Mastitis in Post-Partum Dairy Cows

Periparturient blood T-lymphocyte PD-1 and CTLA-4 expression as potential predictors of new intramammary infections in dairy cows during early lactation (short communication)

BACKGROUND

The periparturient period in dairy cows is marked by immunosuppression which increases the likelihood of infectious disorders, particularly also mastitis. An in-depth understanding of peripartum leukocyte biology is vital for the implementation of highly successful post-partum disease prevention measures. Immune checkpoint molecules, such as programmed death 1 (PD-1) and cytotoxic T-lymphocyte antigen 4 (CTLA-4), are critical inhibitory receptors expressed on immune cells, particularly T cells, that drive immunosuppressive signaling pathways. However, the potential role of immune checkpoint molecules expression in T-cells on udder health has never been explored. Thus, the association between the occurrence of new postpartum intramammary infections (IMIs) and the expression of programmed cell death protein 1 (PD-1) and cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) on blood T-cells during the peripartum period was investigated.

RESULTS

In this study, the incidence of IMIs by any pathogen in early lactation was not associated with a higher expression of PD-1 and CTLA-4 in the periparturient period. However, the incidence of IMIs by major pathogens throughout the first month of lactation was significantly associated with higher expression of PD-1 at 14 days before calving (P = 0.03) and CTLA-4 at parturition (P = 0.03) by blood T-cells. Also, the expression of CTLA-4 at D0 (P = 0.012) by T-cells was associated with the occurrence of persistent IMIs during the first month of lactation.

CONCLUSIONS

To our knowledge, this is the first report to investigate the expression of PD-1 and CTLA-4 by blood T-lymphocytes during the periparturient period in dairy cows and to explore their relationship with the incidence of new IMIs in the postpartum period. Thus, a comprehensive understanding of leukocyte biology during peripartum would appear to be a prerequisite for the identification of resilient dairy cows or targets innovative (immunological) non-antibiotic approaches in the transition period.

Lactococcus garvieae exerts a critical role in inducing inflammation in dairy mastitis by triggering NLRP3 inflammasome-mediated pyroptosis in MAC-T cells

Lactococcus garvieae (L. garvieae) is a pathogenic bacterium that is Gram-positive and catalase-negative (GPCN), and it is capable of growing in a wide range of environmental conditions. This bacterium is associated with significant mortality and losses in fisheries, and there are concerns regarding its potential as a zoonotic pathogen, given its presence in cattle and dairy products. While we have identified and characterized virulent strains of L. garvieae through phenotyping and molecular typing studies, their impact on mammary tissue remains unknown. This study aims to investigate the pathogenicity of strong and weak virulent strains of L. garvieae using in vivo mouse models. We aim to establish MAC-T cell model to examine potential injury caused by the strong virulent strain LG41 through the TLR2/NLRP3/NF-kB pathway. Furthermore, we assess the involvement of NLRP3 inflammasome-mediated pyroptosis in dairy mastitis by silencing NLRP3. The outcomes of this study will yield crucial theoretical insights into the potential mechanisms involved in mastitis in cows caused by the L. garvieae-induced inflammatory response in MAC-T cells.

Understanding mastitis: Microbiome, control strategies, and prevalence - A comprehensive review

Mastitis significantly affects the udder tissue in dairy cattle, leading to inflammation, discomfort, and a decline in both milk yield and quality. The condition can be attributed to an array of microbial agents that access the mammary gland through multiple pathways. The ramifications of this ailment are not merely confined to animal welfare but extend to the financial viability of the livestock industry. This review offers a historical lens on mastitis, tracing its documentation back to 1851, and examines its global distribution with a focus on regional differences in prevalence and antimicrobial resistance (AMR) patterns. Specific microbial genes and communities implicated in both mastitis and AMR are explored, including Staphylococcus aureus, Streptococcus agalactiae,Streptococcus dysagalactiae, Streptococcus uberis Escherichia coli, Klebsiella pneumoniae, Mycoplasma bovis, Corynebacterium bovis, among others. These microorganisms have evolved diverse strategies to elude host immune responses and neutralize commonly administered antibiotics, complicating management efforts. The review aims a comprehensive overview of the current knowledge and research gaps on mastitis and AMR, and to highlight the need for a One Health approach to address this global health issue. Such an approach entails multi-disciplinary cooperation to foster judicious antibiotic use, enhance preventive measures against mastitis, and bolster surveillance and monitoring of AMR in pathogens responsible for mastitis.

Effects of Glucose Levels on Inflammation and Amino Acid Utilization in Lipopolysaccharide-Induced Bovine Mammary Epithelial Cells

Glucose and amino acids are important sources of nutrients in the synthetic milk of dairy cows, and understanding the fate of amino acids is essential to optimize the utilization of amino acids in milk protein synthesis, thereby reducing nutrient inefficiencies during lactation. The purpose of this study was to investigate the effects of LPS and different concentrations of glucose on (1) the expression of inflammatory factors and genes, (2) the glucose metabolism, and (3) amino acid utilization in BMECs. The results showed that there was an interaction (LPS × glucose, p < 0.05) between LPS and glucose content in the inflammatory cytokine genes (IL-6 and TNF-α) and the inflammatory regulatory genes (CXCL2, CXCL8, and CCL5). With the addition of LPS, the HG + LPS group caused downregulated (p < 0.05) expression of IL-6 and TNF-α, compared with the LG + LPS group. Interestingly, compared with the LG + LPS group, the HG + LPS group upregulated (p < 0.05) the expression of CXCL2, CXCL8, and CCL5. LPS supplementation increased (p = 0.056) the consumption of glucose and GLUT1 gene expression (p < 0.05) and tended to increase (p = 0.084) the LDHA gene expression of BMECs under conditions of different concentrations of glucose culture. High glucose content increased (p < 0.001) the consumption of glucose and enhanced (p < 0.05) the GLUT1, HK1, HK2, and LDHA gene expression of BMECs with or without LPS incubation, and there was an interaction (LPS × glucose, p < 0.05) between LPS and glucose concentrations in GLUT1 gene expression. In this study, LPS enhanced (p < 0.05) the consumption of amino acids such as tryptophan, leucine, isoleucine, methionine, valine, histidine, and glutamate, while high levels of glucose decreased (p < 0.01) consumption, except in the case of tyrosine. For histidine, leucine, isoleucine, and valine consumption, there was an interaction (LPS × glucose, p < 0.05) between LPS and glucose levels. Overall, these findings suggest that relatively high glucose concentrations may lessen the LPS-induced BMEC inflammatory response and reduce amino acid consumption, while low glucose concentrations may increase the demand for most amino acids through proinflammatory responses.

