Preliminary Incubation Count Research Articles

The Association between Socioeconomic Profiles, Attitudes, and Knowledge of Dairy Farmers Regarding Somatic Cell Count and Milk Quality.

The primary objective of this study was to investigate the association between the bulk tank somatic cell count (SCC) and dairy farmers' knowledge about milk quality, mastitis control, and their socioeconomic characteristics. Additionally, we estimated the association between the bulk tank SCC and bulk tank milk hygienic quality in dairy herds. Bulk tank milk samples from 120 dairy herds enrolled in the milk quality payment program were collected for the determination of the SCC, the total bacterial count (TBC), the preliminary incubation count (PIC), the laboratory pasteurization count (PC), and the coliform count (CC). Based on the bulk tank SCC results, 63 herds were selected and categorized into three groups: (a) low SCC: ≤250,000 cells/mL (n = 16); (b) medium SCC: >250,000 ≤ 400,000 cells/mL (n = 24); and (c) high SCC: >400,000 cells/mL (n = 23). Socioeconomic profiles, attitudes, and knowledge of somatic cell count and milk quality were assessed using previously tested questionnaires, which were used to interview the herd managers of the 63 selected dairy herds. Among the findings, 87.0% of the dairy herds had an SCC < 400 × 103 cells/mL, and presented milk production as the main economic activity of the farm, whereas only 47.0% of dairy herds with an SCC > 400 × 103 cells/mL had milk production as the main economic activity of the farm (p < 0.031). In a total of 95% of the selected herds (n = 60), milking machines were used, with pipeline milking machines being more predominant, accounting for 70.8% in herds with a medium somatic cell count (SCC) and 78.3% in herds with a high SCC, as opposed to herds with a low SCC at 50% (p < 0.031). The frequency of dairy producers' awareness of the maximum legal requirements for the bulk tank SCC and TBC was higher in herds with a higher SCC than in herds with a medium SCC. In conclusion, the results of this study indicate a significant association between the bulk tank somatic cell count (SCC) and dairy farmers' knowledge about milk quality, mastitis control, and socioeconomic characteristics. These findings emphasize the importance of knowledge and the socioeconomic profiles of dairy farms in maintaining and enhancing milk quality in dairy herds.

Microbiological Evaluation and Molecular Discrimination of Milk Samples from Humans and Different Animals

Milk is a highly nutritious food and it is important to be free of any pathogenic microbes that could be transmitted to humans and affect public health. A total of 145 milk samples were collected from humans and different animal species (cow, buffalo, ewe, goat, camel, mare, and donkey) and underwent physical examination (color, odor, and taste), chemical analysis for its components (water, total salt, fat, protein, lactose, and ash), and finally microbiological (bacteriological and mycological) examinations. Standard plate count, preliminary incubation count, lab pasteurized count, coliform, Escherichia coli, Staphylococcus species, Salmonella species, yeast, and mold counts were measured. PCR test was performed to differentiate milk from different sources (animals and humans) by producing a specific band for each milk type. The results of the physical examination of different kinds of milk showed different grades of white color with the characteristic odor and taste of each milk type. Chemical examination revealed that the highest water content was in donkey milk and the lowest was in buffalo milk while total solids indicated the highest content in sheep milk and the lowest in donkey milk. The microbiological analysis presented that the standard plate count results were the highest in the milk obtained from sheep and camel, while donkey milk was the least in this regard. Yeast counts were the highest in buffalo milk but cow milk was the highest in mold counts. PCR results of milk types using species-specific primers and DNA template extracted from milk somatic cells revealed a specific band for each milk type as 157, 195, 225, 242, 274, and 711 base pair (bp) for goat, human, sheep, buffalo, cattle milk, and camel milk, respectively. It was concluded that more restrictions must be applied to decrease milk contamination as high microbial counts detected in the present study can affect milk quality, public health, and the dairy industry. PCR used in the current work for milk discrimination used milk somatic cells specifically mitochondrial cytochrome b gene which exhibited high specificity in the PCR reactions and this could be served as a cheap and simple method, compared to other types of PCR.

