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In Hong Kong, there is a cattle population of ~1,200 individuals of uncertain origin and genetic diversity. This population shows heterogeneous morphology, both in body type and pigmentation. Once used as draught animals by the local farmers, they were abandoned around the 1970s due to changes in the economy, and since then have lived as feral populations. To explore the origins of these cattle, we analysed ~50k genotype data of 21 Hong Kong feral cattle, along with data from 703 individuals of 36 cattle populations of European, African taurine, and Asian origin, the wild x domestic hybrid gayal, plus two wild bovine species, gaur and banteng. To reduce the effect of ascertainment bias ~4k loci that are polymorphic in the two wild species were selected for further analysis. The stringent SNP selection we applied resulted in increased heterozygosity across all populations studies, compared with the full panel of SNP, thus reducing the impact of ascertainment bias and facilitating the comparison of divergent breeds of cattle. Our results showed that Hong Kong feral cattle have relatively high levels of genetic distinctiveness, possibly due to the low level of artificial selection, and a likely common ancestry with wild species. We found signs of a putative taurine introgression, probably dating to the import of north European breeds during the British colonialism of Hong Kong. We showed that Hong Kong feral cattle, are distinct from Bos taurus and Bos indicus breeds. Our results highlight the distinctiveness of Hong Kong feral cattle and stress the conservation value of this indigenous breed that is likely to harbour adaptive genetic variation, which is a fundamental livestock resource in the face of climate change and diversifying market demands., Competing Interests: The authors have declared that no competing interests exist.

Infectious diseases of cattle, including bovine viral diarrhea (BVD), pose a significant health threat to the global livestock industry. This study aimed to investigate the prevalence and risk factors associated with bovine viral diarrhea virus (BVDV) infections in cattle populations through a systematic review and meta-analysis. PubMed, Web of Science, and Scopus were systematically searched for relevant articles reporting the prevalence of and associated risk factors in studies published between 1 January 2000 and 3 February 2023. From a total of 5111 studies screened, 318 studies were included in the final analysis. BVDV prevalence in cattle populations was estimated using various detection methods. The analysis detected heterogeneity in prevalence, attributed to detection techniques and associated risk factors. Antibody detection methods exhibited a higher prevalence of 0.43, reflecting the cumulative effect of detecting both active and past infections. Antigen detection methods showed a prevalence of 0.05, which was lower than antibody methods. A prevalence of 0.08 was observed using nucleic acid detection methods. The health status of the examined cattle significantly influenced the prevalence of BVDV. Cattle with bovine respiratory disease complex (BRDC) exhibited higher antibody (prevalence of 0.67) and antigen (prevalence 0.23) levels compared to cattle with reproductive problems (prevalence 0.13) or diarrhea (prevalence 0.01). Nucleic acid detection methods demonstrated consistent rates across different health conditions. Age of cattle influenced prevalence, with higher rates in adults compared to calves. Risk factors related to breeding and reproduction, such as natural or extensive breeding and a history of abortion, were associated with increased prevalence. Coinfections with pathogens like bovine herpesvirus-1 or Neospora caninum were linked to higher BVDV prevalence. Management practices, such as commingling, introducing new cattle, and direct contact with neighboring farms, also influenced prevalence. Herd attributes, including larger herd size, and the presence of persistently infected cattle, were associated with higher prevalence. These findings indicated the importance of detection methods and risk factors in BVDV epidemiological studies. [ABSTRACT FROM AUTHOR]

Background: Acute bovine viral diarrhoea virus (BVDV) infections in sheep are largely sub‐clinical although infections of pregnant ewes have shown to result in significant fetal losses and persistently infected lambs. However, the extent and severity of abnormalities in lambs infected with BVDV in utero is still largely unknown. Methods: Twenty‐two ewes were experimentally infected with BVDV‐1c between 59 and 69 days of gestation. Fifteen lambs were submitted for pathological examination and the abnormalities observed in lambs and fetuses characterised. Results: Six lambs were identified as BVDV negative, and nine were identified as BVDV positive. Anasarca and cholestatic hepatopathy was observed in four BVDV positive lambs and associated with ewes with early seroconversion. One BVDV positive lamb was born with muscular tremors and a hairy coat associated with primary follicular dysplasia, a developmental abnormality normally associated with border disease infected lambs. Conclusion: If similar lambing outcomes are identified in a commercial setting then BVDV should be considered, particularly in areas where sheep regularly come in to contact with cattle. In addition, as far as the authors are aware, this is the first reported case of a 'hairy shaker' lamb born as a result of an infection with BVDV‐1c in Australia. [ABSTRACT FROM AUTHOR]

