Severe Mastitis Research Articles

Associations of somatic cell count with milk yield and reproductive performance in grazing dairy cows

Poor udder health status can have a detrimental effect on milk yield and reproductive performance, leading to reductions in the dairy farm profit. The objective of this retrospective longitudinal study was to assess the associations of somatic cell count (SCC) with daily milk yield and reproductive performance. A database with 1,930,376 lactations from 867 Argentinean grazing dairy herds records collected for 14 years was used. The association of the evolution of SCC (healthy vs. new case vs. cured vs. chronic; with 150,000 SCC/mL as threshold) and of the severity of SCC [mild (150,000--400,000 SCC/mL) vs. moderate (400,000-1,000,000 SCC/mL) vs. severe (>1,000,000 SCC/mL)] with the odds for conception were estimated. Finally, the associations of the linear score of SCC (LS-SCC) with daily milk yield were estimated depending on parity and milk production quartile. The odds ratios (CI 95%) for conception at first service were 0.921 (0.902-0.941), 0.866 (0.848-0.884), and 0.842 (0.826-0.859) for the new case, cured, and chronic cows compared with healthy cows, respectively. Also, the odds ratios (CI 95%) for conception were 0.902 (0.881-0.925), 0.837 (0.808-0.866) and 0.709 (0.683-0.736) for mild, moderate and severe cases compared with healthy cows, respectively. An increase of one point of LS-SCC was associated with decreases of 0.349, 0.539, and 0.676 kg in daily milk yield for first-, second-, and third-lactation cows, respectively. In conclusion, SCC is negatively associated with the risk for conception and with daily milk yield in grazing dairy cows. This negative relationship with conception is higher when SCC increase occurs after the service date and it is influenced by severity of mastitis, and in the case of milk yield, the negative association is influenced by parity, milk production quartile, and severity of mastitis.

The Link Between 15-F2t-Isoprostane Activity and Acute Bovine Endothelial Inflammation Remains Elusive.

Modern dairy cattle suffer from increased incidence and severity of mastitis during major physiological transitions of the lactation cycle. Oxidative stress, a condition resulting from inadequate antioxidant defense against reactive oxygen and nitrogen species, is a major underlying component of mastitis pathophysiology. Isoprostanes (IsoP) are molecules derived from cellular lipid membranes upon non-enzymatic interaction with reactive species during inflammation, and are regarded as highly sensitive and specific biomarkers of oxidative stress. Changes in IsoP concentrations have been noted during major physiological transitions and diseases such as coliform mastitis in dairy cattle. However, the biological role of IsoP during oxidative stress in dairy cows has not been well-elucidated. Therefore, this study aimed to characterize the impacts of IsoP on oxidative stress outcomes in a bovine model of acute endothelial inflammation. Bovine aortic endothelial cells (BAEC; n = 4) were stimulated with 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) or lipopolysaccharide (LPS) with or without 15-F2t-IsoP to determine how IsoP influence oxidative stress outcomes. Our endothelial inflammation model showed relatively decreased reactive metabolites and increased barrier integrity in cells treated with both the agonist and IsoP compared to agonist treatment alone. However, IsoP do not appear to affect oxidative stress outcomes during acute inflammation. Understanding the effect of IsoP on BAEC is an early step in elucidating how IsoP impact dairy cows during times of oxidative stress in the context of acute clinical mastitis. Future studies should define the optimal dosing and treatment timing of IsoP to maximize their cytoprotective potential during acute inflammation.

Effects of the anti-sucking device «SuckStop Müller» on calf behavior.