Herd characteristics and management practices associated with bulk tank milk quality of dairy herds in southeastern Brazil.

This study identified the association of management practices and herd characteristics with milk quality of bulk tanks in southeastern, Brazil. Milk samples were collected weekly during 8weeks from 63 dairy herds. Bulk tanks were evaluated for total bacteria (TBC), preliminary incubation (PIC), pasteurization (PC), coliform (CC), and somatic cell counts (SCC). Associations found were type of milking system utilized in the farm with TBC, PIC, and SCC; the use of gloves for milking with TBC and PIC; sanitation of milking equipment prior to milking with PC and CC; strip cup testing of cows with PC; teat washing prior to milking with SCC; pre-milking teat disinfection with TBC and CC; post-dipping with TBC and SCC; and the alkaline-acid washing procedure of milking equipment with PIC and PC. The regression analysis explained the variation of bulk tank PC (- 0.47 log cfu/mL) due to the adoption of strip cup test (P = 0.036) and, by 0.366 log cfu/mL due to alkaline and acid washing of milking equipment (P = 0.036). Herringbone milking systems adopted on farms represented a change of - 0.11 log cfu/mL on the log SCC (P = 0.048). Findings may provide a guideline to prioritize efforts aimed at improving milk quality at the farm level in Brazil.

Discrepancies in Evaluating Farm Management Routines as Risk Factors of Raw Milk and Udder Hygiene in Selected Dairy Farms of Fars Province, Iran

The management practices relevant to bulk tank milk quality were studied in 29 dairy farms of Fars Province, Iran. Farm management practices were obtained by completion of a questionnaire and direct observation. Bulk milk was evaluated by performing standard plate count (SPC), preliminary incubation count (PIC), laboratory pasteurization count (LPC), coliform count (CC), somatic cell count (SCC) and detection of the contagious mastitis agents. The farms were divided into low and high SPC groups (below and above 100,000 CFU/mL) based on Iranian standards. Comparisons of the laboratory results between groups were done using two independent samples t-test. The relationships between the laboratory results were studied by Pearson’s correlation coefficients, all after logarithmic transformation. Associations of managerial risk factors (obtained by the questionnaire and one time of observation) with laboratory results were investigated using two independent samples t-test. P-values 0.05). Strong correlations were detected between SPC and PIC, SPC and CC, and PIC and CC, but many of the well explained risk factors of undesired milk quality lacked any relation with high bacterial counts of raw milk. This could be due to the small number of the studied farms, almost similar faults in the farms, wrong answers of the employees to the questions and modification of the milking practices in the presence of an inspector. Infections with Staphylococcus aureus and Mycoplasma bovis could be potential problems in the studied farms, contributing to the elevation of SCC and/or SPC levels. Veterinary interventions could not be based on the questionnaire results. Direct and frequent observations of farm routines could be recommended.

Short communication: Microbial quality of raw milk following commercial long-distance hauling

Hauling is a critical part of the commercial milk supply chain, yet very few studies have aimed to understand its effect on raw milk quality. This study focused on the effect of extended-duration tanker use during hauling on raw milk quality at a commercial facility. Standard tanker use [cleaned-in-place (CIP) once per 24h] served as a control and an incremental between-load water rinse with sanitizer treatment (RS) was evaluated to mitigate any effect from extended duration hauling. During this study, 1 commercial truck with 2 trailers was monitored for 10d. The truck collected milk at a large dairy farm, transported the milk to a manufacturing facility, and then returned to the same farm for a second load. Each round-trip journey took between 10 and 12h, allowing for 2 loads per 24-h use period. Following the second delivery, the truck was cleaned by CIP treatment starting a new treatment day. Producer samples were collected from the raw milk bulk tank on the farm before loading milk into the tanker. The same milk was sampled directly out of the tanker truck before unloading at the manufacturer. Effect on individual bacteria count, thermophilic spore count, and preliminary incubation count was quantified through common industry tests. Surface sponge swabs were also used to monitor tanker sanitation and the efficacy of cleaning treatments. Results did not identify a negative effect on raw milk quality due to extended duration hauling. Whereas the addition of RS did not provide any measurable quality benefits for the microbial milk quality, swab results demonstrated that the RS treatment was able to reduce surface bacteria in the tanker, although not to the same level as the full CIP treatment. Based on this study, current CIP practices for long distance milk hauling appear to be effective in mitigating any measurable effect on raw milk quality.

