Differences in susceptibility toMannheimia haemolytica-associated mastitis between two breeds of dairy sheep

An Insight into Goat Cheese: The Tales of Artisanal and Industrial Gidotyri Microbiota

The purpose of this study was to determine for the first time the microbiota in artisanal-type and industrial-type Gidotyri cheeses and investigate the influence of the cheese-making practices on their composition using culture-independent techniques. The microbiota present in artisanal with commercial starters (Artisanal_CS, n = 15), artisanal with in-house starters (Artisanal_IHS, n = 10) and industrial (Ind., n = 9) Gidotyri cheese samples were analyzed using a targeted metagenomic approach (16S rRNA gene). The Ind. Gidotyri cheese microbiota were less complex, dominated by the Streptococcaceae family (91%) that was more abundant compared to the artisanal Gidotyri cheeses (p < 0.05). Artisanal cheeses were more diverse compositionally with specific bacterial species being prevalent to each subtype. Particularly, Loigolactobacillus coryniformis (OTU 175), Secundilactobacillus malefermentans (OTU 48), and Streptococcus parauberis (OTU 50) were more prevalent in Artisanal_IHS cheeses compared to Artisanal_CS (p ≤ 0.001) and Ind. (p < 0.01) Gidotyri cheeses. Carnobacterium maltaromaticum (OTU 23) and Enterobacter hormaechei subsp. hoffmannii (OTU 268) were more prevalent in Artisanal_CS cheeses compared to Artisanal_IHS cheeses (p < 0.05) and Ind. cheeses (p < 0.05). Hafnia alvei (OTU 13) and Acinetobacter colistiniresistens (OTU 111) tended to be more prevalent in Artisanal_CS compared to the other two cheese groups (p < 0.10). In conclusion, higher microbial diversity was observed in the artisanal-type Gidotyri cheeses, with possible bacterial markers specific to each subtype identified with potential application to traceability of the manufacturing processes’ authenticity and cheese quality.

Effects of Dietary Omega-3 Enrichment on the Chemical Composition and the Pathogenic Microbiota of Ovine Milk

The demand for ovine milk and ovine dairy products is constantly increasing due to their exceptional sensorial characteristics and their health benefits for consumers. However, dairy fat content and composition are of particular concern for consumers as well as the medical community, as there are risk factors for coronary disease, diabetes mellitus, cancer, and other serious diseases. For this reason, attempts have been made to control/regulate the fat composition of ovine milk by modifying sheep dietary intake of polyunsaturated fatty acids. In this experimental trial, a group of sheep were fed for 30 days a diet enriched in flaxseeds and lupines, feed ingredients rich in omega-3 fatty acids, aiming to investigate the effects on fat composition and the microbiota of ovine milk. Chemical analysis of the collected milk showed that the omega-3 and omega-6 content was increased. On the opposite, the atherogenic and thrombogenic indexes decreased. Of importance was the semi-protective effect on the udder by the increased omega-3 dietary intake, as depicted by its impact on the biodiversity of the pathogenic microbiota. These findings suggest that ovine milk could be modified under specific conditions to be more appropriate for the consumption by people belonging to high-risk groups for various diseases.

Antimicrobial and Methicillin Resistance Pattern of Potential Mastitis-Inducing Staphylococcus aureus and Coagulase-Negative Staphylococci Isolates from the Mammary Secretion of Dairy Goats