When cross-sucking persists beyond calf-hood, it represents an important problem in dairy heifers and cows. It can cause teat injuries and severe mastitis and lead to significant economic losses. The «SuckStop Müller,» a novel anti-sucking device, is designed to give the calf a negative feedback when cross-sucking on a conspecific. The aim of this study was to assess whether wearing a SuckStop would result in behavioral changes other than cross-sucking and thus, impair welfare in the short- and longer-term. Sixteen group-housed calves were observed in groups of four on five days, before and after fitting the SuckStop: day -2, day -1, day 0, day 1, and day 9. Maintenance behaviors (e.g., feeding, drinking, lying) were recorded using instantaneous scan sampling. In addition, the frequency of contact behaviors (e.g., exploring the feeding fence, touching own body) was recorded by means of continuous focal animal observations. Contact behaviors were classified as «impaired» or «normal» depending on whether or not the calf flinched in response to the contact. Finally, the number of visits to the milk and concentrate feeders was extracted from the computer-controlled feeding system. Fitting a SuckStop resulted in a higher proportion of observations spent lying and less exploration behavior on day 0 and day1 than on day -2, day -1, and day 9. On day 0 and day 1, 6,3 % of exploration behaviors were classified as impaired, compared to 0,4 % (day -2, day -1) before and 0,2 % (day 9) after fitting the SuckStop. On day 9, all calves had superficial ulcerations on the nasal septum. In four calves, these ulcerations were moderately severe, whereas all other calves had slight ulcerations. In summary, the calves habituated quickly to this novel anti-sucking device. Follow-up studies are necessary to assess the long-term relevance of tissue alterations in the nasal septum for calf welfare as well as the effect of the SuckStop on cross-sucking behavior.

Efficacy Evaluation of a Combined Hemorrhagic Septicemia-Mastitis Vaccine in Dairy Cows and Buffaloes.

Simple SummaryHemorrhagic septicemia (HS) and mastitis are important diseases of South Asian dairy animals. Seventy S. aureus/Str. agalactiae-free lactating buffaloes (n = 45) and cows (n = 25) and fifty S. aureus/Str. agalactiae-positive lactating (early stage of lactation) buffaloes (n = 25) and cows (n = 25) were subjected to two doses of Montanide® adjuvant combined HS–mastitis vaccine with 21 days of interval. Vaccinated groups showed mean somatic cell counts and mastitis severity scores that were significantly lower (p < 0.05), whereas the milk yield was significantly higher (p < 0.05). In conclusion, this vaccine can be used as a potential preventive measure against HS and mastitis in dairy animals.Hemorrhagic septicemia (HS) and mastitis caused by Pasteurella (P.) multocida, Staphylococcus (S.) aureus and Streptococcus (Str.) agalactiae are important ailments of the dairy industry especially in South Asia. The present study evaluates the efficacy of a locally prepared hemorrhagic septicemia (HS) and mastitis combined vaccine. To this end, a total of 70 HS, S. aureus and Str. agalactiae-free lactating (early stage of lactation) buffaloes (n = 45) and cows (n = 25), and 50 lactating (early stage of lactation) cows (n = 25) and buffaloes (n = 25) positive for S. aureus/Str. agalactiae were subjected to two doses of HS–mastitis combined vaccine with an interval of 21 days. Antibody response was monitored by ELISA up to six months (180 days). Antibody titers against HS and mastitis were significantly (p ˂ 0.05) higher in vaccinated groups as compared to the non-vaccinated groups. Cumulative mean somatic cell counts and mastitis severity scores in vaccinated groups were significantly lower (p < 0.05), and milk yield was significantly higher (p < 0.05) than those in the respective non-vaccinated controls. In conclusion, Montanide®-adjuvanted HS–mastitis combined vaccine showed significant immunogenic effects in dairy cows and buffaloes. However, challenge studies remain overdue.

Biological Characteristics and Pathogenicity of Helcococcus ovis Isolated From Clinical Bovine Mastitis in a Chinese Dairy Herd.

Helcococcus ovis (H. ovis) was first reported in ovine subclinical mastitis milk and post-mortem examination organs in Spain and the United Kingdom in 1999; subsequently, it appeared in cattle, horse, goat, and human. However, isolation and characterization of the pathogen from clinical bovine mastitis is unknown. The objective of this study was to identify the pathogen in clinical bovine mastitis. A total of four strains were isolated from bovine mastitis milk samples from a Chinese dairy farm, and they were identified as H. ovis by microscopic examination and 16S rRNA gene sequencing. Phylogenetic tree was constructed using 16S rRNA gene, and the isolates were closely related to other China strains and strains from Japan. The growth speed of the H. ovis isolated was relatively slower than Streptococcus agalactiae, and the phenotypic characteristics were similar to H. ovis CCUG37441 and CCUG39041 except to lactose. The isolates were sensitive to most of the common used antimicrobials. The H. ovis isolates could lead to mild murine mastitis alone and induce severe mastitis when co-infected with Trueperella pyogenes in the murine mammary infection model constructed.

