Detection of ovine intramammary infection with the California mastitis test

The overall sensitivity of the California mastitis test (CMT) for detecting intramammary infection (the likelihood of a positive CMT score in the presence of intramammary infection) was 69.3%. The specificity of the CMT (likelihood of a negative test in the absence of intramammary infection) was 76.5%. When only infections by major ovine mastitis pathogens were considered, the sensitivity increased to 100% and the specificity decreased to 71.1%. Bacterial cultural examination and CMT scores were recorded for 526 samples of milk obtained from 106 brood ewes. Positive CMT scores were recorded for all samples from udder halves infected with major ovine mastitis pathogens (coagulase-positive staphylococci, Escherichia coli, and Pasteurella haemolytica). The CMT scores for samples from udder halves infected with coagulase-negative staphylococci were variable.     

California mastitis test scores as indicators of subclinical intra-mammary infections at the end of lactation in dairy cows

Insect-borne diseases exact a high public health burden and have a devastating impact on livestock and agriculture. To date, control has proved to be exceedingly difficult. One such disease that has plagued sub-Saharan Africa is caused by the protozoan African trypanosomes (Trypanosoma species) and transmitted by tsetse flies (Diptera: Glossinidae). This presentation describes Trypanosoma evansi (T. evansi) which causes the disease known as trypanosomosis (Surra) or trypanosomiasis in which several attempts have being made to unravel the clinical pathogenic mechanisms in T. evansi infections, yielding various reports which have implicated hemolysis associated to decrease in life span of erythrocytes and extensive erythrophagocytosis being among those that enjoy prominence. T. evansi generates Adenosine Triphosphate (ATP) from glucose catabolism which is required for the parasite motility and survival. Oxidation of the erythrocytes induces oxidative stress due to free radical generation. Lipid peroxidation of the erythrocytes causes membrane injury, osmotic fragility and destruction of the red blood cell (RBC) making anemia a hallmark of the pathology of T. evansi infections.     

Response of dairy cows to protein level in early lactation

The comparison of cows' protein requirements with the supply of microbial and feed proteins digestible in the intestine shows a large deficit for the first weeks just after calving. The magnitude and duration of the deficit is reflected in the blood parameters of the protein status (protein, urea and free amino acid contents and composition) and of the energy status (glucose, free fatty acid content). Great increases in milk production are noted in this period by meeting protein requirements at all times during the first eight weeks after calving. Sometimes they are achieved at the expense of body stores, but in other cases they can be related to an increase in the efficiency of microbial digestion in the rumen, in the ingestibility of the feeds, or in the intake capacity of the cows. The effects on milk protein synthesis and on the intake capacity of the cows seem to be due to the supply of some essential amino acids, particularly methionine, but also to the supply of non-essential glucose precursor amino acids. More studies are needed on the mechanisms involved, on the long-term effects, and on the secondary effects on reproduction and health.     

Patterns of mycoplasma shedding in the milk of dairy cows with intramammary mycoplasma infection

OBJECTIVE: To determine patterns of mycoplasma shedding in the milk of dairy cows with intramammary mycoplasma infection. DESIGN: Prospective clinical trial. ANIMALS: 10 Holstein cows with intramammary mycoplasma infection. PROCEDURE: Milk samples were collected from each cow daily for 28 days and plated on mycoplasma agar to evaluate shedding patterns. To determine whether enrichment improved recovery of organisms, some samples were also inoculated in mycoplasma enrichment medium and incubated for 4 days prior to plating. Somatic cell count (SCC) was determined in samples collected weekly. RESULTS: Mycoplasma organisms were not isolated from 81 of 280 (29%) composite milk samples, but > 10(6) colonies/mL were obtained from 151 (54%). Similarly, mycoplasma organisms were not isolated from 433 of 1,008 (43%) quarter milk samples, but > 10(6) colonies/mL were obtained from 392 (39%). For 71 of 104 (68%) samples, mycoplasma organisms were isolated both following direct plating and following enrichment; for 24 of 104 (23%), mycoplasma organisms were isolated only following enrichment; and for 9 of 104 (9%), mycoplasma organisms were isolated only after direct plating. There was a linear correlation between logarithm of the SCC and logarithm of the number of colony-forming units of mycoplasma per milliliter of milk for composite and quarter milk samples. CONCLUSIONS AND CLINICAL RELEVANCE: Shedding of organisms was inconsistent in dairy cows with intramammary mycoplasma infection, increasing the risk of misdiagnosis if multiple milk samples are not tested.     

