Evaluation of antimicrobial and non-steroidal anti-inflammatory treatments for BRD on health and welfare in fattening bulls: a cross-sectional study

Our study aimed to evaluate the effect of different treatments for BRD on health and welfare in fattening bulls. A total of 264 bulls were enrolled. Welfare was assessed on day 2 (T0) and day 15 (T1) after arrival. A decrease in the welfare level was observed from T0 to T1. All bulls were inspected clinically at T0 and T1 revealing an increase of skin lesions and lameness in T1. In both periods, a high incidence of respiratory disease was observed. A prevalence of 79.55% and 95.45% of Mycoplasma bovis using RT-PCR and culture at T0 and T1 respectively was observed. Blood samples were collected for haematology at T0 and T1. At T0, 36 animals were individually treated for BRD with an antimicrobial (IT), 54 received a metaphylactic treatment with tulathromycin (M), 150 received a metaphylactic treatment with tulathromycin plus a second antimicrobial (M + IT) whereas 24 were considered healthy and therefore not treated (NT). Additionally, 128 were treated with a non-steroid anti-inflammatory (NSAID). Neutrophils of M + IT were significantly higher than groups NT and M and the lymphocytes of M + IT were significantly lower than that of IT. White blood cells, neutrophils and N/L ratio of animals treated with an NSAID was significantly higher than that not treated. Lung inspection of 172 bulls at the abattoir indicated that 92.43% presented at least one lung lesion. A statistically significant effect of the NSAID treatment on the lung lesions was observed. Our findings indicate that BRD was a major welfare and health concern and evidence the difficulties of antimicrobial treatment of M. bovis.

Strategies for Bovine Respiratory Disease (BRD) Diagnosis and Prognosis: A Comprehensive Overview

Despite significant advances in vaccination strategies and antibiotic therapy, bovine respiratory disease (BRD) continues to be the leading disease affecting the global cattle industry. The etiology of BRD is complex, often involving multiple microbial agents, which lead to intricate interactions between the host immune system and pathogens during various beef production stages. These interactions present environmental, social, and geographical challenges. Accurate diagnosis is essential for effective disease management. Nevertheless, correct identification of BRD cases remains a daunting challenge for animal health technicians in feedlots. In response to current regulations, there is a growing interest in refining clinical diagnoses of BRD to curb the overuse of antimicrobials. This shift marks a pivotal first step toward establishing a structured diagnostic framework for this disease. This review article provides an update on recent developments and future perspectives in clinical diagnostics and prognostic techniques for BRD, assessing their benefits and limitations. The methods discussed include the evaluation of clinical signs and animal behavior, biomarker analysis, molecular diagnostics, ultrasound imaging, and prognostic modeling. While some techniques show promise as standalone diagnostics, it is likely that a multifaceted approach-leveraging a combination of these methods-will yield the most accurate diagnosis of BRD.

Zoonotic Disease Risks of Live Export of Cattle and Sheep, with a Focus on Australian Shipments to Asia and the Middle East

The growing human and livestock populations in the world today and increased international transport of livestock is increasing the risk of both emerging and endemic zoonotic diseases. This review focuses on the potential for the live export trade to transmit zoonotic diseases. Both cattle and sheep are exposed to major stresses during the transport process, which are described, together with the impact of these stresses on the immune function of transported animals. Heat stress, overcrowding, inanition, ship and vehicle motion and accumulation of noxious gases are analysed for their ability to potentiate infectious diseases. The major zoonoses are described: pustular dermatitis, pneumonia, salmonellosis, as well as some common conditions, such as conjunctivitis, with specific reference to stressors associated with each disorder. Historical precedents exist for restriction of the trade based on disease risks. Finally, the economic and regulatory frameworks are considered to evaluate ways in which the spread of zoonotic diseases can be controlled.

The combination of high glucose and LPS induces autophagy in bovine kidney epithelial cells via the Notch3/mTOR signaling pathway

BACKGROUND

Aside respiratory diseases, beef cattle may also suffer from serious kidney diseases after transportation. Hyperglycemia and gram-negative bacterial infection may be the main reasons why bovine is prone to severe kidney disease during transportation stress, however, the precise mechanism is still unclear. The purpose of the current study is to explore whether the combined treatment of high glucose (HG) and lipopolysaccharide (LPS) could induce madin-darby bovine kidney (MDBK) cells injury and autophagy, as well as investigate the potential molecular mechanisms involved.

