Temperature effects on Fossomatic cell counts in goats milk

In cows milk, analytical temperature has been identified as one of the possible factors affecting the somatic cell count (SCC). To establish the effect of the temperature used for SCC in goats milk, counts were performed on 45 goats milk samples using the Fossomatic counter. Tests were performed at two temperatures (40° and 60 °C) on preservative-free samples 3 h after collection, and on samples preserved with bronopol (BR) at 3 h, 1, 2, 3, and 4 d post-collection. The test temperature did not modify the SCC of the milk samples analyzed. Incubating samples 3 h post-collection at 60 °C failed to improve the SCC results. Similar counts were obtained for BR-preserved samples stored for 1–4 d at refrigeration temperature, suggesting the possibility of performing Fossomatic SCC in goats milk samples stored for this length of time.     

牛乳体细胞数与稳定性关系的研究

对某牧场30头荷斯坦奶牛的200个奶样进行体细胞数、酒精稳定性和热稳定性的测定。结果表明,所采样本的平均体细胞数为87×104cfu/mL,标准差为147×104cfu/mL,不服从正态分布;随着牛乳体细胞数升高,酒精稳定性随之降低;不同的体细胞组间,牛乳热稳定性随着SCC的升高而降低,组间有极显著差异(P<0.001)。     

Population dynamics of bulk milk somatic cell counts

The population dynamics for bulk milk SCC in 27,000 Dutch dairy farms was studied over 6 yr; SCC declined markedly in 1984 and 1985. This coincided with the introduction of the quota system in the European Community. The CV of SCC was .36, ranging from .15 to .89. Month of year had a significant effect on SCC with the highest SCC in October and the lowest in April. The dynamics of the annual SCC were modeled with a state transition model. Farmers managing herds with a fairly low SCC (less than 450,000) had a reasonable chance to remain in these states. Herds with a higher annual SCC were much more variable. The model simulated, the potential reactions of the farmers to the decrease of the SCC limit from 750,000 to 500,000 starting January 1, 1989. The simulations showed a further decrease in mean annual SCC, although the number of farms in the category with a very low SCC (less than 150,000) is not likely to increase. In all simulations an increased number of farmers will receive a penalty due to the more strict regulations of the European Community.     

牛乳体细胞数与乳蛋白含量相关性的研究

对呼和浩特郊区一牧场30头荷斯坦乳牛进行6个月单个采样，共得427个有效样本，检测乳样中体细胞数、酪蛋白（包括α-酪蛋白、β-酪蛋白、κ-酪蛋白）、乳清蛋白、总蛋白、游离氨基氮、酪蛋白／总蛋白和乳清蛋白／总蛋白。结果表明，乳中总蛋白、游离氨基氮含量及乳清蛋白／总蛋白与SCC呈显著正相关；酪蛋白／总蛋白与SCC呈显著负相关；乳清蛋白含量与SCC呈极显著正相关。酪蛋白、α-酪蛋白／酪蛋白、β-酪蛋白／酪蛋白、κ-酪蛋白／酪蛋白与SCC的相关性不显著。酪蛋白含量与总蛋白含量呈极显著的正相关，与游离氨基氮含量、乳清蛋白／总蛋白呈极显著的负相关。乳清蛋白含量与游离氨基氮、总蛋白含量呈极显著正相关。     

Improved bioluminescent assay of somatic cell counts in raw milk

Somatic cell count (SCC) in milk is considered to be a valuable indicator of cow mastitis. For assessment of SCC in milk, the bioluminescent assay based on determination of ATP from somatic cells ([ATPsom]) in milk was proposed earlier. However, this assay is still not widely used in practice owing to lower reliability compared with conventional methods such as direct microscopy and flow cytometry. We revised the bioluminescent SCC assay and developed a simple protocol based on determination of the total non-bacterial ATP concentration in milk. It was shown that the novel ATP-releasing agent Neonol-10 (oxy-ethylated iso-nonyl phenol) has superior performance providing 100% lysis of somatic cells while not disrupting bacterial cells of milk at a concentration of 1.5% w/w. There was high correlation (R2=0.99) between measured bioluminescence and SCC as measured by direct microscopy. The observed detection limit of the bioluminescent milk SCC assay was as low as 900 cell/ml, time of analysis was 2-3 min per sample. The proposed method has high potential for on-site mastitis diagnostics.     