Efficacy assessment of an intramammary treatment with a new recrystallized enrofloxacin vs ceftiofur and parenteral enrofloxacin in dairy cows with nonsevere clinical mastitis

A recrystallized form of enrofloxacin as dehydrate‐HCl (enro‐C) was assessed for bacteriological and clinical cure efficacies in Holstein‐Friesian cows affected of nonsevere clinical mastitis. Treatments were enro‐C_susp (n = 81), treated with a pharmaceutical suspension of enro‐C/quarter; group enro‐C_pd (n = 80) treated as above, but using enro‐C powder suspended in water; group CF (n = 65), treated with ceftiofur HCl/quarter; and group enro_R (n = 66), treated with standard enrofloxacin solution (5 mg/kg, intramuscular). Cows had a mean milk production of 31 L/day and were 2‐3 lactational periods old. Treatments were administered every 24 hr for 3 days. Groups treated with enro‐C exhibited statistically significant (p > .05) better clinical cure as compared to groups treated with CF or enro_R (95.06%, 96.25%, 67.79%, and 57.55%, for enro‐C_susp, enro‐C_pd, CF, and enro_R, respectively). In contrast, probability of bacteriological cure was not statistically different among treatments. Yet, the outstanding clinical and bacteriological cure rates obtained for enro‐C for nonsevere cases of mastitis is superior to previously reported data for parenteral enrofloxacin and other antibacterial‐intramammary treatments. Impact of using enro‐C on the rate and pattern of bacterial resistance, somatic cell counts and milk electric conductivity, must be studied. Also, the use of enro‐C for complicated cases of mastitis should be studied and milk withdrawal times must be accurately established.     

Response to metabolic challenges in early lactation dairy cows during treatment with bovine somatotropin

Milk production is increased in lactating cows treated with bovine somatotropin (bST) because a greater portion of absorbed nutrients are partitioned for milk synthesis. This homeorhetic action may be caused by alterations in response of key tissues to homeostatic signals. To examine this theory, acute metabolic challenges were administered to 8 multiparous Holstein cows (61 +/- 2 days postpartum) receiving daily subcutaneous injections of pituitary-derived bST (26.3 mg) or excipient during two 14-day treatment periods (crossover experimental design). Treatment with bST increased milk yield 12%. Feed intake did not change so that net energy balance decreased (+ .5 vs. -4.3 Mcal/day). Plasma concentrations of nonesterified fatty acids (NEFA) were chronically elevated in bST-treated cows, consistent with energy balance differences. However, baseline concentrations of glucose, insulin, and glucagon in plasma did not differ. On the last 3 days of treatment, individual metabolic challenges were administered via jugular cannulas: epinephrine (700 ng/kg BW), glucose (250 mg/kg BW), insulin (1.0 micrograms/kg BW), and glucagon (175 ng/kg BW). Plasma glucose was reduced after the insulin challenge to a lesser extent during bST treatment. In bST-treated cows, the increase in plasma NEFA in response to epinephrine was greater, and NEFA concentrations were lowered to a greater extent after insulin and glucose challenges. Glucose, insulin, and glucagon removal rates were not altered, nor was plasma glucose response to epinephrine or glucagon challenges. Treatment of lactating cows with bST primarily altered the response of adipose tissue to homeostatic signals which affect lipid metabolism.     