Dynamics of Milk Parameters of Quarter Samples before and after the Dry Period on Czech Farms

This study aimed to monitor milk parameters on three different dairy farms in the Czech Republic to describe their readiness for implementing selective dry cow therapy. Fat, protein, casein, lactose, solids-not-fat content, total solids content, freezing point, titratable acidity, and somatic cell count of quarter milk samples collected from tested Holstein cows were evaluated. Associations between the tested parameters, as well as the effects of parity, farm, day of calving, and time of evaluation at dry-off and after calving, were assessed. Values of the leading milk components dynamically changed between dry-off and after calving, but only protein content was significantly affected. The most important parameter of our research, the somatic cell count of quarter milk samples, was also not affected by the time of evaluation. Even though a slight increase in the mean of somatic cell count is expected before the dry period and after calving, at dry-off, we observed 30%, 42%, and 24% of quarters with somatic cell counts above 200,000 cells per mL, while after calving, we observed 27%, 16%, and 18% of quarters with somatic cell counts above 200,000 cells per mL on Farm 1, Farm 2, and Farm 3, respectively. High somatic cell counts (>200,000 cells per mL) indicate bacterial infection, as confirmed by the significant negative correlation between this parameter and lactose content. In addition, a deficient milk fat-to-protein ratio was observed on two farms, which may indicate metabolic disorders, as well as the occurrence of intramammary infections. Despite the above, we concluded that according to the thresholds of somatic cell counts for selective dry cow therapy taken from foreign studies, a large part of the udder quarters could be dried off without the administration of antibiotics. However, it is necessary to set up more effective mechanisms for mastitis prevention.

Blood neutrophil extracellular traps: a novel target for the assessment of mammary health in transition dairy cows

Background

Mammary health is important for transition dairy cows and has been well recognized to exert decisive effects on animal welfare. However, the factors influencing mammary health are still unclear. Differential somatic cell count (DSCC) could reflect the mastitis risk since it is the percentage of neutrophils plus lymphocytes in total somatic cells and could be reflective of mammary health of dairy cows. This work aimed to investigate the assessment and prognosis of the health of transition cows based on blood neutrophil extracellular traps (NETs).

Results

Eighty-four transition Holstein dairy cows were selected. The serum was sampled in all the animals at week 1 pre- and postpartum, and milk was sampled at week 1 postpartum. Based on the DSCC in milk at week 1, cows with lower (7.4% ± 4.07%, n = 15) and higher (83.3% ± 1.21%, n = 15) DSCCs were selected. High DSCC cows had higher levels of red blood cell counts (P < 0.05), hemoglobin (P = 0.07), and hematocrit (P = 0.05), higher concentrations of serum oxidative variables [(reactive oxygen species (P < 0.05), malondialdehyde (P < 0.05), protein carbonyl (P < 0.05), and 8-hydroxy-2-deoxyguanosine (P = 0.07)], higher levels of serum and milk NETs (P < 0.05) and blood-milk barrier indicators, including serum β-casein (P = 0.05) and milk immunoglobulin G2 (P = 0.09), than those of low DSCC cows. In addition, lower concentrations of serum nutrient metabolites (cholesterol and albumin) (P < 0.05) and a lower level of serum deoxyribonuclease I (P = 0.09) were observed in high DSCC cows than in low DSCC cows. Among the assessments performed using levels of the three prepartum serum parameters (NETs, deoxyribonuclease I and β-casein), the area under the curve (0.973) of NETs was the highest. In addition, the sensitivity (1.00) and specificity (0.93) were observed for the discrimination of these cows using NETs levels with a critical value of 32.2 ng/mL (P < 0.05).

Conclusions

The formation of NETs in blood in transition dairy cows may damage the integrity of the blood-milk barrier and thereby increase the risk for mastitis in postpartum cows.

Invited review: Selective use of antimicrobials in dairy cattle at drying-off

Administering intramammary antimicrobials to all mammary quarters of dairy cows at drying-off [i.e., blanket dry cow therapy (BDCT)] has been a mainstay of mastitis prevention and control. However, as udder health has considerably improved over recent decades with reductions in intramammary infection prevalence at drying-off and the introduction of teat sealants, BDCT may no longer be necessary on all dairy farms, thereby supporting antimicrobial stewardship efforts. This narrative review summarizes available literature regarding current dry cow therapy practices and associated impacts of selective dry cow therapy (SDCT) on udder health, milk production, economics, antimicrobial use, and antimicrobial resistance. Various methods to identify infections at drying-off that could benefit from antimicrobial treatment are described for selecting cows or mammary quarters for treatment, including utilizing somatic cell count thresholds, pathogen identification, previous clinical mastitis history, or a combination of criteria. Selection methods may be enacted at the herd, cow, or quarter levels. Producers' and veterinarians' motivations for antimicrobial use are discussed. Based on review findings, SDCT can be adopted without negative consequences for udder health and milk production, and concurrent teat sealant use is recommended, especially in udder quarters receiving no intramammary antimicrobials. Furthermore, herd selection should be considered for SDCT implementation in addition to cow or quarter selection, as BDCT may still be temporarily necessary in some herds for optimal mastitis control. Costs and benefits of SDCT vary among herds, whereas impacts on antimicrobial resistance remain unclear. In summary, SDCT is a viable management option for maintaining udder health and milk production while improving antimicrobial stewardship in the dairy industry.