Development and Efficacy Evaluation of an SP01-adjuvanted Inactivated Escherichia Coli Mutant Vaccine Against Bovine Coliform Mastitis

Objective: Escherichia coli (E. coli) is one of the most common pathogens causing clinical mastitis in cattle, but no vaccine is available to prevent this disease in China. Therefore, development of an E. coli vaccine against bovine clinical mastitis is urgently needed. Methods: The candidate vaccine (Ch-O111-1) and challenge (LZ06) strains were screened from milk samples of cows with clinical mastitis. To extend the cross-protection of the Ch-O111-1 strain, we deleted the galE gene fragment of the Ch-O111-1 strain through homologous recombination between the Ch-O111-1 strain and pCVD442/ΔgalE plasmid, which was identified through conventional methods, including PCR, SDS-PAGE and sequencing. The Ch-O111-1/ΔgalE (Z9) strain was characterized by extensive cross-reactivity and attenuated virulence. We prepared inactivated Z9 vaccines with different adjuvants. Results: Immunization of inactivated Z9 antigen induced adjuvant-, dosage- and inoculation time-dependent antibody titers in cows and mice. Furthermore, immunization with SP01-adjuvanted inactivated Z9 vaccine protected cows against severe clinical mastitis caused by LZ06 and protected mice against death due to LZ06. Conclusion: An SP01-adjuvanted inactivated Z9 vaccine was successfully developed and found to protect cows against severe mastitis caused by Escherichia coli.

Correlation between teat length and lactation periods on the level of subclinical mastitis occurrence in Sappy Valley Farm

This study aims to determine the correlation between dairy cattle teat length at several lactation periods and subclinical mastitis profile. This study used 43 dairy cattle at several lactation periods. The lactation periods of the cows studied were lactation periods 1, 2, and 3. Subclinical mastitis testing used IPB-1 Mastitis Test, and teat length was measured using a measuring tape (cm). The data is taken and then analyzed using the average and described. The results showed that the average teat length of 5.11 cm did not experience subclinical mastitis, while the average teat length was 5.48 cm, 6.09 cm, and 7.28 cm, respectively, had subclinical mastitis. The highest incidence of subclinical mastitis is influenced by teat length and lactation period. The length of the teat and the lactation period, the higher the severity of subclinical mastitis. These findings are essential for a practical clinical diagnostic approach in dairy cattle with subclinical mastitis.

Molecular Typing and Antimicrobial Susceptibility Profiles of Streptococcus uberis Isolated from Sheep Milk.