Effect of commercial hauling practices and tanker cleaning treatments on raw milk microbiological quality

Consolidation of the US milk industry has led to use of tankers for up to 24 h in between thorough cleanings. As the heavy use of tankers has not been previously studied, the effect of this form of hauling on raw milk quality is unknown. This study focused on the effect of frequent tanker use during hauling on raw milk quality at a commercial facility. Standard tanker use (cleaned-in-place once per 24 h) served as our control and incremental cleaning treatments (water rinse after each load, water rinse after each load with a sanitizer treatment after 12 h, and 12 h of sanitizer treatment) were added to the study to understand if any effect could be mitigated by more frequent cleaning. Producer samples were collected from the farm before loading milk into the tanker as well as sampling the same milk directly out of the tanker truck before unloading at the manufacturer. The study was repeated at 2 different dairy manufacturing facilities, once during the summer and once during the winter. Milk quality was quantified through industry-relevant microbiological tests: individual bacteria count, thermophilic spore count, and preliminary incubation count. Within the study we defined a negative effect on milk quality as a statistically significant difference between the tanker and producer samples in any of the 3 microbial tests conducted between treatments. Results from the study showed no clear effect due to hauling in individual bacteria count, thermophilic spore count, or preliminary incubation counts. There was also no difference in milk quality between the 2 plants, suggesting that neither season nor location affected our results in the standard use variable. As we did not see a negative effect on milk quality in the standard use variable, the addition of cleaning treatments did not appear to provide any clear benefit. Tanker surface swabs and ATP swabs were also used to monitor tanker sanitation and the efficacy of cleaning treatments. Both surface and ATP swabs revealed differences between cleaning efficacy at the 2 facilities. Although the differences in efficacy did not influence tanker milk quality within our study, variability in sanitation may provide a source of contamination that could negatively affect raw milk quality in other areas. Based on this study, current hauling practices appear to be effective in mitigating any measurable effect on raw milk quality; however, further investigation is needed before making industry-wide recommendations.

The evaluation of udder health status in Holstein dairy farms located in Qom province

BACKGROUND:Mastitis is the most economically importantdisease in dairy industry worldwide. Bulk tank milk (BTM)analysis has been suggested for monitoring the udder healthstatus at herd level. OBJECTIVES: A cross-sectional study wasconducted to evaluate udder health status in 15 Holstein dairyfarms located in Qom province. METHODS: Bulk tank somaticcell count (BTMSCC) was analyzed using opto-fluoroelectroniccounter. Standard plate count, preliminary incubationcount, laboratory pasteurized count, and the number ofenvironmental streptococci, S. agalactiae, S. dysgalactiae, S.uberis, E. coli, K. pneumoniae, coagulase negative streptococci,S. aureus and C. bovis were determined using specific culturemedia. Moreover, clinical and subclinical mastitis were diagnosedusing physical examination and California mastitis test,respectively. RESULTS: Most herds had moderate to highBTMSCC and high bacterial counts. The prevalence of clinicaland subclinical mastitis was 1.3% and 24.7%, respectively.CONCLUSIONS: The present study indicated inefficient stallmanagement, udder hygiene, and milking practices in the herdsinvestigated.

