Reproductive Failure In Cattle Research Articles

Working towards the development of vaccines and chemotherapeutics against neosporosis-With all of its ups and downs-Looking ahead.

Neospora caninum is an apicomplexan and obligatory intracellular parasite, which is the leading cause of reproductive failure in cattle and affects other farm and domestic animals, but also induces neuromuscular disease in dogs of all ages. In cattle, neosporosis is an important health problem, and has a considerable economic impact. To date there is no protective vaccine or chemotherapeutic treatment on the market. Immuno-prophylaxis has long been considered as the best control measure. Proteins involved in host cell interaction and invasion, as well as antigens mediating inflammatory responses have been the most frequently assessed vaccine targets. However, despite considerable efforts no effective vaccine has been introduced to the market to date. The development of effective compounds to limit the effects of vertical transmission of N. caninum tachyzoites has emerged as an alternative or addition to vaccination, provided suitable targets and safe and efficacious drugs can be identified. Additionally, the combination of both treatment strategies might be interesting to further increase protectivity against N. caninum infections and to decrease the duration of treatment and the risk of potential drug resistance. Well-established and standardized animal infection models are key factors for the evaluation of promising vaccine and compound candidates. The vast majority of experimental animal experiments concerning neosporosis have been performed in mice, although in recent years the numbers of experimental studies in cattle and sheep have increased. In this review, we discuss the recent findings concerning the progress in drug and vaccine development against N. caninum infections in mice and ruminants.

Sperm and oocyte as carriers for bovine viral diarrhoea virus biotypes during in vitro fertilization.

Bovine viral diarrhoea virus (BVDV) is an important viral agent causing the reproductive failure in cattle. The objectives of the study were to assess the role of male and female gametes, as carriers of cytopathic (CP) and non-cytopathic (NCP) BVDV to embryonic cells during in vitro fertilization. In this respect, sperm and oocytes were separately exposed to concentrations of 104.5 or 105.5 TCID50 /mL CP and NCP BVDV, for 2 h before fertilization. After washing, the intact gametes with the infected gametes were inseminated. Seven days post-fertilization, the virus-exposed embryos were examined for presence of the viral genome by RT-PCR. One-way anova with post-hoc Tukey's HSD test and an independent samples t-test were used to compare within and between groups, respectively. The results presented a significant decrease in the blastocyst rates for CP-infected groups than NCP-infected groups (p ≤ .01). Compared to the controls and the infected oocyte groups, the cleavage rates of the infected sperm groups (NCP and CP BVDV) were significantly reduced both in low (104.5 TCID50 /mL) and high (105.5 TCID50 /mL) titres of the virus (p ≤ .01). The proportion of embryos which was developed to blastocyst stages was significantly lower for CP and NCP-infected groups than the control groups (p ≤ .001). According to the molecular results, all samples of the retarded/degenerated embryos (at least one blastocyst within each one) in CP and NCP groups, one sample (at least one blastocyst in that) within a CP-infected group, and six samples (at least one blastocyst in each one of those) of NCP-infected groups contained the viral nucleic acid. Likewise, the results of viral enrichment showed all reactions in which RT-PCR were positive induced CPEs in MDBK monolayers. In conclusion, it is clear that CP and NCP BVDV were able to traverse zona pellucida during fertilization, and they had also negative effects on embryo development.

Effect of bovine viral diarrhea virus biotypes exposure on bovine gametes in early embryonic development in vitro.

Bovine viral diarrhea virus (BVDV) is an important viral agent causing reproductive failure in cattle. The objectives of the current study were to investigate the interaction between two BVDV biotypes, cytopathic (CP) and Non-cytopathic (NCP) and bovine gametes during in vitro fertilization (IVF) processing, the existence of the virus within embryonic cells and early embryonic development rates. Sperm and ova were exposed separately to CP and NCP BVDV at two concentrations of 104.5 and 105.5 tissue culture infectious dose 50.00% (TCID50) mL-1 prior to IVF, respectively. After five days post-IVF, early embryonic development rates of infected groups were assessed. Several embryos of each group, normal and degenerated, were selected for a viral assay using reverse transcription polymerase chain reaction technique. The result showed that the early embryonic development rates were decreased in treatment groups. The rates in the CP groups were lower than the NCP groups. In the CP groups, the proportions were, respectively, 10.00, 6.00 and 11.00, and 6.00% in the infected sperm and oocyte groups (104.5 and 105.5 TCID50 mL-1) that were higher than 50.00% in the control group. In NCP groups, the rates were, respectively, 25.00, 18.00 and 24.00, and 21.00% in the infected groups compared to 48.00% in the control group. In the CP groups, no BVDV was detected in normal embryos, whereas, all degenerated embryos were completely virus-positive. In the NCP groups, the virus was detected in both normal and degenerated embryos. In conclusion, this study supported detrimental impacts of CP and NCP BVDV on early embryonic development and the role of sperm and the zona pellucida layer as carriers of the virus.