RESULTS

As we discovered, the combined effect of HG and LPS decreased MDBK cells viability. And, HG and LPS combination also induced autophagy in MDBK cells, which was characterized by increasing the expression of LC3-II/I and Beclin1 and decreasing p62 expression. LC3 fluorescence signal formation was also significantly increased by HG and LPS combination treatment. Furthermore, we measured whether the mammalian target of rapamycin (mTOR) and the Notch3 signaling pathways were involved in HG and LPS-induced autophagy. The results showed that the combination of HG and LPS significantly increased the protein expression of Notch3 and decreased protein expression of p-mTOR, indicating that Notch3 and mTOR signaling pathways were activated. However, co-treatment with the Notch3 inhibitor (DAPT) could reverse the induction of autophagy, and increased the protein expression of p-mTOR.

CONCLUSIONS

This study demonstrated that the combination effect of HG and LPS could induce autophagy in MDBK cells, and the Notch3/mTOR signaling pathway was involved in HG and LPS-induced autophagy.

Animal Welfare Risks in Live Cattle Export from Australia to China by Sea

There are long-standing and ongoing concerns about the welfare of animals in the Australian live export trade by sea. However, scrutiny of animal welfare on board vessels is generally hindered by a lack of independent reporting. Cattle voyages from Australia to China have concerned animal welfare advocates due to their long duration and lack of consistent veterinary oversight. In April 2018, following a media exposé of animal cruelty and declining public trust, the Australian government installed Independent Observers on some live export voyages. Summaries of Independent Observer (IO) reports by the Department of Agriculture and Water Resources (DAWR) provided a new and independent source of information about management of animals in the live export trade. The IO summaries on live cattle export voyages to China for the period July 2018 to December 2019 (n = 37) were reviewed. The IO summaries detailed voyages that carried 147,262 slaughter, feeder or breeder cattle which included both dairy and beef breeds. The long-haul voyages averaged 20 days in duration, generally departing the ports of Fremantle and Portland and discharging at ports in northern China. Key animal welfare risk factors identified in the IO summaries included: hunger, thirst, exposure to extreme temperatures, poor pen conditions, health issues, absence of veterinarians, rough seas, poor ship infrastructure, mechanical breakdown and mismanagement at discharge.

Seroprevalence of bovine coronavirus and factors associated with the serological status in dairy cattle in the western region of Thailand

Background and Aims:

Bovine coronavirus (BCoV) is a pathogen affecting the productivities of dairy cattle worldwide. The present study aimed to determine the seroprevalence and factors associated with BCoV serological status using a commercial indirect enzyme-linked immunosorbent assay (ELISA).

Materials and Methods:

A cross-sectional study was conducted in the western region of Thailand. Blood samples were collected from 30 dairy herds. In total, 617 blood serum samples were tested using a commercial indirect ELISA for BCoV-specific immunoglobulin G antibodies. A questionnaire was used to collect data on the factors which have been identified as risk factors for BCoV antibody detection. The age and history of diarrhea of each animal were recorded. Fisher’s exact test was performed to univariately assess the association between BCoV serological status and possible risk factors. Variables with Fisher’s exact test p<0.10 were then evaluated using multivariate logistic regression to identify factors associated with BCoV serological status. The Bonferroni adjustment was used for multiple comparisons of significant variables in the final multivariate logistic regression model.

Results:

No herd was free from antibodies to BCoV. The individual seroprevalence of BCoV was 97.89% (604/617). The prevalence within herds was in the range of 45.45-100%. Cattle >3 years of age were more likely to be seropositive to BCoV compared to cattle <1 year of age (p=0.003), with the odds ratio being 81.96. Disinfecting diarrhea stools were a protective factor for being BCoV seropositive, with odds ratios of 0.08 and 0.06 compared to doing nothing (p=0.008) and to clean with water (p=0.002), respectively.

Conclusion:

BCoV seropositive dairy cattle were distributed throughout the western region of Thailand. The probability of being seropositive for BCoV increased with increasing animal age. Cleaning the contaminated stool with appropriate disinfectants should be recommended to farmers to minimize the spread of the virus.

