with controls. The decrease in the milk T3 from subclinical mastitic quarters was manifested when somatic cell counts were >106ml−1. TNF -α was on average 2-fold higher in infected milk, and the concentration of IL -6 was unchanged. These results suggest that the decreased T3 content in mammary secretions during naturally occurring mastitis is associated with the severity of inflammation, increased TNF -α concentration and impaired enzymatic activity of 5′- MD.

Somatic cell count determination in cow's milk by near-infrared spectroscopy: a new diagnostic tool.

The potential of near-infrared spectroscopy (NIR) in the region from 1,100 to 2,500 nm to measure somatic cell count (SCC) content of cow's milk was investigated. A total of 196 milk samples from seven Holstein cows were collected for 28, consecutive days, starting from 7th d after calving, and analyzed for fat, protein, lactose, and SCC. Three of the cows were healthy, and the remainder had periods of mastitis during the experiment. Near-infrared transflectance milk spectra were obtained using an InfraAlyzer 500 spectrophotometer. The calibration for logSCC was performed using partial least square (PLS) regression and different spectral data pretreatment. The best accuracy of determination was found for an equation that was obtained using smoothed absorbance data and 10 PLS factors. The standard error of calibration was 0.361, the calibration coefficient of multiple correlation was 0.868, the standard error of prediction for independent validation set of samples was 0.382, the correlation coefficient was 0.854, and the coefficient of variation was 7.63%. The accuracy of logSCC determination by NIR spectroscopy would allow health screening of cows and differentiation between healthy and mastitic milk samples. It has been found that SCC determination by NIR milk spectra is based on the related changes in milk composition. The most significant factors that simultaneously influenced milk spectra with the elevation of SCC were alteration of milk proteins and changes in ionic concentration of milk.

Efeito do nível de células somáticas sobre os constituintes do leite II-lactose e sólidos totais

In laboratory, electronic determination of somatic cell count (SCC) and concentration of lactose and total solids of 1,361 milk samples were carried out in order to evaluate the effects of somatic cell count (SCC) on the concentrations of milk lactose and total solids. All the SCC data were transformed to a linear score. Increases in the SCC score were associated with decreased lactose concentration. This increase was highly significant (p < 0.0001), and about 34% of the lactose concentration variation could be accounted for variation of the SCC score. Total solids were not influenced by the SCC score.

Somatic cell counts determined by the Coulter or Fossomatic Counter and their relationship to administration of oxytocin

The somatic cell count of milk from experimentally inoculated and control mammary glands of primiparous ewes from meat-type breeds were determined by Coulter and Fossomatic Counters. Oxytocin was administered prior to milk collection to avoid stripping of the mammary epithelium while assuring sufficient quantity of milk, but was found to increase ( *** p<0.0001) the somatic cell counts when they were determined by the Coulter Counter. Oxytocin did not significantly alter the somatic cell count of milk samples collected from subclinically infected glands. The mean somatic cell count of normal milk samples determined with the Fossomatic Counter was lower ( *** p<0.0001) than that of milk samples collected without oxytocin and determined by the Coulter Counter. The findings indicated that the Fossomatic Counter is the most reliable method for the experimental determination of somatic cell counts of milk from ewes of meat-type breeds. This method is also free of external influences such as the adverse effects of oxytocin administration.

Efficacy of two antibiotic treatments in curing clinical and subclinical mastitis in lactating dairy cows

Aim. To compare the bacteriological and clinical cure rates for clinical and subclinical mastitis in New Zealand dairy cows following treatment with either an intramammary penicillin-dihydrosptreptomycin preparation or a subcutaneous injection of penethamate hydriodide. Methods. Milk samples were collected from clinical and subclinical cases of mastitis before and 14 and 21 days after initiation of treatment for bacteriological culture, somatic cell count determination and conductivity testing. Results. No significant differences in the bacteriological cure rate of major Gram-positive pathogens, clinical cure rate, somatic cell count or conductivity were found between treatments. However, the bacteriological cure ralte of coagulase-negative staphylococcus infections and the overall bacteriological cure rate was lower for quarters treated with penethamate than with penicillin-dihydrosptreptomycin. Conclusions. The bacteriological cure rate of mastitis caused by major Gram-positive pathogens, the clinical cure rate, somatic cell count and conductivity did not differ between the two antibiotic treatments.

Evaluation of udder health and mastitis in llamas

Objective To investigate intramammary infections in llamas, identify the pathogens responsible, and determine whether effects of intramammary infection could be detected by use of mastitis indicator tests commonly used for cows. Design Observational study. Animals 100 llamas on 10 farms. Procedure Milk samples were evaluated by bacterial culturing and by determination of somatic cell count (SCC), using direct microscopic and automated counting methods, California Mastitis Test score, pH, and N-acetyl-β-d-glucosaminidase activity. Correlation coefficients were determined among the various mastitis indicator tests, and test results were determined for milk from infected and uninfected glands. Results Evidence of intramammary infection was evident in 76 of 369 (21%) milk samples, with 54 of 94 (57%) llamas having at least 1 infected gland. Staphylococcus sp other than Staphylococcus aureus were the predominant pathogens. None of the llamas had clinical signs of mastitis, and significant differences were not detected in SCC, California Mastitis Test score, pH, or N-acetyl-β-d-glucosaminidase activity between infected and uninfected samples. California Mastitis Test scores were negative or trace for 307 of 313 (98%) samples, and SCC were low. In contrast, pH and N-acetyl-β-d-glucosaminidase activity of milk from uninfected glands were higher than values reported for milk from uninfected cows, and neither variable was significantly correlated with the number of somatic cells in samples of llama milk. Clinical Implications Although intramammary infections develop in llamas, inflammation (mastitis) appears to be rare. Values for mastitis indicator tests used for cows cannot be directly extrapolated to llamas. Subclinical mastitis is apparently not an important problem in llamas in the United States. (J Am Vet Med Assoc 1996;209:1457–1463).