Bovine Mastitis: Prevalence, Risk Factors, and Bacterial Pathogens Isolated in Lactating Cows in Gamo Zone, Southern Ethiopia

Purpose

Mastitis is a disease known to cause a great deal of loss of production and has a major economic impact. In the study area, there is little current information on bovine mastitis. Therefore, this study aimed to determine the overall prevalence of bovine mastitis and its associated risk factors and isolate the major pathogenic bacteria.

Methods

A cross-sectional study was conducted from February 2020 to September 2020 in selected dairy farms of Gamo Zone, southern Ethiopia. A total of 422 lactating cows were diagnosed for mastitis using the California mastitis test, clinical examination, and bacteriological methods.

Results

The overall prevalence of bovine mastitis determined in the area was 17.1% (72 of 422), of which 1.9% (eight of 422) was clinical and 15.2% (64 of 422) subclinical. Of 1,662 quarters examined, 7.94% (132) were positive. Bacteriological methods were also used to isolate the major pathogenic bacterial species associated with bovine mastitis. From 72 composite milk samples, growth of six different groups of bacteria was recorded in 64 (88.9%) samples. The most predominant bacterial pathogens isolated were Staphylococcus aureus (42.6%), ahead of Streptococcus spp. (26.2%), non-aureus staphylococci (14.8%), and Escherichia coli (11.5%). Salmonella spp. (3.3%) and Klebsiella pneumoniae (1.6%) were the least isolated bacterial pathogens. Among risk factors, breed, parity, udder depth, and tick infestation of the udder showed statistically significant differences (P<0.05) regarding the occurrence of mastitis.

Conclusion

The current study revealed that mastitis is one of the health problems affecting dairy cows in Gamo. Enhancing the awareness of dairy farmers, regular screening, and improving hygienic conditions are critically important to control and prevent bovine mastitis in the study area.

Invited review: Mechanisms of hypophagia during disease

Suppression of appetite, or hypophagia, is among the most recognizable effects of disease in livestock, with the potential to impair growth, reproduction, and lactation. The continued evolution of the field of immunology has led to a greater understanding of the immune and endocrine signaling networks underlying this conserved response to disease. Inflammatory mediators, especially including the cytokines tumor necrosis factor-α and interleukin-1β, are likely pivotal to disease-induced hypophagia, based on findings in both rodents and cattle. However, the specific mechanisms linking a cytokine surge to decreased feeding behavior are more difficult to pin down and likely include direct effects on appetite centers in the brain, alteration of gastric motility, and modulation of other endocrine factors that influence appetite and satiety. These insights into the mechanisms for disease-induced hypophagia have great relevance for management of neonatal calves, mature cows transitioning to lactation, and cows experiencing mastitis; however, it is not necessarily the case that increasing feed intake by any means possible will improve health outcomes for diseased cattle. We explore conflicting effects of hypophagia on immune responses, which may be impaired by the lack of specific substrates, versus apparent benefits for controlling the growth of some pathogens. Anti-inflammatory strategies have shown promise for promoting recovery of feed intake following some conditions but not others. Finally, we explore the potential for early disease detection through automated monitoring of feeding behavior and consider which strategies may be implemented to respond to early hypophagia.

Graduate Student Literature Review: What do we know about the effects of clinical and subclinical hypocalcemia on health and performance of dairy cows?

This narrative literature review summarizes findings regarding the associations of clinical and subclinical hypocalcemia with postpartum health, reproduction, and milk production. To better understand the effects of hypocalcemia, we reviewed clinical and subclinical presentations of the condition and the dynamics of blood Ca concentration in the early postpartum period. We summarize and discuss the associations between hypocalcemia and performance of dairy cows. Up to 50% of dairy cows suffer from at least one disease event in the transition period. The important roles of calcium in muscle contraction and immune function make it a key component of metabolism, inflammation, and defense against infection. Although the effect of clinical hypocalcemia (milk fever) on health and performance is clear, the definition of subclinical hypocalcemia (SCH) and its consequences for health and performance are still ambiguous. Differences in study designs, sampling protocols, Ca concentration thresholds, and sample sizes that may be underpowered for health and reproduction outcomes lead to inconsistent conclusions on the effects of SCH. On current evidence, classification of SCH should be based on at least 2 measurements of blood calcium, using cutpoints supported with relevant data, which may vary depending on the outcome of interest. Arbitrary or poorly supported interpretative thresholds for blood Ca concentrations should be abandoned. Transient SCH appears to be associated with greater milk yield, whereas SCH that is present several days after calving is associated with lesser production and greater disease risk. However, when blood calcium is measured days after calving, primary effects of calcium metabolism may be confounded by feed intake, inflammation, or disease, which might either contribute to or be a consequence of hypocalcemia. Additional research is needed to refine sampling schemes to classify SCH, and to better inform the goals and means of prevention of SCH.