Prevalence of clinical mastitis in 38 Waikato dairy herds in early lactation

AIM: To determine the prevalence of clinical mastitis in spring-calving dairy herds in the Waikato Region of New Zealand and to identify factors associated with variation in the prevalence of clinical mastitis between herds. METHOD: A total of 799 quarters from 595 dairy cows from 38 dairy herds were diagnosed by herd owners as having clinical mastitis between 8 July and 21 August 1997. Quarters diagnosed with clinical mastitis were sampled for bacterial culture and somatic cell count, and the presence of clots in the milk and the presence of udder oedema were assessed by a technician or veterinarian. RESULTS: Clinical mastitis was diagnosed in an average (+/-s.e.m.) of 9.9% (+/-0.8%, range 0.9-21.4%) of calved cows within the herds. Bacteria were not cultured from an average of 12.4 % (+/- 2.0%, range 0.0-45.5%) of cows and 22.3% (+/- 2.4%, range 0.0-54.0%) of quarters diagnosed as having clinical mastitis. There were significant differences between herds in the proportion of cows diagnosed with mastitis and in the proportion of clinical mastitis cases from which bacteria were not cultured. A decreased prevalence of clinical mastitis (p<0.001) was associated with an increased percentage of the herd treated with dry cow antibiotics. An increased prevalence of clinical mastitis (p<0.0001) was associated with both an increased percentage of cows treated in the previous season with lactating cow antibiotics and an increased percentage of heifers in the herd. Herds that were fed supplements before or during lactation had a higher prevalence of clinical mastitis than herds that were not fed supplements (p<0.001). An increased proportion of quarters diagnosed with clinical mastitis that did not culture bacteria was associated with an increased prevalence of clinical mastitis (p<0.001). The proportion of quarters that the technician or veterinarian found with evidence of clinical mastitis (i.e. a somatic cell count >500,000 cells/ml and the presence of either clots or udder oedema) within a herd was inversely related to the proportion of quarters within a herd from which no bacteria were isolated. CONCLUSION: There was a large variation in the prevalence of clinical mastitis and in the proportion of clinical quarters from which no bacteria were grown between herds. Management factors such as the use of dry cow therapy, feeding regimes and heifer replacement rates all affected the prevalence of clinical mastitis. Herd owners appear to differ in the sensitivity and specificity of their diagnosis of clinical mastitis, with bacteria not isolated from up to 50% of quarters diagnosed with clinical mastitis in some herds. Improvements in the specificity of herd owner diagnosis of clinical mastitis may reduce the use of antibiotics for mastitis during lactation and hence may reduce the risk of antibiotic contamination of milk supplied for human consumption.     

奶牛亚临床酮病对乳房炎发病情况和抗氧化功能的影响

为研究奶牛亚临床酮病与乳房炎的关系以及血液中的酮体成分对奶牛抗氧化功能的影响,以156头健康荷斯坦奶牛为试验动物（SCC〈200000／mL）,共筛选亚临床酮病奶牛69头（1．0mmol／L≤BHBA〈2．6mmol／L）作为试验组,根据年龄、胎次、产奶量、泌乳天数配对的69头奶牛作为时照组（血液BHBA〈1．0mmol／L）,监测乳房炎发病情况并在各组中选取12头奶牛检测血液酮体水平和抗氧化指标。结果表明亚临床酮病奶牛试验期间乳房炎的发病率为43．48％,对照组试验期间乳房炎的发病率为31．88％,但差异不显著（P〉0．05）;试验组奶牛乳房炎高发期为分娩后3～6周,对照组奶牛乳房炎发病时间为分娩后5～8周,亚临床酮病发病后1～3周内为乳房炎的高发期,占试验组奶牛乳房炎总发病比例的73．33％,试验组和对照组病原菌的组成无显著差异（P〉0．05）;试验组奶牛血液中T—AOC显著低于对照组（P〈0．05）,GSH—PX活力、MDA和N0显著高于对照组（P〈0．05）,血液ACAC浓度与GSH—PX活力呈显著正相关（P〈0．05,r=0．595）,ACAC浓度与NO呈显著正相关（P〈0．05,r=0．655）,T—AOC与MDA呈显著负相关（P〈0．05,r=0．533）。结果表明奶牛亚临床酮病可以导致乳房炎的发病率升高,但不是主要影响因素,亚临床酮病对乳房炎病原体构成无影响;外周血酮体水平升高导致机体总抗氧化能力的降低并引起机体脂质过氧化反应;谷胱甘肽过氧化物酶在发挥抗氧化功能时具有一定的抵抗力和自我调节能力。     

Liver function of dairy cows in late pregnancy and early lactation

The possibility that alterations in liver function may occur during late pregnancy as well as after calving has been investigated in healthy dairy cows and the results compared with those from non-pregnant non-lactating cows. There were significant alterations in plasma total bilirubin, glucose, total ketone body and urea concentrations, in bromsulphthalein clearance and in plasma aspartate aminotransferase and creatine kinase activities in periparturient cows compared with non-pregnant non-lactating cows. Of these, only the alterations in glucose, ketone bodies and urea concentrations and bromsulphthalein half-time and retention were markedly different before calving. The degree of fatty infiltration of the liver was significant two weeks before as well as two weeks after calving which differed from previous reports. It seems likely that the changes in the liver in dairy cows are functional and reversible and related to the metabolic demands of late pregnancy and early lactation. The results suggest that such changes in the liver occur well before calving.     

