Evaluation of Two PCR Tests for Coxiella burnetii Detection in Dairy Cattle Farms Using Latent Class Analysis

Different tests performed on bulk tank milk samples (BTM) are available to determine the C. burnetii status of herds. However, these tests, which are based on the detection of either antibodies directed against C. burnetii (ELISA) or bacterial DNA (PCR), have limitations. A currently disease-free herd infected in the past may continue to test positive with ELISA due to the persistence of antibodies in animals that were infected and that subsequently cleared the infection. Infectious herds can also be misclassified using PCR because of the absence of bacteria in the BTM when the test is performed. Recently, PCR has been used for bacterial DNA detection in the farm environment, which constitutes the main reservoir of C. burnetii. The objectives of this study were to assess and compare the sensitivities and specificities of one commonly used PCR test in BTM (PCR BTM) and of a PCR applied to environmental samples (PCR DUST) in dairy cattle farms. BTM and dust samples were collected (using environmental swabs) in 95 herds. The evaluation of the performance of the 2 tests was conducted using latent class models accounting for within herd disease dynamics. Parameter estimation was carried out using MCMC, within a Bayesian framework. Two types of priors were used for the specificity of PCR DUST. A model with a uniform prior on 0–1 fitted the data better than a model with a uniform prior on 0.95–1. With the best model PCR DUST had a lower sensitivity than PCR BTM (0.75 versus 0.83) and a specificity of 0.72. The moderately low value for the specificity of PCR DUST suggests that the presence of bacteria on farm is not always associated with persistent infections and shedding of bacteria in milk.     

Controlling contagious agalactia in artificial insemination centers for goats and detection of Mycoplasma mycoides subspecies capri in semen

Many goat artificial insemination (AI) centers in Spain have adopted new measures to control contagious agalactia (CA). To avoid the introduction of male goats carrying mycoplasma organisms subclinically in their external ear canal (auricular carriers) in these centers, two ear swabs and a blood sample are obtained from all candidate animals for polymerase chain reaction (PCR), culture (swabs) and serologic tests to detect the presence of mycoplasmas. In addition, the semen produced at these centers is routinely cultured and PCR tested also to detect the presence of mycoplasmas. One y after the introduction of this program, we tested 48 ear swabs and 24 blood samples from 24 candidates for admission to these AI Centers. Three of these ear swab samples (3/48, 6.25%) scored positive for the presence of mycoplasmas; Mycoplasma agalactiae (Ma) was detected in two samples and Mycoplasma mycoides subsp. capri (Mmc) in one. All animals were serologically negative for Ma. Also, out of 173 semen samples obtained from 137 admitted animals (2 and 3 samples were obtained in 16 and 10 bucks, respectively), one (1/173, 0.56%) was positive for Mmc. Our findings suggest that ear swab and semen samples are useful tools to control CA at AI Centers. The introduction of this program has also resulted in the first detection of Mmc in semen from a naturally infected goat, confirming the ability of this mycoplasma to colonize the reproductive tract of male goats. These results highlight the need to improve control measures in semen producing centers to minimize the risk of CA transmission.     

Presence of Mycoplasma species and somatic cell counts in bulk-tank goat milk

This cross-sectional study performed on dairy goat herds was designed to establish the relationship between the presence of Mycoplasma species in bulk-tank milk samples from different farms and the bulk-tank milk somatic cell count (BTMSCC) in an area where contagious agalactia (CA) is endemic. Three BTMSCC thresholds, used in payment schemes or as legal requirements for milk quality in Europe and the USA, were considered: (1) 2,000,000 cells/ml; (2) 1,500,000 cells/ml and (3) 1,000,000 cells/ml. Of the 1068 milk samples tested, 7.9% (n = 84) showed the presence of Mycoplasma spp. (Mycoplasma agalactiae 82% and Mycoplasma mycoides subsp. mycoides large colony 17%). Somatic cell counts for bulk-tank samples containing mycoplasmas were higher than those recorded for negative samples (1,176,000 cells/ml vs. 875,000 cells/ml; P < 0.001). Two-by-two table analyses revealed that the presence of mycoplasmas in bulk-tank milk increased the risk of surpassing all SCC thresholds considered, with the highest risk for Mycoplasma positive bulk-tank milk samples exceeding the threshold of 1500 × 10³ cells/ml (odds ratio = 2.42 (1.49 < OR < 3.91). Our results indicate that the presence of mycoplasmas in goat milk had yet another economic consequence and a further incentive to encourage the implementation of specific programs for disease control.     