A new inactivated Tritrichomonas foetus vaccine that improves genital clearance of the infection and calving intervals in cattle.

Bovine trichomonosis is a sexually transmitted disease that is a primary cause of early reproductive failure in cattle. The aim of the present study was to develop a vaccine formulation based on Tritrichomonas foetus trophozoites inactivated by lyophilization and Quil-A-adjuvanted. The safety, immunogenicity and efficacy of this new vaccine formulation (Trichobovis®) administered by two routes (subcutaneous: SC, and intravulvar: IVU) were compared with a commercial vaccine (TrichGuard®) in a well-established experimental bovine model of genital T. foetus infection. The new vaccine was considered safe in cattle because only mild local reactions were found in the vaccination area, which disappeared 3 weeks after administration. Cows immunized with Trichobovis cleared the infection faster than the non-immunized/challenged group (27–28 vs. 60 days; P < 0.05). Not significant differences were observed with the commercial vaccine respect to the positive control group, or between SC and IVU routes. The new vaccine stimulated high serum anti-T. foetus IgG and genital IgA levels and generated an IgG booster effect similar to TrichGuard. IgA levels were associated with significantly earlier genital clearance of T. foetus in cows immunized with Trichobovis by SC route (G1A) or TrichGuard (G2). The strongest association was found in the group G1A on day 14 post-infection (p.i.) (r = −0.74) and in G2 on day 35 p.i. (r = −0.71). The efficacy of vaccination using Trichobovis on the reproductive performance was also investigated under field conditions in a herd where T. foetus was present. The calving intervals were significantly reduced by 45.2 days (P < 0.05), calves were born 28 days earlier (P < 0.05) and an increase of 8.7% in the calving rate (P > 0.05) was observed in the vaccinated group. These results demonstrate that Trichobovis improved the reproductive performance under field conditions in herds where T. foetus infection is present.

Prevalence of Neospora caninum antibodies in fattening pigs and sows from intensive farms in northern Italy

Neospora caninum (Apicomplexa, Sarcocystidae) is a major cause of reproductive failure in cattle. In pigs, only a few studies investigated the effects of this parasite on reproductive efficiency. Considering the relevance of swine farms in northern Italian regions, an epidemiological survey was designed to investigate the spread of N. caninum infection. Three hundred seventy fattening pigs and sows from 23 intensive farms in Lombardy were sampled. Sera were analyzed by a commercial immunofluorescence antibody test. Statistical analysis through univariate and multivariate generalized linear models was conducted to detect farm management practices enhancing the risk of infection. At the farm level, 52.1% (12/23) of the selected farms, 72.7% housing sows and 40% fattening pigs, scored positive. At the individual level, 25 animals (25/370, P = 6.7%) were positive to N. caninum antibodies: one fattening pig and two sows showed an antibody titer of 1:100, and in two sows, an antibody titer of 1:400 and 1:6400 was evidenced. A higher seroprevalence was detected in sows (17/151, P = 11.2%) if compared to fattening pigs (8/219, P = 3.6%) (OR = 1.19, P value = 0.000 in sows). Moreover, a higher seroprevalence was recorded in farms with low and moderate sanitary score (P = 100% and P = 64.2%, respectively) if compared to farms with high sanitary score (P = 22.2%) (OR = 1.24, P value = 0.007 in score = 1 and OR = 1.10, P value = 0.050 in score = 2). This study provides the first data on the circulation of N. caninum in intensive swine farms in Italy, demonstrating the spread of the parasite in fattening pigs and sows in Lombardy region.

