Increase In Somatic Cell Count Research Articles

Differential somatic cell count in milk before, during, and after lipopolysaccharide- and lipoteichoic-acid-induced mastitis in dairy cows

Intramammary infections induce the initiation of the inflammatory response, resulting in an increase in somatic cell count (SCC) in milk. The SCC includes several different types of cells but does not differentiate between them. On the contrary, the new differential somatic cell count (DSCC) parameter allows for the differentiation between 2 groups of cells: polymorphonuclear neutrophils (PMN) and lymphocytes versus macrophages. Therefore, the aim of this paper was to describe the changes of both DSCC and SCC during mastitis induced by cell wall components from typical mastitis-causing pathogens [lipopolysaccharide (LPS), Escherichia coli; lipoteichoic acid (LTA), Staphylococcus aureus] known to trigger different severities of mastitis. In addition, the effect the glucocorticoid prednisolone (PRED), which is known to attenuate the immune response in the mammary gland, was investigated. Twenty dairy cows were equally divided into 5 groups and treated with LPS, LTA, LPS+PRED, LTA+PRED, or a saline control. Milk samples were taken at the following time points: baseline (d -3, -2, and -1), right before treatment (d 0), 5 h after treatment (d 0.2), early cure phase (d 1 and 2), and late cure phase (d 3, 4, 5, 6, 7, and 14) and analyzed for DSCC and SCC. Mean DSCC values increased significantly from <60% at baseline and right before treatment to >81% 5 h after treatment and the early cure phase in all groups, except for the groups control and LTA+PRED. This increase clearly reflects a shift in cell populations to predominantly PMN. The SCC increased significantly following the stimulation, too, as expected. Interestingly, we observed cases where SCC increased moderately only whereas DSCC showed an evident increase, meaning that the shift in cell populations occurred even at low SCC levels. The PRED clearly lowered the cell migration in group LTA+PRED. This is the first ever study investigating DSCC during induced mastitis under controlled conditions. The combination of DSCC and SCC could be employed for the earlier detection of mastitis by revealing the shift in cell population independent from the SCC level. Furthermore, combining DSCC and SCC information could help to determine the stage of mastitis because we observed high DSCC and SCC results in the early stage of mastitis but evidently lower DSCC and high SCC in the cure phase. Hence, our results offer the first fundamental insights on how mastitis monitoring could be improved in the frame of dairy herd improvement programs.

Experimentally induced subclinical mastitis: are lipopolysaccharide and lipoteichoic acid eliciting similar pain responses?

BackgroundPain accompanying mastitis has gained attention recently as a relevant welfare compromising aspect of disease. Adequate pain recognition and therapy are necessary in the context of a modern and ethically acceptable dairy care. For research purposes mastitis is often induced by intramammary infusion of immunogenic bacterial cell wall components. Lipopolysaccharide (LPS) from Escherichia coli and lipoteichoic acid (LTA) from Staphylococcus aureus are commonly administered to this end. While the immune response to specific immunogenic components has been well characterized, not much is known about their role on the expression of pain indicators. The aim of this study was to trial the effects of an intramammary challenge of LTA or LPS on the degree of pain and discomfort as indicated by both physiological and behavioral variables in cows. The hypothesis was that a similar degree of pain can be identified in LTA as well as in LPS induced mastitis.ResultsOn the challenge day, compared to pre-challenge, total pain index increased for all treatment groups (LPS; LTA and control), the LPS group having significantly higher values than the control group (P = 0.01). Similarly, pain visual analogue scale (VAS) increased significantly in all cows following treatment on the challenge day. Furthermore, compared to baseline, higher VAS were found 3, 4 and 5 h after the challenge in cows of the LPS group (P3h, 4h < 0.001 and P5h = 0.001) and 7 h after the challenge in cows of the LTA group (P7h = 0.002). In the control group, VAS was higher 5 h after the challenge (P5h = 0.001). On the challenge day, udder edema was higher in the LPS than in the control group (P = 0.007). Furthermore, 4 h after the challenge, milk cortisol was significantly higher than at baseline in the LPS group (P < 0.001).ConclusionsWhen administered at equipotent doses targeting a standard somatic cell count increase, intramammary LPS seems to be accompanied by a higher degree of pain and discomfort than LTA, as suggested by the modifications of the outcome variables total pain index, VAS, udder edema and milk cortisol.