Presence of contagious agalactia causing mycoplasmas in Spanish goat artificial insemination centres

Male goats admitted to artificial insemination centres come from herds that have shown no clinical symptoms of contagious agalactia (CA) for the last 6 mo. However, prior reports suggest that this control measure may not be completely effective. This study was designed to detect the presence of CA-causing mycoplasmas in 9 Spanish centres, comprising 159 goats (147 males and 12 teaser does) of 8 different breeds. A microbiological study was conducted during 8 mo on 448 samples (318 ear swabs, 119 semen samples and 11 milk samples). In 86 samples (84 swabs, 1 semen sample and 1 milk sample), CA-causative mycoplasmas were detected by PCR or culture, and 52 animals (49 goat males and 3 teaser does) tested positive. Most of these positive animals were auricular carriers (n = 50), mainly of Mycoplasma mycoides subsp. capri (Mmc), although some M. agalactiae (Ma) and, interestingly, M. capricolum subsp. capricolum (Mcc) carriers were also identified. At least 1 animal infected by CA-causing mycoplasmas was detected in 8 of the 9 centres (88.8%) although in most (66.7%) no infected animals or only 1 or 2 positive animals were identified. Our results indicate the presence of CA carriers as asymptomatic animals in reproductive programmes. These findings have already prompted efficient measures to detect and avoid the entry of these carriers in Spanish centres. We recommend similar measures for all centres in areas where CA is endemic.     

Prevalence of mycoplasmas in external ear canal of goats: Influence of the sanitary status of the herd

A study was carried out in 15 French goat herds to assess the presence of mycoplasmas in the external ear canal of goats and to estimate the association between the ear isolates (highly pathogenic or non-pathogenic) and the status of the herds with respect to the mycoplasma infections. In each herd, 20 clinically normal goats were investigated once and mycoplasma isolates were identified by MF-dot tests. Influence of herd status on the proportion of animals carrying highly pathogenic species of mycoplasmas was evaluated by calculating the Odds Ratios. The present study gave first of all an estimate of the relative importance of mycoplasma carriage in healthy French dairy goat herds. The species isolated were MmmLC, Mcc, Ma, Mp (considered as highly pathogenic) and My and Mc (non-pathogenic species). Carriage often involve several strains and/or species in the same ear canal. The highly pathogenic species were significantly more frequent in the herds with prior history of mycoplasma infection. This asymptomatic carrier state makes the sanitary status of a herd ambiguous and represents a risk of subsequent propagation of the etiological agents, during close physical contact or by intervention of vectors (mites).     

Risk factors for <Emphasis Type="Italic">Coxiella burnetii</Emphasis> antibodies in bulk tank milk from Danish dairy herds

The aim was to identify risk factors associated with Coxiella burnetii antibody positivity in bulk tank milk (BTM) samples from 100 randomly selected Danish dairy cattle herds. Antibody levels were measured by an enzyme-linked immuno-sorbent assay. Before testing the herds, the farm managers were interviewed about hired labour, biosecurity, housing and herd health during the 12 months prior to the study. Variables considered important for C. burnetii antibody positivity in multivariable logistic regression analysis included the sharing of machines between farms (OR?=?3.6), human contacts (OR?=?4.2), artificial insemination by other people than artificial insemination technicians (OR?=?7.7), routine herd health contract with the veterinarian (OR?=?4.3) and hygiene precautions taken by veterinarians (OR?=?5). In addition, herd size, hired labour, trading of cattle between farms, quarantine and use of calving and disease pens also showed significant association in univariable analysis. This study demonstrates that strict biosecurity is important for the prevention of infections with C. burnetii.     