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

AbstractSomatic 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.

Subclinical mastitis and milk production in primiparous Simmental cows

The prevalence of subclinical mastitis in beef cows was investigated and its relationship with milk production and 205-d adjusted calf weaning weights (ADJWW) determined. Primiparous Simmental cows (n = 25) were milked six times at approximately 30-d intervals. Before each milking, milk samples were aseptically collected from each quarter for bacteriological analyses. After recording milk weights, samples were obtained for determination of somatic cell counts (SCC), butterfat (BF), and protein (PRO). Somatic cell counts were transformed to Dairy Herd Improvement Association linear scores for statistical analyses. Cows were retrospectively assigned to one of two groups based on their SCC linear score being either less than (LOSCC) or more than (HISCC) 4.5, which corresponded to a SCC of 292 x 10(3) cells/mL. Milk samples from 32% (8/25) of the cows and 18% (18/100) of the quarters were culture-positive for bacteria (Staphylococcus aureus, Streptococcus dysgalactiae, Streptococcus species, Actinomyces pyogenes, and[or] coagulase-negative Staphylococcus) at one or more times. Milk production was higher in LOSCC than in HISCC cows (6.3 +/- .2 vs 5.4 +/- .3 kg/24 h; P = .004). Mean SCC linear score tended to be negatively correlated with mean milk production over the entire study (r = -.36; P = .08). Adjusted weaning weights were similar between calves suckling LOSCC and HISCC cows (243 +/- 5 vs 236 +/- 10 kg; P = .57). In summary, milk SCC concentrations in primiparous Simmental cows were highly variable. Higher SCC concentrations were associated with lower milk production in cows.

Comparison of microbiologic culture, an enzyme-linked immunosorbent assay, and determination of somatic cell count for diagnosing Staphylococcus aureus mastitis in dairy cows

Summary Results of using microbiologic culture of a single milk sample, determination of somatic cell count (scc), an elisa, and a combination of determination of scc and elisa to diagnose Staphylococcus aureus mastitis in dairy cattle were compared. Cows were considered to have S aureus intramammary infections if microbiologic culture of at least 2 of 3 consecutive sets of milk samples yielded growth of the organism. Data were analyzed from milk samples collected over a 4-month period from 185 cows in 5 herds. Sensitivity, specificity, and likelihood ratio of a positive test result for microbiologic culture of a single milk sample were 93%, 99%, and 93.0, respectively. Sensitivity, specificity, and likelihood ratio of a positive test result for elisa were 69%, 61%, and 1.8, respectively, and for determination of scc, they were 79%, 72%, and 2.9, respectively. Combination of determination of scc and elisa had sensitivity, specificity, and likelihood ratio of a positive test result of 80%, 62%, and 3.4, respectively. Results from microbiologic culture of consecutive milk samples were more consistent than results of elisa performed on consecutive samples. These data suggest that microbiologic culture of a single milk sample is the best of the 3 tests studied for diagnosing S aureus intramammary infection.

Effects of Daily Exogenous Oxytocin on Lactation Milk Yield and Composition

Eighty-four Holstein cows were used to determine effects of exogenous oxytocin on 305-d milk production and health. Cows were assigned at parturition by parity group to treatments: 1) oxytocin group, animals received an injection of 1ml (20 IU) of oxytocin at each milking throughout lactation and 2) control group, animals received no injection. Oxytocin injections were given in the thigh region within 3min following the initiation of udder preparation and immediately prior to machine attachment. Udder preparation consisted of forestripping and manual cleaning (10 to 20s) and drying (5 to 10s) of teats. Cows were milked in a parlor, and milk yield was recorded at each milking. Milk samples were collected from each cow biweekly for milk fat, protein, and somatic cell count determination. Individual lactations were modeled using Woods’ lactation equation; resulting coefficients were analyzed using ANOVA. The oxytocin group produced 849kg more milk during the lactation than the control group, with a significant difference occurring after peak milk yield. This suggests that exogenous oxytocin maintained greater persistency during lactation. No significant differences existed for milk fat or protein percentages. The use of exogenous oxytocin at milking increased lactation milk production with no apparent effect on health.

Use of Laboratory Mice to Study Genetic Relationships Among Milk Yield and Number of Somatic Cells

Preliminary results of bidirectional selection for increased and decreased somatic cell counts in milk of laboratory mice were used to assess the usefulness of the laboratory mouse as a pilot organism for the study of yield and somatic cell count relationships in dairy cattle.Procedures developed permit relatively rapid and accurate determination of somatic cell counts in milk of mice. Concentration of somatic cells was three to four times greater in mice than in dairy cows, but counts were distributed similarly. A large effect for stage of lactation existed with high counts in late lactation. Within lactation, repeatability of somatic cell counts and relationships between somatic cell counts and milk yield were similar to those reported for dairy cattle. Heritability of lactation average somatic cell count (3 sample d, log base 2, adjusted for stage of lactation) was .24, indicating lines genetically divergent for somatic cell count can be developed.