Somatic Cell Counts In Raw Milk Research Articles

A novel determination method of milk somatic cell count based on dielectric relaxation parameters

Rapid and accurate raw milk somatic cell count (SCC) monitoring is vital to identify cow mastitis and dairy quality evaluation. This study aimed to explore the influence mechanism of milk SCC on dielectric spectra and the potential of dielectric relaxation parameter (DRP) to predict milk SCC. The dielectric spectra of 272 raw milk samples with different SCC at 20–4500 MHz were measured, and the effects of milk SCC on the DRPs were analyzed. The models based on full spectra (FS), characteristic variables extraction, and DRPs methods were established to predict milk SCC. The results showed that the Cole-Cole plots exhibited apparent differences between sample groups with different SCC. The DRPs-NNuSVR model had the best prediction performance, with the standard error of prediction of 0.166 log SCC/mL and residual predictive deviation of 2.538, better than the FS and characteristic variables extraction models. This study explores the influence of milk SCC on dielectric relaxation and proposes a novel milk SCC prediction method, which helps in dairy farming and raw milk quality assessment.

Analysis of The Effect of Region, Province and Breed on Somatic Cell Count in Dairy Cattle in Turkey By Regression Tree Method

This study aimed to determine the effect of various environmental factors on the somatic cell count (SCC) in cow’s milk. The material of the study consisted of an SCC analysis result obtained from 207.614 raw milk samples collected from 65.288 head cattle had different breeds, ages, lactation number, and lactation length between May and December in 2019. They were raised on 6,305 dairy farms that are members of the Cattle Breeders Association (CBAT). In order to determine the effect of region, city, and cattle breed on SCC in raw milk of cattle, a regression tree was created using the Chi-square Automatic Interaction Detection (CHAID) algorithm, a Data Mining (DM) method. Accordingly, the mean SCC value of all enterprises was determined as 201.253 cells/mL. In this study, it was found that the region, city and breed groups with the highest average somatic cell counts were CAR, MSR, MR and SAR region group (285.430 cells/mL); C09, C45, C20, C64, C48, C43 city group (266.744 cells/mL); and HF, MC, and BS breed group (295.705 cells/mL). As a result of this study, the variables affecting SCC were determined as region, city, and breed respectively, in order of importance. Keywords: CHAID; Dairy cattle; Somatic cell count

Strengthen detection of raw milk somatic cell count - the first step for China milk quality improvement

Milk is a healthy natural beverage and the main raw material of dairy products. It is well known that raw milk is the first link to guarantee and control the quality and safety of milk and dairy products. Only high-quality raw milk can produce high-quality dairy products.

Effect of high somatic cell counts on the sensory acceptance and consumption intent of pasteurized milk and coalho cheese

Abstract Our aim was to evaluate the sensorial acceptance and consumption intent of pasteurized milks and coalho cheeses produced with milk with low (80,000 cells/mL) and high (480,000 cells/mL) somatic cell count (SCC) level. Low SCC pasteurized milk (LCC) obtained statistically higher scores on the aroma, consistency, flavor and overall liking attributes in comparison with high SCC pasteurized milk. LCC mean scores for all attributes were statistically higher than high SCC Coalho Cheese. High SCC in raw milk has a detrimental effect on the quality of pasteurized milk and coalho cheeses as it presented lower sensory acceptance, failing to meet the consumer’s desired expectations.

Changes in the somatic cells counts and total bacterial counts in raw goat milk during lactation and their relationships to selected milk traits

The main aim of our study was to assess changes in the somatic cell count (SCC) and total bacterial count (TBC) in the raw milk of White Short-haired (WSH) goats (n = 13) during lactation and their relationships to daily milk yield (DMY), basic milk components, the acidity of milk and California mastitis test (CMT). All monitored goats were in the second lactation and throughout the study, all these goats were clinically healthy. Individual milk recording and sampling of each goat during lactation were carried, from the end of April to October on the mean 54, 89, 124, 159, 194 and 229 day of lactation and all monitored goats were milked by hand. Throughout lactation, the mean values of Log SCC ranged from 5.60 to 5.91 and the mean values of Log TBC from 2.85 to 3.58, whilst the SL had no significant effect on any of these traits. The Log SCC had a significant positive correlation (p ≤ .01) only with CMT, which suggests that CMT may be a good predictor of the SCC. On the other hand, all correlations of Log TBC with all other traits were insignificant. Regarding the effect of the SL on all other monitored traits, it had a highly significant effect (p ≤ .01) on the DMY, contents of fat and total protein and titratable acidity. The SL had also a significant effect (p ≤ .05) on the pH. Nevertheless, the SL had no significant effect on lactose content and CMT. The results of our study suggest that in clinically healthy WSH goats, the SCCs in goat milk after milking should only rarely be higher than 1,000,000 cells/mL and if strict milking hygiene is applied, the TBCs should be significantly lower than 500,000 cfu/mL. The present study also suggests that the SCCs in milk in WSH goats are comparable to their counts in most other breeds. HIGHLIGHTS The stage of lactation had no significant effect on the SCC and TBC. In clinically healthy WSH goats, the SCCs in raw milk should rarely be higher than 1,000,000 cells/mL. When strict milking hygiene is applied in clinically healthy goats, the TBCs in milk after milking should be significantly lower than 500,000 cfu/mL.

