Somatic Cell Concentration Research Articles

The effect of intracisternal administration of hyaluronidase on the body of cattle

The aim of the research was to determine the magnitude of the irritant effect on breast tissue and the morphobiochemical composition of blood in lactating cows with a single intracisternal administration of hyaluronidase. To do this, 1,280 units of hyaluronidase prepared in 10 ml of 0.9% sodium chloride solution were injected once into the posterior right quarter of the experimental group (n=10). The first heifers of the control group (n = 10) received a saline solution in its pure form. Before and after the administration of the drugs, the electrical conductivity and concentration of somatic cells in milk were determined (by the viscometric method), as well as the morphobiochemical composition of blood was studied. It was found that 12 hours after the introduction of the enzyme, the electrical conductivity of the secretion decreased by 7.6% (P ≤ 0.05), and after the first day it was completely restored to its initial values. The dynamics of the level of somatic cells 6 and 12 hours after the application of hyaluronidase in 40% of animals was characterized by values above 500 thousand / ml, and the average concentration of cells increased by 3 times. After the first and second days, the level of inflammatory reaction cells decreased by 2.0...2.5 times, relative to peak values. After 72 hours, the cell content in the secret decreased by 2.8 times in relation to the values obtained after 6 hours and by 27.7% in relation to the values established a day after the application of hyaluronidase, and did not significantly differ from the indicators before the introduction of the enzyme. The use of the drug did not significantly affect the morphobiochemical parameters of the blood of experimental animals. Thus, a single intracisternal administration of 1280 units of hyaluronidase to lactating cows is accompanied by a slight and short-term irritating effect on udder tissue, which allows further studies of this drug in the pharmacocorrection of breast pathologies.

Occurrence of zearalenone in dairy farms – A study on the determinants of exposure and risk assessment

The Azorean dairy industry is based on a semi-intensive model. Due to the few storage facilities and the large climatic fluctuations that characterize the Azores, the complete feed mixture (total mixed ration - TMR) is susceptible to the proliferation of a variety of fungi and mycotoxin contamination. Thus, chronic ingestion of these xenobiotics may lead to increased susceptibility to disease, loss of reproductive performance and, in the case of dairy cattle, decreased productivity and quality of milk produced. Since it is impossible to eliminate completely the presence of mycotoxins, it is essential to ensure the implementation of strategies to reduce their concentration in products intended for food and feed, as well as to monitor and control the levels present in food.This study aimed to evaluate the occurrence zearalenone (ZEA) in feed (TMR) in four dairy cattle farms on the Azorean Island of São Miguel and relate it to the occurrence of this mycotoxin in the milk produced, by associating several production and health indicators translated by the monthly milk contrast. To this end, the monthly milk contrast data, the determination of ZEA in the ingested feed and the (individual) milk samples from the four farms included in the study were used. Eighty-three (98.8%) of the milk samples under study had detectable ZEA levels (1.56 ± 1.36 μg/L), higher than reported in previous similar studies. Although ZEA concentration was not significantly associated with any production indicator analyzed (days in milk, age at calving, milk yield, protein content, butyrate content, somatic cell concentration and urea), it was found that the production regime and type of feed management is a major factor in the exposure of animals to high mycotoxin contents.Further studies are recommended to ensure continued monitoring and reduction of the risk associated with exposure of animals and humans to ZEA.

ДИАГНОСТКА СКРЫТОГО МАСТИТА ПУТЕМ ПОДСЧЕТА СОМАТИЧЕСКИХ КЛЕТОК В МОЛОКЕ КОРОВ

In this article, we present the course and results of scientific research aimed at calculation of the concentration of somatic cells in cow's milk to detect subclinical mastitis in individual farms of the Republic of Armenia. Comparison of somatic cell concentrations in milk from healthy and sick cows with subclinical mastitis, analysis and comparison of blood morphological parameters in sick and healthy animals has been implemented and the relationship between somatic cell concentration in milk and morphological abnormalities in sick cow blood has been identified. SC concentrations between 300 and 500 thousand/ml are indicative of mastitis risk. In this case, the type of reaction manifested was positive. It was found that the viscosity of the investigated solution "Somatic plus" + milk increases in proportion to the increasing concentration of somatic cells in the milk sample, which indicates subclinical mastitis. A study of the morphological parameters of blood in healthy and subclinical mastitis animals revealed some deviations from the reference values of blood parameters, leading to the conclusion that these changes in animals' blood are related to an increase in the number of milk's somatic cells. Increased leukocytes were found in sick animals' blood. This was followed by an increase in stab neutrophils, eosinophils, monocytes, lymphocytes, and ESR. As a result of all this, the body is experiencing inflammatory processes mobilizing its defensive mechanisms against pathogens.