Unexpected Decrease in Milk Production after Fenbendazole Treatment of Dairy Cows during Early Grazing Season

Gastrointestinal nematodes (GIN) infection can impair milk production (MP) in dairy cows. To investigate whether MP would be optimized by spring targeted-selective anthelmintic treatment in grazing cows, we assessed (1) the effect on MP of an anthelmintic treatment applied 1.5 to 2 months after turn-out, and (2) herd and individual indicators associated with the post-treatment MP response. A randomized controlled clinical trial was conducted in 13 dairy farms (578 cows) in western France in spring 2012. In each herd, lactating cows of the treatment group received fenbendazole orally, control cows remained untreated. Daily cow MP was recorded from 2 weeks before until 15 weeks after treatment. Individual serum pepsinogen and anti-Ostertagia antibody levels (expressed as ODR), faecal egg count and bulk tank milk (BTM) Ostertagia ODR were measured at treatment time. Anthelmintic treatment applied during the previous housing period was recorded for each cow. In each herd, information regarding heifers’ grazing and anthelmintic treatment history was collected to assess the Time of Effective Contact (TEC, in months) with GIN infective larvae before the first calving. The effect of treatment on weekly MP averages and its relationships with herd and individual indicators were studied using linear mixed models with two nested random effects (cow within herd). Unexpectedly, spring treatment had a significant detrimental effect on MP (-0.92 kg/cow/day on average). This negative MP response was particularly marked in high producing cows, in cows not treated during the previous housing period or with high pepsinogen levels, and in cows from herds with a high TEC or a high BTM ODR. This post-treatment decrease in MP may be associated with immuno-inflammatory mechanisms. Until further studies can assess whether this unexpected result can be generalized, non-persistent treatment of immunized adult dairy cows against GIN should not be recommended in early grazing season.     

A robust method for bacterial lysis and DNA purification to be used with real-time PCR for detection of Mycobacterium avium subsp. paratuberculosis in milk

A possible mode of transmission for the ruminant pathogen Mycobacterium avium subsp. paratuberculosis (MAP) from cattle to humans is via milk and dairy products. Although controversially, MAP has been suggested as the causative agent of Crohn's disease and its presence in consumers' milk might be of concern. A method to detect MAP in milk with real-time PCR was developed for screening of bulk tank milk. Pellet and cream fractions of milk were pooled and subjected to enzymatic digestion and mechanical disruption and the DNA was extracted by automated magnetic bead separation. The analytical sensitivity was assessed to 100 organisms per ml milk (corresponding to 1-10 CFU per ml) for samples of 10 ml. The method was applied in a study of 56 dairy herds to compare PCR of farm bulk tank milk to culture of environmental faecal samples for detection of MAP in the herds. In this study, 68% of the herds were positive by environmental culture, while 30% were positive by milk PCR. Results indicate that although MAP may be shed into milk or transferred to milk by faecal contamination, it will probably occur in low numbers in the bulk tank milk due to dilution as well as general milking hygiene measures. The concentration of MAP can therefore be assumed to often fall below the detection limit. Thus, PCR detection of MAP in milk would be more useful for control of MAP presence in milk, in order to avoid transfer to humans, than for herd prevalence testing. It could also be of value in assessing human exposure to MAP via milk consumption. Quantification results also suggest that the level of MAP in the bulk tank milk of the studied Danish dairy herds was low, despite environmental isolation of MAP from the herds.     

Internal teat sealants alone or in combination with antibiotics at dry-off – the effect on udder health in dairy cows in five commercial herds

In the dairy industry, the dry period has been identified as an area for potential reduction in antibiotic use, as part of a one health approach to preserve antibiotic medicines for human health. The objective of this study was to assess the impact of dry cow treatment on somatic cell count (SCC), intramammary infection (IMI) and milk yield on five commercial Irish dairy herds. A total of 842 cows across five spring calving dairy herds with a monthly bulk tank SCC of < 200 000 cells/mL were recruited for this study. At dry-off, cows which had not exceeded 200 000 cells/mL in the previous lactation were assigned one of two dry-off treatments: internal teat seal (ITS) alone (Lo_TS) or antibiotic plus ITS (Lo_AB + TS). Cows which exceeded 200 000 cells/mL in the previous lactation were treated with antibiotic plus ITS and included in the analysis as a separate group (Hi_AB + TS). Test-day SCC and lactation milk yield records were provided by the herd owners. Quarter milk samples were collected at dry-off, after calving and at mid-lactation for bacteriological culture and quarter SCC analysis. Cow level SCC was available for 789 cows and was log-transformed for the purpose of analysis. Overall, the log SCC of the cows in the Lo_TS group was significantly higher than the cows in Lo_AB + TS group and not statistically different to the cows in the Hi_AB + TS group in the subsequent lactation. However, the response to treatment differed according to the herd studied; the log SCC of the cows in the Lo_TS group in Herds 3, 4 and 5 was not statistically different to the cows in Lo_AB + TS group, whereas in the other two herds, the log SCC was significantly higher in the Lo_TS when compared to the Lo_AB + TS group. There was a significant interaction between dry-off group and herds on SCC and odds of infection in the subsequent lactation. The results of this study suggest that the herd prevalence of IMI may be useful in decision-making regarding the treatment of cows with ITS alone at dry-off to mitigate its impact on udder health.     