CCS e amiloide A do leite de quartos mamários tratados na secagem com plasma rico em plaquetas autólogo, associado ou não a antibiótico

RESUMO Este estudo teve como objetivo avaliar biomarcadores de mastite após terapia da secagem com plasma rico em plaquetas (PRP), associado ou não a antibiótico. Trinta e seis quartos mamários foram utilizados em três tratamentos (T): T1 - antibiótico (ATB), T2 - PRP e T3 - PRP + ATB. Amostras de leite foram coletadas antes da secagem (A1), no parto (D0) e 14, 30 e 60 dias pós-parto (D14, D30 e D60), para determinar contagem de células somáticas (CCS) e amiloide A (AA). O delineamento foi inteiramente ao acaso, com arranjo em parcelas subdivididas (SigmaPlot®). Dados de CCS foram transformados (log 10). As médias foram comparadas utilizando-se testes de Tukey ou Holm-Sidak (P<0,05). A CCS em A1 foi elevada em todos os grupos (P>0,05). No D30, CCS foi maior em T2 (P<0,05), igualando-se no D60. Não houve diferença na AA entre Ts em qualquer dia de coleta (P>0,05). Houve diferença nos momentos de coleta (P<0,05), A1 maior que D14 e D30. Houve uma correlação positiva fraca com CCS (0,280). Os tratamentos foram semelhantes em manter a saúde da glândula mamária na lactação subsequente. O PRP intramamário pode ser usado para terapia de vaca seca em casos de mastite subclínica.

Immunization of young heifers with staphylococcal immune evasion proteins before natural exposure to Staphylococcus aureus induces a humoral immune response in serum and milk

Background

Staphylococcus aureus, a leading cause of mastitis in dairy cattle, causes severe mastitis and/or chronic persistent infections with detrimental effects on the cows’ wellbeing, lifespan and milk production. Despite years of research there is no effective vaccine against S. aureus mastitis. Boosting of non-protective pre-existing immunity to S. aureus, induced by natural exposure to S. aureus, by vaccination may interfere with vaccine efficacy. The aim was to assess whether experimental immunization of S. aureus naïve animals results in an immune response that differs from immunity following natural exposure to S. aureus.

Results

First, to define the period during which calves are immunologically naïve for S. aureus, Efb, LukM, and whole-cell S. aureus specific serum antibodies were measured in a cohort of newborn calves by ELISA. Rising S. aureus specific antibodies indicated that from week 12 onward calves mounted an immune response to S. aureus due to natural exposure. Next, an experimental immunization trial was set up using 8-week-old heifer calves (n = 16), half of which were immunized with the immune evasion molecules Efb and LukM. Immunization was repeated after one year and before parturition and humoral and cellular immunity specific for Efb and LukM was determined throughout the study. Post-partum, antibody levels against LukM and EfB were significantly higher in serum, colostrum and milk in the experimentally immunized animals compared to animals naturally exposed to S. aureus. LukM specific IL17a responses were also significantly higher in the immunized cows post-partum.

Conclusions

Experimental immunization with staphylococcal immune evasion molecules starting before natural exposure resulted in significantly higher antibody levels against Efb and LukM around parturition in serum as well as the site of infection, i.e. in colostrum and milk, compared to natural exposure to S. aureus. This study showed that it is practically feasible to vaccinate S. aureus naïve cattle and that experimental immunization induced a humoral immune response that differed from that after natural exposure only.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1765-9) contains supplementary material, which is available to authorized users.

Invited review: Microbiota of the bovine udder: Contributing factors and potential implications for udder health and mastitis susceptibility

Various body sites of vertebrates provide stable and nutrient-rich ecosystems for a diverse range of commensal, opportunistic, and pathogenic microorganisms to thrive. The collective genomes of these microbial symbionts (the microbiome) provide host animals with several advantages, including metabolism of indigestible carbohydrates, biosynthesis of vitamins, and modulation of innate and adaptive immune systems. In the context of the bovine udder, however, the relationship between cow and microbes has been traditionally viewed strictly from the perspective of host-pathogen interactions, with intramammary infections by mastitis pathogens triggering inflammatory responses (i.e., mastitis) that are often detrimental to mammary tissues and cow physiology. This traditional view has been challenged by recent metagenomic studies indicating that mammary secretions of clinically healthy quarters can harbor genomic markers of diverse bacterial groups, the vast majority of which have not been associated with mastitis. These observations have given rise to the concept of "commensal mammary microbiota," the ecological properties of which can have important implications for understanding the pathogenesis of mastitis and offer opportunities for development of novel prophylactic or therapeutic products (or both) as alternatives to antimicrobials. Studies conducted to date have suggested that an optimum diversity of mammary microbiota is associated with immune homeostasis, whereas the microbiota of mastitic quarters, or those with a history of mastitis, are considerably less diverse. Whether disruption of the diversity of udder microbiota (dysbiosis) has a role in determining mastitis susceptibility remains unknown. Moreover, little is known about contributions of various biotic and abiotic factors in shaping overall diversity of udder microbiota. This review summarizes current understanding of the microbiota within various niches of the udder and highlights the need to view the microbiota of the teat apex, teat canal, and mammary secretions as interconnected niches of a highly dynamic microbial ecosystem. In addition, host-associated factors, including physiological and anatomical parameters, as well as genetic traits that may affect the udder microbiota are briefly discussed. Finally, current understanding of the effect of antimicrobials on the composition of intramammary microbiota is discussed, highlighting the resilience of udder microbiota to exogenous perturbants.

The effect of dry cow therapy using systemic tylosin in combination with common intramammary medications on mastitis rate, cull rate, somatic cell count, and milk production in dairy cows affected with subclinical mastitis

Aims

This study was performed to evaluate the effect of systemic tylosin on mastitis rates, cull rates because of mastitis, and quality and quantity of milk production in dairy cows affected with subclinical mastitis.