Effects of bovine lactoferrin by the intramammary infusion in cows with staphylococcal mastitis during the early non-lactating period

To evaluate the clinical effects of bovine lactoferrin on staphylococcal mastitis in Holstein cows during the early non-lactating period, 41 mammary quarters were selected randomly from 36 cows on 3 dairy farms. Twelve quarters were infused intramammarily with bovine lactoferrin. Twenty-nine quarters were infused with antibiotic as a control. In the bovine lactoferrin-infused group, 91.7% of mastitic quarters were cured at 7 days after calving, compared with 48.3% in the control group. Furthermore, the changes in mammary secretion induced by the infusion of bovine lactoferrin were investigated. Mean numbers of staphylococci in mammary gland secretions were significantly decreased in both 5 bovine lactoferrin-infused quarters and 5 antibiotic-infused control quarters (p<0.05). Unlike in the control quarters, the mean total cell concentration in the mammary gland secretions increased in bovine lactoferrin-infused quarters. Similar results were obtained in 6 healthy quarters which were infused with bovine lactoferrin. In these quarters, the cell population contained mainly phagocytes such as polymorphonuclear leukocytes and cells positive for CD11b which is known as a complement receptor. The mean concentration of C3 in mammary gland secretions was significantly increased in 5 mastitic quarters infused with bovine lactoferrin (p<0.05), but showed no significant change in 5 mastitic control quarters. These results suggested that bovine lactoferrin treatment for staphylococcal mastitis in the early non-lactating period might increase the rate of cure through the induction of innate immunity in the host.     

Management practices associated with udder health of first-parity dairy cows in early lactation

This study aimed at investigating associations between management routines including feeding, housing, and milking around calving, and udder health of first-parity cows in early lactation in Swedish large, high producing, low bulk-milk somatic cell count (SCC) dairy herds housed in free stalls. Seventy-two dairy herds participated and data concerning 1189 first-parity cows calving during the study period (October 2005-January 2006) was collected. Multivariable regression analysis were performed with three different outcomes; within-herd number of first-parity cows veterinary treated for clinical mastitis at days -10 to 60 after calving, within-herd number of first-parity cows with a SCC> or =200,000cells/mL at first test-day, and SCC of first-parity cows at first test-day. Cow factors significantly associated with good udder health of first-parity cows (few cases of clinical mastitis and or low SCC) were being of the Swedish Red breed, having a high milk yield at first test-day, and a milk-urea > or =5mmol/L at first test-day. Herd factors significantly associated with good udder health were having mattresses as flooring in the cubicles in the lactating cow housing, and to house the first-parity cows in tie stalls 1 month before calving. Cow factors significantly associated with poor udder health of first-parity cows were having a milk-urea <4mmol/L at first test-day. Herd factors significantly associated with poor udder health of first-parity cows were feeding first-parity cows sugar-beet pulp or corn silage, and to give silage from a different batch to pregnant heifers than to lactating cows. Moreover, to have sawdust or shavings in the calving pen, to be moved from the calving pen > or =2 days after calving, to milk first-parity cows at the calving site instead of in the parlor, and to rinse, clean or disinfect milking units before a first-parity cow was milked were also significantly associated with poor udder health of first-parity cows. The results indicate that different control measures must be taken depending on the nature of the udder health problem.     