Effect of incomplete milking on milk production rate and composition with 2 daily milkings

The primary aim of this study was to assess the effects of incomplete milking on milk secretion and milk composition at the quarter level. Twelve cows were enrolled beginning at 5 d in milk and remained on study through 47 d in milk. Half of each contralateral udder was incompletely milked (treatment), detaching the teat cup early to leave approximately 30% of the total milk yield behind. This target milk remaining in the gland was based on weekly calibration milking measurements of quarter total milk yield. Control quarters were milked completely until milk flow had decreased to 0 kg/min based on visual assessment. Harvested milk yield was measured twice daily at each milking, and milk components (fat, protein, lactose, solids nonfat, milk urea nitrogen) and somatic cell count, were measured twice weekly at the quarter level. The experimental unit in this design was the half-udder, and a mixed-model approach was used to assess the main and interactive effects of experiment week and treatment on milk production rate, milk remaining in the gland, and milk composition. The effect of treatment on milk production rate was significant, with the average control half-udder producing 0.97 kg/h and the treatment half-udder 0.73 kg/h. The effect of week on milk production rate and the interaction of week × treatment were also significant. The effect of treatment on milk remaining in the gland was significant, illustrating that an increase in milk remaining in the cisternal compartment had been achieved. We detected a significant decrease in milk lactose percentage in treatment half-udders, and a significant increase in somatic cell count (log10). The increase was relatively small, from a geometric mean of 26,300 cells/mL in control quarters to 48,300 cells/mL in treatment quarters. The decrease in milk production rate in treatment half-udders supports current knowledge about how mammary epithelial cell secretion, proliferation, and apoptosis are modulated by autocrine-paracrine factors.

Association of &amp;lt;i&amp;gt;TLR4&amp;lt;/i&amp;gt; and &amp;lt;i&amp;gt;CARD15/NOD2&amp;lt;/i&amp;gt; polymorphisms with SCC in Holstein–Friesian cattle

Abstract. Mastitis is one of the most important dairy cattle diseases which results in economic losses in dairy production. Mastitis cases can be classified as subclinical or clinical. All forms of mastitis lead to changes in milk composition and induce an increase in somatic cell count (SCC). SCC is a very important and basic indicator of udder health. An increase in SCC is usually caused by the immune response to the invasion of pathogens contributing to mastitis. The aim of this study was to investigate associations between the polymorphisms of selected genes (TLR4 and CARD15/NOD2) whose products are involved in the identification of pathogen-associated molecular patterns (PAMPs) during the innate immune response to infection, and immunity to mastitis expressed as SCC. The genes under study were also examined for epistatic effects as well as effects of interactions with parity and stages of lactation. In all the studied classes, allele G of TLR4 had a favourable additive effect with negative values, contributing to a lower lnSCC. Allele A of CARD15/NOD2 had a desirable additive effect which varied with time and the changing internal environment during lactation. With regard to the dominance effect, allele A of CARD15/NOD2 was found to be significantly associated with a higher SCC in milk in the first lactation and in the third stage of each single lactation. Moreover, statistically significant epistatic effects were found, in particular additive–additive and dominance–additive interactions were favourably associated with SCC which was lower than expected in the case of no epistasis.

