Severe Clinical Mastitis Research Articles

Ewe characteristics associated with neonatal loss in Norwegian sheep

A case–control study was conducted to identify ewe characteristics that affect the risk of a ewe losing at least one lamb during the first 5 days post lambing. Data were from a national sheep registry, and only ewes that lambed in the spring of 2010 belonging to flocks that reported disease events were included. Ewes registered with abortion or stillbirth were excluded. Cases (n=4850) and controls (n=85,354) from 1153 flocks were studied using logistic regression models, accounting for within flock correlation. The odds of losing at least one lamb increased substantially when litter size exceeded two. For example, in 3-year-old ewes, the odds were 6 times greater for those with 3 lambs than for those with 1 lamb. However, the effect of litter size depended on the age of the ewe; for example for ewes giving birth to triplet lambs, the odds of losing at least one lamb were 2.7 times greater in 1-year-old ewes than in 3-year-old ewes. Dystocia was associated with increased risk of losing at least one lamb, but the effect varied by litter size. In ewes with single lambs, the odds of lamb loss were 5 times greater in those that experienced dystocia than in those that did not, while within subgroups of ewes with twins, triplets or >3 lambs, the corresponding odds ratio (OR) of losing one or more lambs was 2.2, 1.5 and 1.3, respectively. Compared with ewes of the Norwegian White breed, ewes of old Norwegian breeds were less likely to lose lambs (OR=0.8). We also examined the effects of several diseases experienced by the ewe during pregnancy or shortly postpartum on the risk of subsequent neonatal lamb loss. Significantly increased risk was found for ewes with abdominal hernia (OR=2.5) and for ewes treated for moderate to severe clinical mastitis (OR=1.6) when compared with ewes without these disorders. In conclusion, our large study population allowed for a detailed analysis of the combined effect of important ewe factors that affected survival of their lambs in the early neonatal period.

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.

Complete Genome Sequence of Corynebacterium pseudotuberculosis I19, a Strain Isolated from a Cow in Israel with Bovine Mastitis

This work reports the completion and annotation of the genome sequence of Corynebacterium pseudotuberculosis I19, isolated from an Israeli dairy cow with severe clinical mastitis. To present the whole-genome sequence, a de novo assembly approach using 33 million short (25-bp) mate-paired SOLiD reads only was applied. Furthermore, the automatic, functional, and manual annotations were attained with the use of several algorithms in a multistep process.

CTX-M1 ESBL-Producing Klebsiella pneumoniae subsp. pneumoniae Isolated from Cases of Bovine Mastitis