Staphylococcus spp. is an important mastitis-inducing zoonotic pathogen in goats and is associated with antimicrobial resistance (AMR). The objectives of this study were to determine the prevalence and composition of staphylococci in individual mammary secretion (MS) samples of clinically healthy goats and to evaluate the phenotypic AMR pattern and the presence of methicillin resistance in the Staphylococcus spp. strains. Staphylococcus spp. isolates (n = 101) from the MS samples (n = 220) were identified to species level using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The antimicrobial susceptibility testing included a disk diffusion assay and the determination of the minimum inhibitory concentrations (MIC) of resistant strains (n = 46). Presumptive methicillin-resistant strains (n = 9) were assessed for the presence of mecA, mecC and SCCmec/orfx genes. Staphylococcus spp. isolates were recovered from 45.9% of the MS samples, of which, 72.3% was identified as coagulase-negative staphylococci (CoNS), with the remaining being Staphylococcus aureus. CoNS and S. aureus were most commonly resistant to ampicillin (56.2% and 57.1%, respectively), penicillin (26.0% and 39.3%, respectively), amoxicillin (26 % and 25 %, respectively) and cephalexin (12.3% and 25%, respectively) in the disk diffusion method. CoNS exhibited a broader AMR pattern and a higher percentage of resistant strains than S. aureus in the disk diffusion and MIC methods. Of the nine oxacillin- and cefoxitin-resistant strains, three S. aureus and five CoNS strains carried the mecA gene and, thus, were identified as methicillin-resistant. The mecC gene was not found in any of the studied strains. The presence of AMR and methicillin resistance in caprine S. aureus and CoNS poses a concern for animal and public health.

Administration of Vaccines in Dairy Sheep and Goat Farms:Patterns of Vaccination, Associations with Health and Production Parameters, Predictors

This paper reports findings regarding patterns of vaccine usage in sheep and goat farms, in 325 sheep flocks and 119 goat herds throughout Greece. The objectives of the study were (a) to describe the patterns of vaccine administration in small ruminant farms and (b) to highlight factors that were associated with vaccinations in the farms. Vaccination against brucellosis was performed in all farms into the study. Among optional vaccinations, anti-clostridial vaccination was most frequently performed (in 97.8% of farms), followed by vaccination against contagious agalactia, (56.5% of farms), pneumonia (41.2%), chlamydial abortion (38.1%), staphylococcal mastitis (36.0%), and paratuberculosis (9.5%). Vaccinations against pneumonia and staphylococcal mastitis were performed more frequently in sheep flocks, whilst vaccinations against paratuberculosis were performed more frequently in goat herds. On average, 2.8 and 2.7 optional vaccinations (i.e., additionally to vaccination against brucellosis) were performed in sheep and goat farms, respectively. The increased number of vaccines administered was associated with a higher average milk production in the respective farms. There was an association of vaccination against staphylococcal mastitis with a reduced recovery of staphylococci from the bulk-tank raw milk. In multivariable analyses, significant associations of the administration of the various optional vaccines were seen with 15 variables, 11 related to health management practices and 4 related to the demographic characteristics of farmers; the collaboration with a veterinarian, the daily number of milking sessions, and the period spent daily by the farmer at the farm premises were each associated with the administration of vaccines against three infections.

Impact of an Omega-3-Enriched Sheep Diet on the Microbiota and Chemical Composition of Kefalograviera Cheese

Kefalograviera is a well-known hard Greek cheese. The aim of this study was to determine how milk produced from ewes fed omega-3-enriched diets could influence the microbiota as well as the chemical composition of Kefalograviera cheese. At the start of the trial, 30 dairy ewes (Lesvos and Chios crossbreed) were selected and fed a conventional diet, based on alfalfa hay, straw and concentrate feed that contained soybean meal for a period of thirty days. Then, for a period of sixty days the same ewes were fed an omega-3-enriched concentrate feed with a lower level of soybean meal that contained 10% flaxseed and 10% lupins. Milk yield was collected individually on Days 30, 60 and 90 and used to produce three different batches of Kefalograviera cheeses, at the same cheese factory, by using a traditional recipe and identical preparation conditions (pasteurization of milk, salt, rennet and culture). Sample analysis was done after six months of Kefalograviera cheese ripening. MALDI-TOF-MS (matrix-assisted laser desorption/ionization time of flight mass spectrometry) identification was performed by contrasting the samples’ mass spectra with the corresponding reference database. The correlation between the different Kefalograviera cheeses revealed the predominant species being Lactococcus lactis, Lactobacillus rhamnosus, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus paracasei, Enterococcus faecium and Enterococcus faecalis, with significant quantitative differences between the experimental groups and the controls. Pediococcus spp. was isolated only from the experimental groups’ cheeses and Staphylococcus spp. only from the controls’ cheese, suggesting—among other differences—a bacterial microbiota distinction between the groups. Moreover, increased levels of alpha-linolenic acid and total polyunsaturated omega-3 fatty acids were noted in the enriched Kefalograviera cheeses. These promising findings suggest that enriched Kefalograviera cheese could be manufactured via enriching the ewes’ diets, with potential benefits for the consumers’ health.