Materials and Methods

A total of 130 California mastitis test (CMT)-positive cows were randomly selected and divided into four different treatment groups. All treatments were performed on the day of drying off. Cows in Group 1 (n=34) received 12 g of tylosin intramuscularly (IM) and intramammary (IMM) 400 mg novobiocin sodium and 200,000IU penicillin G procaine. Group 2 (n=33) received 12 g tylosin IM and IMM 280 mg benethamine penicillin, 100 mg penethamate hydriodide, and 100 mg framycetin sulfate. Group 3 (n=33) received IMM alone with 400 mg novobiocin sodium and 200,000 IU penicillin G procaine. Group 4 (n=30) received IMM alone with 280 mg benethamine penicillin, 100 mg penethamate hydriodide, and 100 mg framycetin sulfate. The incidence and severity of clinical mastitis (CM), incidence of chronic mastitis, and cow cull rate because of mastitis were recorded during the first 100 days in milk (DIM). In addition, somatic cell count (SCC) and milk production parameters including the average days to peak milk yield, the average milk yield at peak, the average milk yield during the first 100 DIM, and the average 305-corrected milk yield were reported.

Results

The rate of CM was significantly (p≤0.05) less in Group 2 when compared between the current and previous lactations (30% vs. 64%). In Group 1 and 4, the rate of CM was decreased but not significant between the two lactations (59% vs. 79% and 63% vs. 77%, respectively) while in Group 3, the rate of CM was slightly increased (82% vs. 91%). When compared between the four groups in the current lactation, CM rate was significantly (p≤0.05) less in Group 2 compared to the other groups. A significant (p≤0.05) percentage of CM cases in Group 2 was classified as mild. In Groups 1 and 3, a significant (p≤0.05) percentage of CM cases was classified as moderate while severe clinical signs were recorded more significantly (p≤0.05) in Groups 3 and 4. The rate of chronic mastitis was significantly less in Group 1 and Group 2 in the current lactation compared to that in the previous lactation (6% vs. 12% and 0% vs. 6%, respectively). In Groups 3 and 4, the rate of chronic mastitis was not changed significantly when compared between the current and previous lactations. No cows were culled because of mastitis in Groups 1 and 3 while one cow was culled in each of Groups 2 and 4 during the first 100 DIM in the current lactation. The average milk yield during the first 100 DIM and the 305-corrected milk yield were significantly (p≤0.05) increased in Group 2 when compared between the previous and current lactations. Furthermore, cows in Group 2 produced significantly (p≤0.05) more milk during the first 100 DIM and significantly (p≤0.05) more 305-corrected milk yield compared to the other groups. In Group 2, the average SCC dropped significantly (p≤0.05) from 1,600,000 cells/ml at the start of the study to <200,000 cells/ml at 100 DIM.

Conclusions

In dairy herds with subclinical mastitis, dry cow therapy of CMT-positive cows using a combination of tylosin (12 g, IM) and IMM administration of benethamine penicillin, penethamate hydriodide, and framycetin sulfate (Ubrostar; Boehringer Ingelheim, Germany) may result in a significant reduction of the rate and severity of acute and chronic mastitis and cull rates due to mastitis within the first 100 DIM. Furthermore, treated cows may produce significantly more milk with less SCC during the first 100 DIM and therefore produce significantly more 305-corrected milk in the lactation following treatment.

Composition of the teat canal and intramammary microbiota of dairy cows subjected to antimicrobial dry cow therapy and internal teat sealant

Antimicrobial dry cow therapy (DCT) is an important component of mastitis control programs aimed to eliminate existing intramammary infections and prevent the development of new ones during the dry period. However, to what extent the microbiota profiles of different niches of the udder change during the dry period and following administration of DCT remains poorly understood. Therefore, the main objective of the present study was to qualitatively evaluate dynamics of the microbiota of teat canal (TC) and mammary secretions (i.e., milk and colostrum) of healthy udder quarters subjected to DCT using a long-acting antimicrobial product, containing penicillin G and novobiocin, in combination with internal teat sealant. To this end, TC swabs (n = 58) and their corresponding milk (n = 29) and colostrum samples (n = 29) were collected at the time of drying off and immediately after calving from clinically healthy udder quarters of Holstein dairy cows from a commercial dairy farm. All samples were subjected to DNA extraction and high-throughput sequencing of the V1-V2 hypervariable regions of bacterial 16S rRNA genes. Overall, shifts were more pronounced within the microbiota of mammary secretions than the TC. In particular, microbiota of colostrum samples collected immediately after calving were less species-rich compared with the pre-DCT milk samples. Proportions of several bacterial genera belonging to the phylum Proteobacteria, including Pseudomonas, Stenotrophomonas, and unclassified Alcaligenaceae, were enriched within the microbiota of colostrum samples, whereas Firmicutes genera, including Butyrivibrio, unclassified Clostridiaceae, and unclassified Bacillales, were overrepresented in pre-DCT milk microbiota. Apart from shifts in the proportion of main bacterial genera and phyla, qualitative analysis revealed a high degree of commonality between pre-DCT and postpartum microbiota of both niches of the udder. Most importantly, a considerable number of bacterial genera and species commonly regarded as mastitis pathogens or opportunists (or both), including Staphylococcus spp., unclassified Enterobacteriaceae, and Corynebacterium spp., were shared between pre-DCT and postpartum microbiota of mammary secretions. Percentage of shared bacterial genera and species was even higher between pre-DCT and postpartum microbiota of TC samples, suggesting that the DCT approach of the present study had limited success in eliminating a considerable proportion of bacteria during the dry period.