Escherichia coli and Klebsiella spp., followed by Serratia spp. and Enterobacter spp., are the most frequent Gram-negative pathogens isolated from bovine clinical mastitis (8). The incidence of mastitis due to such bacteria has increased in recent years (7). Klebsiella is usually referred as particularly aggressive and prone to cause severe clinical mastitis, which responds poorly to treatment and is likely to have a fatal outcome (6, 13). Klebsiellae are defined as germs that easily produce enzymes like extended-spectrum β-lactamases (ESBL), thanks to their ability to survive longer than other Gram-negative rods in the environment and on the skin and, in particular, to allow ESBL genes to evolve (9). At the onset of clinical mastitis, it is impossible to identify the causative agent; thus, it is necessary to use broad-spectrum intramammary preparations which contain narrow- to extended-spectrum cephalosporins, alone or in combination with other antibiotics (1). The broad-spectrum cephalosporin ceftiofur is used as well in supportive systemic therapy (6). Few recent works have studied Klebsiella isolation and ESBL detection in veterinary medicine (2, 16), and no data are available describing ESBL-mediated resistance in Klebsiella spp. isolated from bovine mastitis. In this research, the antimicrobial susceptibility and ESBL production were evaluated in Klebsiella pneumoniae isolated from animals with bovine clinical mastitis and selected for their resistance to ceftiofur, a broad-spectrum cephalosporin. Susceptibility to a range of antimicrobials, including those approved for both human and animal use (Table ​(Table1),1), was determined by disk diffusion assay according to Clinical and Laboratory Standards Institute interpretative criteria (3). Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 were used as quality control standards. TABLE 1. Comparison of resistance profiles of the nine isolates From March 2008 to March 2009, 140 klebsiellae were isolated from milk samples, representing 26.6% of the total number of Gram-negative isolates obtained from bovine clinical mastitis. The isolates were subcultured on MacConkey agar supplemented with 8 μg/ml of ceftiofur (5). Nine isolates, identified as Klebsiella pneumoniae, were able to grow in the presence of 8 μg of ceftiofur. All Klebsiella pneumoniae isolates were screened against the panel in Table ​Table11 by the disk diffusion method and for ESBLs by the double-disk diffusion assay. A strain was considered an ESBL producer when it showed the expansion of an inhibition zone between a disk containing amoxicillin-clavulanate (20 and 10 μg) and disks containing, respectively, ceftazidime (30 μg) and cefotaxime (30 μg) placed 25 mm apart (10). All Klebsiella pneumoniae isolates were tested by PCR targeting the Ambler class A β-lactamase genes blaSHV, blaTEM, and blaCTX, identified in Klebsiella pneumoniae animal isolates (16), using previously published primer sets (14, 15). Sequencing of amplified genes completed the study. The complete resistance profiles and the PCR results are summarized in Table ​Table1.1. Only isolate 205, identified as Klebsiella pneumoniae subsp. pneumoniae, had a positive result to the double-disk test and was resistant to all the β-lactams, including cefotaxime and ceftriaxone, and sensitive to amoxicillin-clavulanate. The amplification of a CTX-M class enzyme-encoding gene confirmed such a phenotype, and sequencing of the gene identified the blaCTX-M1 group. To our knowledge, it is the first report about a CTX-M1 enzyme produced by a Klebsiella pneumoniae subsp. pneumoniae isolate in a case of bovine clinical mastitis. Isolate 205 also displayed a positive PCR result for genes blaSHV and blaTEM, and so did isolates 204 and 251. A previous randomized search detected only ESBL-producing E. coli and no Klebsiella spp. (11). The generally low level of in vitro resistance and the low prevalence of ESBL-producing strains (0.7%) should guarantee a good outcome of drug treatment for Klebsiella involved in mastitis, but antimicrobial resistance is not the only factor affecting therapy efficacy (1, 4). However, the described isolation must encourage that attention be paid to a phenomenon which could evolve and be enforced under the pressure of antimicrobial therapy, as the use of extended-spectrum cephalosporins in veterinary medicine may select ESBL producers (12). It is recommended to screen klebsiellae from cases of bovine mastitis in order to keep the prevalence of ESBL producers under control.

Somatic cell scores and clinical signs following experimental intramammary infection of dairy cows with a Staphylococcus aureus small colony variant ( S. aureus SCV) in comparison to other bovine strains

A recently isolated bovine Staphylococcus aureus small colony variant (SCV) was shown to persist within cultured endothelial cells. However, the clinical importance of S. aureus SCV in persistent infection of the mammary gland is unknown. The hypothesis tested here was a naturally occurring bovine S. aureus SCV, Heba3231, and a Newbould hemB mutant that was an artificially created SCV would establish mild intramammary infection and induce a different host response compared to their isogenic parental strains, 3231 and Newbould 305. Four groups of clinically healthy cows, 5 cows/treatment group, were infected by the intramammary route with SCV Heba3231, strain 3231, the hemB mutant or strain Newbould 305. Three quarters of the mammary gland of each cow were challenged with ∼5000 colony-forming units of bacteria and the fourth quarter was infused with PBS. Cows were monitored and assigned clinical scores for the first 5 days post-challenge based on rectal temperature, appetite, milk yield, udder uniformity, milk appearance, bacterial culture of foremilk samples and somatic cell score (SCS). All cows were examined for chronic infection up to day 36 post-challenge. Cows challenged with SCV strains developed mastitis that was mild compared with that induced by the parent strains. Cows challenged with strain 3231 developed the most severe clinical mastitis. SCS from all treatment groups were significantly ( P < 0.05) higher at days 2–5 and 14–36 post-infection compared to day 0 before challenge. This milder host response to SCVs may represent an adaptation of S. aureus to the mammary gland environment.