Guidelines for monitoring bulk tank milk somatic cell and bacterial counts

This study was conducted to establish guidelines for monitoring bulk tank milk somatic cell count and bacterial counts, and to understand the relationship between different bacterial groups that occur in bulk tank milk. One hundred twenty-six dairy farms in 14 counties of Pennsylvania participated, each providing one bulk tank milk sample every 15 d for 2 mo. The 4 bulk tank milk samples from each farm were examined for bulk tank somatic cell count and bacterial counts including standard plate count, preliminary incubation count, laboratory pasteurization count, coagulase-negative staphylococcal count, environmental streptococcal count, coliform count, and gram-negative noncoliform count. The milk samples were also examined for presence of Staphylococcus aureus, Streptococcus agalactiae, and Mycoplasma. The bacterial counts of 4 bulk tank milk samples examined over an 8-wk period were averaged and expressed as mean bacterial count per milliliter. The study revealed that an increase in the frequency of isolation of Staphylococcus aureus and Streptococcus agalactiae was significantly associated with an increased bulk tank somatic cell count. Paired correlation analysis showed that there was low correlation between different bacterial counts. Bulk tank milk with low (<5000 cfu/mL) standard plate count also had a significantly low level of mean bulk tank somatic cell count (<200,000 cells/mL), preliminary incubation count (<10,000 cfu/mL), laboratory pasteurization count (<100 cfu/mL), coagulase-negative staphylococci and environmental streptococcal counts (<500 cfu/mL), and noncoliform count (<200 cfu/mL). Coliform count was less likely to be associated with somatic cell or other bacterial counts. Herd size and farm management practices had considerable influence on somatic cell and bacterial counts in bulk tank milk. Dairy herds that used automatic milking detachers, sand as bedding material, dip cups for teat dipping instead of spraying, and practiced pre-and postdipping had significantly lower bulk tank somatic cell and/or bacterial counts. In conclusion, categorized bulk tank somatic cell and bacterial counts could serve as indicators and facilitate monitoring of herd udder health and milk quality.     

Evidence of calmodulin in bovine milk with high somatic cell counts

The objective was to determine whether calmodulin was present in bovine milk with high SCC. A highly specific antibody against calmodulin was developed in rabbits and affinity purified. Enzyme-linked immunoassays were used to determine the presence of calmodulin in the whey and casein fractions in milks with SCC ranging from less than 50,000 to greater than 1,000,000. Percentages of total protein and casein were determined. Calmodulin was detected in some casein fractions regardless of level of SCC. In the whey fraction, calmodulin was positively correlated with increased SCC. Calmodulin may be released into the milk as a result of the elevated proteolytic activity, which is evident in mastitis or as a result of leakage from the serum. This provides further information on the cellular and biochemical changes that occur in the diseased udder. Total protein increased with the increase in SCC while there was an inverse relationship of SCC to the percent casein.     

原料乳中体细胞数与UHT乳中酪蛋白成分的关系研究

研究了原料乳中体细胞数与15批次UHT乳样本中酪蛋白成分之间的关系。将原料乳巴氏杀菌后进行超高温处理。分别于8,30,60,90和120 d采集贮藏于室温条件下的UHT乳样本,并使用高效液相色谱法对酪蛋白成分进行分析。体细胞数范围1.97×105～8×105 mL-1。体细胞数与原料乳或UHT乳中的κ-酪蛋白质量浓度之间没有相关性(P<0.05)。原料乳中αs2-酪蛋白和β-酪蛋白与体细胞数呈负相关(P<0.05)。UHT乳中,αs1-酪蛋白(P<0.05)和β-酪蛋白(P<0.05)与体细胞数在贮藏第8天呈负相关,αs2-(P<0.01)与体细胞数在贮藏第60天呈负相关。结果表明,原料乳中体细胞数较高与β-酪蛋白和αs-酪蛋白的大量水解有关,并且可能导致UHT乳在贮藏期内出现质量问题。     

Effect of freezing on Fossomatic cell counting in ewe milk

Using the Fossomatic method, a total of 10,072 analytical somatic cell count (SCC) observations were carried out on 4760 aliquots taken from 70 individual ewe milk samples with the objective of studying whether freezing showed significant differences of SCC in comparison with refrigeration, according to different analytical conditions. These conditions were four preservation procedures (without preservation, potassium dichromate, azidiol, and bronopol), two storage temperatures (refrigeration and freezing), five milk ages within storage (24 h postcollection in refrigeration, and 24 h, 15, 30, and 60 d postcollection in freezing), two thawing types (rapid and slow), and two analytical temperatures (40 and 60 degrees C). Preservation, storage, and analytical temperature, type of thawing and milk age within storage, and most of the interactions showed a significant effect on the SCC variation. On average, the SCC was lower after freezing than in refrigeration. This effect depended specifically on type of preservation and analytical temperature of milk. The SCC of milk unpreserved or preserved with bronopol or potassium dichromate, and analyzed at 40 degrees C, was not affected by freezing; however, use of azidiol as a preservative before freezing, and heating the milk to 60 degrees C following thawing resulted in significantly decreased SCC. Milk age had little quantitative influence on SCC of thawed milk. The type of thawing (rapid and slow) did not significantly influence SCC of milk analyzed at 40 degrees C. As a result, when using properly handled samples, the Fossomatic method could be used to enumerate SCC in samples frozen over the 60 d.     