Real-Time PCR Investigation of Potential Vectors, Reservoirs, and Shedding Patterns of Feline Hemotropic Mycoplasmas

Three hemotropic mycoplasmas have been identified in pet cats: Mycoplasma haemofelis, “Candidatus Mycoplasma haemominutum,” and “Candidatus Mycoplasma turicensis.” The way in which these agents are transmitted is largely unknown. Thus, this study aimed to investigate fleas, ticks, and rodents as well as saliva and feces from infected cats for the presence of hemotropic mycoplasmas, to gain insight into potential transmission routes for these agents. DNA was extracted from arthropods and from rodent blood or tissue samples from Switzerland and from salivary and fecal swabs from two experimentally infected and six naturally infected cats. All samples were analyzed with real-time PCR, and some positive samples were confirmed by sequencing. Feline hemotropic mycoplasmas were detected in cat fleas and in a few Ixodes sp. and Rhipicephalus sp. ticks collected from animals but not in ticks collected from vegetation or from rodent samples, although the latter were frequently Mycoplasma coccoides PCR positive. When shedding patterns of feline hemotropic mycoplasmas were investigated, “Ca. Mycoplasma turicensis” DNA was detected in saliva and feces at the early but not at the late phase of infection. M. haemofelis and “Ca. Mycoplasma haemominutum” DNA was not amplified from saliva and feces of naturally infected cats, despite high hemotropic mycoplasma blood loads. Our results suggest that besides an ostensibly indirect transmission by fleas, direct transmission through saliva and feces at the early phase of infection could play a role in the epizootiology of feline hemotropic mycoplasmas. Neither the investigated tick nor the rodent population seems to represent a major reservoir for feline hemotropic mycoplasmas in Switzerland.     

Animal model of Mycoplasma fermentans respiratory infection

Background

Mycoplasma fermentans has been associated with respiratory, genitourinary tract infections and rheumatoid diseases but its role as pathogen is controversial. The purpose of this study was to probe that Mycoplasma fermentans is able to produce respiratory tract infection and migrate to several organs on an experimental infection model in hamsters. One hundred and twenty six hamsters were divided in six groups (A-F) of 21 hamsters each. Animals of groups A, B, C were intratracheally injected with one of the mycoplasma strains: Mycoplasma fermentans P 140 (wild strain), Mycoplasma fermentans PG 18 (type strain) or Mycoplasma pneumoniae Eaton strain. Groups D, E, F were the negative, media, and sham controls. Fragments of trachea, lungs, kidney, heart, brain and spleen were cultured and used for the histopathological study. U frequency test was used to compare recovery of mycoplasmas from organs.

Results

Mycoplasmas were detected by culture and PCR. The three mycoplasma strains induced an interstitial pneumonia; they also migrated to several organs and persisted there for at least 50 days. Mycoplasma fermentans P 140 induced a more severe damage in lungs than Mycoplasma fermentans PG 18. Mycoplasma pneumoniae produced severe damage in lungs and renal damage.

Conclusions

Mycoplasma fermentans induced a respiratory tract infection and persisted in different organs for several weeks in hamsters. This finding may help to explain the ability of Mycoplasma fermentans to induce pneumonia and chronic infectious diseases in humans.     

Caprine mycoplasmal mastitis in Nigeria

In a study to investigate the current status of intramammary mycoplasmosis in caprine udders in Nigeria, a total of 57 and 24 milk samples were collected from udders of goats affected by mastitis and from apparently normal goats’ udders, respectively. Acute and chronic mastitis were more commonly observed in goats between 1 and 3 years old. Mycoplasma agalactiae and Mycoplasma capricolum occurred at a significantly higher rate (p<0.05) in udders affected by mastitis than in normal healthy udders. Other mycoplasma occurring in low prevalence include Mycoplasma bovis and Mycoplasma mycoides subsp. mycoides LC. It is concluded that cultural (microbiological) surveillance is necessary for effective treatment and control of the disease in Nigeria.     

