Tank Samples Research Articles

The Influence of Intensively Managed Rotational Grazing, Traditional Continuous Grazing, and Confinement Housing on Bulk Tank Milk Quality and Udder Health

Monthly bulk tank milk samples and veterinary records were analyzed for 1 yr on 15 Vermont dairy farms. Data were evaluated using ANOVA to compare effects of grazing management systems on milk quality and udder health. Systems evaluated were intensively managed rotational grazing, traditional continuous grazing, and confinement housing. Bulk tank samples were evaluated for standard plate count, bacterial type counts on tryptose-blood-esculin agar, and SCC. Veterinary records were evaluated for incidence of clinical mastitis, udder edema, and teat injuries. Within- and between-treatment group analyses were conducted by season, herd size, and udder sanitation systems. Mean standard plate counts were lower in rotationally grazed herds than counts of confined herds during the grazing season. Similarly, rotationally grazed herds with fewer than 60 cows had lower standard plate counts than confined herds of similar size. Mean bulk tank counts of streptococci other than Streptococcus agalactiae during the grazing season differed among treatments. The lowest counts occurred in rotationally grazed herds. Among herd using predip products recognized as efficacious, fewer streptococci other than S. agalactiae were isolated from bulk tank milk of rotationally grazed herds than confined herds. Rotationally grazed herds using postdips recognized as efficacious had lower SCC than those using unrecognized postdips. No udder health differences were observed among grazing treatments.

Use of Bulk Tank and Milk Filter Cultures in Screening for Streptococcus agalactiae and Coagulase-positive Staphylococci

The use of a single bulk tank milk culture and a single milk filter culture was studied for their suitability as screening tests for coagulase-positive staphylococci and Streptococcus agalactiae. Bulk tank and bulk tank milk filter cultures were compared to quarter milk cultures taken from individual cows at 49 Ohio dairy herds selected from all Ohio dairy herds by a stratified random sampling scheme. Individual cow quarter milk samples were collected from a sample of all milking cows using a sampling scheme designed to detect an organism present in 2% of quarters, with 95% confidence intervals between 1 and 3%. Seventeen (35%) herds had one or more cows positive for S. agalactiae and 34 (69%) had one or more cows positive for coagulase-positive staphylococci. Using the results of individual cow sampling as the standard, the sensitivity for S. agalactiae was estimated as 23.5% for a single milk filter sample and 35.3% for a single bulk tank milk sample. The sensitivity for coagulase-positive staphylococci was estimated as 52.9% for a single milk filter culture and 41.2% for a single bulk tank milk culture. Based on these results and those of others, it appears that a single bulk tank or milk filter sample has a relatively low sensitivity for both coagulase-positive staphylococci and S. agalactiae, making these poor screening tests for the presence of these pathogens within a dairy herd.

Isolation of Yersinia enterocolitica and Related Species from Red Meat and Milk

ABSTRACTA total of 150 samples, 50 each of beef, lamb and pork from 10 local retail stores in the Brisbane metropolitan area and 50 pasteurized and 150 raw bovine bulk milk tank samples obtained from Queensland United Foods (QUF), were examined for the presence of Yersinia spp. over 1 yr. Two isolation protocols were used to recover the organism with subsequent biochemical and serological identification. A total of 114 isolates, consisting of Y. enterocolitica (23,12,15,40), Y. intermedia (0,3,5,1), Y. frederiksenii (4,1,0,10) were obtained from beef, lamb, pork, and milk, respectively. No pasteurized milk samples were positive for the organism. None of the isolated strains was found to harbor the virulence plasmid as indicated by the crystal violet‐binding assay.

Incidence of Aeromonas and Listeria spp. in red meat and milk samples in Brisbane, Australia

A total of 150 samples, 50 each of beef, lamb and pork from 10 local retail stores in Brisbane metropolitan area as well as 150 raw bovine bulk milk tank samples obtained from Queensland United Foods (QUF), were examined for the presence of Aeromonas and Listeria spp. over a period of 1 year. Different sets of enrichment and plating media were used to recover the organisms with subsequent identification using conventional biochemical and serotyping techniques. A total of 509 isolates consisting of Aeromonas spp. (350) and Listeria spp. (159) were obtained from 60%, 58%, 74%, 26.6%, 34%, 40%, 30%, 2.6% of samples of beef, lamb, pork and milk respectively. Motile aeromonads ( A. hydrophila, A. sobria, A. caviae) and Listeria innocua were isolated from all kinds of samples whereas L. monocytogenes was only isolated from flesh food. A. hydrophila contributed the largest percentage of the motile aeromonads (60%). The majority of L. monocytogenes cultures were serotype 4.