Intramammary infections are a major problem for dairy sheep farms, and Streptococcus uberis is one of the main etiological agents of ovine mastitis. Surveys on antimicrobial resistance are still limited in sheep and characterization of isolates is important for acquiring information on resistance and for optimizing therapy. In this study, a sampling of 124 S. uberis isolates collected in Sardinia (Italy) from sheep milk was analyzed by multilocus-sequence typing (MLST) and pulsed field gel electrophoresis (PFGE) for genetic relatedness. All isolates were also subjected to antimicrobial susceptibility analysis by the disk diffusion test using a panel of 14 antimicrobials. Resistance genes were detected by PCR assays. MLST analysis revealed that the isolates were grouped into 86 sequence types (STs), of which 73 were new genotypes, indicating a highly diverse population of S. uberis. The most frequently detected lineage was the clonal complex (CC)143, although representing only 13.7% of all characterized isolates. A high level of heterogeneity was also observed among the SmaI PFGE profiles, with 121 unique patterns. Almost all (96.8%) isolates were resistant to at least one antimicrobial, while all exhibited phenotypic susceptibility to oxacillin, amoxicillin-clavulanic acid and ceftiofur. Of the antimicrobials tested, the highest resistance rate was found against streptomycin (93.5%), kanamycin (79.8%) and gentamicin (64.5%), followed by novobiocin (25%) and tetracycline-TE (19.3%). Seventy-four (59.7%) isolates were simultaneously resistant to all aminoglycosides tested. Seventeen isolates (13.7%) exhibited multidrug resistance. All aminoglycosides-resistant isolates were PCR negative for aad-6 and aphA-3′ genes. Among the TE-resistant isolates, the tetM gene was predominant, indicating that the resistance mechanism is mainly mediated by the protection of ribosomes and not through the efflux pump. Three isolates were resistant to erythromycin, and two of them harbored the ermB gene. This is the first study reporting a detailed characterization of the S. uberis strains circulating in Sardinian sheep. Further investigations will be needed to understand the relationships between S. uberis genotypes, mastitis severity, and intra-mammary infection dynamics in the flock, as well as to monitor the evolution of antimicrobial resistance.

Protease-activated receptor 2 expression in the mammary gland tissues in correlation with mastitis severity in goats

Mastitis is a common disease in small ruminant industry. The present study aimed to determine the presence of protease activated receptor-2 (PAR2) mRNA expression in the mammary gland of mastitis challenged goats. 30 clinically healthy mix breed lactating goats were divided into three groups, consisting of Staphylococcus aureus (Group 1), methicillin-resistant S. aureus (Group 2) and sterile phosphate-buffered saline (Control) groups. The data regarding physical condition of udder and clinical parameters of goats were recorded while milk samples and mammary gland tissues were collected at 24 and 48 hours post infection. Somatic cell count (SCC) was measured by direct microscopic method. The presence of PAR2 mRNA in the mammary gland tissue samples was detected by real-time PCR. Goats from group 1 developed mild to moderate clinical signs while Group 2 exhibited moderate to severe clinical signs. SCC was higher in both challenged groups than control group. PAR2 mRNA expression was detected in all mammary gland samples from Group 1 and Group 2. The gene expression was significantly highly in mammary gland tissue with severe clinical signs. The finding of PAR2 expression in caprine mammary gland is novel and important, suggesting serine proteases involved the development of mastitis in goat.

ANALYSIS OF HEREDITARY PREDISPOSITION TO MAMMARY GLAND DISEASES IN ANIMALS

This article presents data on the study of hereditary predisposition to diseases of the mammary gland in cats. The studies were carried out on the basis of veterinary clinics in the cities of Rostov-on-Don, Novocherkassk, Shakhty for 8 years. In the course of the research, a predisposition to the development of mastitis in cats of various breeds with a history of breast disease in the parents was established. A direct relationship was revealed between the incidence of mastitis in daughters and mothers with a history of breast diseases (86.9%). At the same time, mothers without breast disease in the anamnesis were noted in 13% of cases, with breast infl ammation – 18.5%, with a diagnosis of mastopathy – 23.2%, with breast tumors – in 45.2% of cases. It was also determined that in cats whose mothers did not have a history of breast disease, mastitis of moderate severity is most often recorded (47.4%), a severe course of the disease is slightly less common (37%), a mild course of mastitis is noted in 15.5% of cases. During the research, it was found that in cats whose mothers had a history of breast disease, moderate and severe mastitis is most often noted, 36.2% and 39.9%, respectively. Slightly less often mild mastitis is recorded in such animals – 23.8%. It has been determined that in daughters from mothers with a history of breast diseases, moderate and severe infl ammation of the mammary gland prevails.