Mammary Defences and Immunity against Mastitis in Sheep

The objectives of this review paper are to present udder defences, including teat of the udder, mammary epithelial cells, leucocytes, immunoglobulins, complement system and chemical antibacterial agents, to describe cooperation and interactions between them and to elaborate on potentials regarding their significance in mammary immunisation strategies. The teat of the udder provides initial protection to the mammary gland. The mammary epithelial cells synthesise antibacterial proteins and the leucocytes produce various inflammation mediators (cytokines or chemokines), phagocytose bacteria and recognise antigenic structures. In the mammary gland, four immunoglobulins (IgG1, IgG2, IgM and IgA) have important roles against bacterial pathogens. The complement system is a collection of proteins, participating in the inflammatory process through various pathways. Other components contributing to humoral mammary defence include lactoferrin, lysozyme and the lactoperoxidase/myeloperoxidase systems, as well as oligosaccharides, gangliosides, reactive oxygen species, acute phase proteins (e.g., haptoglobin and serum amyloid A), ribonucleases and a wide range of antimicrobial peptides. Management practices, genetic variations and nutrition can influence mammary defences and should be taken into account in the formulation of prevention strategies against ovine mastitis.

Use of Proteomics in the Study of Mastitis in Ewes

The objective of this review is to describe the usage and applicability of proteomics technologies in the study of mastitis in ewes. In ewes, proteomics technologies have been employed for furthering knowledge in mastitis caused by various agents (Staphylococcus aureus, Staphylococcus chromogenes, Mannheimia haemolytica, Streptococcus uberis, Mycoplasma agalactiae). Studies have focused on improving knowledge regarding pathogenesis of the infections and identifying biomarkers for its diagnosis. Findings have revealed that ewes with mastitis mount a defence response, controlled by many proteins and over various mechanisms and pathways, which are interdependent at various points. Many proteins can participate in this process. Moreover, as the result of proteomics studies, cathelicidins and serum amyloid A have been identified as proteins that can be used as biomarkers for improved diagnosis of the disease. In the long term, proteomics will contribute to improvements in the elucidation of the pathogenesis of mastitis. Further in-depth investigations into the various proteomes and application of new methodological strategies in experimental and clinical studies will provide information about mastitis processes, which will be of benefit in controlling the disease. Improvement of diagnostic techniques, establishment of prognostic tools and development of vaccines are key areas for targeted research.

Predisposing factors for bacterial mastitis in ewes

Objective of this review paper is the appraisal of predisposing factors for bacterial mastitis in ewes. Factors that predispose ewes to mastitis can be classified into non-animal-related factors (environmental and climatological factors, housing, nutrition, milking practices) and animal-related factors (anatomic, genetic, litter size-ethological factors, number and stage of lactation period, health problems). There are clear management-environment-animal interactions in mastitis development in ewes, which underline its multifactorial nature. Research and studies regarding risk factors are important, in order to develop strategies for their elimination, control or correction. Control measures for bacterial mastitis, which attempt to eliminate predisposing factors for infection, can thus be developed and implemented.