Smallholder large ruminant production in Lao People’s Democratic Republic (Laos) is characterised by low reproductive efficiency. To determine if common abortifacient bovid infectious diseases are involved, a serological investigation was conducted. Sera was collected from stored and fresh cattle (n = 390) and buffalo (n = 130) samples from 2016–18 from, and then examined for associations in a retrospective risk factor study of 71 herds. The sera were assayed for antibodies to Neospora caninum, bovine viral diarrhoea virus (BVDV), Leptospira interrogans serovar Hardjo and Brucella abortus using commercially available enzyme-linked immunosorbent assay kits. These pathogens were detected in buffalo samples at 78.5% (95% CI 71.4–85.6), 0%, 2.3% (95% CI 0–4.9) and 0%, respectively, and in cattle at 4.4% (95% CI 2.4–6.4), 7.7% (95% CI 3.1–12.3), 12.8% (95% CI 9.5–16.1) and 0.26% (95% CI 0–0.8), respectively. Exposure of buffalo to N. caninum was positively associated with buffalo age, with a predicted seropositivity at birth of 52.8%, increasing to 97.2% by 12 years of age (p = 0.037). Exposure of cattle to L. interrogans serovar Hardjo was more prevalent in females compared to males, was associated with higher titres of BVDV, and was more prevalent in the wet season compared to the dry season. Exposure of cattle to BVDV was more prevalent in males compared to females, the wet and dry seasons were comparable, and was associated with rising antibody titres against N. caninum and L. interrogans serovar Hardjo. The risk factor survey identified that the probability of herds being N. caninum positive increased with farmer age, if farmers believed there were rodents on farm, and if farmers weren’t aware that canids or rodents could contaminate bovid feed on their farm. The probability of a herd being positive to L. interrogans serovar Hardjo increased on farms where multiple cows shared the same bull, where farmers had lower husbandry knowledge, and on farms that used water troughs. The probability of a herd being BVDV seropositive increased with increasing herd size and increasing titres to N. caninum. The benchmarking of bovid exposure to emerging abortifacient pathogens and identification of their risk factors potentially informs disease prevention strategies, supporting efforts to establish a biosecure beef supply for enhanced smallholder livestock productivity, public health and food security in Laos and surrounding countries. [ABSTRACT FROM AUTHOR]

Antigen enzyme-linked immunosorbent assay (ELISA) is used for the detection of Bovine viral diarrhea virus persistently infected (BVDV PI) cattle; however, colostrum-derived antibodies may interfere with antigen detection in serum from young PI calves. Our study aimed to assess serum pretreatment methods for reducing such interference. Dilution of PI serum with serum containing specific antibody showed that antibody levels equivalent to those observed in colostrum-fed calves were able to eliminate all antigen signals in a serum sample. Serum was treated with ethylenediamine tetra-acetic acid at pH 4.5, 5.5, 6.5, and 7.5, then boiled, centrifuged, and the supernatant-recovered. BVDV antibody was undetectable by ELISA in supernatants from treated samples, and the antigen ELISA signal was improved. Maximum antigen signal recovery of >90% was achieved at pH 5 ± 0.5. When this optimal treatment method was applied to field samples from 3 PI calves (which were negative in the antigen-capture ELISA without treatment), the antigen signal improved and gave a positive result in each case. Pretreatment may provide an improvement in the detection of young PI calves. [ABSTRACT FROM AUTHOR]

Colostrum may have the ability to improve the diagnostic accuracy of some tests when compared to serum for important livestock diseases because of the high concentrations of immunoglobulins present within this sample type. The ELISA for Johne’s disease is one such test, as it suffers from low sensitivity when testing serum samples collected during the subclinical stage of infection. Blood and colostrum samples were collected from 34 Jersey dairy cows and tested for antibodies against Mycobacterium avium subspecies paratuberculosis (MAP) by ELISA. Fecal samples were also collected and tested by a high-throughput Johne’s polymerase chain reaction (HT-J PCR) assay and fecal culture (FC), with the latter being used as the reference test. A receiver operating characteristic (ROC) analysis was performed, and the area under the curve (AUC) was calculated. The HT-J PCR and FC results were also compared. Of the 34 cows in this study, 4 had FC results consistent with MAP infection. The HT-J PCR did not identify any FC-positive cows. Using a 1:20 dilution and sample-to-positive (S/P) ratio cutoff threshold of 0.15, the relative sensitivity values of both serum (AUC 0. 56) and colostrum (AUC 0.63) were 0%. With lower sample dilutions, the relative sensitivity values of serum were 0% (1:2, AUC 0.62; 1:5, AUC 0.55); however, the relative sensitivity value of colostrum was 75% (95% confidence interval [CI]: 19–99%) at a dilution of 1:5, S/P ratio cutoff threshold of 0.15, and AUC of 0.73 (95% CI: 0.55–0.87). The testing of colostrum samples for MAP-specific antibodies by ELISA may provide improved identification of animals in the early stages of infection with MAP when compared with serum samples. [ABSTRACT FROM AUTHOR]