Ways of increasing the milk productivity of cows, improving the quality and safety of live-stock products

The article presents the results of studies of the dependence of cows’ milk productivity on the level of lipid peroxidation and antioxidant defense in their body. For the experiment two groups of lactating cows were formed, 10 animals each: group 1 – livestock with a high concentration of lipid peroxidation products in the blood and a low level of antioxidants; group 2 – livestock with the values of these indicators within the reference interval. The results of the research indicate that in animals of the group 1 the average daily milk yield was lower by 9.9% relative to the values of the group 2. According to the quality characteristics and safety fac-tors of milk in cows with an imbalance in the LPO-AOD system relative to the group of animals with normal data, a decrease in the concentration of protein and fat was recorded with an increase in the concentration of somatic cells. Taking it into account, it seems relevant to use antioxidant substances for highly productive dairy cattle in order to increase milk productivity, improve the quality and safety of livestock products.

Genomic Prediction of Complex Traits in Animal Breeding with Long Breeding History, the Dairy Cattle Case.

In accordance with the infinitesimal model for quantitative traits, a very large number of genes affect nearly all economic traits. In only two cases has the causative polymorphism been determined for genes affecting economic traits in dairy cattle. Most current methods for genomic evaluation are based on the "two-step" method. Genetic evaluations are computed by the individual animal model, and functions of the evaluations of progeny-tested sires are the dependent variable for estimation of marker effects. With the adoption of genomic evaluation in 2008, annual rates of genetic gain in the US increased from ∼50-100% for yield traits and from threefold to fourfold for lowly heritable traits, including female fertility, herd-life and somatic cell concentration. Gradual elimination of the progeny test scheme has led to a reduction in the number of sires with daughter records and less genetic ties between years. As genotyping costs decrease, the number of cows genotyped will continue to increase, and these records will become the basic data used to compute genomic evaluations, most likely via application of "single-step" methodologies. Less emphasis in selection goals will be placed on milk production traits, and more on health, reproduction, and efficiency traits and "environmentally friendly" production. Genetic variance for economic traits is maintained by increase in frequency of rare alleles, new mutations, and changes in selection goals and management.

Relationship of daily total somatic cell output with somatic cell concentration and clinical mastitis

Somatic cell count (SCC) measures the concentration of somatic cells in milk and is used as a mastitis diagnostic tool. It is plausible that variation in milk yield could alter the relationship between SCC and mastitis status. Our objective was to evaluate total daily SCC output as a predictor of clinical mastitis. Data included 37,035 test-day records from 4,179 lactations of 1,679 cows and 1,286 mastitis events from an experimental herd. Daily total SCC was derived by multiplying SCC by daily milk yield in milliliters and transformed to daily total somatic cell score (DTSCS) via a log2 transformation. Milk yield, SCS, and DTSCS were evaluated with mixed models that included the proximity of a mastitis event to the test date and days in milk as the main fixed effects. A second series of logistic regression was conducted that considered mastitis (1 = mastitis occurred during a test interval; 0 = no mastitis) as the dependent variable with milk yield, SCS, and DTSCS the main independent effects. Least squares means for test dates associated with mastitis-free lactations were 2.43 and 2.25 for SCS and DTSCS, respectively. The corresponding values were 5.96 for SCS and 5.66 for DTSCS for the week of a mastitis event. Whereas SCS declined rapidly in early lactation and then increased steadily thereafter, DTSCS was lowest in early lactation and increased by a proportionally smaller amount throughout lactation. Including both SCS and DTSCS in the same model improved the logistic regression model fit over a model with SCS only. Dilution effects from milk yield influence SCS, and consideration of DTSCS in management and genetic selection schemes could improve mastitis detection and resistance.