Divergent selection on milk somatic cell count in goats improves udder health and milk quality with no effect on nematode resistance

Milk somatic cell count (SCC) is commonly higher in goats than in cattle and sheep. Furthermore, the ability of milk SCC to predict mastitis is considered lower in goats than in cattle and sheep, and the relevance of somatic cell score (SCS)-based selection in this species has been questioned. To address this issue, we created 2 divergent lines of Alpine goats using artificially inseminated bucks with extreme estimated breeding values for SCS. A total of 287 goats, 158 in high- and 129 in low-SCS lines, were scrutinized for mastitis infections. We subjected 2,688 milk samples to conventional bacteriological analyses on agarose and bacterial counts were estimated for positive samples. The SCS, milk yield, fat content, and protein content were recorded every 3 wk. Clinical mastitis was systematically noted. A subset of 40 goats (20 from each line) was subsequently challenged with Haemonchus contortus and monitored for anemia (blood packed cell volume) and fecal egg counts to see if SCS-based selection had an indirect effect on resistance to gastrointestinal nematodes. Milk production traits, including milk quantity, fat content, and protein content, were similar in both goat lines. In contrast, the raw milk SCC almost doubled between the lines, with 1,542,000 versus 855,000 cells/mL in the high- and low-SCS lines, respectively. The difference in breeding value for SCS between lines was 1.65 genetic standard deviation equivalents. The Staphylococcus spp. most frequently isolated from milk were S. xylosus, S. caprae, S. epidermidis, and S. aureus. The frequency of positive bacteriology samples was significantly higher in the high-SCS line (49%) than in the low-SCS line (33%). The highest odds ratio was 3.49 (95% confidence interval: 11.95-6.25) for S. aureus. The distribution of bacterial species in positive samples between lines was comparable. The average quantity of bacteria in positive samples was also significantly higher in high-SCS goats (69 ± 80 growing colonies) than in low-SCS goats (38 ± 62 growing colonies). Clinical cases were rare and equally distributed between high- (n = 4; 2.5%) and low-SCS (n = 3; 2.3%) lines. Furthermore, the larger the amounts of bacteria in milk the higher the SCS level. Conversely, goats with repeatedly culture-negative udders exhibited the lowest SCC levels, with an average of below 300,000 cells/mL. We therefore confirmed that SCS is a relevant predictor of intramammary infection and hygienic quality of milk in goats and can be used for prophylactic purposes. After challenge with H. contortus, goats were anemic with high fecal egg counts but we found no difference between the genetic lines. This result provides initial evidence that resistance to mastitis or to gastrointestinal nematodes infections is under independent genetic regulation. Altogether, this monitoring of the goat lines indicated that SCS-based selection helps to improve udder health by decreasing milk cell counts and reducing the incidence of infection and related bacterial shedding in milk. Selection for low SCC should not affect a goat's ability to cope with gastrointestinal nematodes.

Somatic Cell Counts Affecting the Casein Fractions of Pasteurized Semi-Skimmed Milk during Storage

Mastitis is generally recognized as an important factor that influences the quality of milk and dairy products. Milk from infected cows is characterized by increased Somatic Cell Counts (SCC) associated with changes in the components and properties of raw milk. The aim of this study was to evaluate the effects of SCC in raw milk on the casein fractions of semi-skimmed pasteurized milk during storage. Raw milk were categorized in SCC groups of low ( 75×104 cells∙mL-1). Four replicates of semiskimmed (1.3-1.4%) pasteurized milk within each SCC category were analyzed for composition, pH, titratable acidity and casein fractions by high performance liquid chromatography after 1, 7, 14, 21 and 28 days of storage. No effect of SCC was observed on the physical-chemical parameters and concentrations of αs-casein, β-casein and κ-casein in pasteurized milk during storage at 5oC. However, chromatograms of milk samples containing high SCC (>75×104 cells∙mL-1) showed increased breakdown products of αs1-casein starting on the seventh day of storage. Results of this trial indicate that SCC in raw milk should not exceed 4x105 cells∙mL-1, to prevent the degradation of casein fractions in pasteurized semi-skimmed milk and the occurrence of quality defects during storage.