Differential quantitative proteomics study of experimental Mannheimia haemolytica mastitis in sheep

Objective was the differential quantitative proteomics study of ovine mastitis induced by Mannheimia haemolytica; clinical, microbiological, cytological and histopathological methods were employed for confirmation and monitoring. Proteins were separated by two-dimensional gel electrophoresis (2-DE) for all samples and differentially abundant proteins were identified by mass spectrometry; comparisons were performed with pre- (blood, milk) and post- (milk of contralateral gland) inoculation findings. Animals developed mastitis, confirmed by isolation of challenge strain and increase of neutrophils in milk and by histopathological evidence. In blood plasma, 33 differentially abundant proteins (compared to findings before challenge) were identified: 6 with decrease, 13 with new appearance and 14 with varying abundance. In a post-challenge milk whey protein reference map, 65 proteins were identified; actin cytoplasmic-1, beta-lactoglobulin-1/B, cathelicidin-1 predominated. Further, 89 differentially abundant proteins (compared to findings before challenge) were identified: 18 with decrease, 53 with new appearance, 3 with increase and 15 with varying abundance; 15 proteins showed status changes in blood plasma and milk whey. Differential abundance from inoculated and contralateral glands revealed 74 proteins only from the inoculated gland. Most differentially abundant proteins in milk whey were involved in cell organisation and biogenesis (n = 17) or in inflammatory and defence response (n = 13). SIGNIFICANCE: The proteomes of blood and milk from ewes with experimental mastitis caused by Mannheimia haemolytica and the differential proteomics in sequential samples after challenge are presented for the first time. This is the first detailed proteomics study in M. haemolytica-associated mastitis in ewes. An experimental model fully simulating natural mastitis has been used. Use of experimentally induced mastitis minimised potential variations and allowed consistency of results. The study included evaluation of changes in blood plasma and milk whey. Protein patterns have been studied, indicating with great accuracy changes that had occurred as part of the disease process and development, during the acute phase of infection. Relevant protein-protein interactions were studied. The entirety of proteomics findings has suggested that affected ewes had mounted a defence response that had been regulated by many proteins (e.g., cathelicidins, haptoglobin, serum amyloid A) and through various pathways (e.g., acute phase response, binding and transporting significant ions and molecules); these were interdependent at various points. Potential biomarkers have been indicated for use in diagnostic assays of mastitis.

Association of subclinical mastitis prevalence with sheep breeds in Greece

The objective of the research described in this Research Communication was to describe potential associations of subclinical mastitis with sheep breeds in Greece. A countrywide survey (2198 ewes in 111 farms) was performed. Prevalence of subclinical mastitis was 0·260. Results did not indicate any difference in the prevalence of subclinical mastitis between farms with pure-bred and farms with cross-bred animals, nor any difference in prevalence between farms with Greek pure-bred animals and farms with imported pure-bred animals. Results indicated that prevalence of subclinical mastitis was smaller in farms with Assaf-breed (0·100) and higher in farms with Frisarta-breed (0·625) (P < 0·02). Prevalence of mastitis was smaller in farms with Greek traditional indigenous breeds (0·221) (P = 0·007). In a model that included sheep breed and management system in farm, breed emerged as a significant factor for prevalence of subclinical mastitis (P = 0·003).

Mastitis in sheep--The last 10 years and the future of research

Bacterial mastitis is a significant welfare and financial problem in sheep flocks. This paper reviews the recently published literature, including publications that highlight the significance and virulence factors of the causal agents, especially Staphylococcus aureus and Mannheimia haemolytica, the primary causes of the disease. Research has also contributed to the understanding of risk factors, including genetic susceptibility of animals to infections, supporting future strategies for sustainable disease control. Pathogenetic mechanisms, including the role of the local defenses in the teat, have also been described and can assist formulation of strategies that induce local immune responses in the teat of ewes. Further to well-established diagnostic techniques, i.e., bacteriological tests and somatic cell counting, advanced methodologies, e.g., proteomics technologies, will likely contribute to more rapid and accurate diagnostics, in turn enhancing mastitis control efforts.