Use of milk amyloid A in the diagnosis of subclinical mastitis in dairy ewes

Subclinical mastitis (SM) is one of the most important diseases affecting dairy ewes worldwide, with negative impact on the animal health, farm income and public health. Animals with SM often remain untreated because the disease may not be revealed. Increase in somatic cell count (SCC) and positive bacteriology for mastitis pathogens in milk samples are indicative of SM but the evidence of only one of these alterations must suggest an uncertain SM (UM). UM is defined when positive bacteriological examination (Latent-SM) or SCC>500000cells/ml (non-specific-SM) are detected in milk. Nevertheless, SCC and bacteriological examination are expensive, time consuming and are not yet in use at the farm level in dairy ewes. Recently, a sensitive acute phase protein, amyloid A, displaying multiple isoforms in plasma and different body fluids including mammary secretion (milk amyloid A-MAA), has been investigated as a marker of mastitis in cows and, in a few studies, in sheep. The aim of this trial was to compare the concentration of MAA of single udder-halves in ewes with healthy udder-halves (HU-control group) and naturally occurring subclinical mastitis, both confirmed (SM group) and uncertain (UM groups: Latent-SM and non-specific-SM), for monitoring udder health. The reliability of a specific ELISA kit for the measurement of MAA was also tested. During a 3-month trial period, 153 udder halves were assigned to the experimental groups based on their health status: 25 with SM, 40 with UM (11 with latent-SM and 29 with non-specific-SM) and 88 HU. SCC and bacteriological analysis were performed to establish the control and subclinical mastitis groups. MAA concentrations in milk samples were measured using a specific commercially milk ELISA kit. The data were submitted to statistical analysis. Significant (P<0·05) differences among the groups SM, non-specific-SM and HU were detected with the SM having the highest level and HU the lowest. MAA concentration is affected by the udder health status and is a useful indicator of subclinical mastitis and increased SCC in sheep.

Status of bovine mastitis and associated risk factors in subtropical Jeju Island, South Korea

The present investigation was carried out to study the prevalence of mastitis in 136 Holstein cows from a subtropical province of South Korea. Out of 527 milk samples studied, 22.6% were found positive for mastitis. On animal level, prevalence was estimated at 55.2%. Late lactating cows were at higher risk for mastitis development as compared to those in early and mid lactations. The study revealed that the risk of an increase in somatic cell count (SSC) and mastitis increased with advanced age and in animals with higher parity. The highest infection rate of 71.4% was found in the age group >9years followed by cows with higher than fifth parity (65.5%). On severity and quarter basis, cows of <3years of age had higher occurrence (12.5%) of severe mastitis. From the present study, it may be concluded that a positive relationship exists between increased prevalence of mastitis and high SCC and the advance in age and parity of Holstein cows.

Ovine subclinical mastitis: Proteomic analysis of whey and milk fat globules unveils putative diagnostic biomarkers in milk

Subclinical mastitis is one of the main causes of alteration in milk content and has a major impact on both animal welfare and economy in the dairy industry. A better knowledge is needed to understand the ovine mammary gland metabolism and its response to bacterial infection. In this study, the proteomic changes in ovine milk as a result of subclinical mastitis were investigated by comparing both whey and fat globule membrane profiles of samples from Staphylococcus chromogenes-positive individuals, with those from non-infected counterparts having high or low somatic cell count; the latter were used as control. 2-DE and combined MS procedures were utilized for this purpose. Although sample bromatological parameters were very similar, proteomic analysis highlighted significant differences between the three experimental groups. Most relevant changes were observed between samples of infected milk and control. Modifications related to the defense response of the mammary gland to the pathogen were evident, with important consequences on nutritional and technological properties of milk. On the other hand, quantitative protein changes between non-infected samples with low and high levels of somatic cells indicated that the latter may result as a consequence of a probable unpaired cellular metabolism due to cellular stress, hormonal variations or previous infections. Putative biomarkers useful for the monitoring of sheep mammary metabolism and for the careful management of ovine subclinical mastitis to avoid its clinical degeneration are proposed and discussed. Proteomics has been here applied to the differentiation of healthy and subclinical mastitic sheep milk samples, evidencing the response of the mammary gland to S. chromogenes infection. Presented results propose useful protein biomarkers for the detection of ewe mammary infection at its subclinical stages and, subsequently, mastitis recognition and treatment. Differently from bovine, these data confirm that the increase in somatic cell count in sheep milk is not always associated with protein factors that characterize the mammary gland infection; accordingly, somatic cell count cannot be considered as a useful parameter to certainly diagnose subclinical mastitis in ovine.

