Infected Calves Research Articles

Application of the PCR for diagnosis and monitoring of rotavirus in calves during treatment with the antiviral agent Triazavirin

Background: Rotavirus is a significant cause of morbidity and mortality in neonatal calves, leading to severe gastrointestinal and systemic illnesses. Current treatments primarily focus on symptomatic relief and prevention through vaccines, with limited use of antiviral agents. This article considers the issue of experiments using the antiviral agent Triazavirin in the treatment of rotavirus infection in calves, with tracking the amount of virus during the polymerase chain reaction examination in fecal samples.Methods: The experiment was conducted at a Mordovian Republican Veterinary Laboratory in the National Research Mordovian State University named after N.P. Ogarev (Republic of Mordovia, Russia), between February and March 2023. Two groups of calves, experimental and control, were assessed. The experimental group received Triazavirin orally at a dose of 500 mg per day for 7 days. Before and after the experiment, fecal samples were taken from experimental calves for the PCR study of the ribonucleic acid of group A rotaviruses.Results: Treatment with Triazavirin resulted in a reduction of the rotavirus load by an average of 35.2%. The PCR analyses before and after treatment indicated a substantial decrease in viral RNA in the majority of treated calves, with variable individual responses.Conclusions: Triazavirin demonstrates potential as an effective antiviral treatment for rotavirus in calves, reducing viral load and possibly improving clinical outcomes. The use of PCR provided a reliable method for monitoring viral levels, thereby facilitating effective management of this infectious disease.Keywords: Calves; Treatment; Digestive and Respiratory Organs; Antiviral Agent; Rotavirus; Treatment

Brain invasion of bovine coronavirus: molecular analysis of bovine coronavirus infection in calves with severe pneumonia and neurological signs.

Although the role of bovine coronavirus (BCoV) in calf diarrhea and respiratory disorders is well documented, its contribution to neurological diseases is unclear. This study conducted virological investigations of calves showing diarrhea and respiratory and neurological signs. An outbreak of diarrhea, respiratory, and neurological disorders occurred among the 12 calves in July 2022 in Istanbul, Türkiye. Two of these calves exhibited neurological signs and died a few days after the appearance of symptoms. One of these calves was necropsied and analyzed using molecular and histopathological tests. BCoV RNA was detected in the brain, lung, spleen, liver, and intestine of the calf that had neurological signs by real-time reverse transcription polymerase chain reaction. Immunostaining was also observed in the intestine and brain. A 622 bp S1 gene product was noted on gel electrophoresis only in the brain. Phylogenetic analysis indicated that the BCoV detected in this study had a high proximity to the BCoV strain GIb with 99.19% nucleotide sequence homology to the strains detected in Poland, Israel, Türkiye, and France. No distinct genetic lineages were observed when the brain isolate was compared with the respiratory and enteric strains reported to GenBank. In addition, the highest identity (98,72%) was obtained with the HECV 4408 and L07748 strains of human coronaviruses. The strain detected in a calf brain belongs to the GIb-European lineage and shares high sequence homology with BCoV strains detected in Europe and Israel. In addition, the similarity between the human coronaviruses (4408 and L07748) raises questions about the zoonotic potential of the strains detected in this study.

Cryptosporidium spp. Infection and Genotype Identification in Pre-Weaned and Post-Weaned Calves in Yunnan Province, China.

Cryptosporidium is a globally distributed zoonotic protozoan parasite in humans and animals. Infection is widespread in dairy cattle, especially in calves, resulting in neonatal enteritis, production losses and high mortality. However, the occurrence of Cryptosporidium spp. in pre- and post-weaned calves in Yunnan Province remains unclear. We collected 498 fecal samples from Holstein calves on 10 different farms in four regions of Yunnan Province. Nested PCR and DNA sequencing were used to determine the infection, species and genotypes of Cryptosporidium spp. in these animals. The overall occurrence of Cryptosporidium spp. in Holstein calves was 32.9% (164/498), and the prevalence in pre- and post-weaned calves was 33.5% (106/316) and 31.9% (58/182), respectively. Four Cryptosporidium species were identified in these animals, namely C. bovis (n = 119), C. parvum (n = 23), C. ryanae (n = 20) and C. andersoni (n = 2). Based on sequencing analysis of the 60 kDa glycoprotein gene of C. bovis, C. parvum and C. ryanae, six subtypes of C. bovis (XXVIe, XXVIb, XXVIf, XXVIa XXVIc and XXVId), two subtypes of C. parvum (IIdA19G1 and IIdA18G1) and four subtypes of C. ryanae (XXIf, XXId, XXIe and XXIg) were identified. These results provide essential information to understand the infection rate, species diversity and genetic structure of Cryptosporidium spp. populations in Holstein pre-weaned and post-weaned calves in Yunnan Province. Further, the presence of IIdA18G1 and IIdA19G1 in C. parvum implies significant animal and public health concerns, which requires greater attention and more preventive measures.