Production,partial cash flows and greenhouse gas emissions of simulated dairy herds with extended lactations

The transition period is the most critical period in the lactation cycle of dairy cows. Extended lactations reduce the frequency of transition periods, the number of calves and the related labour for farmers. This study aimed to assess the impact of 2 and 4 months extended lactations on milk yield and net partial cash flow (NPCF) at herd level, and on greenhouse gas (GHG) emissions per unit of fat- and protein-corrected milk (FPCM), using a stochastic simulation model. The model simulated individual lactations for 100 herds of 100 cows with a baseline lactation length (BL), and for 100 herds with lactations extended by 2 or 4 months for all cows (All+2 and All+4), or for heifers only (H+2 and H+4). Baseline lactation length herds produced 887 t (SD: 13) milk/year. The NPCF, based on revenues for milk, surplus calves and culled cows, and costs for feed, artificial insemination, calving management and rearing of youngstock, was k€174 (SD: 4)/BL herd per year. Extended lactations reduced milk yield of the herd by 4.1% for All+2, 6.9% for All+4, 1.1% for H+2 and 2.2% for H+4, and reduced the NPCF per herd per year by k€7 for All+2, k€12 for All+4, k€2 for H+2 and k€4 for H+4 compared with BL herds. Extended lactations increased GHG emissions in CO₂-equivalents per t FPCM by 1.0% for All+2, by 1.7% for All+4, by 0.2% for H+2 and by 0.4% for H+4, but this could be compensated by an increase in lifespan of dairy cows. Subsequently, production level and lactation persistency were increased to assess the importance of these aspects for the impact of extended lactations. The increase in production level and lactation persistency increased milk production of BL herds by 30%. Moreover, reductions in milk yield for All+2 and All+4 compared with BL herds were only 0.7% and 1.1% per year, and milk yield in H+2 and H+4 herds was similar to BL herds. The resulting NPCF was equal to BL for All+2 and All+4 and increased by k€1 for H+2 and H+4 due to lower costs for insemination and calving management. Moreover, GHG emissions per t FPCM were equal to BL herds or reduced (0% to −0.3%) when lactations were extended. We concluded that, depending on lactation persistency, extending lactations of dairy cows can have a positive or negative impact on the NPCF and GHG emissions of milk production.     

Mycoplasma lipoproteins are major determinants of neutrophil extracellular trap formation

Neutrophil granulocytes are paramount to innate responses as major effectors of acute inflammation. Among the various strategies enacted by neutrophils to eliminate microbes NETosis is a novel distinct antimicrobial activity in which an interlacement of chromatin fibres rich in granule‐derived antimicrobial peptides and enzymes is extruded (NETs, neutrophils extracellular traps ). NETs contribute to the pathogenesis of acute and chronic inflammatory disorders. The interactions of mycoplasmas and innate immune cells, in particular neutrophil granulocytes, are poorly defined. Here, we describe NET formation in vivo in the mammary gland and milk of sheep naturally infected by Mycoplasma agalactiae. Also, we assess the contribution of liposoluble proteins, the most abundant component of the Mycoplasma membrane, in inducing NETosis. We demonstrate that Mycoplasma liposoluble proteins induce NET release at levels comparable to what observed with other stimuli, such as lipopolysaccharides and phorbol 12‐myristate 13‐acetate. Stimulation of neutrophils with synthetic diacylated lipopeptides based on the M. agalactiae P48, P80, and MAG_1000 proteins, combined in a mix or used individually, suggests that NETosis might not be dependent on a specific lipopeptide sequence. Also, NETosis is partially abolished when TLR2 is blocked with specific antibodies. The results presented in this work provide evidences for the mechanisms underlying NET activation in mycoplasma infections, and on their contribution to pathogenesis of mycoplasmosis.     