Bacteriological Quality of Raw Milk Used for Production of a Brazilian Farmstead Raw Milk Cheese

The objective of this study was to evaluate the bacteriological quality of raw cow's milk utilized for the production of Traditional Minas Serro cheese, a Brazilian farmstead raw milk cheese. Raw milk samples were collected from six farmstead cheese operations manufacturing raw milk cheese from cow's milk. Coliform count (CC) and Escherichia coli counts were determined using Petrifilm™ EC plates, and Staphylococcus aureus counts were determined using Petrifilm™ Staph Express count plates. The standard plate count (SPC) was determined using plate count agar. The somatic cell count (SCC) was determined with a DeLaval cell counter. The detection of Listeria monocytogenes was based in the ISO 11290-1 protocol. A total of 165 samples were analyzed, and the SPC was 1.85-7.88 log CFU/mL. Coliform were detected in 140 (84.8%) of the 165 samples, with counts of 1-6.39 log CFU/mL. E. coli was detected in 17 (10.3%) samples, with counts of 1-2.18 log CFU/mL. The SCC in raw milk was 10,000-1,390,000 cells per mL, with mean and geometric mean values of 247,000 and 162,181, respectively. The SCC did not differ significantly between the seasons (p>0.05), but differed between different farms (p<0.05). None of the 155 samples were positive for the presence of Listeria monocytogenes. S. aureus was isolated in 145 (94.1%) of the 154 samples, and the count was 1.47-5.03 log CFU/mL. The median of SPC, CC, and S. aureus counts differed significantly between seasons and between farms (p<0.05). Our results indicate that raw milk for production of farmstead raw milk cheese has a low incidence of L. monocytogenes and a high incidence of S. aureus, and suggest that measurements (such as SCC or SPC) may not serve as a predictor of other bacterial (including pathogenic) presence.

Atividade de plasmina e plasminogênio no leite longa vida com alta e baixa contagem de células somáticas durante o armazenamento

O objetivo deste estudo foi avaliar o efeito da contagem de células somáticas (CCS) do leite na atividade de plasmina e plasminogênio durante o período de armazenamento do leite longa vida integral. Os leites crus foram categorizados em grupos de CCS de baixa (342.000-487.000 células mL-1) e alta contagem (603.000-808.000 células mL-1). Dois lotes de leite longa vida em cada categoria de CCS foram analisados para determinação de plasmina e plasminogênio após 10, 30, 60, 90 e 120 dias de armazenamento em temperatura ambiente. Para a fabricação do leite longa vida, o leite cru foi submetido à pasteurização rápida seguida da esterilização industrial do leite por injeção de vapor pelo método direto e embalagem asséptica do produto. A CCS não apresentou efeitos sobre as características físico-químicas do leite cru, e nem sobre a atividade de plasmina e plasminogênio nos leites cru e longa vida, armazenados por 120 dias. Entretanto, independentemente da CCS, a atividade de plasmina e plasminogênio aumentou no leite longa vida ao longo do armazenamento, indicando a possibilidade de aumento da proteólise no produto durante sua vida de prateleira.

Transmission Electron Microscopy Study of Casein Micelle in Raw Milk with Different Somatic Cell Count Levels

The relationship between elevated raw milk somatic cell count (SCC) and casein micelle dimension was investigated by transmission electron microscopy (TEM). Milk samples collected from the dairy cattle with three different levels of SCC (<200,000, 200,000 to 800,000, and >800,000 cells/ml) were studied by TEM. The results indicated that an increase in SCC resulted in a decrease in the casein micelle size with an increase in their aggregation. The present research supported the hypothesis that elevated proteolytic activity, reduced secretary ability of the mammary glands, lower electrostatic and steric repulsion as well as different mineral contents of mastitic milk could affect casein micelle properties.