Genome-wide association study identifies loci associated with milk leukocyte phenotypes following experimental challenge with Streptococcus uberis

Mastitis is a detrimental disease in the dairy industry that decreases milk quality and costs upwards of $2 billion annually. Often, mastitis results from bacteria entering the gland through the teat opening. Streptococcus uberis is responsible for a high percentage of subclinical and clinical mastitis. Following an intramammary experimental challenge with S. uberis on Holstein cows (n = 40), milk samples were collected and somatic cell counts (SCC) were determined by the Dairy Herd Improvement Association Laboratory. Traditional genome-wide association studies (GWAS) have utilized test day SCC or SCC lactation averages to identify loci of interest. Our approach utilizes SCC collected following a S. uberis experimental challenge to generate three novel phenotypes: (1) area under the curve (AUC) of SCC for 0-7 days and (2) 0-28 days post-challenge; and (3) when SCC returned to below 200,000 cells/mL post-challenge (< 21 days, 21-28 days, or > 28 days). Polymorphisms were identified using Illumina's BovineSNP50 v2 DNA BeadChip. Associations were tested using Plink software and identified 16 significant (p < 1.0 × 10^-4) single-nucleotide polymorphisms (SNPs) across the phenotypes. Most significant SNPs were in genes linked to cell signaling, migration, and apoptosis. Several have been recognized in relation to infectious processes (ATF7, SGK1, and PACRG), but others less so (TRIO, GLRA1, CELSR2, TIAM2, CPE). Further investigation of these genes and their roles in inflammation (e.g., SCC) can provide potential targets that influence resolution of mammary gland infection. Likewise, further investigation of the identified SNP with mastitis and other disease phenotypes can provide greater insight to the potential of these SNP as genetic markers.

Whole blood transcriptome analysis reveals potential competition in metabolic pathways between negative energy balance and response to inflammatory challenge

Negative Energy Balance (NEB) is considered to increase susceptibility to mastitis. The objective of this study was to improve our understanding of the underlying mechanisms by comparing transcriptomic profiles following NEB and a concomitant mammary inflammation. Accordingly, we performed RNA-seq analysis of blood cells in energy-restricted ewes and control-diet ewes at four different time points before and after intra mammary challenge with phlogogenic ligands. Blood leucocytes responded to NEB by shutting down lipid-generating processes, including cholesterol and fatty acid synthesis, probably under transcriptional control of SREBF 1. Furthermore, fatty acid oxidation was activated and glucose oxidation and transport inhibited in response to energy restriction. Among the differentially expressed genes (DEGs) in response to energy restriction, 64 genes were also differential in response to the inflammatory challenge. Opposite response included the activation of cholesterol and fatty acid synthesis during the inflammatory challenge. Moreover, activation of glucose oxidation and transport coupled with the increase of plasma glucose concentration in response to the inflammatory stimuli suggested a preferential utilization of glucose as the energy source during this stress. Leucocyte metabolism therefore undergoes strong metabolic changes during an inflammatory challenge, which could be in competition with those induced by energy restriction.

Effects of aqueous extracts of Taraxacum Officinale on expression of tumor necrosis factor-alpha and intracellular adhesion molecule 1 in LPS-stimulated RMMVECs

Background

Mastitis gives rise to big financial burden to farm industry (mainly dairy production) and public health. Its incidence is currently high and therefore, highly effective treatments for therapy, especially with natural products are required. Taraxacum officinale has been reported to use for anti-inflammation. However, its effect on endothelium during mastitis has not been reported.

Methods

We firstly established inflammation experimental model of rat mammary microvascular endothelial cells (RMMVECs). We evaluated the effects of dandelion leaf aqueous extracts (DAE) on LPS-induced production of inflammatory mediators in RMMVECs by enzyme-linked immunosorbent assay and Western blot. We treated RMMVECs with 1 μg/ml LPS for 4 h and then incubated with 10, 100 and 200 μg/mL DAE for 4, 8, 12 and 24 h. The expression (mRNA and protein level) of targets (tumor necrosis factor-alpha (TNF- α) and Intracellular Adhesion Molecule 1 (ICAM1) was analyzed by employing real-time PCR and Western blots. The in vivo anti-inflammatory effect of DAE on mastitis within an Staphylococcus aureus-induced mouse model was also determined.

Results

The obtained results showed that dandelion extracts at the concentration of 100 and 200 μg/mL could significantly inhibit both TNF-α and ICAM-1 expression in all time points checked while 10 μg/mL of dandelion only suppress both expression at 8 and 12 h post-treatment. The in vivo tests showed that the DAE inhibited the expression of TNF-α and ICAM-1 in a time-dependent manner.

Conclusions

All results suggest that the endothelium may use as as a possible target of dandelion for anti-inflammation.

Associations between lipid metabolism and fertility in the dairy cow

Dairy cows mobilise body tissues to support milk production and, because glucose supplies are limited, lipids are used preferentially for energy production. Lipogenic activity is switched off and lipolytic mechanisms in adipose tissue increase through changes in the expression of several key enzymes. This results in a loss of body condition, together with high circulating concentrations of non-esterified fatty acids. Changes in the synthesis, secretion and signalling pathways of somatotrophic hormones (insulin, growth hormone, insulin-like growth factor 1) and adipokines (e.g. leptin) are central to the regulation of these processes. A high reliance on fatty acids as an energy source in the peripartum period causes oxidative damage to mitochondria in metabolically active tissues, including the liver and reproductive tract. The expression of genes involved in insulin resistance (PDK4, AHSG) is increased, together with expression of TIEG1, a transcription factor that can induce apoptosis via the mitochondrial pathway. Polymorphisms in TFAM and UCP2, two autosomal mitochondrial genes, have been associated with longevity in dairy cows. Polymorphisms in many other genes that affect lipid metabolism also show some associations with fertility traits. These include DGAT1, SCD1, DECR1, CRH, CBFA2T1, GH, LEP and NPY. Excess lipid accumulation in oocytes and the regenerating endometrium reduces fertility via reductions in embryo survival and increased inflammatory changes, respectively.

