Differential Somatic Cell Count Research Articles

Comparison of the milk quality of the South African Boer and Australian Rangeland goats

Milk composition studies on goats are limited and have mainly concentrated on traditional dairy breeds. Since goats have the advantage of producing larger volumes over a longer lactation period, systematic studies to define the quality of goats milk is warranted. There is anecdotal evidence amongst goat breeders suggesting that some breeds of goat produce highly nutritious milk. In this study, the milk composition of the South African Boer and the Australian Rangeland goats were evaluated. Milk from the Boer goat contained significantly higher fat concentration compared to the Australian Rangeland goat (7.1 versus 3.3% at week 6). There were significant differences in the milk protein levels in the early stages of lactation between the Boer and Rangeland goats (5.1 versus 3.6% at week 4), however the levels were similar at week 6. In contrast, there was no significant difference in Somatic Cell Counts between the milk from the two breeds of goat. The milk lactose level of the Australian Rangeland goat was significantly higher than in the Boer goat (5.0 versus 5.3% at week 4, and 5.4 versus 5.6% at week 6).

Comparison of the milk quality of the South African Boer and Australian Rangeland goats

Milk composition studies on goats are limited and have mainly concentrated on traditional dairy breeds. Since goats have the advantage of producing larger volumes over a longer lactation period, systematic studies to define the quality of goats milk is warranted. There is anecdotal evidence amongst goat breeders suggesting that some breeds of goat produce highly nutritious milk. In this study, the milk composition of the South African Boer and the Australian Rangeland goats were evaluated. Milk from the Boer goat contained significantly higher fat concentration compared to the Australian Rangeland goat (7.1 versus 3.3% at week 6). There were significant differences in the milk protein levels in the early stages of lactation between the Boer and Rangeland goats (5.1 versus 3.6% at week 4), however the levels were similar at week 6. In contrast, there was no significant difference in Somatic Cell Counts between the milk from the two breeds of goat. The milk lactose level of the Australian Rangeland goat was significantly higher than in the Boer goat (5.0 versus 5.3% at week 4, and 5.4 versus 5.6% at week 6).

Post Milking Teat Dip Effect on Somatic Cell Count, Milk Production and Composition in Cows and Buffaloes

The effect of post milking teat dipping on somatic cell count (SCC) of milk was determined in 20 Crossbred cows and 20 Murrah buffaloes selected from institute's herd. The animals were divided into two groups of 10 each. Animals of Group I (control) were teat washed with water before the milking while Group II animals were applied teat dipping solution after the completion of milking. The cows were milked 3 times a day while buffaloes were milked twice a day. The milk samples were collected from control and treated animals on day 0, 5, 10, 15, respectively. The milk samples were analyzed for milk constituents like fat, protein, lactose, chloride, IgG, NEFA, pH and EC and total and differential somatic cell counts. The changes in milk composition and somatic cell counts were significantly different (p<0.01) between the animals and between the breeds. However SCC, chloride content (p<0.05) and epithelial cells (p<0.01) varied during different days of study. The alterations in SCC, epithelial cells, TLC, lymphocyte, neutrophil, IgG, and protein content were significantly different (p<0.01) between control and treated groups. The pH, EC, protein, SCC, epithelial cells, lymphocyte and neutrophil cells of milk declined significantly (p<0.05) after the application of teat dipping, the respective values were 6.5 vs 6.40, 2.28 vs 2.37 mhos, 3.33 vs 4.04%, 1.00 vs 0.87×10 5 cells/ml, 0.39 vs 0.34×10 5 cells/ml, 0.36 vs 0.31×1,000 cells/ml and 0.17 vs 0.14×1,000 cells/ml in cows. However in buffaloes, epithelial cells, lymphocytes, neutrophils, EC and SCC declined (p<0.05) after application of teat dipping, the values being 0.37 vs 0.29×10 5 cells/ml, 0.37 vs 0.25×1,000 cells/ml, 0.14 vs 0.11×1,000 cells/ml, 2.56 vs 2.37 mhos and 0.94 vs 0.73×10 5 cells/ml, respectively. The study indicated that post milking teat dipping could be used as an effective method for the lowering of SCC in milk of crossbred cows and buffaloes. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 10 : 1517-1522)

Comparative study of the effects of testing laboratory, counting method, storage and shipment on somatic cell counts in goat milk

Somatic cell counts (SCC) in goat milk from different stages of lactation were determined at four laboratories (I, II, III and IV) using the pyronin Y-methyl green (PYMG) direct microscopic method and/or Fossomatic machines calibrated with either goat or cow milk standards. The effects of sample shipment and storage on SCC of goat milk were also determined. Results of this study indicated that the PYMG microscopic method and the Fossomatic machine calibrated with goat milk standards gave comparable estimates of SCC in goat milk ( p>0.05). However, on average the Fossomatic machines ( n=3) calibrated with cow milk standards estimated SCC of goat milk to be 24.5% higher than a Fossomatic machine calibrated with goat milk standards ( p<0.05). No significant difference in SCC of goat milk existed ( p>0.05) between laboratories ( n=2) when the PYMG microscopic method was used. Shipping milk samples in an ice box (3 days) and storing in a refrigerator (3 days) did not affect SCC results ( p>0.05).