Toll like receptor 9 (TLR9) polymorphism G520R in sheep is associated with seropositivity for Small Ruminant Lentivirus

Infectious diseases of sheep are of major economic importance causing direct and indirect losses. Among the major sheep infectious agents are Small Ruminant Lentivirus, Chlamydophila abortus and Mycobacterium avium subsp. paratuberculosis infections, mainly due to their worldwide distribution and economic impact that they cause. Based on the differential susceptibility to infectious diseases between and within breeds and on the recent findings regarding the putative involvement of TLR9 in disease susceptibility, the aim of this study was to evaluate the levels of nucleotide variation of TLR9 and its mediator MyD88 in three sheep flocks originated from different breeds and assess their possible association with seropositivity/seronegativity for different infectious agents. The analysis indicated that the change of G to R at codon 520 of TLR9 polypeptide shows a significant association with Small Ruminant Lentivirus seropositivity. This amino-acid substitution, which can result in polarity change, might influence structure and function of LRR17, interfering with ligand binding and thus could be used in studies investigating susceptibility/resistance to Small Ruminant Lentivirus infections in sheep.

An assessment of opportunities to dissect host genetic variation in resistance to infectious diseases in livestock

This paper reviews the evidence for host genetic variation in resistance to infectious diseases for a wide variety of diseases of economic importance in poultry, cattle, pig, sheep and Atlantic salmon. Further, it develops a method of ranking each disease in terms of its overall impact, and combines this ranking with published evidence for host genetic variation and information on the current state of genomic tools in each host species. The outcome is an overall ranking of the amenability of each disease to genomic studies that dissect host genetic variation in resistance. Six disease-based assessment criteria were defined: industry concern, economic impact, public concern, threat to food safety or zoonotic potential, impact on animal welfare and threat to international trade barriers. For each category, a subjective score was assigned to each disease according to the relative strength of evidence, impact, concern or threat posed by that particular disease, and the scores were summed across categories. Evidence for host genetic variation in resistance was determined from available published data, including breed comparison, heritability studies, quantitative trait loci (QTL) studies, evidence of candidate genes with significant effects, data on pathogen sequence and on host gene expression analyses. In total, 16 poultry diseases, 13 cattle diseases, nine pig diseases, 11 sheep diseases and three Atlantic salmon diseases were assessed. The top-ranking diseases or pathogens, i.e. those most amenable to studies dissecting host genetic variation, were Salmonella in poultry, bovine mastitis, Marek's disease and coccidiosis, both in poultry. The top-ranking diseases or pathogens in pigs, sheep and Atlantic salmon were Escherichia coli, mastitis and infectious pancreatic necrosis, respectively. These rankings summarise the current state of knowledge for each disease and broadly, although not entirely, reflect current international research efforts. They will alter as more information becomes available and as genome tools become more sophisticated for each species. It is suggested that this approach could be used to rank diseases from other perspectives as well, e.g. in terms of disease control strategies.

Effects of experimental challenge of ewes with Mannheimia haemolytica on subsequent milk composition

The objective was to describe the physicochemical changes during the early phase of subclinical mastitis and to associate them with pathological findings. A Mannheimia haemolytica strain was deposited into one teat duct of 25 ewes and the clinical, bacteriological, cytological, physicochemical (pH, milk composition), gross-pathological and histological findings were subsequently recorded. The organism was consistently isolated from samples of teat duct material (140/150) but not from mammary secretion (50/150). California Mastitis Test (CMT) scores increased (>1) and remained high (143/150 samples) after challenge; polymorphonuclear neutrophils (PMN) predominated in milk films, but the proportion of lymphocytes and macrophages progressively increased. Increased pH values (>7.0) were recorded in the mammary secretion from the challenged side. Furthermore, content of fat, total proteins and lactose therein decreased markedly. Histological changes (leucocytic infiltration, destruction of epithelial cells) were observed in the mammary parenchyma of the ewes. The present results confirm that the reduction of milk constituents is the effect of cellular damage and can occur soon after infection.