Experimentally induced mastitis and metritis modulate soy bean derived isoflavone biotransformation in diary cows

The present study compared the changes in isoflavone (daidzein and genistein) and their metabolite (equol and para-ethyl-phenol) concentrations in the blood plasma of cows with induced mastitis and metritis after feeding with soy bean. Sixteen cows were divided into four groups: control for mastitis group, cows with induced mastitis group, control for metritis group, and cows with induced metritis group. All cows were fed a single dose of 2.5 kg of soy bean and then blood samples were taken from the jugular vein for 8 h at predetermined intervals. The concentrations of soy bean-derived isoflavones and their active metabolites were measured in the blood plasma on HPLC system. β-Glucuronidase activity in the blood plasma of cows was measured by fluorometric method. In the blood plasma of cows with induced mastitis and metritis, we found considerably higher concentrations and time-dependent increase in isoflavone metabolites (equol and para-ethyl-phenol) with reference to cyclic cows (P < 0.05). Moreover, we noticed significant decrease of genistein in the blood plasma of the cows with induced metritis compared with control cows (P < 0.05). In addition, in the blood plasma of the cows with induced metritis, we found an increase in β-glucuronidase activity compared with control cows (P < 0.05). In conclusion, health status of the females influenced the concentrations of isoflavone metabolites in the blood plasma of the cows. Experimentally induced mastitis and metritis increased isoflavone absorption, biotransformation and metabolism. Therefore, we suggest that cows with induced mastitis and metritis are more exposed to active isoflavone metabolite actions than healthy cows.

Changes in thermal nociceptive responses in dairy cows following experimentally induced Escherichia coli mastitis

BACKGROUND

Mastitis is a high incidence disease in dairy cows. The acute stage is considered painful and inflammation can lead to hyperalgesia and thereby contribute to decreased welfare. The aim of this study was to examine changes in nociceptive responses toward cutaneous nociceptive laser stimulation (NLS) in dairy cows with experimentally induced Escherichia coli mastitis, and correlate behavioral changes in nociceptive responses to clinical and paraclinical variables.

METHODS

Seven Danish Holstein-Friesian cows were kept in tie-stalls, where the E. coli associated mastitis was induced and laser stimulations were conducted. Measurements of rectal temperature, somatic cell counts, white blood cell counts and E. coli counts were conducted. Furthermore, scores were given for anorexia, local udder inflammation and milk appearance to quantify the local and systemic disease response. In order to quantify the nociceptive threshold, behavioral responses toward cutaneous NLS applied to six skin areas at the tarsus/metatarsus and udder hind quarters were registered at evening milking on day 0 (control) and days 1, 2, 3, 6 and 10 after experimental induction of mastitis.

RESULTS

All clinical and paraclinical variables were affected by the induced mastitis. All cows were clinically ill on days 1 and 2. The cows responded behaviorally toward the NLS. For hind leg stimulation, the proportion of cows responding by stepping was higher on day 0 than days 3 and 6, and the frequency of leg movements after laser stimulation tended to decrease on day 1 compared to the other days. After udder stimulation, the proportion of cows responding by stepping was higher on day 1 than on all other days of testing. Significant correlations between the clinical and paraclinical variables of disease and the behavioral responses toward nociceptive stimulation were found.

CONCLUSIONS

Changes in behavioral responses coincide with peaks in local and systemic signs of E. coli mastitis. During the acute stage of E. coli mastitis nociceptive thermal stimulation on hind leg and mammary glands results in decreased behavioral responses toward nociceptive stimulation, which might be interpreted as hypoalgesia.

Population structure of rumen Escherichia coli associated with subacute ruminal acidosis (SARA) in dairy cattle

Previous studies indicated that only subacute ruminal acidosis (SARA), induced by feeding a high-grain diet, is associated with an inflammatory response and increased abundance of Escherichia coli in the rumen. We hypothesized that ruminal E. coli in grain pellet-induced SARA carried virulence factors that potentially contribute to the immune activation during SARA. One hundred twenty-nine E. coli isolates were cultured from the rumens of 8 cows (4 animals per treatment) in which SARA had been nutritionally induced by feeding a high-grain diet (GPI-SARA) or a diet containing alfalfa pellets (API-SARA). The population structure of the E. coli was evaluated with the ABD genotyping system and repetitive sequence-based (rep)-PCR fingerprinting. Twenty-five virulence factors were evaluated with PCR. Escherichia coli numbers were higher in the GPI-SARA treatment than in the API-SARA treatment. The genetic structure of the E. coli was significantly different between SARA challenge models. Isolates from GPI-control (46%), API-control (70%), and API-SARA (53%) were closely related and fell into one cluster, whereas isolates from GPI-SARA (54%) grouped separately. The ABD typing indicated a shift from an A-type E. coli population to a B1-type population only due to GPI-SARA. Of the 25 virulence factors tested, curli fiber genes were highly associated with GPI. Curli fibers were first identified in E. coli mastitis isolates and are potent virulence factors that induce a range of immune responses. Results suggest that under low rumen pH conditions induced by a grain diet, there is a burst in the number of E. coli with virulence genes that can take advantage of these rumen conditions to trigger an inflammatory response.

The Hsp72 response in peri-parturient dairy cows: relationships with metabolic and immunological parameters

The study was aimed at assessing whether the peri-parturient period is associated with changes of intracellular and plasma inducible heat shock proteins (Hsp) 72 kDa molecular weight in dairy cows, and to establish possible relationships between Hsp72, metabolic, and immunological parameters subjected to changes around calving. The study was carried out on 35 healthy peri-parturient Holstein cows. Three, two, and one week before the expected calving, and 1, 2, 3, 4, and 5 weeks after calving, body conditions score (BCS) was measured and blood samples were collected to separate plasma and peripheral blood mononuclear cells (PBMC). Concentrations of Hsp72 in PBMC and plasma increased sharply after calving. In the post-calving period, BCS and plasma glucose declined, whereas plasma nonesterified fatty acids (NEFA) and tumor necrosis factor-alpha increased. The proliferative responses of PBMC to lipopolysaccharide (LPS) declined progressively after calving. The percentage of PBMC expressing CD14 receptors and Toll-like receptors (TLR)-4 increased and decreased in the early postpartum period, respectively. Correlation analysis revealed significant positive relationships between Hsp72 and NEFA, and between PBMC proliferation in response to LPS and the percentage of PBMC expressing TLR-4. Conversely, significant negative relationships were found between LPS-triggered proliferation of PBMC and both intracellular and plasma Hsp72. Literature data and changes of metabolic and immunological parameters reported herein authorize a few interpretative hypotheses and encourage further studies aimed at assessing possible cause and effect relationships between changes of PBMC and circulating Hsp72, metabolic, and immune parameters in dairy cows.