Relationships between milk culture results and composite milk somatic cell counts in Norwegian dairy cattle

Associations between test-day composite milk somatic cell counts (CMSCC) and results from quarter milk cultures for various pathogens associated with mastitis, including Staphylococcus aureus, Streptococcus spp., coagulase-negative staphylococci (CNS), were investigated. S. aureus was dichotomized according to sparse (≤1,500 colony forming units/mL of milk) or rich (>1,500 colony forming units/mL of milk) growth of the bacteria. Quarter milk samples were obtained on between 1 and 4 occasions from 2,714 cows in 354 Norwegian dairy herds, resulting in a total of 3,396 samples. Cows included in the study were randomly selected, without regard to current or previous udder health status. Measures of test-day CMSCC were obtained every second month, and related to 3528 microbiological diagnoses at the cow level. Mixed linear regression models incorporating a compound symmetry covariance structure accounting for repeated test-day CMSCC within cow, and a random effect variable on herd level, was used to quantify the relationship between a positive milk culture and the natural logarithm of test-day CMSCC (LnCMSCC). The material was stratified in time periods before 151 d in milk (DIM) and after 150 DIM. A positive diagnosis for any category of mastitis pathogen was significantly associated with elevated CMSCC. Pathogen positive cows sampled for microbiological diagnosis during the first 150 DIM had higher levels of CMSCC throughout lactation than cows with a positive diagnosis after 150 DIM. Streptococcus spp.-positive milk cultures were associated with steadily elevated values for CMSCC throughout lactation both when sampled before and after 150 DIM. Cows diagnosed with rich growth of S. aureus after 150 DIM experienced a characteristic and sharp increase in CMSCC, but this effect was not observed in cows with a positive diagnosis for rich growth of S. aureus during the first 150 DIM. A considerable increase in CMSCC in cows positive for CNS during the first part of the lactation period was also observed. The practicability of using CMSCC in a diagnostic test to identify cows with a positive milk culture for mastitis pathogens was also assessed. The sensitivity, specificity, and positive predictive values of the tests were regarded as low when sampling for milk culture was conducted, irrespective of cow level characteristics.     

Bacterial cell counts in goat milk and their correlations with somatic cell counts, percent fat, and protein

Representative milk samples at morning and afternoon milking were collected periodically for 5 mo from 32 does in a Prairie View A&M University milking herd to test the concentrations of total bacterial, coliform, and staphylococcus counts and to determine the correlations among the bacterial cell counts, somatic cell counts, percent fat, and percent protein. Bacterial cell counts were assayed by microbiogical methods using different nutrient media for the three cell types. Somatic cell counts were determined by an automated fluorescent microscopic somatic cell counter. Percent fat and protein were analyzed by an automated dual beam infrared absorption analyzer. Mean counts for total bacterial, coliform, staphylococcus, and somatic cell were 2.54 X 10(4), .966 X 10(3), 3.32 X 10(3), and 9.08 X 10(5) cells/ml, respectively. The Nubian goats had higher counts in all three bacterial cell types than the Alpines, and the difference in staphylococcus counts between breeds was significant (P less than .05). However, Alpine milk contained slightly higher somatic cell counts than the Nubians. None of the correlation coefficients (r) between somatic cell and bacterial cell counts was significant for the pooled data from the two breeds, but r between staphylococcus and somatic cell counts for Alpine breed was significant (P less than .05). The r between somatic cell counts and percent fat or protein were significant (P less than .01) for combined or separated breed data. Bacterial cell counts could not explain high somatic cell counts in the goat milk with the present testing standards of cow milk.     