265 Awardee Talk: Maternal and Paternal Contributions to Fertility

Abstract Using over 56,000 pregnancy diagnostic records in beef cattle, a meta-analysis was conducted to objectively determine that 28.4 % of embryos will not develop past day 7 of gestation with most embryonic losses occurring before day 4. Furthermore, by day 30 of gestation, 47.9 % of cows submitted to a single insemination at day 0 will not be pregnant and pregnancy loss between days 32 and 100 was 5.8%. Reproductive success, however, is highly variable and influenced by maternal and paternal factors. Maternal characteristics, including subspecies, parity and reproductive tract size, intersect with breeding management decisions regarding estrus expression and detection to influence conception and pregnancy rates. The maternal endocrine environment, from estradiol associated with estrus around fertilization to elevated prostaglandins during the embryonic to fetal transition period, play critical roles in pregnancy success. Despite the numerous maternal factors involved with pregnancy establishment, sire contribution to reproductive failure should not be overlooked. Sires are reported to influence pregnancy loss during the second month of gestation in both beef and dairy herds. These differences in sire field fertility could not be explained by differences in semen characteristics nor differences in sire conception rate (SCR) score. To understand parental contribution to pregnancy development during the second month of gestation we developed parthenogenetic (PA) embryos (embryos lacking paternal genome). We observed that PA conceptus had well developed trophectoderm tissue at day 31 of gestation but no site of embryo attachment to the endometrium. Moreover, conceptus secretion such as pregnancy-associated glycoproteins and interferon-stimulated genes were not found in maternal circulation. These results suggest that paternal genetics is required for post-elongated embryo attachment to endometrium. Further exploring the maternal vs paternal contribution to pregnancy development can help elucidate the mechanism that drives reproductive failure in cattle.

Infection of polarized bovine respiratory epithelial cells by bovine viral diarrhea virus (BVDV)

ABSTRACT Bovine viral diarrhea virus (BVDV) is affecting cattle populations all over the world causing acute disease, immunosuppressive effects, respiratory diseases, gastrointestinal, and reproductive failure in cattle. The virus is taken up via the oronasal route and infection of epithelial and immune cells contributes to the dissemination of the virus throughout the body. However, it is not known how the virus gets across the barrier of epithelial cells encountered in the airways. Here, we analyzed the infection of polarized primary bovine airway epithelial cells (BAEC). Infection of BAEC by a non-cytopathogenic BVDV was possible via both the apical and the basolateral plasma membrane, but the infection was most efficient when the virus was applied to the basolateral plasma membrane. Irrespective of the site of infection, BVDV was efficiently released to the apical site, while only minor amounts of virus were detected in the basal medium. This indicates that the respiratory epithelium can release large amounts of BVDV to the environment and susceptible animals via respiratory fluids and aerosols, but BVDV cannot cross the airway epithelial cells to infect subepithelial cells and establish systemic infection. Further experiments showed that the receptor, bovine CD46, for BVDV is expressed predominantly on the apical membrane domain of the polarized epithelial cells. In a CD46 blocking experiment, the addition of an antibody directed against CD46 almost completely inhibited apical infection, whereas basolateral infection was not affected. While CD46 serves as a receptor for apical infection of BAEC by BVDV, the receptor for basolateral infection remains to be elucidated.

Not gone but forgotten: Tritrichomonas foetus in extensively-managed bulls from Australia’s Northern Territory

Bovine trichomonosis, caused by infection with the protozoan parasite Tritrichomonas foetus, is globally recognised as a cause of reproductive failure in cattle. Maintained in clinically normal bulls, T. foetus infection results in infertility and abortion in infected cows. In Australia’s Northern Territory (NT), logistical limitations associated with extensive livestock production inhibit wide-scale testing and diagnosis, allowing the parasite to persist undetected. In the present study, T. foetus was detected in 18/109 preputial cultures collected from bulls on a property in the NT with a history of low birth rates and reproductive failure using real-time PCR testing. Of the T. foetus-positive samples, 13/18 were genotyped using the internal transcribed spacer regions (ITS1 and ITS2) and the 5.8S rDNA unit. Selected samples were further characterised using the protein-coding genes of cysteine proteases (CP-1, 2, 4–9) and cytosolic malate dehydrogenase 1 (MDH-1) to determine if the isolates were ‘bovineʼ, ‘felineʼ or ‘Southern Africaʼ genotypes. All samples were 100% identical to the T. foetus ‘bovine’ genotype across all markers. This is the first reported case of trichomonosis in Australian cattle since 1988 and is a reminder that T. foetus should be considered whenever reproductive failure occurs in extensive cattle systems.