The diagnosis of neonatal and young calves persistently infected (PI) with Bovine viral diarrhea virus (BVDV) by antigen-capture enzyme-linked immunosorbent assay (ACE) may be complicated by interference from colostrum-derived specific antibodies. Ten calves, with 3 calves identified as PI and 7 as non-PI were used in the current study. All non-PI calves were shown to be seropositive for BVDV-specific antibodies by antibody enzyme-linked immunosorbent assay (Ab-ELISA) on serum. Serum samples, ear notch samples, and nasal and saliva swabs were collected from each calf from birth until 12 weeks of age and tested by ELISA for BVDV-specific antigen and antibodies. Following colostrum ingestion, Ab-ELISA sample-to-positive (S/P) ratios rose by a mean of 0.95 (95% confidence interval [CI] = 0.64–1.25) and 1.72 (95% CI = 1.55–1.89) in seropositive, non-PI calves and in PI calves, respectively. The mean S/P ratios then declined to approximately 1.1 in non-PI calves and 0.5 in PI calves at between 60 and 80 days of age. In PI calves, testing for antigen in serum and nasal and saliva swabs was subject to interference by colostrum-derived antibodies in calves up to 3 weeks of age. Nasal swabs were less affected than serum and saliva swabs. Ear notches maintained positive ACE corrected optical densities at all sample times, despite a drop in the signal following the ingestion of colostrum. [ABSTRACT FROM PUBLISHER]

Abstract: Neospora caninum is regarded as one of the most important infectious causes of abortions in cattle worldwide, yet the global economic impact of the infection has not been established. A systematic review of the economic impact of N. caninum infections/abortions was conducted, searching PubMed with the terms ‘cattle’ and ‘Neospora’. This yielded 769 publications and the abstracts were screened for economically relevant information (e.g. abortion prevalence and risk, serological prevalence). Further analysis was restricted to countries with at least five relevant publications. In total, 99 studies (12.9%) from 10 countries contained data from the beef industry (25 papers (25.3%)) and 72 papers (72.8%) from the dairy industry (with the remaining two papers (2.0%) describing general abortion statistics). The total annual cost of N. caninum infections/abortions was estimated to range from a median US $1.1 million in the New Zealand beef industry to an estimated median total of US $546.3 million impact per annum in the US dairy population. The estimate for the total median N. caninum-related losses exceeded US $1.298 billion per annum, ranging as high as US $2.380 billion. Nearly two-thirds of the losses were incurred by the dairy industry (US $842.9 million). Annual losses on individual dairy farms were estimated to reach a median of US $1,600.00, while on beef farms these costs amounted to just US $150.00. Pregnant cows and heifers were estimated to incur, on average, a loss due to N. caninum of less than US $20.00 for dairy and less than US $5.00 for beef. These loss estimates, however, rose to ∼US $110.00 and US $40.00, respectively, for N. caninum-infected pregnant dairy and beef cows. This estimate of global losses due to N. caninum, with the identification of clear target markets (countries, as well as cattle industries), should provide an incentive to develop treatment options and/or vaccines. [Copyright &y& Elsevier]

Abstract: Neospora caninum is a protozoan parasite that causes abortion in cattle around the world. Although the clinical signs of disease in both dogs and cattle have now been recognised for over 20years, treatment and control options are still limited, despite the availability of a commercial vaccine in some countries of the world. The case for an efficacious vaccine has not been convincingly waged by farmers, veterinarians and other members of the agricultural and rural communities. In recent times, however, economic modelling has been used to estimate the industry losses due to Neospora-associated abortion, providing, in turn, the business case for forms of control for this parasite, including the development of vaccines. In this review, we document progress in all areas of the vaccine development pipeline, including live, killed and recombinant forms and the animal models available for vaccine evaluation. In addition, we summarise the main outcomes on the economics of Neospora control and suggest that the current boom in the global dairy industry increases the specific need for a vaccine against N. caninum-associated abortion. [Copyright &y& Elsevier]