Recovery Rates of Treated vs. Non-Treated Dairy Cows with Subclinical Mastitis

The term “spontaneous recovery” refers to a return to a previous condition without any external treatment. In cow mastitis, it refers to cases exhibiting visual symptoms (clinical) or an increase in somatic cell count (SCC) with no visual symptoms (subclinical), with or without identification of a pathogen, from which the animal recovers. A large retrospective analysis of data compiled from the Israeli Dairy Herd Book was performed to evaluate the occurrence of: (i) actual “spontaneous recovery” from the inflammation; (ii) recovery from the inflammation due to antibiotic treatment. In 2018, 123,958 cows from 650 herds with first elevation of SCC at monthly test-day milk yield were clustered into five SCC-cutoff levels (CL) (×103 cells/mL): CL1 (200–299), CL2 (300–399), CL3 (400–499), CL4 (500–999), CL5 (≥1000). Each cutoff level was analyzed separately, and each cow appeared only once in the same lactation and cutoff level, thus resulting in five independent analyses. Recovery was defined as decreased SCC on all three monthly test days, or on the second and third test days, set to: R1 (&lt;100 × 103 cells/mL); R2 (&lt;250 × 103 cells/mL). No difference was found among cutoff levels when the recovery was set to R1, with only 10–12% of the cows presenting spontaneous recovery. When the recovery was set to R2, percent spontaneous recovery was 25–27% at the three higher cutoff levels (CL3–CL5) and 35–41% at the lowest levels (CL1, CL2). Antibiotic treatment was administered to only ~10% of the cows, and in only the higher cutoff-level groups—CL4 and CL5. No difference was found between spontaneous recovery and recovery after antibiotic treatment. Moreover, percentage culled cows treated with antibiotics was significantly higher (p &lt; 0.01) than that of non-treated culled cows (18 and 10.2, respectively), suggesting that the more severe mastitis cases were treated. We concluded that (i) actual spontaneous recovery from inflammation is low and does not depend on the number of cells in the milk at time of infection, and (ii) recovery from inflammation following antibiotic treatment is not higher.

Field Evaluation of Staphylococcus aureus Bacterin Use in Dairy Farms

A total of 420 lactating Holstein cows in three dairy farms in Damietta (farm A, 120 lactating cows and farm C, 160 lactating cows) and El-Sharkia (farm B, 140 lactating cows) Governorates; were examined for the presence of clinical and subclinical mastitis among the resident cows, then were vaccinated by Staph. aureus bacterin and then were observed during the period from May 2015 to December 2017 for evaluating the efficacy of the vaccine in reducing the number of infected animals and preventing new infections. Clinical mastitis and subclinical mastitis were respectively reported in 286 (17.54%) and 726 (44.53%) out of the total examined quarters (n=1630) from 420 animals in 3 farms. Before vaccination, the overall prevalence rate of Staph. aureus was (19.5% versus 46.5%) in mastitic quarters and (32.1% versus 44.6%)in subclinical mastitis. Vaccination of cows with 5 ml of Staph. aureus bacterin 2 doses with 14-day interval decrease the severity of mastitis in the new cases of clinical mastitis and reduce the prevalence of Staph. aureus and coagulase-negative staphylococcal mastitis, improved clearance rates of existing Staph. aureus mastitis, but it has little effect on reducing new mastitic cases. However, it was found to be effective in preventing new infections with Staph. aureus and coagulase-negative staphylococci in dairy heifers, and minimizing somatic cell count, and increasing milk yield. Also, the total bacterial count, total Staphylococcal count, and Staph. aureus count was reduced. Vaccine efficacy was stretched to fat, protein percent and milk yield were elevated.

DNase I improves blood-milk barrier integrity and alleviates inflammation induced by Staphylococcus aureus during mastitis

Mastitis is an inflammation of mammary gland, which directly affects the milk production performance and causes huge economic losses in the dairy industry. During mastitis, the blood-milk barrier (BMB) loses its integrity and aggravates the severity of mastitis. Exogenous DNase I has been exerted protective effects in different model of tissue injury. Here, we designed a study to investigate the effects of DNase I on inflammation and BMB in a mice model of Staphylococcus aureus-induced mastitis. In the model, we found that DNase I treatment significantly alleviated the inflammatory response through decrease of inflammatory cells in mammary alveoli, MPO activity and cytokines in mammary gland. Furthermore, immunofluorescent staining and western blotting demonstrated that exogenous DNase I obviously reduced BMB permeability and changed the expression of tight junction proteins to support the re-establishment of the barrier integrity. Mechanismly, DNase I treatment inhibited NF-κB and enhanced AKT signaling pathways. Therefore, our results indicate that DNase I may be an effective treatment for attenuating mastitis.