An intramammary implant in the prevention of infectious mastitis in cows

A sterile polyethylene device was introduced in the milk cistern of two mammary quarters of forty dairy cows. The cows were divided into three groups according to the length of exposure of the device in the cistern (3 days, 14 days, 365 days). The somatic cell counts were studied for a year in the first 10 ml fraction of milk and an increase in the somatic cell counts was found in the quarters having the intramammary device, as compared with the control quarters (having no devices). This difference was marked during lactation and prior to the onset of drying off. For the reduction in the frequency of occurrence of new natural intramammary infections, the activity of the device against S. aureus was limited and no activity against S. agalactiae was proved. The proportions of polymorphonuclears, round-cell elements and macrophages were histologically studied and compared for the udder quarters with and without the intramammary body in correlation with the time of exposure of the device to the milk cistern milieu. The most marked differences in favour of the udder quarters with the intramammary device were recorded in the alveoli containing more cells with a significant proportion of polymorphonuclear leucocytes. Small differences were found in the interstitial and subepithelial zone of the milk cistern. The activity of acid and alkaline phosphatase and adenosine triphosphatase was histochemically determined in the tissue structures of the udder and was found not to change under the influence of the device. Leucocytes and macrophages adhering to the surface of the body were observed under scanning electron microscope.     

Evaluation of PetrifilmsTM as a diagnostic test to detect bovine mastitis organisms in Kenya

The study purpose was to validate Petrifilms^TM (3M Microbiology, 2005) against standard culture methods in the diagnosis of bovine mastitis organisms in Kenya. On 128 smallholder dairy cattle farms in Kenya, between June 21, 2010 and August 31, 2010, milk samples from 269 cows that were positive on California Mastitis Test (CMT) were cultured using standard laboratory culture methods and Petrifilms^TM (Aerobic Count and Coliform Count –3M Microbiology, 2005), and results were compared. Staphylococcus aureus was the most common bacterium isolated (73 % of samples). Clinical mastitis was found in only three cows, and there were only two Gram-negative isolates, making it impossible to examine the agreement between the two tests for Gram-negative- or clinical mastitis samples. The observed agreement between the standard culture and Petrifilm^TM (3M Microbiology, 2005) results for Gram-positive isolates was 85 %, and there was fair agreement beyond that expected due to chance alone, with a kappa (κ) of 0.38. Using culture results as a gold standard, the Petrifilms^TM had a sensitivity of 90 % for Gram-positive samples and specificity of 51 %. With 87 % of CMT-positive samples resulting in Gram-positive pathogens cultured, there was a positive predictive value of 93 % and a negative predictive value of 43 %. Petrifilms^TM should be considered for culture of mastitis organisms in developing countries, especially when Gram-positive bacteria are expected.     

Effects of intramammary infusion of Bifidobacterium breve on mastitis pathogens and somatic cell response in quarters from dairy cows with chronic subclinical mastitis

The present study assessed the effects of intramammary infusion of Bifidobacterium breve (B. breve) on mastitis‐causing pathogens and on the somatic cell counts (SCC) in lactating cows with chronic subclinical mastitis. The bacteriological cure rates of 42 quarters from 42 cows infected with Staphylococcus aureus, Corynebacterium bovis, coagulase‐negative staphylococci, and environmental streptococci were 18.2% (2/11), 14.3% (1/7), 58.8% (10/17), and 28.6% (2/7), respectively, on day 14 after B. breve infusion. In a second trial, B. breve was infused into 18 quarters from 18 cows with chronic subclinical mastitis from which pathogens had not been isolated; the rates of quarters showing SCC > 50 × 10⁴ cells/ml prior to B. breve infusion that decreased to < 30 × 10⁴ cells/ml after infusion were significantly (p < .01) increased to 61.1% (11/18) on day 14 compared to that prior to infusion (0/18). The intramammary infusion of B. breve appears to be a non‐antibiotic approach for elimination of minor pathogens and decreasing SCC in quarters with chronic subclinical mastitis in dairy cows.     

Bacterial growth during the early phase of infection determines the severity of experimental Escherichia coli mastitis in dairy cows