Effect of hyperimmunization with an Escherichia coli J5 bacterin in adult lactating dairy cows

To determine the effect of hyperimmunization with an Escherichia coli J5 bacterin on serum IgG2 concentration, incidence of clinical mastitis, and rate of survival to the end of the lactation period (ie, day 305) in adult lactating dairy cattle. Randomized controlled trial. 1,012 Holstein cows in their second lactation and greater. All cows were given 3 doses of the J5 bacterin; cows in the hyperimmunization group were given an additional 3 doses during the first 3 months of lactation. Blood was collected from a small sample of cows to determine anti-J5 IgG2 concentrations. Cows in the hyperimmunization group had higher mean serum anti-J5 IgG2 concentrations than did control cows 28 days after administration of the fourth, fifth, and sixth doses of the J5 bacterin. However, mean serum anti-J5 concentrations during the subsequent lactation were not significantly different between groups. The proportions of cows that developed clinical mastitis were not significantly different between groups. However, control cows were more likely to have severe clinical mastitis than were cows in the hyperimmunization group. The percentage of control cows that remained in the herd to day 305 was significantly lower than the percentage of cows in the hyperimmunization group that did. Results suggested that hyperimmunization of mature lactating dairy cattle was associated with increased serum anti-J5 IgG2 concentrations and decreased incidence of severe clinical mastitis, but did not alter survival rate of cows that developed severe clinical mastitis.

Comparison of J5 Vaccinates and Controls for Incidence, Etiologic Agent, Clinical Severity, and Survival in the Herd Following Naturally Occurring Cases of Clinical Mastitis

Holstein dairy cattle in 3 commercial herds were randomly allocated to J5 vaccination (n=251) or untreated control (n=306) groups. There were 221 new cases of clinical mastitis (CM) affecting 120 cows. Coliform mastitis cases had a higher percentage of severe quarter swelling or signs of systemic illness among control cows but not among J5 vaccinates, in comparison to noncoliform cases. Culling or death from CM affected 13 controls (4.3%) and 4 vaccinates (1.6%), with losses occurring earlier in lactation among controls, a higher hazard (probability of a cow dying on each day of lactation) for controls than vaccinates. The J5 vaccination was significantly associated with protection from culling for mastitis among the 15 Klebsiella cases; 2 out of 10 (20%) Klebsiella-infected controls were culled and 0 out of 5 vaccinates were culled. Cows in second lactation were at reduced hazard of culling for mastitis compared with older animals, even when adjusting for effects of J5 vaccination. When all CM cases (including subsequent new cases during the same lactation and multiple quarters or pathogens within the same cow on the same day) were evaluated, for the 221 cases of CM, the rate was significantly higher among vaccinates than controls (0.10 and 0.07 cases/30 d in milk, respectively). This was because J5 vaccinates had more subsequent new cases of CM in the same cow than controls. Pathogens isolated, which included mainly environmental bacteria, were not different among J5 vaccinates and controls. Immunization with J5 was associated with protection against severe clinical coliform mastitis signs, culling, and death loss from CM but not with any reduction in overall CM.

Bovine blood neutrophil acyloxyacyl hydrolase (AOAH) activity during endotoxin and coliform mastitis

The dynamics of blood neutrophil acyloxyacyl hydrolase (AOAH) activity, the appearance of endotoxin (lipopolysaccharide, LPS) in blood and the role of blood neutrophil AOAH in the severity of Escherichia coli and endotoxin mastitis were investigated in early postpartum dairy cows experimentally challenged with either endotoxin (n = 6) or E. coli (n = 6). The AOAH activity of blood neutrophils started to decrease significantly at post challenge hours (PCH) 6-24 and 12-24 in the endotoxin and E. coli-challenged groups, respectively; it returned to pre-challenged values at PCH 48 in both endotoxin- and E. coli-challenged groups. The cows were classified as moderate and severe responders according to milk production loss in the non-challenged quarters at PCH 48. There were no severe responders in the endotoxin-challenged group. In the E. coli-challenged group, only 1 severe responder was identified. The pre-challenge neutrophil AOAH activity of the severe responder was approximately 30% lower than that of moderate responders. No LPS was detected in the plasma of endotoxin-challenged cows; neither was it found in the plasma of moderate responders in the E. coli-challenged group at any PCH. However, at PCH 6, a remarkable amount of LPS was detected in the plasma of the severe responder from the E. coli-challenged group. Furthermore, neutrophil AOAH activity was increased by approximately 70% in the severe responder at PCH 6, but it increased by only approximately 15% in moderate responders. This was followed by a decreased neutrophil AOAH activity at PCH 12-24 and 24-72 in moderate and severe responders, respectively; the decreased AOAH activity at those PCH was more pronounced in the severe responder. The pronounced decreased neutrophil AOAH activity during mastitis often coincided with extreme leukopenia, neutropenia and a maximal number of immature neutrophils in the blood. Our results demonstrate that a decrease in neutrophil AOAH activity results in the appearance of LPS in the blood, and low blood neutrophil deacylation activity could be considered as a risk factor for severe clinical coliform mastitis.