Intramammary Immunisation Provides Short Term Protection Against Mannheimia haemolytica Mastitis in Sheep.

Mastitis affects both dairy and meat/wool sheep industries with losses due to reductions in milk quality and quantity, increased treatment costs and restricted lamb growth. Effective vaccines would be important tools for mastitis control. However, the development of vaccines against mastitis has proved challenging due to the failure to target protective immunity to the mammary gland. In order to target responses to the mammary gland, this study tested whether local administration directly into the gland through the teat canal or in the udder skin confers protection against an intramammary infection. In this study, we tested a vaccine that confers protection against respiratory disease caused by Mannheimia haemolytica to determine if it also protects against intramammary infection by the same organism. No evidence of protection was observed in animals that received a subcutaneous immunisation in the udder skin, however, intramammary immunisation provided almost complete protection against an experimental challenge administered 7 days post immunisation but not if the challenge was delivered 14 days post immunisation. To investigate further the nature of this variation in response, the somatic cell count and concentration of cytokines Interleukin-1β, Interleukin-10 and Interleukin-17A was determined in milk over the course of each study. Intramammary immunisation induced an inflammatory response within the mammary gland, characterised by increases in SCC and in the production of cytokines IL-1β, IL-10, and IL-17A. This response was similar to that observed in un-vaccinated control animals post challenge. The SCC and cytokine levels had returned to levels comparable with un-vaccinated controls prior to challenge at both 7 and 14 days post immunisation. The transient nature of the protective effect is consistent with the priming of an innate antibacterial response within the mammary gland which provides protection against challenge at 7 days but is diminished by 14 days post-vaccination. Further studies are planned to determine the nature of the innate immune mechanisms associated with the protective effect described here to determine whether it may be exploited to improve ruminant udder health.

Feeding supplemental 25-hydroxyvitamin D3 increases serum mineral concentrations and alters mammary immunity of lactating dairy cows

Objectives were to determine the effects of feeding supplemental 25-hydroxyvitamin D3 [25(OH)D3] on concentrations of vitamin D metabolites and minerals in serum, mammary immune status, and responses to intramammary bacterial infection in dairy cows. Sixty multiparous, pregnant lactating Holstein cows with somatic cell count <200,000/mL were blocked by days in milk and milk yield and randomly assigned to receive a daily top-dressed dietary supplement containing 1 or 3 mg of vitamin D3 (1mgD or 3mgD), or 1 or 3 mg 25(OH)D3 (1mg25D or 3mg25D) for 28 d (n = 15/treatment). Cows were kept in a freestall barn and fed a total mixed ration in individual feeding gates. Individual dry matter intake (DMI) and milk yield were recorded daily, and milk and blood samples were collected at 0, 7, 14, and 21 d relative to the start of treatment. At 21 d, cows fed 1mgD and 3mg25D received an intramammary challenge with Streptococcus uberis. Cows were observed for severity of mastitis, and blood and milk samples were collected every 12 h to measure inflammation. The 1mg25D and 3mg25D cows had greater serum 25(OH)D3 concentrations at 21 d compared with 1mgD and 3mgD cows (62 ± 7, 66 ± 8, 135 ± 15, and 232 ± 26 ng/mL for 1mgD, 3mgD, 1mg25D, and 3mg25D, respectively). The 3mg25D cows had greater concentrations of Ca and P in serum at 21 d compared with other treatments (Ca = 2.38, 2.4, 2.37, and 2.48 ± 0.02 mM, 1.87, 1.88, and 2.10 ± 0.08 mM for 1mgD, 3mgD, 1mg25D, and 3mg25D, respectively). Yields of milk and milk components, DMI, body weight, and concentrations of 1,25-dihydroxyvitamin D and Mg in serum did not differ among treatments. Abundance of mRNA transcripts for interleukin-1β (IL1B) and inducible nitric oxide synthase (iNOS) in milk somatic cells before S. uberis challenge were increased in cows fed 25(OH)D3 compared with cows fed vitamin D3. Furthermore, IL1B, iNOS, β-defensin 7, and β-defensin 10 in milk somatic cells increased as concentrations of 25(OH)D3 increased in serum. Cows fed 3mg25D had less severe mastitis at 60 and 72 h after challenge with S. uberis compared with cows fed 1mgD. Concentrations of bacteria, somatic cells, and serum albumin in milk after challenge did not differ between treatments; however, an interaction between treatment and day was detected for lactate dehydrogenase in milk. Expression of adhesion protein CD11b on milk neutrophils after the S. uberis challenge was greater among 3mg25D cows compared with 1mgD cows. Transcripts of CYP24A1 and iNOS in milk somatic cells during mastitis also were greater in 3mg25D cows compared with 1mgD cows. Feeding 25(OH)D3 increased serum 25(OH)D3 more effectively than supplemental vitamin D3, resulting in increased serum mineral concentrations, increased expression of vitamin D-responsive genes, and altered immune responses to intramammary bacterial challenge.