Aeration induced dynamics of different nitrogen species in tanks

The responses of different nitrogen species to artificial aeration were examined in water and sediment samples of experimental tanks used for varying hours (5.0, 2.5 and 0) of daytime aeration under high (100,000/ha) and low (60,000/ha) stocking density of fish. While the mean concentrations of ammonia‐N and Kjeldahl‐N were markedly increased in water and sediments of non‐aerated system over aerated ones and nitrate‐N in a 5 hour aerated tank with normal stocking density compared to an identical aerated system with high density culture or the control system. It is estimated that induction of nitrification in aerated system ranged from 79 to 86%.

Use of Dry Period Intramammary Antibiotic Therapy and Other Forms of Mastitis Control in Dairy Cows

The objective of this report is to present preliminary results from a survey of producers regarding their use of mastitis control practices. However, the overall objective of a larger study, which will utilize the survey data summarized here, is to determine tbe economics of OCT. OCT economics will be considered conditional on the predominant mastitis agents in a herd. The study has three components: a microbiologic assessment of herd bulk tank samples, evaluation of herd SCC, and evaluation of herd mastitis control practices.

Determination of regulatory organic compounds in radioactive waste samples. Semivolatile organics in aqueous liquids

The regulatory semivolatile organic compounds present in radioactive aqueous waste samples are extracted and concentrated in a small-scale version of a standard EPA procedure normally used for ground waters. Decontamination is sufficient to permit analysis of the extract in a conventional gas chromatography/mass spectrometry laboratory. The performance of the modified procedure, based on surrogate standards, matrix spikes and matrix spike duplicates, and blanks, is comparable to that of the standard method. The modified procedure was applied to a variety of aqueous radioactive waste tank samples. Only 12 of the EPA Appendix VIII compounds were present, and none in concentrations exceeding the reporting limit (500 or 2,500 {mu}g/L). The most common semivolatile present was tributyl phosphate, an organic extractant commonly used in radiochemical processing, at 2,000-30,000 {mu}g/L.

Legionella in Dublin hospital water supplies

An environmental survey was carried out which consisted of periodic and random sampling of water tanks and showers in two large Dublin hospitals. Of the samples 5.3% yielded Legionella bacteria. Legionella pneumophila of serogroups 3, 5 and 6 were isolated from these sites with viable counts ranging from 3.0 x 10(2) - 2.5 x 10(3) c.f.u./litre. The implementation of periodic sampling may, however, not be a worthwhile exercise unless an environmental site has been associated with cases of legionellosis. Emphasis should be placed on the prevention of contamination of environmental sites with legionellae and on the development and implementation of protocols and procedures for the isolation of legionellae to gain the necessary expertise should an epidemiological survey be required.

Effects of Several Factors on Quantification of Fat, Protein, and Somatic Cells in Milk

Two studies were conducted to determine sources of variation in analysis of milk samples subjected to combinations of handling procedures typical of the Alabama DHIA testing program compared with those of a local milk processing plant. In study 1, cooled bulk tank samples from Jersey and Holstein herds were split and sent to five DHIA laboratories and one milk plant laboratory. All five DHIA laboratories reported similar results for fat with slight differences in percentage protein and SCC. Addition of preservative, shipping on ice, or method of shipping did not affect percentage fat. Milk plant electronic analysis was approximately .05% higher than DHIA. Because the statistical difference is less than the accuracy of the Babcock test (± .1%), the practical significance of the difference is minimal. Samples without preservative or shipped on ice had a higher percentage of protein and lower SCC. Holding preserved samples up to 96h did not affect electronic analysis of percentage fat but resulted in increased percentage protein. In study 2, samples held over the weekend by a commercial transport company had a similar percentage of fat but higher protein and SCC than in samples delivered directly.

Intracellular multiplication ofLegionella pneumophila in amoebae isolated from hospital hot water tanks

We studied the ability ofLegionella to multiply in potable water samples obtained from investigations of nosocomial legionellosis. AutochthonousLegionella multiplied in three of 14 hospital water samples after incubation at 35°C and 42°C. All three samples were from hot water tanks. Multiplication did not occur when a selected sample was filtered through a 0.45-μm membrane and reinoculated with indigenousLegionella. We isolated bothLegionella pneumophila and one or more species of free-living amoebae, primarity members of theHartmannellidae, from each of these hot water tank samples. Amoebae from a total of six hot water tank samples were used for cocultivation studies withL. pneumophila. All amoebae supported multiplication ofLegionella in coculture at 35°C. Four of six isolates of amoebae supported multiplication oflegionella at 42°C, while none supported multiplication at 45°C. Gimenez staining and electron microscopy showed thatLegionella multiplied intracellularly in amoebae. Control of these amoebae in potable water may prevent colonization and multiplication ofLegionella in domestic hot water systems.