Short communication: Role of Mycoplasma arginini in mastitis caused by Streptococcus dysgalactiae

We performed a comparative study on the development of mastitis induced by Mycoplasma arginini or Streptococcus dysgalactiae after challenging the cows. Mycoplasma arginini did not cause any clinical symptoms on its own, resulting in only a transient increase of somatic cell count (SCC; increase ranging from 0.5×106 to 0.8×106 cells/mL) and a slight decrease of milk production (10%) for 5 d. In contrast, Strep. dysgalactiae induced more severe clinical signs in animals and SCC increased to 1.60×106 to 2.11×106 cells/mL for 10 d. In addition, milk production decreased (22.9 to 27.0%) for 10 d. After 3mo (2mo after the first challenge), animals that were challenged previously with M. arginini were rechallenged with Strep. dysgalactiae. Severe clinical mastitis developed, with very high SCC (5.00×106 to 21.5×106 cells/mL), and a very significant reduction of milk production (28.6 to 68.7%), which lasted more than 4wk, was observed. The severe clinical mastitis developed not only in cows inoculated with Strep. dysgalactiae andM. arginini in the same udder quarter but also in cows infected in the quarter previously not challenged with mycoplasma. Cows challenged first with Strep. dysgalactiae and rechallenged with M. arginini 2mo later developed only slight changes in both SCC and milk production, similar to those when the cows were challenged with M. arginini alone. We conclude that M. arginini infection does not cause remarkable mastitis (characterized by decrease in milk production and increase of SCC) but it significantly predisposes animals to infection with Strep. dysgalactiae, leading to severe clinical mastitis.

Improved Method for Mastitis Detection and Evaluation of Disinfectant Efficiency During Milking Process

In automatic milking systems, rapid methods to detect mastitis and also to prevent mastitis are very important since reduced milk quality and economic losses are the consequences of mastitis. Based on IDF Standard 148 a rapid and reliable method to detect somatic cell count with Coulter Counter technique was developed in this study and the efficiency of peracetic acid (PAA) to prevent bacterial cross-contamination was investigated using Escherichia coli as test microorganism. Besides conventional microbiological methods, flow cytometric analysis using carboxyfluorescein diacetate, thiazole orange, propidium iodide and DiOC2(3) were applied using E. coli as test organism to study the efficiency of PAA. Acceleration of mastitis detection method was realised using centrifugation for lipid separation of foremilk samples before Coulter Counter measurements. During inflammation, an increase in somatic cell count was detected by Coulter Counter with a peak at particle sizes between 8 and 12 µm. E. coli was reduced by 5.6 log cycles, 7.7 log cycles and 4.9 log cycles after 0.25% PAA treatment for 15 s at 0 °C, 10 °C and 20 °C. However, flow cytometric analysis showed that most of the cells are damaged but still have metabolic activity. The efficiency of PAA against mastitis-related bacteria was shown with plate count methods but flow cytometric analysis indicates that the cells may still have the potential to cause mastitis. The potential of Coulter Counter to detect somatic cell count within a short time was shown in this study. Important data regarding safety monitoring and quality control can be derived with this method.