Abstract: Recent work on Neospora caninum, a protozoan parasite that causes abortions in dairy cattle has focused on a number of different control options. Modelling has suggested the most effective options for control but the present paper argues that the most effective option might not necessarily be optimal from an economic point of view. Decision trees, using published quantitative data, were constructed to choose between four different control strategies. The costs of these interventions, such as ‘test and cull’, therapeutic treatment with a pharmaceutical, vaccination or “doing nothing” were compared, and modelled, in the first instance, on the New Zealand and Australian dairy situation. It is argued however, that the relative costs in other countries might be similar and that only the availability of a registered vaccine will change the decision tree outcomes, as does the within-herd prevalence of N. caninum infection. To “do nothing” emerged as the optimal economic choice for N. caninum infections/abortions up to a within-herd prevalence of 18%, when viewed over a 1-year horizon, or 21% when costs were calculated over a 5 years horizon. For a higher (≥21%) within-herd prevalence of N. caninum infection vaccination provided the best (i.e. most economic) strategy. Despite being the most efficacious solutions, ‘test and cull’ or therapeutic treatment never provided a viable economic alternative to vaccination or “doing nothing”. Decision tree analysis thus provided clear outcomes in terms of economically optimal strategies. The same approach is likely to be applicable to other countries and the beef industry, with only minor changes expected in the relationships of decisions versus within-herd prevalence of N. caninum infection. [Copyright &y& Elsevier]

Bovine viral diarrhoea virus (BVDV) is an economically important and highly prevalent virus of domestic cattle. Infections with BVDV may lead to both, reproductive and immunological effects that can result in widespread calf losses and increased susceptibility to diseases, such as mastitis and respiratory disease. While BVDV is generally considered to be host specific, it and other Pestivirus species, such as Border disease virus (BDV) in sheep, have been shown to be infecting species other than those from which they were originally isolated from. Recently BVDV was placed on the OIE's list of notifiable disease and control and eradication programmes for BVDV have been developed throughout much of Europe, the United States, and the United Kingdom. While some countries, including Sweden and Ireland have successfully implemented eradication programmes, other countries such as New Zealand and Australia are still in the early stages of BVDV control. Despite effective control methods, incursions of BVDV into previously cleared herds still occur. While the cause of these incursions is often due to lapses in control methods, the ability of ruminant pestiviruses to infect species other than cattle poses the question as to whether non-bovine species could be impeding the success of BVDV eradication and control. As such, the aim of this review is to make mention of what is known about the cross-species transmission of BVDV, BDV and other pestiviruses between cattle and non-bovine ungulate species and draw conclusions as to the risk non-bovine species pose to the successful control and eradication of BVDV from cattle. [ABSTRACT FROM AUTHOR]

Johne's disease is characterised by a long incubation period, and the sensitivity of serological tests against Mycobacterium avium subspecies paratuberculosis (MAP) is low during the subclinical stage of infection. Due to the relatively high concentration of immunoglobulins present in colostrum, testing of this sample might improve diagnostic test sensitivity and detection of infected animals. Blood, colostrum and whey samples were analysed from 26 vaccinated Merino-cross ewes and were tested for antibodies against MAP by indirect enzyme-linked immunosorbent assay (ELISA). At the recommended dilution for serum (1:20), the diagnostic sensitivity (DSe) of colostrum and whey were significantly higher compared to serum, but not significantly different from each other. The significant improvement in DSe when using colostrum compared to serum suggests that it might be possible to detect a greater proportion of infected animals using this sample. [ABSTRACT FROM AUTHOR]

Background: Neospora caninum has been recognised world-wide, first as a disease of dogs, then as an important cause of abortions in cattle for the past thirty years. Over that time period, there have been improvements in the diagnosis of infection and abortion, new tests have been developed and validated, and it is timely to review progress to date. Methods: Bibliometric methods were used to identify major trends and research topics present in the published literature on N. caninum. The tools used were SWIFT-Review, VOSviewer and SciMAT, along with the published papers found in the MEDLINE, Dimensions and Web of Science databases. A systematic review of the published Neospora literature (n = 2933) was also carried out via MEDLINE and systematically appraised for publications relevant to the pathogenesis, pathology and diagnosis of Neospora abortions. Results: A total of 92 publications were included in the final analysis and grouped into four main time periods. In these four different time periods, the main research themes were "dogs", "abortion", "seroprevalence" and "infection". Diagnostics, including PCR, dominated the first two time periods, with an increased focus on transmission and abortions, and its risk factors in cattle. Conclusions: Longitudinal analyses indicated that the main themes were consistently investigated over the last 30 years through a wide range of studies, with evolving emphasis initially on dogs and diagnostic test development, followed by application to cattle, the identification of the risk factors leading to abortion, and in the latter time periods, an understanding of the immunity and a search for vaccines. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article regarding the role of colostrum and whey in testing for the presence of bovine tuberculosis (TB) and Johne's disease in cattle.