Gliotoxinogenic Aspergillus fumigatus in the dairy herd environment

The potential association between hygienic conditions in the environment of lactating cows and the presence of gliotoxinogenic Aspergillus fumigatus strains was studied. Milk samples (individual cow’s milk [ICM], bulk tank milk [BTM]) from 44 dairy farms were sampled. In ICM samples, eight different species of Aspergillus were identified. A. flavus and A. fumigatus were predominant, with 37.8 % and 26.1 % relative densities, respectively. A. fumigatus strains were isolated from 61.4 % of the BTM samples, and 34 % of these strains were able to produce gliotoxin. Principal component analysis was used to associate the presence of A. fumigatus with some hygienic and sanitary practices. A significant and positive correlation was observed between dry cow therapy and forestripping. The presence of A. fumigatus gliotoxin producers in milk was associated with high somatic cells count (SCC) samples. Good hygienic and sanitary practices were associated with absence of A. fumigatus and relatively low SCCs of <250,000 cells/ml. In general, a high percentage of dairy farms were positive for A. fumigatus in BTM samples. This is the first work that indicates the positive effects of adequate hygienic and sanitary practices in dairy herds on the control of A. fumigatus and related species. By reducing the frequency of Aspergillus spp. in the dairy environment, the risk of farm handlers’ exposure and the risk of intramammary fungal infections would also be reduced.     

Experimental Infections with Mycoplasma agalactiae Identify Key Factors Involved in Host-Colonization

Mechanisms underlying pathogenic processes in mycoplasma infections are poorly understood, mainly because of limited sequence similarities with classical, bacterial virulence factors. Recently, large-scale transposon mutagenesis in the ruminant pathogen Mycoplasma agalactiae identified the NIF locus, including nifS and nifU, as essential for mycoplasma growth in cell culture, while dispensable in axenic media. To evaluate the importance of this locus in vivo, the infectivity of two knock-out mutants was tested upon experimental infection in the natural host. In this model, the parental PG2 strain was able to establish a systemic infection in lactating ewes, colonizing various body sites such as lymph nodes and the mammary gland, even when inoculated at low doses. In these PG2-infected ewes, we observed over the course of infection (i) the development of a specific antibody response and (ii) dynamic changes in expression of M. agalactiae surface variable proteins (Vpma), with multiple Vpma profiles co-existing in the same animal. In contrast and despite a sensitive model, none of the knock-out mutants were able to survive and colonize the host. The extreme avirulent phenotype of the two mutants was further supported by the absence of an IgG response in inoculated animals. The exact role of the NIF locus remains to be elucidated but these data demonstrate that it plays a key role in the infectious process of M. agalactiae and most likely of other pathogenic mycoplasma species as many carry closely related homologs.     

Mycoplasma agalactiae detected in the semen of goat bucks

Contagious agalactia (CA) is among the most significant diseases affecting small ruminant populations in Mediterranean countries. This study was designed to detect the excretion in semen of CA-causing mycoplasmas in goats (Capra hircus) reared in Spain, where the disease is considered endemic. Culture techniques and PCR were conducted on 147 semen samples collected from 113 goat bucks to detect mycoplasmas. No animal showed clinical symptoms of CA at the moment of the screening. M. agalactiae was identified using both diagnostic methods in three semen samples collected from three different bucks. These animals belonged to a group of animals in which semen had been analyzed twice and only the second sample proved positive, suggesting the possibility of intermittent excretion. This is the first report of the isolation of M. agalactiae from semen collected from naturally infected goats. Future studies should investigate whether semen could be a real source of CA infection by determining if the agent may be transmitted during natural service or when semen is used for artificial insemination.     

Mycobacterium avium Subspecies paratuberculosis Cultured from Locally and Commercially Pasteurized Cow's Milk in the Czech Republic

Between November 2002 and April 2003, 244 bottles and cartons of commercially pasteurized cow's milk were obtained at random from retail outlets throughout the Czech Republic. During the same period, samples of raw milk and of milk that was subsequently subjected to a minimum of 71.7°C for 15 s in a local pasteurization unit were also obtained from two dairy herds, designated herds A and B, with low and high levels, respectively, of subclinical Mycobacterium avium subsp. paratuberculosis infection, and from one herd, herd C, without infection. Infection in individual cows in each herd was tested by fecal culturing. Milk samples were brought to the Veterinary Research Institute in Brno, Czech Republic, processed, inoculated onto Herrold's egg yolk slants, and incubated for 32 weeks. Colonies were characterized by morphology, Ziehl-Neelsen staining, mycobactin J dependency, and IS900 PCR results. M. avium subsp. paratuberculosis was cultured from 4 of 244 units (1.6%) of commercially pasteurized retail milk. M. avium subsp. paratuberculosis was also cultured from 2 of 100 (2%) cartons of locally pasteurized milk derived from infected herds A and B and from 0 of 100 cartons of milk from uninfected herd C. Raw milk from 1 of 10 (10%) fecal culture-positive cows in herd A and from 13 of 66 (19.7%) fecal culture-positive cows in herd B was culture positive for M. avium subsp. paratuberculosis. These findings confirm that M. avium subsp. paratuberculosis is present in raw milk from subclinically infected dairy cows. The culture of M. avium subsp. paratuberculosis in the Czech Republic from retail milk that had been pasteurized locally or commercially to the required national and European Union standards is in agreement with similar research on milk destined for consumers in the United Kingdom and the United States and shows that humans are being exposed to this chronic enteric pathogen by this route.     