Bovine respiratory disease in beef calves supported long transport stress: An epidemiological study and strategies for control and prevention

BRD is associated with infectious agents, but management and transport-stress are trigger factors. Metaphylactic administration of antimicrobial reduces colonization of respiratory tract by pathogens, but the development of antibiotic-resistance raises public health concerns leading to propose new control strategies. The study analyzed nasopharyngeal swabs of 231 imported cattle, 10% of 49 trucks, transported from France to southern Italy and, through Real-time PCR identified the prevalence of the involved pathogens speculating on strategies to reduce the impact of BRD. The samples were tested by Real-time PCR, for the detection of bovine coronavirus (BCoV), bovine respiratory syncytial virus (BRSV), bovine parainfluenza virus (BPiV), bovine adenovirus (BAdV), Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis. Yates-corrected chi squared, or Fisher's exact test were used to compare both animal-health status and positivity/negativity to pathogens, and the relationship between presence/absence of clinical signs and Real-time PCR-positivity. H. somni and BCoV were the most frequently identified pathogens. In BRD-diagnosed cattle, BAdV was detected in 13.8% (19/138), BRSV in 14.5% (20/138) and BPiV in 4.3% (6/138). Healthy cattle were mostly positive for H. somni (89.2%, 83/93). A statistically significant association was observed between clinical signs and positivity to M. haemolytica (p value = 0.016). Although mass-medication and vaccination are used for BRD control, it still remains a primary health problem. Our results highlight that the nasopharyngeal microbiota could be affected by transport and that strategies to enhance calf immunity for reducing BRD-risk development would be more effective if applied at farm of origin prior to loading.

A Systematic Review of Heat Load in Australian Livestock Transported by Sea

Simple Summary

The transport of livestock by sea (‘live export’) is an important contemporary animal welfare issue in Australia. There is particular concern for the effects of heat load on the welfare of sheep being shipped live from Australia to the Middle East during the Northern Hemisphere summer. To reduce bias in a contentious context, we performed a systematic review of the literature relevant to Australian sea transport, heat load, and livestock. We discuss the factors contributing to harmful heat load, pathways for mitigating risks and existing knowledge gaps. We identified several areas requiring research to address these knowledge gaps.

Abstract

The transport of animals by sea (‘live export’) is one of the most important current animal welfare issues in Australian society. Recent media attention has highlighted concerns regarding the effects of high environmental temperature and humidity on the welfare and mortality of sheep being shipped live from Australia to the Middle East, especially during the Northern Hemisphere summer. To improve understanding of how and why harmful heat load occurs, we systematically reviewed Australian research into heat load and sea transport. High thermal load occurs during the sea transport of sheep and cattle from Australia when animals are subject to hot and humid environmental conditions and cannot remove heat generated by metabolic processes in the body, potentially also gaining heat from the environment. Several approaches have been proposed to mitigate these risks, including avoidance of voyages in hot seasons, selection of heat-resistant livestock breeds, reducing stocking density, and improved ventilation. We identified a lack of scientific literature relating to heat load in animals transported by sea and considerable potential for bias in the literature that was found. We identified the following priority research areas: (i) experimental manipulation of variables thought to influence the incidence and severity of harmful heat load, including sheep density; (ii) further assessment of the Heat Stress Risk Assessment (HSRA) model used to predict heat load events, and (iii) development of a suite of animal welfare indicators that may allow identification of ‘at risk’ sheep before they reach debilitating heat load condition. Addressing these knowledge gaps will assist efforts to reduce the frequency and intensity of harmful heat load events.

Risk factors associated with exposure to bovine respiratory disease pathogens during the peri-weaning period in dairy bull calves

Background

Bovine respiratory disease (BRD) remains among the leading causes of death of cattle internationally. The objective of this study was to identify risk factors associated with exposure to BRD pathogens during the peri-weaning period (day (d)-14 to d 14 relative to weaning at 0) in dairy bull calves using serological responses to these pathogens as surrogate markers of exposure.

Clinically normal Holstein-Friesian and Jersey breed bull calves (n = 72) were group housed in 4 pens using a factorial design with calves of different breeds and planes of nutrition in each pen. Intrinsic, management and clinical data were collected during the pre-weaning (d − 56 to d − 14) period. Calves were gradually weaned over 14 days (d − 14 to d 0). Serological analysis for antibodies against key BRD pathogens (BRSV, BPI3V, BHV-1, BHV-4, BCoV, BVDV and H. somni) was undertaken at d − 14 and d 14. Linear regression models (for BVDV, BPI3V, BHV-1, BHV-4, BCoV and H. somni) and a single mixed effect random variable model (for BRSV) were used to identify risk factors for changes in antibody levels to these pathogens.