Hard ewe's milk cheese manufactured from milk of three different groups of somatic cell counts

As ovine milk production increases in the United States, somatic cell count (SCC) is increasingly used in routine ovine milk testing procedures as an indicator of flock health. Ovine milk was collected from 72 East Friesian-crossbred ewes that were machine milked twice daily. The milk was segregated and categorized into three different SCC groups: < 100,000 (group I); 100,000 to 1,000,000 (group II); and > 1,000,000 cells/ ml (group III). Milk was stored frozen at -19 degrees C for 4 mo. Milk was then thawed at 7 degrees C over a 3-d period before pasteurization and cheese making. Casein (CN) content and CN-to-true protein ratio decreased with increasing SCC group 3.99, 3.97, to 3.72% CN, and 81.43, 79.72, and 79.32% CN to true protein ratio, respectively. Milk fat varied from 5.49, 5.67, and 4.86% in groups I, II, and III, respectively. Hard ewe's milk cheese was made from each of the three different SCC groups using a Manchego cheese manufacturing protocol. As the level of SCC increased, the time required for visual flocculation increased, and it took longer to reach the desired firmness for cutting the coagulum. The fat and moisture contents were lower in the highest SCC cheeses. After 3 mo, total free fatty acids (FFA) contents were significantly higher in the highest SCC cheeses. Butyric and caprylic acids levels were significantly higher in group III cheeses at all stages of ripening. Cheese graders noted rancid or lipase flavor in the highest SCC level cheeses at each of the sampling points, and they also deducted points for more body and textural defects in these cheeses at 6 and 9 mo.     

Relationship of milk proteins in blood with somatic cell counts in milk of dairy cows

Intramammary leucocytosis was induced by injection of Escherichia coli endotoxin via the teat canal in three lactating Holstein cows. Concentrations of alpha-lactalbumin and casein in blood serum were measured, and somatic cell concentration and yield and composition of milk were determined. Endotoxin injection elicited mean increases of 100-fold in somatic cell concentration and 50% in protein concentration, whereas milk yield declined 5-fold and lactose concentration was halved. Concentrations of alpha-lactalbumin and casein in blood rose from 80 to 1909 and 0 to 1231 ng/ml, respectively. By 96 h postinjection, all variables were approximately equal to those preinjection. In a second study, concentration of alpha-lactalbumin was determined in blood of lactating cows in two herds (n = 332) and related to milk somatic cell count. Concentrations of alpha-lactalbumin in blood were correlated with somatic cell counts (r = .60). Mean concentrations of alpha-lactalbumin increased with increasing cell count even at low somatic cell concentrations (25 to 250 X 10(3)). Concentrations of milk proteins in blood serum apparently reflect competency of the blood-milk barrier and may therefore yield an indirect measure of udder health.     

Factors affecting somatic cell counts and their relations with milk and milk constituent yield in buffaloes

Data concerning daily milk yield (MY), percentage of milk fat (%F), protein (%P), lactose (%LT), and total solids (%TS), and somatic cell counts (SCC) for a herd of 222 Murrah buffalo reared in the state of S?o Paulo, Brazil, were collected monthly from 1997 to 2000 in order to study the factors affecting SCC and their relation to milk production and constituents during lactation. SCC decreased in the second month of lactation and increased thereafter, up to the ninth month of lactation. The interaction of month of lactation x order of calving was significant. Mean MY observed during the first month of lactation was 6.87 kg, which increased to 7.65 kg during the second month, and then decreased until the ninth month of lactation (3.83 kg). During the different months of lactation, %F, %P, %LT, and %TS ranged from 6.28 to 8.38%, 4.05 to 4.59%, 4.96 to 5.34%, and 16.94 to 18.55%, respectively. Calving year, calving order, and order of month of lactation significantly affected MY, %F, %P, %LT, and %TS. The regression coefficients of transformed SCC on MY and %LT were negative and significant during all months of lactation, showing that milk and lactose yield decreased with increased transformed SCC, causing losses to buffalo milk producers.     

Proteolysis and texture of hard ewes' milk cheese during ripening as affected by somatic cell counts

Ewes' milk samples with low (<500,000 ml(-1)), medium (1,000,000-1,500,000 ml(-1)) and high (> 2,500,000 ml(-1)) somatic cell counts (SCC) were used to manufacture hard ewes' cheese using the Zamorano cheese manufacturing protocol. Cheeses that had been ripened for 1, 2 and 3 months were used to obtain isoelectric ovine casein that was analysed by capillary electrophoresis. The texture of the cheeses during ripening was determined instrumentally using the Warner-Bratzler maximum shear force and assessed for sensory qualities by consumers using hedonic tests. The study revealed that the pH value and the lactose content of the milk were affected by high SCC and that the coagulation properties were dependent on the somatic cell content. The protein and moisture contents of the cheeses were unaffected by SCC but a significant increase of pH with ripening time were observed in high-SCC cheeses. The results also pointed to a significant increase in proteolysis related to SCC levels, showing that intact casein, both alphas1 and beta-casein, decreased as the SCC of milk increased, and that the proteolytic fragments, mainly I-alphas1, increased with SCC levels. Significant differences in texture were found among the samples, the cheeses made with high levels of SCC being significantly less compact at each ripening time. The differences in texture were detected by the consumers, who reported defects in cheeses made with high levels of SCC. Indeed, high SCC cheeses were significantly less well accepted.     