Use of commercial somatic cell counters to quantify somatic cells in non-lactating bovine mammary gland secretions

Measurement of the somatic cell count (SCC) in milk is commonly used to detect mastitis in lactating dairy cows. Many techniques and tools have been developed and adapted to quantify milk SCC, but few tools have been evaluated in their ability to enumerate somatic cells in non-lactating bovine mammary secretions. This limits the tools available for detecting mastitis in non-lactating animals. The objective of these studies was to evaluate methods of somatic cell quantification, originally developed for milk, in their ability to quantify the SCC in non-lactating bovine mammary secretions when compared to the gold standard microscopic quantification method. Two experiments were conducted. In a first experiment, 222 mammary secretions were collected and diluted 1:10 with PBS. Cells in these suspensions were quantified microscopically and with a DeLaval Cell Counter. Microscopic SCC (MSCC) ranged from 1.9 × 106 to 259.5 × 106 cells/mL while DeLaval Cell Counter SCC (DSCC) ranged from 1.8 × 106 to 27.0 × 106 cells/mL; a measurement of agreement between the 2 measures, based on the Lin’s Concordance Correlation Coefficient (CCC) suggested moderate agreement between measures (CCC = 0.60). In a second experiment 72 mammary secretions were collected and diluted 1:50 in PBS. Somatic cells in these suspensions were quantified microscopically, with a DeLaval Cell Counter, and by a DHIA laboratory using a Fossomatic™ FC. MSCC ranged from 1.6 to 47.5 × 106 cells/mL, DSCC ranged from 1.0 to 35.7 × 106 cells/mL, and Fossomatic SCC (FMSCC) ranged from 1.6 to 46.7 × 106 cells/mL. CCCs of 0.81 and 0.88 resulted when DSCC and FMSCC were paired with the MSCC, respectively. The results of this work indicate that a significantly greater concentration of somatic cells exist in non-lactating mammary secretions and dilution of these mammary secretions influences accuracy of SCC estimates. Future studies seeking to quantify somatic cells in mammary secretions from non-lactating cows should identify the most appropriate dilution factors specific to each method of measure, given that these two factors will influence the accuracy of SCC estimates. Development of a standardized approach for quantifying somatic cells in non-lactating dairy animals such as heifers and cows, via a rapid automated counter, can allow for the detection of mastitis in non-lactating dairy animals.

Staphylococcus aureus intramammary challenge in non-lactating mammary glands stimulated to rapidly grow and develop with estradiol and progesterone

Intramammary infections (IMI) are prevalent in non-lactating dairy cattle and their occurrence during periods of significant mammary growth and development (i.e. pregnant heifers and dry cows) is believed to interfere with growth, development, and subsequent milk production. However, direct study of IMI impacts on non-lactating but developing mammary glands is lacking. The objectives of this study were to (1) define how IMI affected total and differential mammary secretion somatic cell counts in mammary glands stimulated to rapidly grow using estradiol and progesterone, and (2) characterize changes in mammary morphology in response to IMI. Mammary growth was stimulated in 19 non-pregnant, non-lactating cows and 2 quarters of each cow were subsequently infused with either saline (n = 19) or Staphylococcus aureus (n = 19). Mammary secretions were taken daily until mammary tissues were collected at either 5 or 10 days post-challenge. Staph. aureus quarter secretions yielded greater concentrations of somatic cells than saline quarters and contained a greater proportion of neutrophils. Staph. aureus mammary tissues exhibited higher degrees of immune cell infiltration in luminal and intralobular stroma compartments than saline quarters. Infected tissues also contained reduced areas of epithelium and tended to have greater amounts of intralobular stroma. Results indicate that IMI in non-lactating glands that were stimulated to grow, produced immune cell infiltration into mammary tissues and secretions, which was associated with changes in mammary tissue structure. The observed reduction of mammary epithelium indicates that IMI impair mammary development in rapidly growing mammary glands, which may reduce future reduced milk yields.