Results

BRSV was the only pathogen which demonstrated clustering by pen. Jersey calves experienced significantly lower changes in BVDV S/P than Holstein-Friesian calves. Animals with a high maximum respiratory score (≥8) recorded significant increases in H. somni S/P during the peri-weaning period when compared to those with respiratory scores of ≤3.

Haptoglobin levels of between 1.32 and 1.60 mg/ml at d − 14 were significantly associated with decreases in BHV-1 S/N during the peri-weaning period. Higher BVDV S/P ratios at d − 14 were significantly correlated with increased changes in serological responses to BHV-4 over the peri-weaning period.

Conclusions

Haptoglobin may have potential as a predictor of exposure to BHV-1. BRSV would appear to play a more significant role at the ‘group’ rather than ‘individual animal’ level. The significant associations between the pre-weaning levels of antibodies to certain BRD pathogens and changes in the levels of antibodies to the various pathogens during the peri-weaning period may reflect a cohort of possibly genetically linked ‘better responders’ among the study population.

Detection and characterization of viruses as field and vaccine strains in feedlot cattle with bovine respiratory disease

This study investigated viruses in bovine respiratory disease (BRD) cases in feedlots, including bovine herpesvirus-1 (BoHV-1), bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine coronaviruses (BoCV) and parainfluenza-3 virus (PI3V). Nasal swabs were collected from 114 cattle on initial BRD treatment. Processing included modified live virus (MLV) vaccination. Seven BRD necropsy cases were included for 121 total cases. Mean number of days on feed before first sample was 14.9 days. Swabs and tissue homogenates were tested by gel based PCR (G-PCR), quantitative-PCR (qPCR) and quantitative real time reverse transcriptase PCR (qRT-PCR) and viral culture. There were 87/114 (76.3%) swabs positive for at least one virus by at least one test. All necropsy cases were positive for at least one virus. Of 121 cases, positives included 18/121 (14.9%) BoHV-1; 19/121 (15.7%) BVDV; 76/121 (62.8%) BoCV; 11/121 (9.1%) BRSV; and 10/121 (8.3%) PI3V. For nasal swabs, G-PCR (5 viruses) detected 44/114 (38.6%); q-PCR and qRT-PCR (4 viruses) detected 81/114 (71.6%); and virus isolation detected 40/114 (35.1%). Most were positive for only one or two tests, but not all three tests. Necropsy cases had positives: 5/7 G-PCR, 5/7 q-PCR and qRT-PCR, and all were positive by cell culture. In some cases, G-PCR and both real time PCR were negative for BoHV-1, BVDV, and PI3V in samples positive by culture. PCR did not differentiate field from vaccines strains of BoHV-1, BVDV, and PI3V. However based on sequencing and analysis, field and vaccine strains of culture positive BoHV-1, BoCV, BVDV, and PI3V, 11/18 (61.1%) of BoHV-1 isolates, 6/17 (35.3%) BVDV isolates, and 1/10 (10.0%) PI3V identified as vaccine. BRSV was only identified by PCR testing. Interpretation of laboratory tests is appropriate as molecular based tests and virus isolation cannot separate field from vaccine strains. Additional testing using sequencing appears appropriate for identifying vaccine strains.

Associations between exposure to viruses and bovine respiratory disease in Australian feedlot cattle