Entry and intracellular location of Mycoplasma hominis in Trichomonas vaginalis

The parasite Trichomonas vaginalis causes one of the most common non-viral sexually transmitted infections in humans. The coexistence of different sexually transmitted diseases in the same individual is very common, such as vaginal infections by T. vaginalis in association with Mycoplasma fermentans or Mycoplasma hominis. However, the consequences and behavior of mycoplasma during trichomonad infections are virtually unknown. This study was undertaken to elucidate whether mycoplasmas enter and leave trichomonad cells and if so how. M. hominis was analyzed in different trichomonad isolates and the process of internalization and the pathway within the parasite was studied. Parasites naturally and experimentally infected with mycoplasmas were used and transmission electron microscopy, cytochemistry and PCR analyses were performed. The results show that: (1) M. hominis enters T. vaginalis cells by endocytosis; (2) some mycoplasmas use a terminal polar tip as anchor to the trichomonad plasma membrane; (3) some trichomonad isolates are able to digest mycoplasmas, mainly when the trichomonads are experimentally infected; (4) some fresh virulent isolates are able to maintain mycoplasmas as cohabitants in the cell’s interior; (5) some mycoplasmas are able to escape from the vacuole to the trichomonad cytosol, and trichomonad plasma membrane budding suggested that mycoplasmas could leave the parasite cell.     

Initial insights on the performances and management of dairy cattle herds combining two breeds with contrasting features

Finding ways of increasing animal production with low external inputs and without compromising reproductive performances is a key issue of livestock systems sustainability. One way is to take advantage of the diversity and interactions among components within livestock systems. Among studies that investigate the influence of differences in animals’ individual abilities in a herd, few focus on combinations of cow breeds with contrasting features in dairy cattle herds. This study aimed to analyse the performances and management of such multi-breed dairy cattle herds. These herds were composed of two types of dairy breeds: ‘specialist’ (Holstein) and ‘generalist’ (e.g. Montbeliarde, Simmental, etc.). Based on recorded milk data in southern French region, we performed ANOVA: (i) to compare the performances of dairy herds according to breed-type composition: multi-breed, single specialist breed or single generalist breed and (ii) to test the difference of milk performances of specialist and generalist breed cows (n = 10 682) per multi-breed dairy herd within a sample of 22 farms. The sampled farmers were also interviewed to characterise herd management through multivariate analysis. Multi-breed dairy herds had a better trade-off among milk yield, milk fat and protein contents, herd reproduction and concentrate-conversion efficiency than single-breed herds. Conversely, they did not offer advantages in terms of milk prices and udder health. Compared to specialist dairy herds, they produce less milk with the same concentrate-conversion efficiency but have better reproductive performances. Compared to generalist dairy herds, they produce more milk with better concentrate-conversion efficiency but have worse reproductive performances. Within herds, specialist and generalist breed cows significantly differed in milk performances, showing their complementarity. The former produced more milk for a longer lactation length while the latter produced milk with higher protein and fat contents and had a slightly longer lactation rank. Our results also focus on the farmers’ management of multi-breed dairy herds underlying herd performances. Three strategies of management were identified and structured along two main axes. The first differentiates farmers according to their animal-selection practices in relation with their objectives of production: adapting animal to produce milk with low-feeding inputs v. focussing on milk yield trait to intensify milk production. The second refers to the purpose farmers give to multi-breed dairy herds: milk v. milk/meat production. These initial insights on the performances and management of multi-breed dairy herds contribute to better understanding the functioning of ruminant livestock systems based on individual variability.