Validation Study of a Receptor-Based Lateral Flow Assay for Detection of Beta-Lactam Antibiotics in Milk

A validation study designed to meet the requirements of the AOAC Research Institute and the U.S. Food and Drug Administration (FDA), Center for Veterinary Medicine, was conducted for a receptor-based, immunochromatographic method (BetaStar US) for detection of beta-lactam antibiotic residues in raw, commingled bovine milk. The assay was found to detect amoxicillin, ampicillin, cephapirin, cloxacillin, and penicillin G at levels below the FDA tolerance/safe levels but above the maximum sensitivity thresholds established by the National Conference on Interstate Milk Shipments. Results of the Part I (internal) and Part II (independent laboratory) dose-response studies using spiked samples were in very close agreement for all five drugs tested, with differences between the Part I and Part II 90/95% sensitivity values ranging from 0 to 1 ppb. The test was able to detect all five drugs at the approximate 90/95% sensitivity levels when present as incurred residues in milk collected from cows that had been treated with the specific drug. A sixth drug, ceftiofur, was found to be undetectable at levels of < or = 500 ppb (as total ceftiofur metabolites from incurred residues in milk samples). The selectivity of the assay was 100%, because no false-positive results were obtained in tests of >1000 control milk samples. The assay was found to be applicable to the testing of frozen raw milk samples. Results of ruggedness experiments established the operating parameter tolerances for the BetaStar US assay. Results of cross-reactivity testing established that the assay detects certain other beta-lactam drugs (dicloxacillin and ticarcillin), but it does not cross-react with any of 30 drugs belonging to other classes. Abnormally high bacterial or somatic cell counts in raw milk produced no interference with the ability of the test to detect beta-lactams at tolerance/safe levels.

Microbial and Sensory Changes Throughout the Ripening of Prato Cheese Made from Milk with Different Levels of Somatic Cells

The objective of this research was to evaluate the effects of 2 levels of raw milk somatic cell count (SCC) on the composition of Prato cheese and on the microbiological and sensory changes of Prato cheese throughout ripening. Two groups of dairy cows were selected to obtain low-SCC (<200,000 cells/mL) and high-SCC (>700,000 cells/mL) milks, which were used to manufacture 2 vats of cheese. The pasteurized milk was evaluated according to the pH, total solids, fat, total protein, lactose, standard plate count, coliforms at 45°C, and Salmonella spp. The cheese composition was evaluated 2 d after manufacture. Lactic acid bacteria, psychrotrophic bacteria, and yeast and mold counts were carried out after 3, 9, 16, 32, and 51 d of storage. Salmonella spp., Listeria monocytogenes, and coagulase-positive Staphylococcus counts were carried out after 3, 32, and 51 d of storage. A 2×5 factorial design with 4 replications was performed. Sensory evaluation of the cheeses from low- and high-SCC milks was carried out for overall acceptance by using a 9-point hedonic scale after 8, 22, 35, 50, and 63 d of storage. The somatic cell levels used did not affect the total protein and salt:moisture contents of the cheeses. The pH and moisture content were higher and the clotting time was longer for cheeses from high-SCC milk. Both cheeses presented the absence of Salmonella spp. and L. monocytogenes, and the coagulase-positive Staphylococcus count was below 1×102 cfu/g throughout the storage time. The lactic acid bacteria count decreased significantly during the storage time for the cheeses from both low- and high-SCC milks, but at a faster rate for the cheese from high-SCC milk. Cheeses from high-SCC milk presented lower psychrotrophic bacteria counts and higher yeast and mold counts than cheeses from low-SCC milk. Cheeses from low-SCC milk showed better overall acceptance by the consumers. The lower overall acceptance of the cheeses from high-SCC milk may be associated with texture and flavor defects, probably caused by the higher proteolysis of these cheeses.

Casein fractions of ultra high temperature milk with different somatic cell counts

The objective of this work was to evaluate the effect of somatic cell counts (SCC) in casein fractions of ultra high temperature (UHT) milk. Raw milks were categorized in SCC groups of low (200,000-320,000 cells mL-1), intermediate (380,000-560,000 cells mL-1) and high cells (600,000-800,000 cells mL-1). Five replicates of UHT milks within each SCC category were analyzed for casein fractions after 8, 30, 60, 90 and 120 days of storage through high performance liquid chromatography. SCC showed effect only on beta-casein reduction. SCC in raw milk increases the proteolysis of UHT milk, as a consequence of beta-casein degradation.