Barium selenate supplementation and its effect on intramammary infection in pasture-based dairy cows

A significant proportion of cattle receive inadequate dietary Se because of its low content in soils and pastures of various regions of the world. Several economically important diseases in dairy cows, such as mastitis, have been associated with Se deficiency. The objective of this study was to evaluate the effect of a single injection of a long-acting form of Se at drying off on the risk and incidence rate of new intramammary infections and on milk somatic cell count in the subsequent lactation in pasture-based dairy cows. Forty-nine Chilean Holstein-Friesian cows were fed a diet containing <0.05mg of Se/kg of ration dry matter. During the dry period, cows were allocated to 1 of 2 groups, a supplemented (n=24) group treated with a single subcutaneous injection of barium selenate 2 mo before calving and a control group (n=25) that remained unsupplemented. Duplicate foremilk samples were aseptically collected within 6 d after calving and every 2 wk until drying-off for bacteriological culture. Milk samples were also collected monthly for somatic cell count evaluation. Blood samples were collected before treatment and at 30, 90, 180, and 270 d after treatment for analysis of blood glutathione peroxidase (GPx) activity. The activity of glutathione peroxidase was higher in supplemented cows 30 d after the injection until the end of the study. The risk and incidence rate of new intramammary infections was not affected by supplementation. A progressive increase in somatic cell count was observed throughout lactation, but there was no effect of supplementation. In conclusion, a one-time injection of barium selenate 2 mo before calving in these pasture-based dairy cows did not affect udder health in the subsequent lactation, indicating that Se basal intake was adequate for preventing subclinical mastitis in pasture-based cows in southern Chile.

Associations between bovine coronavirus and bovine respiratory syncytial virus infections and animal performance in Swedish dairy herds

To assess the economic impact of bovine coronavirus (BCV) and bovine respiratory syncytial virus (BRSV) infections, accurate estimates of their associated effects on animal performance are needed. This study aimed to quantify the variation in individual test-day milk yield and somatic cell count, risk of reproductive failure after first service of dairy cows, and risk of death of calves and heifers according to the BCV and BRSV status of the herd. Three types of status were defined for BCV and BRSV infections, based on 1) the dynamics over a 7-mo period of BCV- and BRSV-specific antibody levels in pooled milk of primiparous cows; 2) the possible occurrence of presumably BCV- and BRSV-related clinical outbreaks; and 3) the combination of both pieces of information. A total of 36,184 test days, 2,716 cows with a first service, and 4,104 calves and heifers in 65 Swedish herds were included in the analyses. Animal performance associated with BCV and BRSV infections was quantified using hierarchical mixed generalized and survival models, after adjustment for covariates known to influence the performance under study. A significant reduction in milk yield was observed for cows in presumably BRSV recently infected herds, as well as in herds having a presumably BRSV-related clinical outbreak (of 0.57 and 0.91kg/d, respectively), compared with cows in presumably infection-free herds. There was also a significant increase in somatic cell count (of 12,000 cells/mL) for cows located in herds with a BRSV outbreak. The risk of failure after first service, as well as the risk of death in calf and heifer, was numerically higher in BRSV-infected herds, although this was not statistically significant. In contrast, BCV infection herd status, as defined in the present study, was not significantly associated with any production losses in animals from infected herds compared with those in infection-free herds.

Effects of level and form of dietary zinc on dairy cattle performance and keratin production in the teat canal

The teat canal in dairy cows is lined with keratin, which is considered to be a natural physical and chemical barrier involved in providing resistance to bacteria gaining entry into the mammary gland. Keratin is partially removed during milking therefore requiring regeneration. It has been estimated that a cow needs to regenerate 1.3 mg per teat between each milking to replace the amount lost (Capuco et al., 1992). Zinc is important in the process of keratinisation and previous studies have reported an 2.4 kg/d increase in milk yield when supplemented with Zn in an organic form at the recommended level and an increase in somatic cell counts (SCC) in cattle receiving 0.66 of the recommended level of dietary Zn (Atkin et al., 2007), although mechanisms for this observation are unclear. The objective of this study was to establish the effect of level and form of Zn (organically chelated (Bioplex ZnTM; Alltech Inc., Nicholasville, USA) vs. inorganic (ZnO)) and no supplemental Zn on dairy cow performance and keratin production in the teat canal.