Comparison between direct and indirect immunofluorescence method for determination of somatic cell count

A sensitive indirect immunofluorescence (IF) assay for bovine neutrophil and somatic cell counting was developed. The obtained indirect IF was compared with direct IF. The direct IF method uses a single-fluorophore-conjugated antibody directed against the target of interest. The indirect IF method uses two antibodies. The primary antibody is unconjugated. The secondary antibody is directed against the primary and has fluorescent marker. Calibration curves for somatic cells (SC) in buffer model solutions were obtained by both methods, using fluorescence spectrophotometry. The measured linear range of somatic cells by the direct method was from 2 × 104 to 3 × 106 cells and by the indirect method was from 3 × 104 to 3 × 106 cells. The signal obtained by the indirect method was higher than the direct method at low concentrations of SC (from 30,000 to 100 000 cells/mL). That signal amplification probably is due to more than one fluorescent secondary antibody coupling to bound primary antibody. The same effect is observed by fluorescence microscopy. Consequently, the indirect IF method is more sensitive than the direct IF method. Conjugated primary antibodies are more expensive than their unconjugated counterparts, and secondary antibodies are relatively inexpensive. Therefore, using the same conjugated secondary antibody to detect different primary antibodies is cost-effective. Furthermore, a two-color staining microscopic procedure was proposed for simultaneous estimation of total SC count and neutrophil cell count.

Applicability of haptoglobin as a health bioindicator in beef and dairy cattle

Haptoglobin is the main acute phase protein in ruminants, and its use is being widely investigated in animal clinics as an early biomarker of inflammation, infection, tissue damage and stress conditions. This occurs due to the fact that this protein presents blood values close to 0.05 mg / ml in healthy cattle, but it increases more than 100 times during the pathological conditions, even before clinical signs appear and changes in the leukogram occur. Considering these characteristics, haptoglobin has a high potential for use in different areas of the Brazilian livestock industry. Thus, the aim of this literature review is to compile the scientific studies that used this protein as a bioindicator of animal health in beef and dairy cattle. In beef cattle, it was verified that the quantification of haptoglobin may contribute to the screening of animals in the ante morten inspection, allowing the identification of animals with subclinical disease that were not diagnosed by visual inspection; can also contribute to the verification of animal welfare in the moments after transportation and pre-slaughter, avoiding the slaughter of animals with possible stresses that may alter the quality of the meat products. In dairy cattle, haptoglobin can directly contribute to the identification of cows with different levels of clinical and subclinical mastitis, besides allowing the identification of lots of milk with high concentration of somatic cells or from herds affected by infectious agents. In order to promote its inclusion as a monitoring tool within the Brazilian livestock industry, for use by both veterinarians and industrial establishments of animal products, it is recommended to carry out validation studies on the use of haptoglobin as an animal health bioindicator in partnership with companies of the sector, so that its practical utility is verified directly by the professionals involved.

A new somatic cell count index to more accurately predict milk yield losses

Abstract. Intramammary infection and clinical mastitis in dairy cows leads to considerable economic losses for farmers. The somatic cell concentration in cow's milk has been shown to be an excellent indicator for the prevalence of subclinical mastitis. In this study, a new somatic cell count index (SCCI) was proposed for the accurate prediction of milk yield losses caused by elevated somatic cell count (SCC). In all, 97 238 lactations (55 207 Holstein cows) from 2328 herds were recorded between 2010 and 2014 under different scenarios (high and low levels of SCC, four lactation stages, different milk yield intensities, and parities (1, 2, and ≥ 3). The standard shape of the curve for SCC was determined using completed standard lactations of healthy cows. The SCCI was defined as the sum of the differences between the measured interpolated values of the natural logarithm of SCC (ln(SCC)) and the values for the standard shape of the curve for SCC for a particular period, divided by the total area enclosed by the standard curve and upper limit of ln(SCC) = 10 for SCC. The phenotypic potential of milk yield (305-day milk yield – MY305) was calculated using regression coefficients estimated from the linear regression model for parity and breeding values of cows for milk yield. The extent of daily milk yield loss caused by increased SCC was found to be mainly related to the early stage of lactation. Depending on the possible scenarios, the estimated milk yield loss from MY305 for primiparous cows was at least 0.8 to 0.9 kg day−1 and for multiparous cows it ranged from 1.3 to 4.3 kg day−1. Thus, the SCCI was a suitable indicator for estimating daily milk yield losses associated with increased SCC and might provide farmers reliable information to take appropriate measures for ensuring good health of cows and reducing milk yield losses at the herd level.