Herd composite somatic cell counts: average linear score and weighted average somatic cell count score and milk production

The relationship between herd production weighted average somatic cell count (average of somatic cell count weighted by individual cow milk production) and average linear score (average of individual cow linear score somatic cell counts) was investigated using three models. The model with the highest R2 was log weighted average somatic cell count versus average linear score. Use of the regression model results to convert an average linear score to weighted average somatic cell count results in a bulk tank somatic cell count approximately twice that of conversion of a linear score somatic cell count when done on an individual cow basis. Rolling herd average milk decreased 190 kg as average linear score increased by 1.     

Bulk milk somatic cell counts are related to bulk milk total bacterial counts and several herd-level risk factors in dairy goats

The aim of this study was to describe the temporal variation in bulk milk somatic cell count (BMSCC) on Dutch dairy goat farms and to assess the correlation of BMSCC with bulk milk total bacterial counts (BMTBC) and with several herd management factors. Bulk milk somatic cell count and BMTBC data were recorded from 90% of the dairy goat farms in the Netherlands over the years 2005 to 2007. Farm characteristics and management information was collected by means of questionnaires. The bulk milk data and the questionnaire data were linked and linear mixed models were used to identify risk factors for increased BMSCC and BMTBC. Bulk milk somatic cell count was found to display a distinct pattern throughout the year, being highest around December and lowest around June. Bulk milk somatic cell count correlated to BMTBC (r = 0.4). Significant factors in the BMSCC model were month in lactation, treating mastitic animals instead of culling, caprine arthritis encephalitis status, milk fever prevalence, and liner material. Month in lactation and treating mastitic animals instead of culling were also significant in the BMTBC model. In the high-BMSCC period, a higher number of goats with an extended lactation significantly reduced the BMSCC. Thus, this study indicates that mastitis-related factors account for some of the variation in BMSCC and BMTBC levels between dairy goat herds. It shows that intramammary infection is probably the most important factor driving the correlation between BMSCC and BMTBC, suggesting that programs to improve udder health may have a positive effect on both BMSCC and BMTBC.     

Factors related to milk loss in quarters with low somatic cell counts

Relationship between milk production and milk composition was studied through comparisons of udder halves within cow. Cows were milked by milking unit for separate quarters of udder. Six trials had six cows per trial. Trial length was 3 d, and milkings were at 12-h intervals. Foremilk samples were taken aseptically for bacterial analysis. Milk weights by quarter were recorded, and samples by quarter were analyzed for concentrations of lactose, somatic cells, and chloride. Milk cell differential counts and N-acetyl-B-D-glucosaminidase activity also were determined. Eighty-four percent of quarter milk samples contained less than 400,000 cells/ml. Differences between right and left udder halves with respect to all measurements were computed. For halves of udders within-cow correlation coefficients for differences between production and log(base 2) somatic cell count, lactose, chloride, bacterial presence, neutrophil percent, lymphocyte percent, macrophage percent, and N-acetyl-B-D-glucosaminidase activity were -.16, .23, -.31, .09, .12, .01, -.14, and -.41. Regression coefficients of milk production (kg) on somatic cell count log(base 2) cells per milliliter, lactose (%), chloride (mg/100 ml), and N-acetyl-B-D-glucosaminidase (nmol/min per ml) were -.12, .57, -.05, and -.46. From negative correlations between production and concentrations of chloride, somatic cells, and N-acetyl-B-D-glucosaminidase activity, differences between udder halves in production may be related to changes of the blood-milk barrier, leukocyte diapedesis, and loss of integrity of secretory cells.     

原料乳体细胞数及总蛋白、非蛋白氮、尿素氮含量间相关性的研究

对乳牛随机采样，共采样16次，得到530个有效乳样；检测乳样中体细胞数（SCC）、总蛋白、非蛋白（NPN）、尿素氮（MUN）含量。结果表明，SCC与总蛋白含量间呈极显著的正相关；SCC与尿素氮含量间呈极显著的负相关；SCC与非蛋白氮含量间相关性不显著；总蛋白含量与NPN含量间呈极显著正相关；NPN与MUN含量间呈极显著的正相关。按月份分组，各组SCC及总蛋白、非蛋白氮、尿素氮含量之间均有极显著差异（均为P〈0．001）。