Introduction of automatic milking system in Finland effect on milk quality

When an automatic milking system (AMS) is introduced on a farm the milking of cows and related work is changed in many ways compared to farms with traditional milking systems. The objective of this paper was to study the effect of the introduction of robotic milking in Finland on the composition and hygienic quality of milk. The study was carried out on three farms which were the first in Finland to introduce the automatic milking system (Volontary Milking System™). Main chemical composition, somatic cell count, total bacteria count, freezing point, free fatty acids, as well as Bacillus cereus, Clostridium spores, psychrotrophic bacteria and coliforms were determined. After the introduction of the automatic milking system an increase in somatic cell count and total bacteria count, psychrotrophic bacteria and coliforms was observed; however, the differences were not statistically significant. The counts for Clostridium spores were at the same level in the automatic and the conventional milking system. Bacillus cereus counts were very low in both milking systems studied. Milk fat content and free fatty acids were elevated when AMS was introduced. The introduction of AMS resulted in a significant increase (P &lt; 0.01) in the freezing point during the first three months. Though there was a trend that the overall quality of milk was impaired after the introduction of AMS, the quality of milk remained at premium class.;

Influence of space allowance and housing conditions on the welfare, immune response and production performance of dairy ewes

The experiment used 45 Comisana ewes, divided into 3 groups of 15. The aim was to determine the effects of two different stocking densities and two different housing conditions on welfare, and on production performance of dairy ewes. The stocking densities tested were: high stocking density (1 x 5 m2/ewe, HD group) and low stocking density (3 m2/ewe, LD group); the two housing conditions tested were: ewes housed indoors (LD group, 3 m2/ewe) and ewes allowed to use an outdoor area (LDP group, 3 m2/ewe divided into 1 x 5 m2/ewe indoors and 1 x 5 m2/ewe outdoors). At the beginning of the experiment, and then every 2 months, the cell-mediated immune status of sheep was evaluated. One month after the beginning of the experiment, and 20 d later, the ewes were injected with chicken egg albumin (OVA) to assess their humoural immune responses. Starting from the beginning of the experiment and then monthly, behavioural activities of ewes were monitored using 15-min scans. After lamb weaning, milk yield from individual ewes was measured and milk composition analysed weekly. Housing conditions (low density reared ewes indoors v. low density reared ewes with free access to an outdoor area) affected cell-mediated response, which was higher in LDP than in LD ewes. Concentrations of anti-OVA IgG were mainly influenced by space allowance, with higher antibody titres in LD than in HD ewes throughout the experiment. Both housing conditions and space allowance affected sheep behavioural activities: a greater proportion of LDP ewes displayed standing and drinking behaviours than LD ewes, and a greater proportion of LD ewes was observed walking than HD ewes. Ewes allowed access to the outdoor area had a higher protein content and lower somatic cell count in their milk, whereas reduced space allowance led to a reduction in milk yield and an increase in somatic cell count of milk. Results indicate that both increased space allowance and availability of outdoor area can improve the welfare and production performance of the lactating ewe.

Practical Approach to Reducing the Incidence of Intramammary Infection in Heifers by Using Prepartum Systemic Tylosin Therapy

While mastitis in heifers is recognized as a problem, most dairymen often view heifers at parturition as free of intramammary infections (IMI) For example, in a survey (Bormet al, 2006) that included farms in seven states and one province, as many as 63% of heifers and 34% of their quarters had a IMI at calving. IMI during lactogenesis can impair mammary development and cause a decrease in milk yield in the productive life at the animal level. At the herd level IMI could cause an increase in somatic cell counts (SCC) and clinical mastitis cases. To prevent and treat IMI in heifers, infusion of antibiotics in the mammary gland before calving was proposed. However, systemic administration of antimicrobials to heifers before calving could offer advantages related to its relative lower cost and easier administration when compared to intramammary infusion. Tylosin offers an excellent diffusion into the mammary gland related to its basic pK, which results in a very high milk to plasma concentration ratio.