Randomized controlled trial of pegbovigrastim as an adjunct therapy for naturally occurring severe clinical mastitis cases in dairy cows

The main objective of this study was to quantify the effect of pegbovigrastim (PEG) as an adjunct therapy for naturally occurring severe mastitis cases on survival, intramammary bacteriological cure, and subsequent milk production. A double-blinded, randomized controlled trial was conducted on a single commercial dairy farm. During the study period, all cows having a case of severe clinical mastitis, defined as the presence of abnormal milk and inflammation in one quarter or more combined with the presence of systemic signs (pyrexia, dehydration, or recumbency), were enrolled in the study. In addition to a standardized therapy combining systemic and intramammary antimicrobials as well as systemic anti-inflammatory drugs, cows received a subcutaneous injection of either 2.7 mL of 0.9% sterile saline (control group; CON) or 2.7 mL of PEG (PEG group). A milk sample for bacteriological analysis was taken before treatment was administered and a second sample was taken 14 d after enrollment. Survival (30 d post-treatment) and bacteriological cure (14 d post-treatment) were analyzed by survival analysis and chi-squared tests, respectively, whereas daily milk production was treated as a repeated measure in mixed regression models. The 77 cows enrolled in the study were of parity 2 to 4 (mean = 3) and between 3 and 302 d in milk (mean = 154). The bacteria identified in milk at enrollment were Klebsiella spp. (n = 48; 62%), Escherichia coli (n = 16; 21%), Enterobacter spp. (n = 10; 13%), or no growth (n = 3; 4%). The probability of survival during the first 30 d after treatment was higher in the PEG group (84%) than in the control group (46%). Daily milk production over the 30-d period following treatment and bacteriological cure 14 d post-treatment did not differ between groups. Overall, cows treated with PEG as an adjunct therapy for naturally occurring cases of severe clinical mastitis had a better survival than cows treated with saline.

Novel ways to use sensor data to improve mastitis management

Current sensor systems are used to detect cows with clinical mastitis. Although, the systems perform well enough to not negatively affect the adoption of automatic milking systems, the performance is far from perfect. An important advantage of sensor systems is the availability of multiple measurements per day. By clearly defining the need for detection of subclinical mastitis (SCM) and clinical mastitis (CM) from the farmers' management perspective, detection and management of SCM and CM may be improved. Sensor systems may also be used for other aspects of mastitis management. In this paper we have defined 4 mastitis situations that could be managed with the support of sensor systems. Because of differences in the associated management and the epidemiology of these specific mastitis situations, the required demands for performance of the sensor systems do differ. The 4 defined mastitis situations with the requirements of performance are the following: (1) Cows with severe CM needing immediate attention. Sensor systems should have a very high sensitivity (>95% and preferably close to 100%) and specificity (>99%) within a narrow time window (maximum 12 h) to ensure that close to all cows with true cases of severe CM are detected quickly. Although never studied, it is expected that because of the effects of severe CM, such a high detection performance is feasible. (2) Cows with mastitis that do not need immediate attention. Although these cows have a risk of progressing into severe CM or chronic mastitis, they should get the chance to cure spontaneously under close monitoring. Sensor alerts should have a reasonable sensitivity (>80%) and a high specificity (>99.5%). The time window may be around 7 d. (3) Cows needing attention at drying off. For selective dry cow treatment, the absence or presence of an intramammary infection at dry-off needs to be known. To avoid both false-positive and false-negative alerts, sensitivity and specificity can be equally high (>95%). (4) Herd-level udder health. By combining sensor readings from all cows in the herd, novel herd-level key performance indicators can be developed to monitor udder health status and development over time and raise alerts at significant deviances from predefined thresholds; sensitivity should be reasonably high, >80%, and because of the costs for further analysis of false-positive alerts, the specificity should be >99%. The development and validation of sensor-based algorithms specifically for these 4 mastitis situations will encourage situation-specific farmer interventions and operational udder health management.