Pyroptosis executioner gasdermin D contributes to host defense and promotes Th 1 immune response during Neospora caninum infection

Neospora caninum (N. caninum) is an intracellular parasite and is the causative agent of neosporosis, which leads to reproductive failure in cattle. Pyroptosis is a recently discovered form of programmed cell death executed by gasdermin D (GSDMD). This cell death mechanism is an important host defense against intracellular pathogens. However, pyroptosis induced by N. caninum is poorly understood. The aim of this study was to explore the roles of GSDMD-mediated pyroptosis during N. caninum infection in vivo. N. caninum-infected wild type mice and GSDMD-deficient mice were used to evaluate host resistance and its ability to affect immune response against this parasite. The results showed that GSDMD deficiency significantly reduced survival and impaired the host’s abilities to clear parasite loads in tissues, monocytes/macrophages and neutrophils. Additionally, GSDMD was essential for circulating IL-18 and IFN-γ production induced by N. caninum infection, indicating that GSDMD can mediate the Th 1 immune response against N. caninum infection. Additional data revealed that treatment with exogenous recombinant IL-18 in N. caninum-infected Gsdmd−/− mice rescues the reduction of circulating IFN-γ production to help eliminate the parasite. Taken together, our data indicate that GSDMD-mediated pyroptosis plays a vital role in maintaining host resistance to N. caninum and is essential for clearing the parasite. This form of programmed cell death promotes the Th 1 immune response by controlling IL-18 release and is considered a host defense against N. caninum. This study expands our understanding of interactions between host immune response/defense and N. caninum infection.

Enhancing the Detection of Brucella-Specific CD4+ T Cell Responses in Cattle via in vitro Antigenic Expansion and Restimulation.

Bovine brucellosis, cause by infection with Brucella abortus, causes reproductive failure in cattle, has a major economic impact to producers, and as a zoonoses, it is a disease of public health concern. Characterization of the protective immune response against Brucella infection is important to our understanding of disease pathogenesis and for the development of diagnostic assays and vaccines. Most of the knowledge regarding protection against Brucella comes from studies in the murine model, but less is known about the immune responses in cattle. Assessment of antigen-specific T cell frequency and functional phenotype are critical to understand the immune status of the host, characterize mechanisms of protective immunity and immunopathology, and to predict immune protection. The frequency of circulating T cells specific for a particular pathogen is often very low, making analysis of such responses difficult. Our goal was to develop a flow-cytometry based approach to better track Brucella-specific T cell responses. Using peripheral blood mononuclear cells (PMBC) from Brucella abortus strain RB51-vaccinated cattle, we optimized an in vitro stimulation protocol based on a combination of antigen and pan-T cell stimulation. We then assessed RB51-specific T cell responses by concurrently measuring proliferation and cytokine production using flow-cytometry. This methodology enhances the detection of peripheral, Brucella-specific responses in cattle following RB51 vaccination. This protocol is versatile in that it can be modified to fit other in vitro stimulation systems and additional functional or phenotypic parameters can be added for flow cytometric detection and characterization of antigen-specific T cells.

New approaches to diagnose and target reproductive failure in cattle.

Reproductive failure and pregnancy loss in cattle are some of the largest economic burdens to cattle producers and one of most perplexing factors influencing management decisions. Pregnancy loss may occur at any point during gestation with the largest percentage of loss occurring in the first 30 days and, subsequently, decreasing as the pregnancy progresses. Losses may be attributed to numerous factors, predisposed issues or environmental conditions such as nutritional stressors or disease. From a research perspective, determining the exact causes of pregnancy loss or embryonic mortality in cattle have been difficult, due to limitations of accurately determining early gestation pregnancy status. Until methods that precisely determine embryo success early in gestation are available, our understanding of in vivo pregnancy loss will lack clarity necessary to develop management strategies to decrease such loss. In this review, we will briefly discuss the pivotal periods of pregnancy loss affecting beef and dairy cattle, methods and technologies to determine pregnancy status and embryo viability and potential opportunities to decrease reproductive failure.