Physiology of the periparturient period and its relation to severity of clinical mastitis

Incidence of clinical mastitis is highest at drying off and during the periparturient period. Intramammary Escherichia coli infection in high-yielding cows can show a severe clinical response during the early post-partum period. Severe clinical mastitis is mainly determined by cow factors, in particular the functionality of the circulating polymorphonuclear leukocytes (PMN) which are recruited to the mammary gland during the inflammatory reaction. There is a co-incidence between the periods of highest incidence of clinical mastitis and specific structural changes in the mammary gland. During the periparturient period, marked changes in various systemic and local hormones are related to the secretory state of the mammary gland epithelium (lactogenesis). Estrogen and progesterone induce proliferation of the mammary epithelium throughout gestation and act as survival factors in different tissues, although conflicting data have been reported on their effect on PMN oxidative burst. Somatotropin (STH), responsible for maintenance of lactation in ruminants, has been shown to positively influence innate immunity and a more rapid recovery in milk production of severely affected animals. The concentration of STH, and as a result also IGF-I levels is, however, quite low during early lactation. IGF-I and its regulating binding proteins are associated with cell survival, modulation of apoptosis and functionality of PMN in humans. During early lactation, bio-availability of IGF-I is decreased, which might reduce its stimulating effects on PMN quality and functionality. PRL, concomitantly known as a lactogenic hormone and an immunoregulatory cytokine, has also been associated with modulation of the immune system. It is expected that in periparturient animals, hormone changes could interfere with the immune response and the clinical response of mastitis.

ITIH4 (inter-alpha-trypsin inhibitor heavy chain 4) is a new acute-phase protein isolated from cattle during experimental infection.

We have isolated from calf serum a protein with an apparent M(r) of 120,000. The protein was detected by using antibodies against major acute-phase protein in pigs with acute inflammation. The amino acid sequence of an internal fragment revealed that this protein is the bovine counterpart of ITIH4, the heavy chain 4 of the inter-alpha-trypsin inhibitor family. The response of this protein in the sera was determined for animals during experimental bacterial and viral infections. In the bacterial model, animals were inoculated with a mixture of Actinomyces pyogenes, Fusobacterium necrophorum, and Peptostreptococcus indolicus to induce an acute-phase reaction. All animals developed moderate to severe clinical mastitis and exhibited remarkable increases in ITIH4 concentration in serum (from 3 to 12 times the initial values, peaking at 48 to 72 h after infection) that correlated with the severity of the disease. Animals with experimental infections with bovine respiratory syncytial virus (BRSV) also showed increases in ITIH4 concentration (from two- to fivefold), which peaked at around 7 to 8 days after inoculation. Generally, no response was seen after a second infection of the same animals with the virus. Because of the significant induction of the protein in the animals in the mastitis and BRSV infection models, we can conclude that ITIH4 is a new positive acute-phase protein in cattle.