Application of a New Portable Microscopic Somatic Cell Counter with Disposable Plastic Chip for Milk Analysis

The somatic cell count (SCC) is one of the international standards for monitoring milk quality, and it is a useful indicator of mastitis. The current reference method for determining the SCC in raw milk is direct microscopic analysis, but this method requires well-trained staff to maintain its accuracy and reproducibility. To overcome these inconveniences, we developed a portable system (the C-reader system) that utilizes the capillary flow of a microfluidic chamber by surface modification of the hydrophilicity. The microfluidic technology of disposable microchips allows for low consumption of reagents, and a combination of ready-to-use reagents makes the daily work easier. The repeatability test of the C-reader using 10 composite bovine milk samples satisfied the recommended values for SCC equipment. In addition, an acceptable accuracy level of the natural logarithmic-transformed SCC [ln(SCC/1,000):±0.059 to 0.112] was achieved using composite raw milk samples and various somatic cell standard solutions from the American Eastern Laboratory and the Korean National Veterinary Research and Quarantine Service. After testing 875 composite milk samples, the C-reader showed a high correlation coefficient (R2=0.935 to 0.964) and a low mean difference value in log-transformed SCC (−0.088 to 0.004) compared with 3 automatic commercialized somatic cell counters (Fossomatic 4000, Somacount 150, and Somascope). In conclusion, the C-reader system is a new, easy-to-use automatic on-farm method with acceptable repeatability and accuracy for measuring SCC in large dairies and smaller laboratories.

Effect of Somatic Cell Count on Proteolysis and Lipolysis in Pasteurized Fluid Milk During Shelf-Life Storage

The general goal of this research was to provide fluid milk processors with data to enable them to estimate the economic benefits they might derive from longer fluid milk shelf-life or new marketing opportunities due to a reduction in raw milk SCC. The study objectives were: 1) to measure the time in days for pasteurized homogenized 2% milk to achieve a level of lipolysis and proteolysis caused by native milk enzymes present in milks of different somatic cell count (SCC) at 0.5 and 6°C that would be sufficient to produce an off-flavor, 2) to determine whether milk fat content (i.e., 1, 2, and 3.25%) influences the level of proteolysis or lipolysis caused by native milk enzymes at 6°C, and 3) to determine the time in days for milks containing 2% fat with different SCC to undergo sufficient lipolysis or proteolysis to produce an off-flavor due to the combination of the action of native milk enzymes and microbial growth at 0.5 and 6°C. In experiment 1, pasteurized, homogenized milks, containing 2% fat were prepared from raw milk containing four different SCC levels from <100,000 to >1,000,000 cells/ml. Each of the four milks was stored at 0.5 and 6°C for 61 d. In experiment 2, pasteurized, homogenized milks containing 1, 2, and 3.25% fat were prepared starting from two raw milks containing two different SCC levels, one <100,000 and the other >1,000,000 cells/ml. In experiment 3, pasteurized, homogenized 2% fat milks were prepared starting from raw milks containing two different SCC levels, one <100,000 and the other >1,000,000 cells/ml. For experiments 1 and 2, all milks were preserved with potassium dichromate to prevent microbial growth but to allow the activity of native milk proteases and lipases during storage. For experiment 3, one set of milk was preserved with potassium dichromate to prevent microbial growth but to allow the activity of native milk proteases and lipases, and a second set of milk was unpreserved during storage at 0.5 and 6°C for 29 d. Based on previous work, an off-flavor due to proteolysis was detected by 50% of panelists when the decrease in casein as a percentage of true protein (CN/TP) was>4.76%. Our data indicated (assuming 50% of consumers would detect an off-flavor when CN/TP decreases 5%) that pasteurized milk containing 2% fat would develop an off-flavor at a time long after 61 and at 54 d for the low SCC milk, and at about 54 and 19 d for the high SCC milk, at 0.5 and 6°C, respectively. Previous research reported that 34% of panelists could detect an off-flavor in milk containing 2% fat due to lipolysis at a (free fatty acid) FFA concentration of 0.25 meq/kg of milk. Based on these results, it was estimated in the present study that 34% of panelists would detect an off-flavor in a 2% fat pasteurized milk with low SCC at a time long after 61 and just after 61 d at 0.5 and 6°C, respectively, while for milk with high SCC, an off-flavor would be detected by 34% of panelists at slightly longer than 61 and 35 d at 0.5 and 6°C, respectively. The combination of low SCC milk and low storage temperature when coupled with processing technology to produce very low initial bacteria count in fluid milk could produce fluid milk that will maintain flavor quality for more than 61 d of storage at temperatures<6°C.

Calibration of somatic cell count in milk based on near-infrared spectroscopy

A PLS model for prediction of somatic cell count (SCC) based on near-infrared (NIR) spectra of unhomogenized milk is presented in the study. Samples of raw milk were collected from cows in the early lactation period (from 7th to 29th day after parturition). The NIR spectra were measured in the region 400–1100 nm. As reference method a fluoro-opto-electronic method was applied. Different preprocessing methods were investigated. The robust version of PLS regression was applied to handle outliers present in the dataset and the uninformative variable elimination–partial least squares (UVE–PLS) method was used to eliminate uninformative variables. The final model is acceptable for prediction of SCC in raw milk.