Effect of microbiological testing on subsequent mid-infrared milk component analysis of the same milk sample

Our objectives were to determine if mixing and sampling of a raw milk sample at 4°C for determination of total bacteria count (TBC) and if incubation at 14°C for 18h and sampling for a preliminary incubation (PI) count influenced the accuracy of subsequent fat, protein, or lactose measurement by mid-infrared (IR) analysis of milk from the same sample container due to either nonrepresentative sampling or the presence of microbial metabolites produced by microbial growth in the milk from the incubation. Milks of 4 fat levels (2.2, 3, 4, and 5%) reflected the range of fat levels encountered in producer milks. If the portion of milk removed from a cold sample was not representative, then the effect on a milk component test would likely be larger as fat content increases. Within the milks at each fat level, 3 treatments were used: (1) 20 vials of the same milk sampled for testing TBC using a BactoScan FC and then used for a milk component test; (2) 20 vials for testing TBC plus PI count followed by component test; and (3) 20 vials to run for IR component test without a prior micro sampling and testing. This was repeated in 3 different weeks using a different batch of milk each week. No large effect on the accuracy of component milk testing [IR fat B (carbon hydrogen stretch) and fat A (carbonyl stretch)] due to the cold milk sample handling and mixing procedures used for TBC was detected, confirming the fact that the physical removal of milk from the vial by the BactoScan FC (Foss Electric, Hillerød, Denmark) was a representative portion of the milk. However, the representativeness of any other sampling procedure (manual or automated) of a cold milk sample before running milk component testing on the same container of milk should be demonstrated and verified periodically as a matter of routine laboratory quality assurance. Running TBC with a BactoScan FC first and then IR milk analysis after had a minimal effect on milk component tests by IR when milk bacteria counts were within pasteurized milk ordinance limits of <100,000 cfu/mL. Running raw milk PI counts (18h of incubation at 13–14°C) with the BactoScan FC before milk component testing by IR milk analysis had an effect on component tests. The effect was largest on fat test results and would decrease the accuracy of milk payment testing on individual producer milks. The effect was most likely due to the absorption of light by bacterial metabolites resulting from microbial growth or other chemical degradation processes occurring in the milk during the PI count incubation, not by the sampling procedure of the BactoScan. The direction of the effect on component test results will vary depending on the bacteria count and the type of bacteria that grew in the milk, and this could be different in every individual producer milk sample.

A comparative microbiological quality assessment of rural and urban milk samples

The present study deals with the comparative microbiological quality assessment of raw cow milk samples procured from rural and urban farms of Sambalpur City, Odisha, India. The bacterial load of both the rural and urban milk samples in terms of total viable count was observed to be much higher than the acceptable limits. The average total viable count of urban sample was observed to be 8.756 ± 0.803 log CFU/ml. The preliminary incubation count was significantly higher in urban samples (8.889 ± 0.424 log CFU/ml) indicating un-hygienic milk production / handling practices. However, the laboratory pasteurization count of the rural milk samples was noted to be comparatively higher than the urban samples (8.083 ± 0.081 log CFU/ml). The enteric microorganisms isolated from both rural and urban milk samples were identified to beEscherichia coli, Enterobacter sp., Klebsiella sp. and Shigella. Salmonella andPseudomonas sp. were present in urban samples alone, indicating the urban samples to be highly contaminated in comparison to that of the rural ones. Key words: Contamination, enteric bacteria, health, quality, raw milk.

Short communication: Evaluation of bulk tank milk microbiological quality of nine dairy farms in Tennessee

The purpose of this study was to evaluate the bulk tank milk (BTM) quality of 9 East Tennessee dairy farms and to determine its relationship with selected quality milk parameters. Bulk tank milk samples (n=1,141) were collected over a 42-mo period (June 2006 through November 2009) from farms, based on their preliminary incubation count (PIC) history. Parameters of BTM quality evaluated in this study included somatic cell count (SCC), standard plate count (SPC), PIC, laboratory pasteurization count (LPC), Staphylococcus spp. count, Streptococcus spp. count, and coliform count. Strong correlations between SPC and Streptococcus spp. counts (0.72) and between SPC and PIC (0.70) were found. However, moderate correlations were seen among other milk quality parameters. In addition, seasonal variations for some milk quality parameters were noted. For example, milk quality parameters such as SCC, SPC, LPC, and coliform count were significantly higher in summer, whereas Streptococcus spp. counts were significantly higher in winter. No seasonal variation in PIC or Staphylococcus spp. counts was observed. Summarizing, results from this investigation showed the importance of using several bacterial counts (SCC, SPC, PIC, LPC, Streptococcus spp. count, Staphylococcus spp. count, and coliform counts) as simultaneous indicators of milk quality.