Diagnóstico Serológico de Neospora caninum en vacas del municipio de Tuta, Boyacá

N. caninum es un parásito protozoario del filo Apicomplexa , y ha sido reconocido como una causa importante de aborto y falla reproductiva en el ganado de todo el mundo. Aunque en Colombia existen algunos estudios sobre la seroprevalencia de esta enfermedad, la información sigue siendo limitada. Objetivo. Establecer la seroprevalencia de N. caninum en vacas lecheras del municipio de Tuta (Boyacá, Colombia). Materiales y Métodos. Se muestrearon 375 animales. Las muestras se procesaron bajo la técnica de ELISA indirecta, se realizó un análisis estadístico con la prueba de Chi-cuadrada de asociación-independencia para determinar si existía relación entre la presencia de anticuerpos contra N. caninum y las diferentes variables reproductivas. Resultados. Se observó que el 52% de los individuos fueron positivos a anticuerpos contra N. caninum, la única variable reproductiva que presentó relación estadística con la presencia del protozoo fue repetición de celo, no existió relación entre edad y raza de los bovinos y la presentación de N. caninum. Conclusión. La seroprevalencia es elevada si se tienen en cuenta los datos de seroprevalencia reportados con anterioridad en otras regiones del país, no obstante, estos resultados no demostraron la presencia de enfermedad en los animales analizados, pero si la evidencia antigénica, lo que sugiere que en algún momento de la vida se infectaron con el agente y promovieron la formación de anticuerpos específicos.

Detection of Neospora caninum and Toxoplasma gondii in Semen of Naturally Infected Rams

Background: Neospora caninum and Toxoplasma gondii are closely related cyst-forming apicomplexan parasites identified as important causes of reproductive failure in cattle. Moreover, abortion cases attributed to N. caninum and T. gondii infection have been occasionally reported in sheep. Due to the relatively scarce information on the molecular detection of N. caninum in the semen of naturally infected rams, this study aimed to detect parasitic DNA in fresh semen samples and in frozen extended semen straws from male sheep from artificial inseminations centers in Southern Brazil.Materials, Methods &amp; Results: Semen samples of 38 rams from artificial insemination centers were evaluated. Eleven rams were naturally infected (seropositive for anti-N. caninum and/or anti-T. gondii IgG) and were selected for fresh semen collection. We tested all the samples for the closely related protozoan T. gondii to detect a possible cross-reaction and co-infection, due to the close similarity with N. caninum. The indirect fluorescent antibody test was used to detect IgG antibodies in the 11 serum samples from rams. Fresh semen samples were collected from 11 rams on days 1, 50, 55, and 58 using an artificial vagina and ewe in estrus. Other 27 rams had their frozen extended semen straws analyzed. A total of 20 fresh semen samples and 27 frozen extended semen straws samples were used to detect the presence of N. caninum and T. gondii DNA by polymerase chain reaction (PCR). Nc-5 and B1 genes were used as target regions to detect N. caninum and T. gondii DNA, respectively. The presence of N. caninum DNA was confirmed in the third collection of a fresh semen sample of one seropositive ram. T. gondii DNA was detected in a fresh semen sample of one seropositive ram. The DNA sequences of 186 bp from N. caninum (GenBank accession: MH806393) and 492 bp from T. gondii (GenBank accession: MH793503) were obtained by sequencing, and analysis revealed 99% and 100% identity, respectively, compared with other sequences deposited at GenBank. N. caninum and T. gondii DNAs were not detected in any of the 27 frozen extended semen straws used for artificial insemination.Discussion: This study demonstrated the presence of N. caninum and T. gondii DNA in fresh semen samples of naturally infected rams. The non-detection of N. caninum and T. gondii DNA in frozen semen samples of rams could be due to the dilution that was used to prepare the semen straws (GGL diluent and 5% glycerol), since fresh semen samples were not diluted prior to the test. Moreover, in our study, the volume of frozen semen samples (0.25 mL) used for PCR was lower than the volume of sediment obtained from fresh semen (0.5 mL), and the fresh semen centrifugation to obtain the sediment may have grouped the tachyzoites, increasing the sensitivity of the technique employed. No high IgG serological titers were detected in the rams at the time they were eliminating the parasite through fresh semen. The final titer of anti-N. caninum and anti-T. gondii IgGs in serum was 1:100, suggesting chronic infection. It is suggested that a new parasite elimination pathway is occurring among rams used for reproduction, due to the presence of N. caninum and T. gondii DNA in fresh semen samples from seropositive animals. Although the detection of genomic DNA of N. caninum and T. gondii in semen does not necessarily imply the presence of infectious stages of the parasites and does not determine their viability, these results demonstrate the need for further studies. Our study also indicates the need to reinforce preventive measures for sheep in artificial insemination centers until the risks are evaluated, by performing serological examinations with anti-N. caninum and anti-T. gondii antibodies, for instance, to select the rams that will be used for breeding.