Bovine respiratory disease (BRD) is the most important cause of clinical disease and death in feedlot cattle. Respiratory viral infections are key components in predisposing cattle to the development of this disease. To quantify the contribution of four viruses commonly associated with BRD, a case-control study was conducted nested within the National Bovine Respiratory Disease Initiative project population in Australian feedlot cattle. Effects of exposure to Bovine viral diarrhoea virus 1 (BVDV-1), Bovine herpesvirus 1 (BoHV-1), Bovine respiratory syncytial virus (BRSV) and Bovine parainfluenza virus 3 (BPIV-3), and to combinations of these viruses, were investigated. Based on weighted seroprevalences at induction (when animals were enrolled and initial samples collected), the percentages of the project population estimated to be seropositive were 24% for BoHV-1, 69% for BVDV-1, 89% for BRSV and 91% for BPIV-3. For each of the four viruses, seropositivity at induction was associated with reduced risk of BRD (OR: 0.6-0.9), and seroincrease from induction to second blood sampling (35-60 days after induction) was associated with increased risk of BRD (OR: 1.3-1.5). Compared to animals that were seropositive for all four viruses at induction, animals were at progressively increased risk with increasing number of viruses for which they were seronegative; those seronegative for all four viruses were at greatest risk (OR: 2.4). Animals that seroincreased for one or more viruses from induction to second blood sampling were at increased risk (OR: 1.4-2.1) of BRD compared to animals that did not seroincrease for any viruses. Collectively these results confirm that prior exposure to these viruses is protective while exposure at or after feedlot entry increases the risk of development of BRD in feedlots. However, the modest increases in risk associated with seroincrease for each virus separately, and the progressive increases in risk with multiple viral exposures highlights the importance of concurrent infections in the aetiology of the BRD complex. These findings indicate that, while efficacious vaccines could aid in the control of BRD, vaccination against one of these viruses would not have large effects on population BRD incidence but vaccination against multiple viruses would be expected to result in greater reductions in incidence. The findings also confirm the multifactorial nature of BRD development, and indicate that multifaceted approaches in addition to efficacious vaccines against viruses will be required for substantial reductions in BRD incidence.

Estimation of nasal shedding and seroprevalence of organisms known to be associated with bovine respiratory disease in Australian live export cattle

The prevalence of organisms known to be associated with bovine respiratory disease (BRD) was investigated in cattle prior to export. A quantitative reverse transcription polymerase chain reaction assay was used to detect nucleic acids from the following viruses and bacteria in nasal swab samples: Bovine coronavirus (BoCV; Betacoronavirus 1), Bovine herpesvirus 1 (BoHV-1), Bovine viral diarrhea virus 1 (BVDV-1), Bovine respiratory syncytial virus (BRSV), Bovine parainfluenza virus 3 (BPIV-3), Histophilus somni, Mycoplasma bovis, Mannheimia haemolytica, and Pasteurella multocida. Between 2010 and 2012, nasal swabs were collected from 1,484 apparently healthy cattle destined for export to the Middle East and Russian Federation. In addition, whole blood samples from 334 animals were tested for antibodies to BoHV-1, BRSV, BVDV-1, and BPIV-3 using enzyme-linked immunosorbent assay. The nasal prevalence of BoCV at the individual animal level was 40.1%. The nasal and seroprevalence of BoHV-1, BRSV, BVDV-1, and BPIV-3 was 1.0% and 39%, 1.2% and 46%, 3.0% and 56%, and 1.4% and 87%, respectively. The nasal prevalence of H. somni, M. bovis, M. haemolytica, and P. multocida was 42%, 4.8%, 13.4%, and 26%, respectively. Significant differences in nasal and seroprevalence were detected between groups of animals from different geographical locations. The results of the current study provide baseline data on the prevalence of organisms associated with BRD in Australian live export cattle in the preassembly period. This data could be used to develop strategies for BRD prevention and control prior to loading.

Risk factors for mortality in cattle during live export from Australia by sea

OBJECTIVE

This study investigated mortality trends and risk factors for death for cattle exported live from Australia by sea.

METHODS

Mortality data for all voyages from Australia to all destinations between 1995 and 2012 were analysed retrospectively. Daily mortality trends were assessed for 20 long-haul voyages from Australia to the Middle East and to the Russian Federation between 2010 and 2012.

RESULTS

The overall voyage mortality percentage was 0.17% across the 13 million cattle exported on 6447 voyages. Mortality rates decreased significantly after 2000 and stabilised at low levels from 2003. The mortality rate for voyages to the Middle East and north Africa (0.44%) was significantly higher than for voyages to south-east Europe (0.28%), north-east Asia (0.12%) and south-east Asia (0.09%). Cattle exported from ports in southern Australia carried a higher mortality risk than those exported from northern ports for both long- and short-haul voyages. The daily mortality rate on long-haul voyages peaked at 3-4 weeks post-departure, although there was a smaller peak at 1-2 weeks.

CONCLUSION

The marked reduction in mortality rate since 2000 is related to a number of factors, including industry initiatives, government legislation and market demand, that have resulted in changes to both the selection of cattle for export and the management of cattle prior to and during voyages. Routine collection of animal performance data, combined with NLIS records and use of methods described here, have the potential to contribute to more effective management of mortality risks across the export chain.