A New Rapid, On-Site Test for Detection and Major Classification of Bacteria in Milk from Cows with Moderate and Severe Clinical Mastitis

new simple diagnostic test has been developed for rapid on-site detection of bacteria in bovine milk samples. The procedure can be performed in less than 5 minutes, and detects bacteria in milk samples, in addition to providing information about Gram staining features. Prior to application on a filter device, a small volume of milk (500 μl) is mixed with an equal volume of a solubilising reagent and heated for a few second under hot tap water to increase filterability. The mixture is pre-filtered through a hydrophobic mesh to remove clumps or debris, and to reduce fat content. drop of the pre-filtered mixture is thereafter filtered through a porous polysulfone membrane, placed in a vertical flow-through device, with a pore size retaining and concentrating bacteria from the sample. Vertical flow through the polysulfone membrane is achieved by placing an absorptive media directly under the membrane. Any bacteria concentrated on the surface of the membrane are visualized by staining with a cationic dye (toluidine blue) and can be directly read as a blue coloured spot, by the naked eye. Following staining, and confirmation of bacteria in the sample, a drop of ethanol-acetic acid mixture (pH 2.83.0) is put on the same membrane, to cause decolourisation of Gram-negative bacteria, whereas Gram-positive bacteria retain the stain. The method is simple to perform, and does not require heat fixation, electrical power, microscopic examination or specially trained personnel. Detection limit was determined using over-night cultures of S.aureus and E. coli, diluted in milk from a mastitis free cow, and was found to be 5x106 for S.aureus and 1x106 bacteria/ml for E. coli, respectively. The test described, identified correctly bacteria in 51 of 55 milk samples from cows with moderate or severe clinical mastitis, giving an accuracy of 93%, and a sensitivity of Gram classification in the same samples found to be positive for bacteria (48 samples), of 94%. Using a flow through device, instead of a syringe filter, makes the assay more user-friendly and enables immediate confirmation of a positive staining and Gram status, without the need of cumbersome opening and remounting of a syringe-filter housing. This new rapid method should therefore be a useful on-site aid for the veterinarian in optimising the use of antibiotics in therapy of moderate and severe clinical For additional information, reference is also made to the oral presentation by Siamak P. Yazdankhah; A rapid method for detection of Gram-positive and -negative bacteria in milk from cows with moderate and severe clinical mastitis. Abstracts – Poster presentations at 11th ICPD 271

Development of a Rapid Method for Detection of Gram-Positive and -Negative Bacteria in Milk from Cows with Severe and Moderate Clinical Mastitis

Development of a Rapid Method for Detection of Gram-Positive and -Negative Bacteria in Milk from Cows with Severe and Moderate Clinical Mastitis

Efficacy of Systemic Ceftiofur as a Therapy for Severe Clinical Mastitis in Dairy Cattle

The objectives of this study were to determine the efficacy of intramuscular administration of ceftiofur to reduce the incidence of case-related death and culling following severe clinical mastitis in lactating dairy cattle. A total of 104 cows with severe clinical mastitis (systemic signs) were enrolled in the study and randomly assigned to one of two treatment groups. Immediately after detection of the case, one group was administered 2.2 mg/kg of ceftiofur intramuscularly, and the dose repeated at 24-h intervals for a total of five doses. The second group of cows did not receive systemic antibacterial therapy. Additionally, all cows in both treatment groups received intramammary pirlimycin (Pirsue®) in the affected quarter every 24h for a total of up to three doses. Also at the onset of the case, all cows on the trial were administered a supportive therapeutic regimen of fluids and anti-inflammatory agents that varied from farm to farm, but was standard within each herd at the discretion of the herd manager and veterinarian. Of all cases 14/104 (13.5%) resulted in a lost cow (died or culled). The proportion of cases that resulted in a lost cow and were treated with ceftiofur (4/51; 7.8%) did not statistically differ from cows that were not treated with ceftiofur (10/53; 18.9%). However, the proportion of cases that resulted in lost cows was higher for those cases that yielded a coliform organism on culture (14/56; 25.0%) than cases that did not yield coliforms (0/48; 0.0%; P<0.001). Thus, among coliform cases, cows that were not treated with ceftiofur were more likely to be culled or die (10/27, 37.0%; P<0.05) than cows treated with ceftiofur (4/29, 13.8%). We conclude that intramuscular administration of ceftiofur did not affect the outcome of severe clinical mastitis when all etiologic agents are included in the analysis. However, for severe clinical mastitis cases caused by coliform organisms, ceftiofur therapy reduced the proportion of cases that resulted in cow death or culling. This benefit may be realized because of the amelioration of bacteremic-related pathogenesis.