A portable somatic cell counter based on a multi-functional counting chamber and a miniaturized fluorescence microscope

A somatic cell count is the concentration or density of somatic cells in milk, and is an important indicator for monitoring mastitis incidence and milk quality in the dairy industry. Managing and controlling mastitis based on somatic cell counts can help ensure high milk quality and yield. A major challenge when translating existing cell counting methods to such application is that they require off-chip sample preparation and complicated sample and reagent delivery steps that cannot be easily performed in resource-limited settings such as dairy farms. Here, we describe an integrated cell counting platform that enables automatic sample delivery into a cell counting chamber and on-chip sample preparation without requiring any off-chip processes, and that simultaneously provides a miniaturized, hand-held fluorescence device for the identification of fluorescently-labelled somatic cells. Our platform thus allows simple, rapid and accurate enumeration of somatic cells in milk. We successfully demonstrated its capability of counting somatic cells in milk, which can be easily performed even by non-experts without additional instrumentation. The platform represents a promising tool for everyday milk-quality tracking and for controlling mastitis occurrence.

A multilevel model with clustered management practices differentiating dairy herd environments in southeastern Sicily

Herd environments constitute productivity potentials, or aggregate opportunity outcomes, resulting from management actions taken with the available inputs. Management outcomes from cow nutrition, udder health and milking practices were quantified with the help of surveys of 254 dairy producers in southeastern Sicily. Objectives were to disentangle environmental opportunities by disaggregating herd effects into causal inputs. Average ME milk production was 8640kg/lactation for the 183 Friesian herds containing 35 lactating cows and 10 dry cows. Seventy-one Brown Swiss herds averaged 6443kg ME milk from 25 lactating and 10 dry cows. For Friesian (Brown Swiss) herds 10 (11) management practices affected milking performance and 9 (8) practices influenced somatic cell concentration (P<0.05). Multilevel analysis and herd clustering procedures differentiated low from high opportunity herd environments but altering relative weightings among management practices did not further discriminate them. This clustering methodology helps ensure unbiased estimation of management input effects and could help target priority management substitutions and technical support priorities in dairy extension programs.

Genome wide scan for somatic cell counts in holstein bulls

BackgroundMastitis is the most costly disease for dairy production, and control of the disease is often difficult, due to its multi-factorial nature. Susceptibility to mastitis is under partial genetic control and the industry uses indirect selection for decreased concentrations of somatic cells in milk to reduce mastitis.MethodsA genome-wide scan was performed to identify genomic regions associated with deregressed estimated breeding values (EBVs) for somatic cell counts (SCC) in Holstein bulls. In total 1183 proven bulls of the Italian of Holstein population, were genotyped with the BovineSNP50 BeadChip (Illumina, San Diego, CA) and a whole genome association analysis was performed using the R package GenABEL.ResultsTwo chromosomal regions showed association with SCC, a region on chromosome 14 with high significance (P < 5x10-6) and a region on chromosome 6 with moderate significance (P < 5x10-5).ConclusionsTwo regions with effects on SCC have been identified with good statistical support. A further study of these candidate regions will be performed to verify the results and identify the causal mutations.