Microbiological quality and related factors of sheep milk produced in farms of NE Greece

Sheep herds are a significant capital of dairy industry in Greece, but as dairy farming becomes more complex and intense the need to provide assistance to dairy producers on milk quality is critical. In this study, the quality of raw milk produced in sheep farms of NE Greece was surveyed and the role of various factors was explored. In total, 21 dairy ewe’s farms from the regions of Xanthi and Evros, in the north-eastern Greece were monitored. Milk samples were sampled after the morning milking every 15 days throughout the dairy period (March–June). For the study, a questionnaire was also filled by personal interview with the owners in order to collect information about herd characteristics, health status, handling practices etc. From each farm, air was also sampled for microbiological analysis. Milk samples were examined for chemical components: fat content, protein, lactose, non-fat dry matter (NFDM) and somatic cells count (SCC). Microbiological examination involved the estimation of Total Bacterial Counts (TBC), coliform count (CC), Staphylococcus aureus, Streptococcus sp., and preliminary incubation count (PIC). The possible correlation among different bacterial species and their interaction with SCC and chemical components of milk was also considered. It was examined whether farm management practices could influence the hygiene and the quality of milk. Our results show that as an average TBCs were 5.48 log cfu/ml, SCC: 6.05 log cells/ml, CC: 4.49 log cfu/ml, S. aureus: 3.94 log cfu/ml, Streptococcus sp.: 4.95 log cfu/ml and PIC: 5.7 log cfu/ml. The mean fat, protein, lactose and NFDM were 6.17%, 5.28%, 4.73% and 10.95% respectively. The study revealed significant positive correlation between TBC and PIC (0.825), while SCC was marginally positive correlated with protein and NFDM. No statistically significant correlations observed among SCC with any of the bacterial species. Herd size and farm management practices had considerable influence on SCC and bacterial species.

Results from raw milk microbiological tests do not predict the shelf-life performance of commercially pasteurized fluid milk

Analytical tools that accurately predict the performance of raw milk following its manufacture into commercial food products are of economic interest to the dairy industry. To evaluate the ability of currently applied raw milk microbiological tests to predict the quality of commercially pasteurized fluid milk products, samples of raw milk and 2% fat pasteurized milk were obtained from 4 New York State fluid milk processors for a 1-yr period. Raw milk samples were examined using a variety of tests commonly applied to raw milk, including somatic cell count, standard plate count, psychrotrophic bacteria count, ropy milk test, coliform count, preliminary incubation count, laboratory pasteurization count, and spore pasteurization count. Differential and selective media were used to identify groups of bacteria present in raw milk. Pasteurized milk samples were held at 6°C for 21 d and evaluated for standard plate count, coliform count, and sensory quality throughout shelf-life. Bacterial isolates from select raw and pasteurized milk tests were identified using 16S ribosomal DNA sequencing. Linear regression analysis of raw milk test results versus results reflecting pasteurized milk quality consistently showed low R2 values (<0.45); the majority of R2 values were <0.25, indicating small relationship between the results from the raw milk tests and results from tests used to evaluate pasteurized milk quality. Our findings suggest the need for new raw milk tests that measure the specific biological barriers that limit shelf-life and quality of fluid milk products.