Study of clinical mastitis in British dairy herds with bulk milk somatic cell counts less than 150,000 cells/ml

A 12-month prospective study of clinical mastitis was conducted in 482 British dairy herds with a bulk milk somatic cell count (BMSCC) of less than 150,000 cells/ml. The mean proportion...

Health disorders and their association with production and functional traits in Holstein Friesian cows

Logistic regression models were used for studying the relationships between milk yield, body condition score (BCS), somatic cell score and some disorders of periparturient cows (mammary edema and retained placenta) with the occurrence of ovarian cysts, clinical mastitis and lameness. Data from milk recording (milk yield and somatic cell content) collected at nearly monthly intervals (time period: 35 ± 3 d) were merged with BCS recorded on the same dates of milk recording on periparturient heifers, lactating and dry cows, and with health disorders data (retained placenta, severe mammary edema, ovarian cysts and clinical mastitis and lameness) collected during regular herd activities over nearly 3.5 years. Data were from one commercial herd consisting of over 200 lactating dairy cows and exhibiting an average 305-d milk yield of nearly 10,000 kg. A total of 5,315 records from 728 lactations and 429 cows were used in the analyses. The time period incidence rate was 11.9%, 6.6% and 4.6% for ovarian cysts, lameness and mastitis, respectively, and the lactational incidence rate was 44.1%, 33.4% and 28.1% for ovarian cysts, lameness and mastitis, respectively. Occurrence of both ovarian cysts and mastitis was more common in the early lactation than afterwards, whereas lameness tended to occurr erratically during lactation. The risk of occurrence of mastitis and lameness was lower in primiparous when compared to multiparous cows. The increase of milk yield increased the risk of occurrence of ovarian cysts (odds ratio: 1.32, P < 0.01) and of mastitis (odds ratio: 1.12, P < 0.10), whereas no significant relationship was found between milk yield and lameness. An increase of somatic cell score was found to be a risk factor for mastitis (odds ratio: 1.36, P<0.01) and for the occurrence of lameness (odds ratio: 1.06, P<0.05). The occurrence of relative risk of disorders was not related to BCS at calving, and monthly variation of BCS was related to the onset of mastitis only. Retained placenta did not appear to present a risk factor for the occurrence of diseases of concern, whereas the presence of severe mammary edema at calving increased the risk of mastitis occurrence by nearly 50%. Regular recording of herd health data seems advisable for a better understanding of the relationships between production and functional traits and the occurrence of health disorders.

Cow status monitoring (health and oestrus) using detection sensors

Abstract In-line sensors were used to measure quarter milk conductivity and milk temperature in the milking claw for monitoring mastitis in dairy cows. In a preliminary experiment, sensor data were used to develop algorithms and threshold values for the detection of mastitis. In a later experiment, these thresholds were implemented in a monitoring system. Thresholds were determined in order to detect severe (clinical) mastitis in an early stage and subclinical mastitis, respectively. Daily milk yield and temperature served to establish the severity of mastitis. Nearly all cases of clinical and 50% of the cases of subclinical mastitis were detected. From results of measurements it appeared that onset and cessation of oestrus-related mounting activity could be predicted by pedometers. This information was used to correlate oestrus-insemination interval and conception rate. The probability of conception was highest between 6 and 17 h after increased pedometer activity with an estimated optimum at 12 h. To improve the reliability a detection model has been developed to process the measured variables in a combined way. It can be concluded that the detection model improves the sensitivity of oestrus detection by 10–20%. The sensitivity of detection of clinical and subclinical mastitis appeared to be 90% and 76%, respectively. However, the demands concerning the specificity (defined as: percentage of truly negatives indicated correctly) may not be met.

Acute phase response in heifers with experimentally induced mastitis.

Ten pregnant heifers were inoculated in both hind udder quarters with a mixture of Actinomyces pyogenes, Fusobacterium necrophorum and Peptostreptococcus indolicus. Development of the experimental mastitis was monitored by sequential clinical and bacteriological examinations, and by blood acute phase protein profiles. Sequential changes in plasma fibrinogen, serum haptoglobin, acid-soluble glyco-proteins and alpha 1-proteinase inhibitor activity were analysed and compared with both the clinical and bacteriological findings and the final outcome of the disease after calving. All ten heifers developed moderate to severe clinical mastitis. Four recovered completely, had a normal lactation after calving and exhibited only transient fever and moderate local signs. In six of the heifers the course of the disease was severe, and the inoculated quarters failed to produce milk after calving. The acute phase response of the four heifers that recovered was also significantly milder than that of the other six heifers. Haptoglobin and acid-soluble glycoproteins were most effective in indicating the severity of the infection and predicting the final outcome of the disease. Fibrinogen was a reliable indicator for detecting the presence of bacterial infection in all heifers. alpha 1-Proteinase inhibitor activity was of low diagnostic value in this study.