THE QUALITY OF MILK PRODUCED IN "FADHILIA VILLAGE" NEAR BAGHDAD IN IRAQ

A study on the quality of milk produced in "Fadhilia Village" near Baghdad extending over a period of one year, revealed that the total bacterial and coliform counts for milk samples from individual producers were 7.4x105 and 2.5x103 in summer, and 1.8x10 and 5.4x10 in winter respectively. The above counts for bulk milk samples were 3.3x10 and 1.8x101 in sumer and 5.1x10 and 3.3x103 in winter respectively. All over the year the preliminary incubation and psychrotrophic counts for both individual and bulk milk samples were strictly higher than all the proposed standards. There was a significant drop in methylene blue reduction time in summer samples compared to winter samples. A similar drop was noticed in bulk tank samples as compared to individual producer samples. Besides that a significant increase in lactic acid content in Surner samples compared to winter samples.

Evaluation of Method 25 Nonmethane Organic Analyzer Design

Under contract to the U.S. Environmental Protection Agency, Research Triangle Institute has been conducting research to improve the precision, accuracy and limit of detection attainable with the EPA Method 25 nonmethane organic (NMO) analyzer. In Method 25, volatile organic carbon (VOC) samples are collected by drawing gas from an emitting source through a dry ice cooled sample trap and into an evacuated collection tank. The hydrocarbon concentration emitted from the source is determined on a per-carbon basis by catalytically converting the trap and tank sample fractions to CO2 and quantitating the amount of CO2 produced using the NMO analyzer. A reduction catalyst evaluation led to the selection of an NMO analyzer reduction catalyst which operates at a moderate temperature and displays no appreciable effect on peak shape. A gas chromatographlc column system which provides better permanent gas separation and hydrocarbon quantitation was also selected for use in the NMO analyzer.

Effects of metals on Legionella pneumophila growth in drinking water plumbing systems.

An investigation of the chemical environment and growth of Legionella pneumophila in plumbing systems was conducted to gain a better understanding of its ecology in this habitat. Water samples were collected from hospital and institutional hot-water tanks known to have supported L. pneumophila and were analyzed for 23 chemical parameters. The chemical environment of these tanks was found to vary extensively, with the concentrations of certain metals reaching relatively high levels due to corrosion. The effect of various chemical conditions on L. pneumophila growth was then examined by observing its multiplication in the chemically analyzed hot-water tank samples after sterilization and reinoculation with L. pneumophila. L. pneumophila and associated microbiota used in these experiments were obtained from a hot-water tank. These stains were maintained in tap water and had never been passaged on agar. The results of the growth studies indicate that although elevated concentrations of a number of metals are toxic, lower levels of certain metals such as iron, zinc, and potassium enhance growth of naturally occurring L. pneumophila. Parallel observations on accompanying non-Legionellaceae bacteria failed to show the same relationship. These findings suggest that metal plumbing components and associated corrosion products are important factors in the survival and growth of L. pneumophila in plumbing systems and may also be important in related habitats such as cooling towers and air-conditioning systems.

Use of Individual Cow Somatic Cell Counts and Bulk Tank Samples to Monitor Herd Mastitis Status

With the advent of automated cell counting, there has been a proliferation of milk somatic cell count (SCC) data for bothbulk tank samples and individual cows. The optimal use of this data in monitoring mastitis is still being debated. Thepurpose of this paper is to discuss the use of SCC data from both individual cow and bulk tank samples for monitoringmastitis on a herd basis.

Eradication of Mycoplasma bovis infection from a dairy herd in Great Britain.

Mycoplasma bovis infection was eradicated from a naturally infected dairy herd in Great Britain by a programme of identification, segregation and culling of infected animals. A series of group and whole milking herd tests was carried out over a period of 15 months, followed by a whole herd nasal swabbing. Cows were also sampled after calving and at drying off and bulk tanks were sampled at weekly intervals during the same period and for a further nine months. Fifty-nine cows were identified as excretors, the majority in group or herd tests, but five after calving and three at drying off. Eight of the original clinical cases were retained in the herd, after repeated negative test results. Bulk tank sampling was found to be extremely useful in detecting infection even down to one cow in a milking herd of 300. The value of milking hygiene and the indications for eradication are also discussed.