Effect of Freezing on Somatic Cell Count of Quarter Milk Samples as Determined by a Fossomatic Electronic Cell Counter

The objective of this study was to determine the effect of freezing and the duration of freezing on somatic cell count (SCC) in milk samples from quarters with no signs of clinical mastitis. Effect was determined by a fluoro-opto-electronic cell counter. Samples were frozen in a commercial freezer at approximately –20°C. The milk samples were thawed at 1, 2, 3, 4, 7, 14, or 28 d. Another batch of samples was frozen 1 d, thawed, frozen again for 1 d, and then thawed. The SCC was determined on the fresh samples and after any one of the freezing periods. On average, the SCC were lower after all freezing periods than they were before freezing. However, the difference in SCC before and after freezing was small and relatively constant on the natural logarithm scale. The decrease in SCC was larger with longer freezing periods. When SCC thresholds of 200,000, 250,000, and 500,000 cells/ml were used to predict infection, freezing appeared to have little impact on the sensitivity and specificity of diagnostic parameters. Therefore, SCC, as determined by a fluoro-opto-electronic cell counter, determined for frozen quarter milk samples can be used in mastitis control and research programs.

Cytokines and tumours: problems and perspectives

Somatic cell count (SCC) is used as key indicator in mastitis screening programs typically applied in the frame of Dairy Herd Improvement (DHI) testing programs. However, mastitis is still causing tremendous economic losses to the dairy industry. Hence, new biomarkers are needed that can be used for enhanced management of mastitis on dairy farms. Besides the determination of SCC, differentiation of cells has been described to be beneficial for a more definite description of the actual udder health status of dairy cows. The aim of this study was to develop a new method for rapid and simultaneous determination of SCC and a new parameter, differential somatic cell count (DSCC), in individual cow milk samples using flow cytometry. The method is sought to be applied in central milk testing laboratories, so that existing DHI infrastructures can be used. The DSCC represents the combined proportion of polymorphonuclear leukocytes (PMN) and lymphocytes expressed in percentage. The proportion of macrophages can be calculated by subtracting DSCC from 100%. Our research revealed increasing proportions of PMN, but decreasing proportions of macrophages as SCC increased. However, lymphocytes occurred fairly constantly with low proportions across the entire SCC range. Hence, the DSCC parameter reflects the antidromic trend of PMN and macrophages. Fluorescence microscopy was used to evaluate the specificity of the new Foss DSCC method in terms of DSCC and a high correlation was found. Apart from that, the accuracy of cell differentiation using the Foss DSCC method was confirmed in a cell sorting trial. Total SCC could be determined equally well using the new method as compared with existing methods. The new method was further proven to be robust toward a range of method and milk-sample-related factors. In an initial field trial, regular DHI samples of a local dairy herd were analyzed. The DSCC values occurred in a broad range from 34 to 79% in samples with <400,000 cells/mL. Higher DSCC values (53–89%) were found in samples with >400,000 cells/mL. In conclusion, the new Foss DSCC method allows reliable, repeatable, fast, robust, and accurate determination of both DSCC and SCC at low cost. This, in turn, provides more accurate information on the actual udder health status of dairy cows. The practical application of DSCC in the frame of DHI testing programs, however, needs further investigation.

Diagnostic performance of two serologic tests and fecal culture for subclinical paratuberculosis, and associations with production

A sample of three dairy herds served by the same private veterinary practice was selected on the basis of similarrity of size, calf-rearing practices and owner cooperation. All animals were tested for paratuberculosis three or four times at 6-month intervals by fecal culture, enzyme-linked immunosorbent assay (ELISA), agar-gel immunodiffusion (AGID) serology. Fecal-culture results were reported to herd owners through their veterinary practitioner. Production data and somatic-cell counts were collected from two of the herds using DHI (Dairy Herd Improvement, Powell, OH) records. Sensitivity and specificity relative to fecal culture of single test results were 71% and 83% for ELISA and 38% and 100% for AGID, respectively. Repeated tests gave sensitivity and specificity of 73% and 61% for ELISA and 33% and 100% for AGID when tests were interpreted in parallel testing. A maximum-likelihood procedure was used to generate estimates of sensitivity and specificity of single (91% and 82%) and repeated (73% and 66%) ELISA testing. There were no significant differences by sign test between fecal culture and ELISA in the time period which infection was first identified ( P=0.38). Fecal culture detected infection earlier than AGID. Mean milk production (controlling for differences in somatic-cell counts) was 3275 lbs. per lactation or 18.8% higher in fecal culture-negative cows than in fecal culture-positive cows. No associations were found between milk production and ELISA results.