Toll-Like Receptor 3-TRIF Pathway Activation by Neospora caninum RNA Enhances Infection Control in Mice.

Neospora caninum is a protozoan parasite closely related to Toxoplasma gondii and has been studied for causing neuromuscular disease in dogs and abortions in cattle. It is recognized as one of the main transmissible causes of reproductive failure in cattle and consequent economic losses to the sector. In that sense, this study aimed to evaluate the role of Toll-like receptor 3 (TLR3)-TRIF-dependent resistance against N. caninum infection in mice. We observed that TLR3-/- and TRIF-/- mice presented higher parasite burdens, increased inflammatory lesions, and reduced production of interleukin 12p40 (IL-12p40), tumor necrosis factor (TNF), gamma interferon (IFN-γ), and nitric oxide (NO). Unlike those of T. gondii, N. caninum tachyzoites and RNA recruited TLR3 to the parasitophorous vacuole (PV) and translocated interferon response factor 3 (IRF3) to the nucleus. We also observed that N. caninum upregulated the expression of TRIF in murine macrophages, which in turn upregulated IFN-α and IFN-β in the presence of the parasite. Furthermore, TRIF-/- infected macrophages produced lower levels of IL-12p40, while exogenous IFN-α replacement was able to completely restore the production of this key cytokine. Our results show that the TLR3-TRIF signaling pathway enhances resistance against N. caninum infection in mice, since it improves Th1 immune responses that result in controlled parasitism and reduced tissue inflammation, which are hallmarks of the disease.

Vertical transmission of Neospora caninum in bovine fetuses from a slaughterhouse in Brazil.

Neospora caninum is considered as one of the main causes of reproductive failure in cattle. Vertical transmission is the main route of infection in the bovine host and plays an important role in maintaining the parasite in the herd. Molecular detection of N. caninum is important to determine the occurrence of the disease and to evaluate the genetic diversity of the parasite. The present study aimed at assessing the vertical transmission of N. caninum using molecular techniques to detect the parasite in tissue samples from bovine fetuses collected in a slaughterhouse in the state of São Paulo, Brazil. Seventy fetuses and 70 blood samples from pregnant cows were collected in a slaughtering line. Fresh samples of heart and brain tissue from fetuses were analyzed using molecular assays. Serum samples from fetuses and cows were subjected to an indirect fluorescent antibody test (IFAT) to detect antibodies against N. caninum. Nested PCR targeting the internal transcriber 1 (ITS1) region of the protozoan organism was used in the molecular testing. From the total of fetuses examined, 71.42% were positive for N. caninum by PCR. A higher number of heart samples (47.1%) were positive for the parasite using this technique. Antibodies against the protozoa were detected in 12.9% of serum samples of cows; 2.8% of fetuses were seropositive for this pathogen. Our results show that vertical transmission of N. caninum occurs in cattle from this region of Brazil, and that the use of different diagnostic techniques contributes to successful diagnosis of congenital transmission of the parasite in cattle.

Simultaneous Detection of Brucella, Leptospira, Mycoplasma and Listeria Species by Multiplex-PCR

Reproductive disorders in farm animals represent a great importance due to economic losses for breeder and country economy. The main cause of reproductive failure in cattle is infectious abortion. Brucella, Leptospira, Mycoplasma and Listeria are important zoonosis and leading to sever economic losses in animals around the world, especially in Mediterranean countries and Egypt. Since early detection is crucial in control and treatment, molecular techniques proved to be a more rapid, sensitive and specific diagnostic tool. The present study is aimed to detect these four important pathogens using multiplex- PCR. The multiplex PCR has been standardized by using 4-pairs of primers to amplify 31kDa gene encoding protein in Brucella spp., lig gene in pathogenic Leptospira, hlyA gene in Listeria monocytogenes and 16S rDNA in Mycoplasma spp. A total of 161 different clinical samples were used, an expected band at 223bp, 468p, 370 bp and 270bp were obtained from Brucella spp., pathogenic Leptospira, Listeria monocytogenes and Mycoplasma bovis, respectively. In conclusion, the results of this conventional m-PCR assay revealed that it can be a valuable tool for simultaneous, rapid, cost saving and reliable detection of these microbial agents causing bovine abortion.