Escherichia coli infection induces distinct local and systemic transcriptome responses in the mammary gland

Background

Coliform bacteria are the most common etiologic agents in severe mastitis of cows. Escherichia coli infections are mostly restricted to a single udder quarter whereas neighboring quarters stay clinically inapparent, implicating the presence of a systemic defense reaction. To address its underlying mechanism, we performed a transcriptome study of mammary tissue from udder quarters inoculated with E. coli (6 h and 24 h post infection), from neighboring quarters of the same animals, and from untreated control animals.

Results

After 6 h 13 probe sets of differentially expressed genes (DEG) were detected in infected quarters versus control animals. Eighteen hours later 2154 and 476 DEG were found in infected and in neighboring quarters vs. control animals. Cluster analysis revealed DEG found only in infected quarters (local response) and DEG detected in both infected and neighboring quarters (systemic response). The first group includes genes mainly involved in immune response and inflammation, while the systemic reaction comprises antigen processing and presentation, cytokines, protein degradation and apoptosis. Enhanced expression of antimicrobial genes (S100A8, S100A9, S100A12, CXCL2, GNLY), acute phase genes (LBP, SAA3, CP, BF, C6, C4BPA, IF), and indicators of oxidative stress (GPX3, MT1A, MT2A, SOD2) point to an active defense reaction in infected and neighboring healthy quarters. Its early onset is indicated by increased transcription of NFIL3 at 6 h. NFIL3 is a predicted regulator of many genes of the systemic response at 24 h. The significance of our transcriptome study was evidenced by some recent findings with candidate gene based approaches.

Conclusions

The discovery and holistic analysis of an extensive systemic reaction in the mammary gland significantly expands the knowledge of host-pathogen interactions in mastitis which may be relevant for the development of novel therapies and for genetic selection towards mastitis resistance.

Apoptosis of resident and inflammatory macrophages before and during the inflammatory response of the virgin bovine mammary gland

Background

Macrophages may play a prominent role in defense of the bovine mammary gland, and their functionality is necessary for successful eradication of bacterial pathogens. In contrast to necrosis, however, apoptosis has not yet been studied in macrophages from bovine mammary glands. Therefore, the aim of this study was to confirm the occurrence of apoptosis in macrophages from resting heifer mammary glands and during the inflammatory response.

Methods

Inflammatory response was induced by phosphate buffered saline (PBS) and by lipopolysaccharide (LPS). Resident macrophages (_RESMAC) were obtained before and inflammatory macrophages (_INFMAC) 24, 48, 72 and 168 hours after inducing inflammatory response in mammary glands of unbred heifers. Cell samples were analyzed for differential counts, apoptosis and necrosis using flow cytometry.

Results

Populations of _RESMAC and _INFMAC contained monocyte-like cells and vacuolized cells. Apoptosis was detected differentially in both morphologically different types of _RESMAC and _INFMAC and also during initiation and resolution of the inflammatory response. In the _RESMAC population, approximately one-tenth of monocyte-like cells and one-third of vacuolized cells were apoptotic. In the _INFMAC population obtained 24 h after PBS treatment, approximately one-tenth of monocyte-like cells and almost one-quarter of vacuolized cells were apoptotic. At the same time following LPS, however, we observed a significantly lower percentage of apoptotic cells in the population of monocyte-like _INFMAC and vacuolized _INFMAC. Moreover, a higher percentage of apoptotic cells in _INFMAC was detected during all time points after PBS in contrast to LPS. Comparing _RESMAC and _INFMAC, we observed that vacuolized cells from populations of _RESMAC and _INFMAC underwent apoptosis more intensively than did monocyte-like cells.

Conclusions

We conclude that apoptosis of virgin mammary gland macrophages is involved in regulating their lifespan, and it is involved in the resolution process of the inflammatory response.

Invited review: The role of contagious disease in udder health

Contagious diseases are a threat to animal health and productivity, both nationally and at the farm level. This makes implementation of biosecurity measures to prevent their introduction and spread within countries and farms a necessity. Mastitis is the most common and costly contagious disease affecting dairy farms in the western world. The major mastitis pathogens are endemic in most countries, and biosecurity measures to prevent introduction and transmission must therefore be implemented at farm level. The 40-yr-old mastitis control plan remains a solid foundation to prevent the spread of contagious intramammary infections. Contagious diseases that do not affect the mammary gland directly may have an indirect effect on mastitis. This is true for list A diseases such as foot and mouth disease, for which biosecurity measures may need to be taken at national level, and for other infections with nonmastitis pathogens such as bovine viral diarrhea virus and Mycobacterium avium ssp. paratuberculosis. Maintaining a closed herd decreases the risk of introduction of pathogens that affect udder health directly or indirectly. If animals are purchased, their udder health history should be evaluated and they should be examined and tested for contagious diseases. Transmission of infections by and to humans and nonbovine animals may occur. Contact with visitors and nonbovine animals should therefore be minimized. Because of globalization and heightened consumer awareness, the importance of biosecurity now supersedes individual farms, and increased pressure to control transmission of contagious diseases can be expected at industry or government levels in western countries and elsewhere.