Influence of milking number and frequency on milk production in Martina Franca breed asses

Two experiments were carried out in Martina Franca asses in order to study milk yield and udder healthy conditions in relation to daily milking number and frequency. Experiment I - A total of 15 asses were subdivided into three groups (N.5) corresponding to: one milking per day, after a 3 hour interval from foal separation by dams (Group A); three milkings per day with 3 hour frequency (Group B); three milkings per day with 2 hour frequency (Group 3M). Experiment II - Evaluation was made of the effect of a schedule of 6 milkings per day with frequency of 2 hours on milk yield (Group 6M; N. 5), compared to Group 3M). Healthy udder conditions in relation to the number of milking per day was monitored in 3M) and 6M) Groups, by somatic cell count. Average yield per milking was highest (P<0.01) following 3 rather 1 milkings per day and with milking frequency of 3 hours rather than 2 hours (P<0.01). A schedule of six milkings per day did not improve mean milk yield and determined an increase in somatic cell count compared to 3 daily milkings regimen (63.2 vs 17.5 x 1000/mL; P<0.05).

Polymorphonuclear neutrophils and Escherichia coli proteases involved in proteolysis of casein during experimental E. coli mastitis

Abstract An Escherichia coli mastitis model was used to characterize enzymes involved in bovine mammary tissue damage and proteolysis in milk. One-quarter each of four cows were inoculated with a suspension (104 cfu mL−1) of E. coli P4:O32. Blood and milk were collected before inoculation and for 216 h afterwards. Intracellular elastase, collagenase and cathepsin activities were measured by flow cytometry of peripheral blood leukocytes and milk polymorphonuclear neutrophils (PMNs). Leukopenia occurred in peripheral blood 9 h after infection, concomitant with an increase in somatic cell count in milk. Milk PMNs had lower activity of cathepsins and collagenase than peripheral blood PMNs. In parallel, milk samples were studied by zymography, and several proteases were detected in mastitic milk. These activities increased after infection, to reach a peak in 6 h. However, total protease profiles and plasmin activities differed. It was concluded that proteases released by PMNs and E. coli contribute to proteolysis of casein during mastitis, as well as plasmin.

Bovine protothecal mastitis: a review.

Abstract Bovine mastitis is a multi-aetiological ailment that accounts for the immense economic losses due to fall in milk production and poor quality of milk as well as therapeutic expenditures. Bovine protothecal mastitis is caused by Prototheca zopfii and P. wickerhamii and has been reported in most of the countries of the world. Dirty environment and lack of hygiene in herd play a vital role in transmission of the malady. Faeces from infected cows transmit the organisms into environment. Age, stage of lactation, host's immune status and previous exposure to treatment as well as other ailments predispose the animal to the disease. Multiplication of the organisms in the mammary gland and regional lymph node results in damage of mammary parenchyma leading to fall in milk yield and, sometimes, drying of infected quarters. Organisms infrequently disseminate from the site of lesion to visceral organs. Though intense inflammatory reaction is not seen in protothecal mastitis, still induration, fibrotic hard udder, fall in milk yield with presence of clots in milk and increase in somatic cell count are commonly associated with algal mastitis. Diagnosis is usually accomplished by selective isolation and light microscopic demonstration of the organism, which can be further aided by carbohydrate and alcohol assimilation test, fluorescence microscopy, fine needle aspiration associated with electron microscopy or detection of antibodies by counter-flow electrophoresis. Poor sensitivity of the organism to the conventional antibiotics limits their use in treatment. Antifungals like nystatin, amphotericin, polymyxin, miconazole as well as levamisole tetramisole proved beneficial to some extent. Eradication of the pathogen from herd is a difficult and practically an impossible task, leaving only preventive measures as the resort for controlling the disease.