Transcriptomic analysis of milk somatic cells in mastitis resistant and susceptible sheep upon challenge with Staphylococcus epidermidis and Staphylococcus aureus

BackgroundThe existence of a genetic basis for host responses to bacterial intramammary infections has been widely documented, but the underlying mechanisms and the genes are still largely unknown. Previously, two divergent lines of sheep selected for high/low milk somatic cell scores have been shown to be respectively susceptible and resistant to intramammary infections by Staphylococcus spp. Transcriptional profiling with an 15K ovine-specific microarray of the milk somatic cells of susceptible and resistant sheep infected successively by S. epidermidis and S. aureus was performed in order to enhance our understanding of the molecular and cellular events associated with mastitis resistance.ResultsThe bacteriological titre was lower in the resistant than in the susceptible animals in the 48 hours following inoculation, although milk somatic cell concentration was similar. Gene expression was analysed in milk somatic cells, mainly represented by neutrophils, collected 12 hours post-challenge. A high number of differentially expressed genes between the two challenges indicated that more T cells are recruited upon inoculation by S. aureus than S. epidermidis. A total of 52 genes were significantly differentially expressed between the resistant and susceptible animals. Further Gene Ontology analysis indicated that differentially expressed genes were associated with immune and inflammatory responses, leukocyte adhesion, cell migration, and signal transduction. Close biological relationships could be established between most genes using gene network analysis. Furthermore, gene expression suggests that the cell turn-over, as a consequence of apoptosis/granulopoiesis, may be enhanced in the resistant line when compared to the susceptible line.ConclusionsGene profiling in resistant and susceptible lines has provided good candidates for mapping the biological pathways and genes underlying genetically determined resistance and susceptibility towards Staphylococcus infections, and opens new fields for further investigation.

Fresh cow mastitis monitoring on day 3 postpartum and its relationship to subsequent milk production

The purpose was to determine the association of milk California Mastitis Test (CMT), somatic cell concentration (SCC), and milk differential cell count results on day 3 postcalving with subsequent lactation production and health events. On d 3 postcalving, the CMT was performed and quarter milk samples were collected from 130 dairy cows. Quarter SCC and milk differential cell counts were determined. Microbiology on duplicate quarter milk samples was used to determine the presence of intramammary infection by major or minor pathogens. Production measures obtained using Dairy Herd Improvement Association testing were 150-d standardized and summit milks. Milk culture results on a cow basis included 82 (63.1%) samples with no growth, 31 (23.9%) with major pathogens, and 17 (13.1%) with minor pathogens. Milk culture results comparing cows with no growth to those with any growth (major or minor pathogens) were not associated with statistically significant differences in milk production. Milk culture results comparing cows with major pathogens to those with no growth and minor pathogens combined were associated with statistically significant differences in 150 d milk. Milk production did not differ for cows with CMT results above and below a cut-off of trace, and for SCC results above and below cut-offs of 200,000, 300,000, and 400,000/mL, respectively. Statistically significant differences in milk production were found for cows above and below cut-offs for percentage neutrophils in milk and for absolute neutrophil counts. Associations were found for milk production and number of quarters (0, 1, 2, or 3 and 4 combined) above respective cut-offs for SCC, percentage neutrophils in milk, and absolute numbers of neutrophils in milk, but not for CMT. Milk production differed for cows experiencing any health event versus those with no health event. The most commonly recorded health event was clinical mastitis. Statistically significant associations were detected between health events and milk culture results, SCC, neutrophil percentage, and neutrophil absolute counts. Results of the present investigation indicate that milk monitoring on d 3 of lactation using milk neutrophil percentage or neutrophil absolute counts may be useful as an indication of subsequent milk production.

Rheology of the gel formed in the California Mastitis Test

The California Mastitis Test has previously been adapted for use in an inline, cow-side sensor and relies on the fact that the viscosity of the gel formed during the test is proportional to the somatic cell concentration. In this paper, the use of capillary and rotational viscometry was compared in light of the expected rheology of the gel formed during the test. It was found that the gel is non-Newtonian, but the initial phase of viscosity increase was not due to shear dependence, but rather due to the gelation reaction. The maximum apparent viscosity of the gel was shear dependent while the time it took to reach the maximum was not truly shear dependent, but was rather dependent on the degree of mixing during gelation. This was confirmed by introducing a delay time prior to viscosity measurement, in both capillary and rotational viscometry. It was found that by mixing the reagent and infected milk, then delaying viscosity measurement for 30 s, shortened the time it took to reach maximum viscosity by more than 60 s. The maximum apparent viscosity, however, was unaffected. It was found that capillary viscometry worked well to correlate relative viscosity with somatic cell count, but that it was sensitive to the reagent concentration. It can therefore be deduced that the rheology of the gel is complicated not only by it being non-Newtonian, but also by the strong dependence on test conditions. These make designing a successful sensor much more challenging.