The seroprevalence of Neospora caninum infection in water buffalo ( Bubalus bubalis ) and domestic cattle in the Northern Territory (NT) of Australia has never been determined. A total of 480 serum samples from water buffalo and 192 serum samples from cattle, collected by the NT Government from 1993 through to 2001, at 18 different survey sites throughout the Northern Territory were tested by commercial ELISA for anti- N. caninum antibodies. The water buffalo samples demonstrated a seroprevalence of 88.3% (95% CI ± 2.9%), while 31.8% (± 6.1%) of the cattle sera tested positive for N. caninum antibodies. Individual buffalo from the same herd, sampled over years, showed considerable fluctuations in S/P ratios. Overall, seropositivity was consistent across buffalo herds, and showed a slight decline over the years. The study presents evidence for the first time that N. caninum infection in water buffalo in the Northern Territory is a highly endemic and that infection rates are higher than those for cattle. This is important for an understanding of any potential sylvatic life cycle of N. caninum in Northern Australia. This survey also tests cattle from that territory for the first time for evidence of N. caninum infection and makes an important contribution to the understanding of disease management issues for the beef industry in the region. [ABSTRACT FROM AUTHOR]

Bovine viral diarrhoea virus (BVDV) is an economically important disease of cattle, causing severe reproductive losses and immunosuppressive effects in cattle populations worldwide. Before a national BVDV control programme can be developed in Australia, it is important to explore the possibility of sources of transmission from and through alternative susceptible populations, such as sheep. Transmission of BVDV to species other than cattle has been shown to occur following both experimental and natural infection of other ruminants. The aims of this study were to investigate the impact of an experimental infection with a local Australian strain of BVDV (Type 1c) on the reproductive performance of pregnant ewes and the potential for natural transmission of BVDV from persistently infected (PI) cattle to naive sheep. Twenty-three BVDV naïve, pregnant ewes were experimentally infected with BVDV by subcutaneous inoculation with 2 mL freeze-thawed PI cow serum. Severe reproductive losses including low lambing rates and a high number of young lamb deaths were seen in these ewes. One PI lamb was also produced in this trial, but died at 15 days of age. Nine BVDV naïve sheep wethers were co-mingled with three BVDV PI calves in a 1500 sqm paddock for four weeks. Transmission of infection, as indicated by seroconversion, occurred in four of nine wethers during a four-week period of co-mingling. The trials suggest that the potential for infection with BVDV derived from cattle for sheep exists and needs to be taken into account when controlling BVDV infection in cattle. [ABSTRACT FROM AUTHOR]

Abstract: A serological survey for Neospora caninum and Besnoitia besnoiti was carried out in beef and dairy cattle in South Australia. Serum samples of dairy cattle (n =133) from 9 properties and tank milk samples from a further 122 dairy herds were tested. An additional 810 sera from beef cattle from 51 properties were also tested. Testing at the individual animal level by IDEXX NEOSPORA X2 Ab test ELISA revealed a low prevalence of N. caninum antibodies of only 2.7% (95% CI; 1.6–3.7%) sera positive, as did the milk testing that showed 2.5% (95% CI; 1.4–3.6%) of tank milks being positive. At the herd level, 29.4% (95% CI; 16.9–41.9%) of beef, and 44.4% (95% CI; 12.0–76.9%) of dairy cattle herds showed serum antibodies. The highest within-herd prevalence in beef was 20% and 25%in dairy, which explains the low herd prevalence in dairy detected by bulk milk testing. Testing for B. besnoiti antibodies by PrioCHECK® Besnoitia Ab 2.0 ELISA initially identified 18.4% (95% CI: 15.8–21.0%) of 869 individual cattle sera as positive by ELISA at the manufacturer''s suggested cut-off threshold (15 PP). Additional tests by immunoblot and IFAT, however, could not confirm any of the ELISA results. The use of a higher (40 PP) threshold in the ELISA is suggested to improve specificity. There is thus no evidence of B. besnoiti infection in South Australian cattle. [Copyright &y& Elsevier]