Isolation and characterization of two anti-staphylococcal bacteriophages specific for pathogenic Staphylococcus aureus associated with bovine infections

The aim of this study was to isolate and characterize bacteriophages against bovine Staphylococcus aureus associated with mastitis. We describe the isolation of two anti-staphylococcal phages namely DW2 and CS1 from farmyard slurry. Both phages were characterized by electron microscopy and restriction analysis and shown to belong to the Siphoviridae family. CS1 and DW2 were lytic for representatives of all three clonal groups of Irish mastitis-associated staphylococci. These phages were compared with the previously characterized Myoviridae phage K. Infusion of a cocktail of all three phages at 10(8) PFU ml(-1) into live cow teats resulted in no detectable increase in somatic cell counts in milks indicating that the phages did not irritate the animal. Two new anti-staphylococcal phages CS1 and DW2 were isolated and characterized and tested for immunogenicity in animal teats. The phages isolated in this study are active against pathogenic S. aureus and may be incorporated into teat-dips or teat-washes as a non-antibiotic prophylaxis against staphylococcal bovine mastitis.

Bovine ephemeral fever in a dairy cattle herd in the Jordan Valley

BOVINE ephemeral fever (BEF), caused by the BEF virus (family Rhabdoviridae, genus Ephemerovirus), is a short-term inflammatory disease which affects cattle (Uren and others 1992). The BEF virus life cycle is maintained through a vectorhost system, probably involving mosquitoes and cattle (Walker and Boreham 1976). The viral agent has been isolated from various species of midges and mosquitoes, which probably act as vectors (Mellor 1996, Venter and others 2003). However, there is no evidence to suggest which vector species can transmit the BEF virus. BEF is spread by movement of the host or by vectors (St George 1988, Murray 1997). It is most likely that windborne carriage of infected insects over large distances is responsible for the spread of BEF in various countries (Newton and Wheatley 1970, St George 1988). It is becoming increasingly apparent that BEF occurs as a direct result of disruption of the normal functioning of the physiological and immunological systems of the host (Uren and others 1992). The clinical signs and pathological changes are a reflection of the effect of the growth of the virus and the host’s response (Burgess and Spradbrow 1977). Significant economic losses in dairy cattle herds may result from morbidity, reduced milk production (Newton and Wheatley 1970, Theodoridis and others 1973, Davis and others 1984, Wenbin and others 1991, Nandi and Negi 1999, Yeruham and others 2002), an increase in somatic cell count (Yeruham and others 2003), abortions (Wenbin and others 1991, Nandi and Negi 1999, Yeruham and others 2003) and mortality (Newton and Wheatley 1970, Uren and others 1989, Yeruham and others 2003). However, there is little information on whether the fertility of dairy cattle is affected, particularly under a subtropical climate. This short communication describes the morbidity, mortality and reproductive failure caused by outbreaks of BEF in a high-yielding dairy cattle herd in the Jordan Valley in Israel in 1999 and 2001. Field observations were carried out during 1999 and 2001, at the Gilgal kibbutz , which is located in the Jordan Valley (32°00′N, 35°26′E). This is a part of the Rift Valley and forms a part of the leeside dry lands east of the hill region; it belongs to the Irano-Turanian zoogeographical zone. The region is semiarid with a mean annual precipitation of 189 mm. BEF outbreaks had occurred in a Holstein-Israeli dairy herd comprising 480 animals with an average of 200 lactating cows. The lactating cows were divided into three groups, heifers, first calvers and cows; dry cows and heifers were kept in separate sheds. The herd was kept under a zero-grazing management system, and each lactating cow produced an average milk yield of 10,200 kg/year. The herd was visited twice weekly by the attending veterinarian, and morbidity, mortality, fertility, number of abortions, milk production and somatic cell counts were recorded by computerised dairy management systems. Oestrus was detected by pedometers and visually, three times daily, and the cows in heat were inseminated artificially every morning. The conception rate was then compared with data from the same herd during the three years before the 1999 BEF outbreak (1996 to 1998), and the year after the 2001 outbreak (2002). Cases of BEF were diagnosed clinically. Viruses were isolated from cattle which had severe disease incursions at Veterinary Record (2005) 156, 284-286