Total and Differential Somatic Cell Counts and N-Acetyl-β-D-glucosaminidase Activity in Mammary Secretions During Dry Period1,2

Eighteen Holstein cows free of intramammary infection were sampled during dry period to measure changes in total SCC, differential cell counts, and N-acetyl-β-D-glucosaminidase activity of milk or dry secretion. The design was to sample prior to and at drying off, two or more times during wk 1 of dry period, at 14 and 21 d of dry period, and after calving; 7 cows were sampled rotationally by quarters at 7, 14, and 21 d to avoid altering normal processes by repeated sampling. Total SCC of secretions declined just after drying off, increased to a peak of 6.593 (log10 scale) at 2 wk, and then declined slightly at 3 wk. Percentage of neutrophils rose from 33.3 at drying off to 83.8 at 1 wk and declined to 59.2 at 3 wk. Lymphocyte percentage declined in wk 1 of dry period but increased during wk 2 and 3. Activity of N-acetyl-β-D-glucosaminidase in secretion rose throughout the first 3 wk of dry period.

Effects of antibiotics on phagocyte recruitment, function, and morphology in the bovine mammary gland during the early nonlactating period

SUMMARY The effects of 2 antibiotic preparations administered intramammarily on phagocyte recruitment, function, and morphology were evaluated at the beginning of the nonlactating period. Twelve cows with no clinical or microbiologic evidence of mastitis were assigned to 1 of 2 treatment groups. At the end of lactation, 1 of the antibiotic preparations was infused in a fore- and hind quarter of each cow; the remaining quarters were untreated controls. One group was given benzathine cephapirin; the second group was given sodium novobiocin. Secretion samples were collected from 1 treated and 1 control quarter at 16 hours, and from the remaining 2 quarters at 64 hours after treatment. Total and differential somatic cell counts were determined, and morphology of mammary polymorphonuclear neutrophils (pmn) and macrophages was observed by transmission electron microscopy. In vitro ingestion and killing of Staphylococcus aureus by mammary pmn and macrophages were assessed by fluorescent microscopy, using acridine orange stain. Cells resident in a fixed volume of secretion were incubated with a known concentration of S aureus. Total cell and pmn concentrations were higher in treated than in control quarters. Neutrophils were the predominant cell type in both treated and control quarters over the sampling period. As measured in this study, in vitro ingestion and killing of S aureus by individual pmn from treated quarters was reduced. Antibiotic treatment also increased the proportion of morphologically abnormal phagocytes. There were significant correlations among pmn ingestion, killing, and morphology. However, increased pmn concentrations tended to compensate for the reduced phagocytic function of individual cells. Therefore, efficacy of antibiotic treatment of nonlactating cows may depend, at least in part, on increased pmn concentration, which may tend to compensate for reduced phagocytic function. Compared with pmn, macrophages appeared to have only a minor role in phagocytosis of bacteria.

Collagen binding, elastase production, and slime production associated with coagulase-negative staphylococci isolated from bovine intramammary infections

Collagen binding, elastase production, slime production, and associated somatic cell counts were determined with 160 strains of coagulase-negative staphylococci isolated from bovine intramammary infections. Mean binding values for type I and II collagen with Staphylococcus epidermidis, S. chromogenes, and S. hyicus strains were 5.8, 6.6, and 7.4 and 4.3, 4.2, and 4.9%, respectively. Eleven of 28 (39.3%) S. epidermidis, 1 of 38 (2.6%) S. chromogenes, and 1 of 94 (1.1%) S. hyicus strains were elastase positive. Slime production was noted with 12 (42.9%) S. epidermidis, 1 (2.6%) S. chromogenes, and 11 (11.7%) S. hyicus strains. No differences in somatic cell counts were observed with type I or type II collagen binding, elastase production, or slime production with S. epidermidis or S. chromogenes. However, somatic cell counts associated with S. hyicus strains with collagen type I binding affinities of greater than 5 and type II binding affinities of greater than 3 were 320.7 x 10(3) compared with 163.9 x 10(3) for strains with lower binding affinities.

Inflammatory Reactions in the Teat and Udder of the Dry Cow

The inflammatory reactions in the teat and udder of the dry cow were studied by total and differential somatic cell counts (SCC) and by measuring bovine serum albumin, N-acetyl-beta-D-glucosaminidase (NAGase), plasminogen and plasmin. The teat and udder cisterns were surgically separated from each other in two udder quarters of each cow. Salmonella endotoxin was infused in one teat cistern and one udder quarter, and saline was infused in one teat cistern and one udder quarter. The inflammatory response was followed by several samplings post infusion. The reactions in the dry udder quarters were mainly in line with the results of similar studies in lactating glands. The differential SCC and the NAGase results were, however, somewhat different. The teats were capable of a strong inflammatory response. Reactions different from those seen in the glands were observed with regard to permeability changes and NAGase. The experimental model used showed promising results and is suitable for further studies of the inflammatory process.