The aim of this study was to investigate the importance of bacterial growth for the severity of experimental Escherichia coli mastitis, indirectly expressed as the area under the curve of bacterial counts in milk over time. The association of pre-infusion somatic cell count and post-infusion influx of inflammatory cells in milk with severity of infection was also examined. Bacterial growth was studied through culture in milk samples (in vitro) and through monitoring of bacterial counts in milk during the early phase of infection (in vivo) in 36 cows. Individual variation in bacterial counts was more than 2 x 10(2)-fold after 6 h of in vitro incubation, and more than 8 x 10(2)-fold 6 h after intramammary infusion. In vitro growth in milk was not associated with in vivo growth during the early phase of infection, nor with severity of E. coli mastitis. Somatic cell count before experimental E. coli mastitis was negatively associated with in vivo bacterial growth during the early phase of infection (R2 = 0.28), but was not associated with severity of E. coli mastitis (R2 = 0.06). In vivo bacterial growth during the early phase of infection (positive association; R2 = 0.41), together with influx of inflammatory cells in milk, expressed as mean hourly increase of somatic cell count between 6 and 12 h post-infusion (negative association; R2 = 0.11), are major determinants for the severity of experimental E. coli mastitis (R2 = 0.56).     

Effect of prepartum intramammary treatment with pirlimycin hydrochloride on prevalence of early first-lactation mastitis in dairy heifers

OBJECTIVE: To determine whether prepartum intramammary treatment of dairy heifers with pirlimycin hydrochloride would reduce the prevalence of intramammary infection (IMI) and lower the somatic cell count (SCC) during early lactation or improve 305-day mature equivalent milk production. DESIGN: Prospective clinical trial. ANIMALS: 183 Holstein-Friesian heifers (663 quarters) from 2 dairy farms. PROCEDURE: Heifers were assigned to treatment and control groups. Treated heifers received a single 50-mg dose of pirlimycin in each mammary quarter approximately 10 to 14 days prior to parturition. Prepartum mammary gland secretions and postpartum milk samples were collected for bacterial culture. Postpartum milk samples were also collected for determination of SCC or California mastitis testing and were tested for pirlimycin residues. Mature equivalent 305-day milk production data were recorded. RESULTS: Treated heifers in herd A had a higher overall cure rate, higher cure rates for IMI caused by coagulase-negative staphylococci (CNS) and Staphylococcus aureus, lower SCC, and lower prevalence of chronic IMI, compared with control heifers. Treated heifers in herd B had a higher overall cure rate and cure rate for IMI caused by CNS, compared with control heifers, but postpartum California mastitis test scores and prevalence of chronic IMI did not differ between groups. Mature equivalent 305-day milk production did not differ between herds or treatment groups. No pirlimycin residues were detected in postpartum milk samples. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that prepartum treatment of dairy heifers with pirlimycin may reduce the prevalence of early lactation IMI, particularly IMI caused by CNS, without causing pirlimycin residues in milk.     

Prototheca zopfii mastitis in a herd of dairy cows

Mastitis caused by the colourless alga Prototheca zopfii was diagnosed in 17 of 120 cows in a dairy herd. Infection occurred in animals varying from 3-14 years old and was present in one to four quarters of each cow. Nine cases were associated with clinical mastitis characterised by the presence in milk of flakes or small clots. Somatic cell counts consistent with subclinical mastitis (>500 x 10(3) cells/ml) were recorded in five of the eight remaining cows. Histological examination of udder tissue showed the presence of granulomatous lesions associated with the presence of Prototheca. The problem was identified and controlled by repeated microbiological examination of milk samples from all lactating cows and immediate culling of infected animals. P. zopfii was also recovered from environmental water samples on this farm. It is suggested that infection may have occurred as a result of teat sores caused by trauma from a milking machine, and the tendency for cows to lay down on a race, the surface of which was sometimes flooded by drain water in which Prototheca were present.     

Prototheca zopfii mastitis in a herd of dairy cows

Mastitis caused by the colourless alga Prototheca zopfii was diagnosed in 17 of 120 cows in a dairy herd. Infection occurred in animals varying from 3–14 years old and was present in one to four quarters of each cow.

Nine cases were associated with clinical mastitis characterised by the presence in milk of flakes or small clots. Somatic cell counts consistent with subclinical mastitis (>500 × 10³ cells/ml) were recorded in five of the eight remaining cows.

Histological examination of udder tissue showed the presence of granulomatous lesions associated with the presence of Prototheca.

The problem was identified and controlled by repeated microbiological examination of milk samples from all lactating cows and immediate culling of infected animals.

P. zopfii was also recovered from environmental water samples on this farm. It is suggested that infection may have occurred as a result of teat sores caused by trauma from a milking machine, and the tendency for cows to lay down on a race, the surface of which was sometimes flooded by drain water in which Prototheca were present.