An outbreak of Corynebacterium pseudotuberculosis infection in an Israeli dairy herd

An outbreak of Corynebacterium pseudotuberculosis infection in an Israeli dairy herd appeared in four clinical forms: cutaneous, mastitic, visceral and a mixed form. Only cows were affected and susceptibility increased with age. Most cases occurred during a short period in the summer months. The total morbidity rate was 13.7 per cent involving 41 cows. Thirty cows were affected by the cutaneous form, five by the mastitic form, four by the mastitic and cutaneous forms, one by the mastitic and visceral forms and one by the visceral form. The cutaneous form appeared as one or two pyogranulomatous lesions affecting the body or head. Subclinical to severe clinical mastitis was found in the mastitic form. In the visceral form the upper and lower respiratory system were affected by multiple purulent lymphadenitis. All the cutaneous lesions recovered irrespective of treatment. Mastitis did not respond to treatment and severely affected milk production in most cases. All the isolates of C pseudotuberculosis were nitrate reductase negative. Most isolates were sensitive to norfloxacin, cephalothin, methicillin, kanamycin and furazolidone and resistant to ampicillin, lincomycin and neomycin.

Possible Effects of Dihydroheptaprenol on Neutrophil Function of Postpartum Dairy Cows

The parturient cow is highly susceptible to environmental mastitis. Severe clinical mastitis may occur shortly after parturition and is more severe than most cases of mastitis occurring in mid and late lactation periods (3). The enhanced susceptibility to mastitis may be attributable to the suppression of host defense mechanisms (3,4). The function of neutrophils is important for protection in the early phase of infection. However, little data are available on the function of neutrophils in dairy cows during the perinatal period (6, 7,10). Immunomodulators that might abrogate the development of periparturient immunosuppression have not been evaluated. Dihydroheptaprenol (DHP) is a polyprenol derivative and is known as a stimulator of neutrophils under experimental systems of mice (1,11) and swine (2). The present study was performed to determine whether DHP administration alters neutrophil function in dairy cows during the postpartum period.

The efficacy of in-line measurement of quarter milk electrical conductivity, milk yield and milk temperature for the detection of clinical and subclinical mastitis

In-line sensors were developed for measuring quarter milk electrical conductivity (QMC) to detect mastitis in dairy cattle. The sensors were built into the milking claws of a six-point open tandem milking parlour, in which 65 cows were milked daily. For individual cows, deviations were calculated between averages of the 20 highest values of QMC, measured every 5 s during milking. Over a 12-month period, 2-monthly bacteriological examinations, cell counts of quarter milk samples and observations for clinical mastitis served as references for the conductivity measurements. High and low thresholds for QMC were determined in order to detect severe (clinical) mastitis and subclinical mastitis, respectively. The first should be considered for treatment during lactation and the latter for dry cow therapy. The lowest running average QMC was defined as a “reference quarter” for each cow after each milking. A quarter indicated severe mastitis if its running average QMC deviated in excess of 15% from the reference quarter and if actual QMC was 20% over the running average of the reference quarter during two successive milkings. In considering dry cow therapy, cows were selected if the running average of QMC deviated≥10, 15 or 20% from the running average of the reference quarter during at least five milkings in the last 2 months of lactation. Automated data collection of daily milk yield and milk temperature in addition to QMC established the severity of mastitis. All cases of clinical mastitis (25) were detected by the high threshold values and 50% of the cases of subclinical mastitis and secretion disturbance were detected. Using the low threshold during the last 2 months of lactation, 50% of the cows were selected for dry cow therapy. In 24% of the cows recommended for treatment, there were no signs of subclinical mastitis in the quarter milk samples.