The association between bulk tank milk analysis for raw milk quality and on-farm management practices

Our objective was to determine the risk factors associated with bacteriological quality of bulk tank milk. Bulk tank milk samples were collected from all Prince Edward Island dairy herds (n=235) from March 2005 to March 2007. Biweekly total bacterial, preliminary incubation, laboratory pasteurization, and coliform counts were conducted using a Petrifilm culture system. Data for on-farm risk factors were collected via a mail-out survey which consisted of 4 main sections: (1) general farm demographics and management, (2) cow cleanliness and hygiene, (3) milking procedures and mastitis control, and (4) equipment maintenance and cleaning.Of 235 producers, 153 completed the mail-out survey giving a response rate of 65%. Both total aerobic and preliminary incubation counts were positively associated with the amount of soiling on the teats prior to udder preparation, manual cleaning of the bulk tank, and the use of a specific type of detergent. Additionally, various methods of premilking udder preparation were important, with pre-dip followed by drying being superior to other methods in reducing the bacterial counts. The laboratory pasteurization count was positively associated with the presence of a plate cooler and inadequate frequency of acid wash, whereas having a water purification system was negatively associated with laboratory pasteurization count. Finally, coliform count was negatively associated with clipping udder hair and automated washing of the bulk tank, whereas increasing herd size and inadequate frequency of acid wash were risk factors. Season was a significant predictor for all bacterial counts with the lowest counts tending to occur in winter.

A Survey of Bacteriological Quality and the Occurrence of Salmonella in Raw Bovine Colostrum

In recent years, bovine colostrum has gained popularity as a human food because it is an excellent source of bioactive proteins, which have been claimed to inhibit viral and bacterial pathogens, improve gastrointestinal health, and enhance body condition. A study was conducted to determine bacteriological quality and occurrence of Salmonella in colostrum collected from dairy herds (n = 55) in Pennsylvania. Colostrum samples were analyzed for standard plate count, preliminary incubation count, laboratory pasteurization count, Staphylococcus aureus, Streptococcus agalactiae, coagulase negative staphylococci, streptococci, coliforms, and non-coliforms. A standardized polymerase chain reaction assay was used for detection of Salmonella in colostrum. Salmonella were detected in 8 of 55 (15%) of colostrum samples. Streptococcus agalactiae (1000 colony-forming units [CFU]/mL) was detected in one colostrum sample. The mean standard plate count (977,539 CFU/mL), preliminary incubation count (12,094,755 CFU/mL), laboratory pasteurization count (615 CFU/mL), Staphylococcus aureus (306 CFU/mL), coagulase negative staphylococci (164,963 CFU/mL), streptococci (256,722 CFU/mL), coliforms (323,372 CFU/mL), and non-coliforms (111,544 CFU/mL) counts in colostrum were considerably higher than raw bulk tank milk counts reported previously from Pennsylvania. Analysis revealed that farm size did not influence the bacteriological quality of colostrum. Collection, handling, and storage of colostrum need to be addressed to improve bacteriological quality of colostrum intended not only for feeding calves but also for human consumption.

Environmental Sampling To Predict Fecal Prevalence of Salmonella in an Intensively Monitored Dairy Herd

Although dairy cattle are known reservoirs for salmonellae, cattle that are shedding this organism are often asymptomatic and difficult to identify. A dairy herd that was experiencing a sustained, subclinical outbreak of Salmonella enterica subsp. enterica Cerro was monitored for 2 years. Fecal samples from the lactating cows were collected every 6 to 8 weeks and tested for the presence of Salmonella. Fecal prevalence of Salmonella fluctuated throughout the observation period and ranged from 8 to 88%. Manure composites and water trough samples were collected along with the fecal samples, and bulk milk and milk filters were cultured for the presence of Salmonella on a weekly basis. Over 90% of the manure composites—representing high-animal-traffic areas—were positive at each sampling. Salmonella was detected in 11% of milk samples and in 66% of the milk filters. Results of weekly bulk milk quality testing (i.e., bulk tank somatic cell score, standard plate count, preliminary incubation count) were typically well within acceptable ranges. Milk quality variables had low correlations with herd Salmonella fecal prevalence. When observed over time, sampling period average prevalence of Salmonella in milk filters closely paralleled fecal prevalence of Salmonella in the herd. Based on results of this study, milk filters appear to be an effective method for monitoring shedding prevalence at the herd level. In-line filter testing is also a more sensitive measure of Salmonella, and perhaps other pathogens, in raw milk than testing the milk alone.