Effect of chronic oxytocin-treatment on the bovine mammary gland immune system

The aim of this study was to evaluate the effect of chronic oxytocin (OT) treatment on the mammary gland immune system. In &lt;I&gt;Experiment I&lt;/I&gt; fourteen healthy cows were used to study the effect of chronic intramuscular (im) OT administration on concentration of milk somatic cells and white blood cells (WBC). Cows in the OT-group (6) were im injected with 50 IU OT (5 ml) whereas animals of the C-group (6) were im injected with 5 ml of saline (9 g/l) for eight days (Day 1–8) before each milking. Milk samples were taken during normal milking time on Day 0–3, 5, 7, 9–11 and 18. Blood samples were taken immediately after each milking and analysed for WBC count, polymorphonuclear neutrophils, potassium (K), sodium (Na) and chloride (Cl) ions, and blood lactose. All milk samples were analysed for somatic cell counts (SCC), lactose, Na, Cl and electrical conductivity (EC). Furthermore mRNA expression of tumor necrosis factor-&amp;alpha; (TNF&amp;alpha;), interleukin (IL)-1&amp;beta;, IL-6, IL-8 and cyclooxygenase-2 (COX2) in milk cells were measured via real-time RT-PCR. None of the investigated milk and blood parameters changed significantly in response to the OT treatment. The mRNA-expression of TNF&amp;alpha; decreased (&lt;I&gt;P&lt;/I&gt; &lt; 0.05) to a minimum on Day 3 in response to OT administration. IL-1&amp;beta; and IL-6-mRNA expression decreased (&lt;I&gt;P&lt;/I&gt; &lt; 0.05) to a minimum within three day. IL-8 and COX2 expression did not change in response to OT treatment. In &lt;I&gt;Experiment II&lt;/I&gt; twelve cows, randomly divided into two groups of six, were used to investigate the effect of chronic im OT administration on mammary tissue. Cows were im administered 50 IU OT (OT-group) or 5 ml saline (9 g/l; C-group) before each milking during eight days. Biopsy samples were taken after every morning milking. The mRNA expression of various inflammatory factors and the tight junction (TJ) proteins occludin (OCLN) and zonula occludens (ZO)-1, ZO-2 and ZO-3 were measured via real-time RT-PCR. TNF&amp;alpha;-mRNA expression decreased (Day 2 with &lt;I&gt;P&lt;/I&gt; &lt; 0.05) within the first four days of OT administration and increased (&lt;I&gt;P&lt;/I&gt; &lt; 0.05) in the C-group on Day 2. IL-1&amp;beta; expression levels of the OT-group increased transiently and decreased on Day 3 and in the C-group values increased significantly on Day 3 as compared to Day 0. IL-6 expression in the OT-group decreased (&lt;I&gt;P&lt;/I&gt; &lt; 0.05) to a minimum on Day 1 and increased (&lt;I&gt;P&lt;/I&gt; &lt; 0.05) as compared to Day 0 on Day 7 and increased significantly on Day 1 and Day 5 compared to Day 0 in group C. IL-8 and COX2 expression did not change in response to OT administration. The mRNA-expression of OCLN and ZO-3 decreased (&lt;I&gt;P&lt;/I&gt; &lt; 0.05) as compared to Day 0 with a minimum on Day 7. ZO-1 and ZO-2 expression did not change due to OT administration. ZO-2-mRNA expression in C-group decreased significantly on Day 2 compared to Day 0. In conclusion, chronic OT administration induced increasing SCC and EC levels in milk as well as K and lactose in blood while nearly all investigated cytokines in milk cells and mammary tissue were down regulated. The mRNA expressions of the TJ proteins OCLN and ZO-3 were down-regulated in response to the OT treatment what indicates an increasing TJ permeability. Besides the effect on TJ proteins there was no obvious change of the immunological competence of the mammary gland in response to OT. However, a more complete milk ejection should help to remove pathogens during milking.