Examination of Poultry Giblets, Raw Milk and Meat for Campylobacter fetus subsp. jejuni

An MPN procedure was used to determine the presence of Campylobacter fetus subsp. jejuni in poultry giblets. This procedure consists of (a) subculturing a sample in Brucella broth supplemented with 0.15% agar, 0.05% sodium pyruvate and the following antimicrobial agents per liter: vancomycin 10 mg, trimethoprim 5 mg, polymyxin B sulfate 2,500 IU, amphotericin B 2 mg and cephalothin 15 mg and (b) subsequent streaking of a loopful of Brucella broth held at 42 C for 48 h on plates of Brucella agar supplemented with 10% defibrinated horse blood and the concentrations of antimicrobial agents identified above. C. fetus subsp. jejuni was present in 85% of the chicken livers and in 89% of the chicken gizzards obtained immediately after evisceration. The organism was not recovered from samples treated with chlorinated water. C. fetus subsp. jejuni was not recovered from raw milk (bulk tank samples or individual cow samples) or from beef (infraspinatus or biceps femoris muscles).

Agitation and sampling of tankers and storage tanks

Methods for mixing the contents of road tankers and storage tanks are discussed in broad outline. In particular, examples are given of the efficiency of various mixing methods on the contents of road tankers. There is a need for a more positive approach to this important aspect of process and quality control.

Distribution of Bacterial Contaminants in a South African Lager Brewery

Bacteria isolated from contaminated pitching yeast, fermenting wort and beer samples from a South African lager brewery over a one‐year period were tentatively identified by an improved, rapid diagnostic procedure as pediococci (41%), homofermentative lactobacilli (5%), heterofermentative lactobacilli (9%), Acetobacter spp. (7%), Gluconobacter spp. (13%) and Hafnia protea (25%). Pediococci and lactobacilli dominated samples taken from fermentation, storage and ‘bright’ beer tanks but were absent from pitched wort samples, from collection vessels and the single pitching yeast sample investigated. Acetic acid bacteria and H. protea were widely distributed in collection vessel, fermentation and storage tank samples, and H. protea was isolated from recycled pitching yeast.

Slurry flow metering by pressure differential devices

A simple system for measuring slurry concentrations and flow rates by pressure difference devices has been studied. Solids concentrations have been determined by pressure measurements in vertically upwards and downwards sections of the flow, and flow rates measured by a venturi meter located alternately in horizontal, vertically upwards and vertically downwards flows. The venturi performance has been described in terms of a discharge coefficient based on mixture density, and the concentration measurements have been compared to values determined by weigh tank samples. A range of sand slurries with median particle size from 150 to 740μm and an ilmenite slurry with a median particle size of 170μm have been tested. A limited number of tests on a 17μm sand slurry have also been recorded. For fine sand slurries (150μm or below) it was found that the water value of venturi-discharge coefficient applied, so that the accuracy of flow measurements will be limited only by the accuracy of the pressure and specific weight measurements. Experimental values of specific weight from the vertical loop section were on average within 1% of the values from the weigh tank, where the majority of this scatter was caused by the limitations of the weigh tank method. For coarser slurries, the venturi-discharge coefficients depended primarily on solids concentration, with a secondary dependence on Reynolds number, and values were below the water value. An analysis of the flow based on a one-dimensional momentum balance indicated that relative velocity between the phases could account for these low values of discharge coefficient. This was verified by high-speed photography of the flow which suggested a movement of particles towards the centre of the flow at the throat. The overall indications are that the combination of a vertical loop section of flow (for concentration or specific weight measurements) and a venturi meter (for flow rates) provides a simple and accurate means of metering slurry flows. For fine slurries only water calibrations or calibrations from Standards are required.

THE SPOKANE CITY HEALTH DEPARTMENT MASTITIS CONTROL PROGRAM

The City of Spokane Health Department was asked by the U. S. Public Health Service to study and instigate a practical abnormal milk control program in 1962. From May until November 1962 composite bulk tank samples were tested using the Modified Whiteside Test. Some abnormal milk appeared in 42% of the bulk tank samples. With this information, a meeting was called which included personnel from the U. S. Public Health Service, State Department of Health, State Department of Agriculture, Idaho Health Department, Extension Service, Dairy Industry, the Dairy Science Departments of Washington State University and the University of Idaho. A program was started using five committees recommended by the National Mastitis Council and a steering committee. The Direct Microscopic Leucocyte Count (DMLC) was adopted for official use and an educational program was started.In April 1965, it was agreed that enforcement was needed to bring the leucocyte level below 1,000,000 per ml. After a few suspensions, the results were amazing, dropping from 22% to 1% of the producers continually with over a million per ml of milk.In April 1966, the City adopted the 1965 U. S. Public Health Service Grade “A” Milk Ordinance and included an Abnormal Milk Section with 800,000 leucocytes/ml as a limit and using the 3 out of 5 method of suspension. At present, the DMLC is the official method and the industry is using the Wisconsin Mastitis Test monthly on all their producers.The program has been very successful because of the cooperation of the milk industry, machine installers, Extension Service, Dairy Science Departments and Health Departments. It will be possible in the future to meet the 500,000 leucocytes per ml limit.