Infectious reproductive disease pathogens in dairy herd bulls

Bacterial DNase activity as a putative inductor of sperm DNA fragmentation in infected bull frozen-thawed semen samples

The aim of this study was to investigate the relationship between DNase activity associated with bacterial contamination of incubated bovine frozen-thawed spermatozoa and elevated sperm DNA fragmentation. Electrophoresis analysis of plasmid PBR322 incubated for 30 min at 37 °C with the supernatant of the diluent of frozen-thawed centrifuged bovine semen straws infected with bacteria showed clear evidence of DNase activity when compared to plasmid incubated in similarly prepared non-infected bovine diluent supernatant (Experiment 1). This DNase activity was subsequently found to be time dependent (0-60 min) and its activity prevented in the presence of EDTA (10 and 20 mM; Experiment 2). Semen straws infected (n = 10) and not infected (n = 10) with bacteria where incubated at 37 °C for up to 48h post-thaw. Semen infected with bacteria showed an exponential increase in bacterial growth and a corresponding increase in sperm DNA fragmentation. Non-infected semen samples showed no change in the incidence of sperm DNA fragmentation over the same period of incubation (Experiment 3). Our experiments reinforce the idea that exogenous DNases present in the semen should be considered as one of the primary contributing causes of sperm DNA fragmentation post ejaculation. In the case of the bull, post-thaw incubation of commercial straws contaminated with bacteria, resulted in increased levels of sperm DNA fragmentation, most likely associated with DNase activity (potentially restriction endonucleases) derived from the bacteria. Such adverse changes in sperm DNA fragmentation, as described here in vitro, may be also operative after insemination in the female reproductive tract (in vivo) and highlight the importance of implementing high levels of hygiene practice during semen processing, especially in light of future trends of bacterial resistance to the common antibiotics used in semen diluents.

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.

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The first published case of bovine trichomonosis in Australia since 1988.

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Extensive genotyping of two isolates using 10 divergent markers.

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Isolates were determined to be 100% homologous with the Tritrichomonas foetus ‘bovine’ genotype.

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.

Prevalence and risk factors associated with Tritrichomonas foetus infection in cattle in the state of Paraíba, Brazil

The objective of this study was to determine the prevalence of Tritrichomonas foetus infection and to evaluate risk factors associated with this infection among cattle in the state of Paraíba in northeastern Brazil. Samples of cervicovaginal mucus from 290 females and smegma from 59 males [beef, 31; mixed aptitude (beef and dairy), 10; and dairy, 18] from 31 farms were collected. Modified Diamond's medium and polymerase chain reaction (PCR) were used for the laboratory diagnosis of T. foetus infection. Univariate analysis and logistic regression were performed to test for potential risk factors in addition to prevalence mapping. No sample was positive for T. foetus in culture, and the prevalence of T. foetus infection using PCR was 3.7% (13/349) [confidence interval (CI) 95%, 2.1%-6.4%]. In total, 19.3% (6/31) of the farms had at least one animal positive for T. foetus. The contact of females with males from other farms [Odds ratio, 5.9; 95% CI, 1.5-22.4; p = 0.009] was identified as a risk factor for T. foetus infection. This study demonstrates that T. foetus infection is prevalent among dairy cows in the state of Paraíba, Brazil. Sexual resting, removal of positive females, and avoiding contact of females with males from other farms are recommended to reduce the risk of infection.