N-acetyl-β-D-glucosaminidase biomarker quantification in milk using Ag-porous Si SERS platform for mastitis severity evaluation

Bovine mammary gland is susceptible to numerous bacterial infections resulting in inflammatory disease condition of bovine mastitis (BM) with a staggering economic impact on the dairy industry worldwide. Early BM detection is crucial for infection control within the dairy herd, which can be alleviated by antimicrobial therapy. N-acetyl-β-D-glucosaminidase (NAGase) is a prominent BM inflammatory biomarker secreted onto the blood circulation upon pathogenesis and then released into milk, capable of separating healthy quarters from subclinical and clinical BM cases. Herein, we report a sensitive, cost-effective and handy-to-use BM severity assay based on NAGase inherent content found in whole milk samples. Silver-coated porous Si (Ag-PSi) Fabry–Pérot interferometers were employed for quantifying the lysosomal activity in different milk qualities using surface-enhanced Raman spectroscopy (SERS). The optical response was proportional to the occurring pathogenesis induced by predominant bacteria found in dairy farms at different somatic cell levels. The optimized Ag-PSi SERS substrates were utilized for quantitative analysis of NAGase levels found at clinically relevant BM concentrations while presenting the detection limit of 0.27 μM min−1. The optical performances were associated with the conventional standardized approach in terms of recovery values (85–98%), thus presenting sufficient adaptability to complex matrix analysis as whole milk.

A COMPREHENSIVE REVIEW ON MILK YIELD, LACTATION EFFICIENCY, MILK COMPOSITION AND MASTITIS INCIDENCE AT DIFFERENT PARITY IN MURRAH BUFFALOES

Murrah buffaloes are the most important milch animal which has gained immense popularity due to its higher milk production capacity coupled with adaptation to wide ecological conditions and feed conversion efficiency. Milk yield, milk composition, lactation efficiency, and severity of mastitis varies with parity. The main objective of this article is to review the existing literature regarding the effect of parity on milk yield, lactation efficiency, milk composition, and mastitis in Murrah. Parity plays a crucial role in the productivity, profitability, and economic efficiency of Murrah buffaloes. Most of the researchers reported that parity has a significant effect on 305 MY, Total milk yield, milk composition while the non-significant effect on colostrums period, lactation length, and mastitis. Milk quantity and quality was superior in mid parity as compared to early and late parity. Days to reach peak milk yield, dry period, and mastitis incidence were reported minimum in mid parity. The milk of Murrah is mainly composed of water, lactose, fat, solid not fat, total solid, vitamins, minerals, casein, and protein. Milk constituents such as protein, casein, lactose were superior in mid parity except for milk fat and total solid due to reduced milk yield. However, the research paper regarding the effect of parity on most of these parameters is very scanty. So, further research should be conducted using a large sample size and wider agro-ecological zones to gain a better understanding and to obtain a more precise result.

Virulence profiles of Klebsiella pneumoniae isolated from 2 large dairy farms in China