Potential of Differential Somatic Cell Counts as Indicators of Mastitis in Quarter Milk Samples from Dairy Cows

Bacteriological status, somatic cell counts and proportions of lymphocytes, granulocytes and monocytes were determined in 1,659 quarter milk samples from 39 dairy cows. Discriminant analysis was performed in order to assess the ability of total and differential somatic cell counts and combinations of total somatic cell count and each of the differential cell counts, to discriminate between infected and pathogen-free quarters, as well as between quarters infected with minor pathogens and quarters infected with major pathogens. Total somatic cell count classified 82.9% of all quarters correctly with respect to bacteriological status. Differential somatic cell count was less effective than total somatic cell count in discriminating between infected and pathogen-free quarters, as well as between quarters infected with minor vs. major pathogens. Combination of total and differential somatic cell counts did not improve the rate of correctly classified quarters. Inclusion of demographic data into the discriminant function increased the number of quarters correctly classified, mainly through an increase in the proportion of correctly classified infected quarters.

Efficacy of an Iodine Backflush for Preventing New Intramammary Infections

Efficacy of an iodine backflush system for reducing new intramammary infection was tested in two 11-wk trials. Forty cows in each trial were paired by breed, age, stage of lactation, and intramammary infection status. Each pair was assigned randomly either to a group milked with clusters that were reverse flushed with water, 25ppm iodine, water and air or to a group milked with clusters receiving no backflush treatment between cows. Back-flushing clusters reduced infections caused by Corynebacterium bovis and coagulase-positive staphylococci in both trials. However, backflushing clusters produced no clear advantage for reducing new infections with coagulase-negative staphylococci, Gram-negative bacilli, or streptococci (species other than Streptococcus agalactiae). No differences in somatic cell counts between experimental groups were observed. Teat cup liners and teat ends were swabbed after 120 and 1200 milkings/liner. Total microbial counts were significantly greater for liners that were not backflushed than from backflushed liners at each swabbing. However, no differences were significant between groups for mean teat end microbial counts in either trial.

Cytospin Centrifuge in Differential Counts of Milk Somatic Cells

A procedure was developed for a cytospin centrifuge to concentrate cells from milk onto microscope slides in a circle with 6mm diameter. Differential somatic cell counts with cytospin were compared to the conventional hand smearing technique to ascertain variation in differential counts. Milk samples were from each of 30 cow quarters, 10 within each of three total milk somatic cell count ranges of less than .7, .7 to 1.5, and more than 1.5×106/ml. Two cytospin and two hand smears were prepared from each sample. All smears were air dried; and stained with modified Wright's stain, the first 200 cells were counted. Differential cell counts from smears prepared by the two procedures were not different. Variation between duplicate smears in differential cell counts was less for cytospin technique. Cytospin can be used to obtain rapid and accurate differential cell counts in milk over a wide range of total somatic cell counts.

Use of Total and Differential Somatic Cell Counts to Differentiate Potentially Infected from Potentially Non-infected Quarters and Cows and Between Herds of Various Levels of Infection

The objective of this study was to ascertain the value of variables measured on bulk tank and composite milk samples as predictors, respectively, of the level of mastitis in herds and individual cows. The standard of comparison was the results obtained by bacteriological examination of the secretion from individual mammary quarters. It was found, whether sampling at the herd or cow level, that of the three variables measured on each sample, namely somatic cell count, percentage of cell volume in channel 8 (includes cells with individual volumes from 89.2 to 178.3 μm3) and presence or absence of Streptococcus agalactiae, that the ability of the first two variables to discriminate (predict) was not significantly improved by the inclusion of the latter variable. Using values for the former two variables as measured on bulk tank milk and collected at the time of quarter sampling, it was possible to correctly classify 45.5% of the study herds into one of the three quarter infection rate categories considered, namely, < 10, 10–25 or > 25%. The percentage of herds correctly classified was increased to over 80% by inclusion of five monthly counts recorded previous to the time of quarter sampling. Using the same two variables but measured on composite milk samples, 79.4% of cows were correctly classified as being either positive or negative when a positive cow was defined as one having at least one positive quarter. The overall percentage of cows correctly classified decreased from 79.4 to 77.9% when an attempt was made to distinguish between negative cows and cows with one positive quarter. However, this overall percentage progressively increased to 92.7% as the definition of a positive cow was changed from one having one positive quarter to one having two, three or four positive quarters. The procedure shows promise for monitoring the level of mastitis infection in either dairy herds or cows but requires further refinement before consideration could be given to its implementation.