Bulk Tank Raw Milk Quality

Raw bulk tank milk (BTM) quality (SCC and bacteria burden) is used to quantify the health and safety of milk. Laboratory-based studies have demonstrated that milk with lower bacteria and somatic cell count produces milk products with superior quality attributes and shelf-life. Raw BTM is subjected to a number of tests to indicate udder health, milk harvest hygiene and storage conditions on the farm. These tests include; total bacterial count (TBC) (or standard plate count (SPC)), preliminary incubation count (PIC), laboratory pasteurization count (LPC) and coliform count (CC), as well as SCC. The objective of this study was to examine the relationship between raw BTM quality and consumer experience with fluid milk products and to survey on-farm risk factors for bacterial milk quality.

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.

Herd Level Information and Bulk Tank Milk Analysis

When milk produced on a farm is examined for bacteriological milk quality and mastitis causing bacteria, it can disclose descriptive information about the general udder health status of the herd, milk hygiene and milking practices on the farm. Many dairy producers periodically receive information about their bulk tank milk with reference to standard plate counts and bulk tank somatic cell counts. Some dairy producers also receive a report on preliminary incubation counts. This information, when collected over a period of time, in combination with bulk tank mastitis culture reports can become a significant knowledge base. This comprehensive data, when interpreted in context with the farm's management practices, provides a rationale to determine current and potential milk quality and mastitis problems in a herd. This paper describes the process of collecting, analyzing, and interpreting bulk tank milk microbiology test results, and utilizing the information to make decisions on improving udder health of the herd and improving milk quality.

Microbiological and Chemical Quality of Raw Milk in New York State

Between December 1993 and January 1996, samples of raw milk from bulk tanks were collected by licensed milk haulers at the time of pick-up from 855 randomly selected farms in New York State (representing ∼10% of all dairy farms in the state). The milk was examined for microbial and chemical qualities. Bacterial numbers were determined by standard plate count, laboratory-pasteurized count, coliform count, heat-resistant spore-forming psychrotroph count, aerobic spore count (mesophilic), rapid psychrotrophic count, and preliminary incubation count. The frequency distributions for these counts are presented. Paired correlation analyses between the microbiological parameters showed low correlations between test results; no correlation coefficients were >0.8. The four highest positive correlation coefficients were found between standard plate count and rapid psychrotrophic count (0.7685), rapid psychrotrophic count and preliminary incubation count (0.6648), standard plate count and preliminary incubation count (0.5800), and aerobic spore count and laboratory-pasteurized count (0.5393). All other correlation coefficients were <0.5. Milk freezing points and acid degree values were determined for all samples. Frequency distributions for these results are also presented.

Use of Individual, Premoistened, Disposable Wipes in Preparing Cow Teats for Milking and Resultant Raw Milk Quality and Production

Two methods of preparing cows for milking were compared. One preparation consisted of wiping each teat clean with individual, premoistened, disposable wipes. This method was compared with washing teats with a hand-held water nozzle and drying with individual paper towels. Two groups of eight Holstein cows each were randomly assigned to the two treatments. Aseptically collected weigh jar milk samples from individual cow milkings were analyzed for standard plate count, preliminary incubation count, laboratory pasteurization count, and coliform count. Pretrial bacterial counts were monitored for 2 d and were used as covariates in statistical analyses. Cows were sampled for 7 d followed by a 2-d rest after which treatments were switched and cows sampled for another week. Method of udder preparation did not affect daily milk production, fat or protein percent. Standard plate counts and preliminary incubation counts were significantly lower for wipe treatment (363 vs 933 CFU/ml and 263 vs 661 CFU/ml). There was no treatment difference for laboratory pasteurization count or coliform count. Raw milk quality as determined by standard plate count and preliminary incubation count was improved by the wipe treatment.