We recently reported on the diversity of Klebsiella pneumoniae isolated from dairy herds in China. In our previous work, isolates from subclinical mastitis (SCM) had lower indices of diversity when compared with bacteria from other sources, possibly due to a contagious-like spread of udder adapted strains. Here we explored the virulence profile and capsular types of K. pneumoniae isolated from different sources on 2 dairy farms in China. Our overarching goal was to gain insights on the role of virulence genes toward the severity of mastitis caused by K. pneumoniae. A total of 1,484 samples were collected from clinical mastitis (CM; n = 355), SCM (n = 561), bulk tank milk (BTM; n = 130), and environmental and extramammary (EE) sites (n = 438). From those, 431 K. pneumoniae isolates were obtained, including 129, 77, 66, and 159 isolates from CM, SCM, BTM, and EE samples, respectively. Polymerase chain reactions were used to determine the capsular types and to detect potential virulence genes in all isolates. No significant farm effects were observed when comparing the distribution of most virulence genes in K. pneumoniae isolated from each source. K57 was the most prevalent capsular type in K. pneumoniae from all sources, but with increased detection rate in isolates from CM. entB, kfu, fimH1, mrkD, and β-d-lacZ were frequently detected in K. pneumoniae from all sources. β-d-lacZ, entB, and ituA were more prevalent in isolates from CM, whereas kfu, allS, and nif were more frequently detected in isolates from SCM. ybtS, aerobactin, and rpmA had increased prevalence in K. pneumoniae from BTM when compared with bacteria from other sources. No association was detected between virulence genes and the severity of CM. K57 and the nif gene had the highest discriminatory power to classify isolates from CM and SCM, respectively. Based on our findings, it is likely that K57 is the dominant capsular type in K. pneumoniae causing CM in large Chinese dairy herds. Likewise, we demonstrated that β-d-lacZ is disseminated in K. pneumoniae isolated from large Chinese dairy farms, irrespectively of the source of bacteria. Our results also suggest a low contribution of the virulence profile of K. pneumoniae toward CM severity. Finally, the role of nif in increasing the adaptability to the udder and promoting a contagious-like spread of K. pneumoniae warrants further investigation.

English

Bovine mastitis is a host response to the microorganisms linked with the host immune system efficiency. Tumor necrosis factor-alpha (TNF-α) is a proinflammatory cytokine that plays a significant role in the innate and adaptive immune response. In this study, we characterized the upstream regulatory region and evaluated the relative mRNA expression of TNF-α gene of Sahiwal cows. A single nucleotide polymorphism A&gt;G was identified located within a sequence (MT_919286) at the 5´ upstream region. For gene expression, the ΔΔCt was calculated by adjusting the target gene expression for the expression of the housekeeping gene (GAPDH) through real-time qPCR. The results revealed that relative mRNA expression of TNF-α most explains the change in the unit of ΔCt and would result in a significantly higher expression of TNF-α gene in animals with mastitis. The relative mRNA expression of TNF-α gene was 35 and 9.53 times higher in animals with clinical and subclinical mastitis respectively, as compared to non-mastitic animals. The effect of the fold change of TNF-α and GAPDH was also assessed based on response surface methodology via Box Behnken design. The analysis depicted that all parameters had a significant impact on mastitis incidence in Sahiwal cows. This study would hopefully contribute towards a better understanding of the use of TNF-α gene marker as an authentic source of identification of severity of bovine mastitis. The findings of study may be helpful for the development of new strategies to control mastitis and preserve the health of dairy animals. © 2021 Friends Science Publishers

Staphylococcus aureus Isolated from Ruminants with Mastitis in Northern Greece Dairy Herds: Genetic Relatedness and Phenotypic and Genotypic Characterization.

Staphylococcus aureus is the most common mastitis-related pathogen in dairy cattle, goats, and sheep worldwide. However, the population structure and genomic characteristics of mastitis-associated S. aureus in small ruminants are limited. Furthermore, the genotypic and phenotypic characteristics involved in the pathogenicity of S. aureus have been thoroughly defined, yet their association with the severity of mastitis is not fully established. Here, we performed genotyping by pulsed-field gel electrophoresis (PFGE) and spa analyses to assess the genetic diversity and relatedness of 162 S. aureus strains recovered from clinical mastitis (CM) and subclinical mastitis (SCM) cases from goats, sheep, and bovines. PFGE analysis revealed 108 distinguishable pulsotypes and 3 main clusters that comprised isolates from the three host species, while according to spa typing, 32 different spa types were identified. Genotypic analysis revealed a spreading of genetically related or indistinguishable S. aureus strains among ovine, caprine, and bovine farms of distant geographical regions. In total, 28 different staphylococcal enterotoxin (SE) gene profiles were observed, revealing a diverse range of SE genes among isolates. By evaluating the antimicrobial resistance, we found low phenotypic antimicrobial resistance among all ruminant isolates. We also performed multiple correspondence analysis, which indicated that the presence of the sec gene, biofilm production, and high autoaggregation ability are associated with CM cases.