Embryo development in cattle and interactions with the reproductive tract.

Embryo mortality is a major contributor to poor reproductive efficiency and profitability in cattle production systems. Coordinated interaction between the developing embryo or conceptus and the maternal reproductive tract is essential for pregnancy establishment in mammals. Up to the blastocyst stage, the embryo can grow in the absence of contact with the oviduct or uterus; however, conceptus elongation after hatching and before implantation, a characteristic of ruminant early development, is entirely maternally driven and is essential to ensure that sufficient quantities of interferon-τ (IFNT) are secreted by the developing conceptus to abrogate the mechanisms that bring about luteolysis. Surprisingly, many questions, such as the threshold level of IFNT required for pregnancy maintenance, remain unanswered. Failure of the conceptus to elongate undoubtedly results in embryonic loss and is thus believed to contribute greatly to reproductive failure in cattle.

Review of Diagnostic Procedures and Approaches to Infectious Causes of Reproductive Failures of Cattle in Australia and New Zealand.

Infectious causes of reproductive failure in cattle are important in Australia and New Zealand, where strict biosecurity protocols are in place to prevent the introduction and spread of new diseases. Neospora caninum ranks highly as an important cause of reproductive wastage along with fungal and bacterial infections. Brucella, a leading cause of abortion elsewhere in the world, is foreign, following successful programs to control and eradicate the disease. Leptospirosis in cattle is largely controlled by vaccination, while Campylobacter and Tritrichomonas infections occur at low rates. In both countries, Bovine Viral Diarrhea virus (BVDV) infection rates as the second most economically important disease of cattle and one that also has an effect on reproduction. Effective disease control strategies require rapid diagnoses at diagnostic laboratories. To facilitate this process, this review will discuss the infectious causes of reproductive losses present in both countries, their clinical presentation and an effective pathway to a diagnosis.

Embryonic maternal interaction in cattle and its relationship with fertility.

Embryo mortality is a major contributor to poor reproductive efficiency and profitability in cattle production systems. While conception is achieved (i.e., the oocyte is fertilized) in the vast majority of cases if insemination is carried out correctly, a significant proportion of the resulting embryos fail to develop to term. Appropriate communication between the developing conceptus and the maternal endometrium is essential for the establishment and maintenance of pregnancy in all mammals. Up to the blastocyst stage, around Days 7-9, contact worth the female reproductive system is not required. However, the process of conceptus elongation after hatching and prior to implantation is entirely maternally driven and is essential to ensure that sufficient quantities of interferon-tau (IFNT) are secreted by the developing conceptus to abrogate the mechanisms that bring about luteolysis. While the importance of conceptus-derived IFNT in maternal recognition of pregnancy and prevention of luteolysis in cattle is unequivocal, many questions, such as the threshold level of IFNT required for pregnancy maintenance, remain unanswered. Furthermore, the precise role of IFNT-independent mechanisms in pregnancy establishment remains to be elucidated. Irrespective of this, failure of the conceptus to elongate undoubtedly results in embryonic loss and is thus believed to contribute greatly to reproductive failure in cattle. This review will address some of these answered questions and try to shed some light on those gaps in knowledge that could potentially contribute to improved embryo survival and reproductive efficiency.

Leptospirosis seropositivity and its serovars among cattle in Northeastern Malaysia.

Background:Leptospirosis is a zoonotic disease that infects human and livestock which causes economic losses to the farmers. It has been reported as one of the causes of reproductive failure in cattle and other ruminants, determining abortions, stillbirth, weak newborns, and decrease in their growth rate and milk production.Aim:The objectives of this study were to determine the leptospirosis seroprevalence and to identify the predominant infecting serovars among cattle.Materials and Methods:A cross-sectional study involving 420 cattle from six randomly selected districts in Kelantan was conducted. A serological test using the microscopic agglutination test was conducted in the Institute of Medical Research with a cutoff titer for seropositivity of ≥1:100.Results:The overall prevalence of leptospirosis seropositivity among cattle in this study was 81.7% (95% confidence interval: 63.5, 80.1). The most common reaction obtained with the sera tested was from the serovar Sarawak with 78.8%.Conclusion:A high seroprevalence of leptospiral antibodies was found among cattle in Northeastern Malaysia. These findings urge that more studies are required to determine the reasons for the high seroprevalence among the cattle along with its transmission and pathogenicity of the local serovar Sarawak.