Evaluation of bovine coronavirus in Korean native calves challenged through different inoculation routes

Bovine coronavirus (BCoV) is a pneumoenteric virus that can infect the digestive and respiratory tracts of cattle, resulting in economic losses. Despite its significance, information regarding BCoV pathogenesis is limited. Hence, we investigated clinical signs, patterns of viral shedding, changes in antibody abundance, and cytokine/chemokine production in calves inoculated with BCoV via intranasal and oral. Six clinically healthy Korean native calves (< 30 days old), initially negative for BCoV, were divided into intranasal and oral groups and monitored for 15 days post-infection (dpi). BCoV-infected calves exhibited clinical signs such as nasal discharge and diarrhea, starting at 3 dpi and recovering by 12 dpi, with nasal discharge being the most common symptoms. Viral RNA was detected in nasal and fecal samples from all infected calves. Nasal shedding occurred before fecal shedding regardless of the inoculation route; however, fecal shedding persisted longer. Although the number of partitions was very few, viral RNA was identified in the blood of two calves in the oral group at 7 dpi and 9 dpi using digital RT-PCR analysis. The effectiveness of maternal antibodies in preventing viral replication and shedding appeared limited. Our results showed interleukin (IL)-8 as the most common and highly induced chemokine. During BCoV infection, the levels of IL-8, monocyte chemoattractant protein-1, and macrophage inflammatory protein-1β were significantly affected, suggesting that these emerge as potential and reliable biomarkers for predicting BCoV infection. This study underscores the importance of BCoV as a major pathogen causing diarrhea and respiratory disease.

Pathogenic diversification of the gut commensal Providencia alcalifaciens via acquisition of a second type III secretion system.

Providencia alcalifaciens is a Gram-negative bacterium found in a wide variety of water and land environments and organisms. It has been isolated as part of the gut microbiome of animals and insects, as well as from stool samples of patients with diarrhea. Specific P. alcalifaciens strains encode gene homologs of virulence factors found in other pathogenic members of the same Enterobacterales order, such as Salmonella enterica serovar Typhimurium and Shigella flexneri. Whether these genes are also pathogenic determinants in P. alcalifaciens is not known. Here we have used P. alcalifaciens 205/92, a clinical isolate, with in vitro and in vivo infection models to investigate P. alcalifaciens -host interactions at the cellular level. Our particular focus was the role of two type III secretion systems (T3SS) belonging to the Inv-Mxi/Spa family. T3SS 1b is widespread in Providencia spp. and encoded on the chromosome. T3SS 1a is encoded on a large plasmid that is present in a subset of P. alcalifaciens strains, which are primarily isolates from diarrheal patients. Using a combination of electron and fluorescence microscopy and gentamicin protection assays we show that P. alcalifaciens 205/92 is internalized into eukaryotic cells, rapidly lyses its internalization vacuole and proliferates in the cytosol. This triggers caspase-4 dependent inflammasome responses in gut epithelial cells. The requirement for the T3SS 1a in entry, vacuole lysis and cytosolic proliferation is host-cell type specific, playing a more prominent role in human intestinal epithelial cells as compared to macrophages. In a bovine ligated intestinal loop model, P. alcalifaciens colonizes the intestinal mucosa, inducing mild epithelial damage with negligible fluid accumulation. No overt role for T3SS 1a or T3SS 1b was seen in the calf infection model. However, T3SS 1b was required for the rapid killing of Drosophila melanogaster . We propose that the acquisition of two T3SS by horizontal gene transfer has allowed P. alcalifaciens to diversify its host range, from a highly virulent pathogen of insects to an opportunistic gastrointestinal pathogen of animals.

PREVALENCE OF GASTROINTESTINAL NEMATODES INFECTION IN BALI CATTLE CALVES AT BERINGKIT ANIMAL MARKET BADUNG REGENCY

Calves infected with gastrointestinal nematodes can spread diseases to other livestock in a new environment, causing a decrease in quality, and financial losses for farmers. This study aims to determine the prevalence and intensity of infection, as well as the gastrointestinal nematodes infecting Bali cattle calves at the Beringkit Livestock Market, Badung Regency. The study used a floatation method to identify worm egg morphology and continued with the McMaster method to determine infection intensity. Out of 100 fecal samples examined, 65 samples were found positive for gastrointestinal nematode infection, resulting in a prevalence of 65% infection among Bali cattle calves at the Beringkit Livestock Market, Badung Regency. The identified nematodes were strongyle-type worms (64%) with an infection intensity of 203 ± 384 EPG, Strongyloides papillosus (10%) with an infection intensity of 100 ± 89 EPG, and Toxocara vitulorum (9%) with an infection intensity of 155 ± 287 EPG. It is concluded from this study that the prevalence of gastrointestinal nematode infections in Bali cattle calves at the Beringkit Livestock Market, Badung Regency was high with infection intensity falling into the mild category. Regular and continuous deworming is necessary as a control and prevention measure for gastrointestinal nematode infections in Bali cattle calves.

Behavioural response to gastrointestinal parasites of yearling dairy calves at pasture

ABSTRACT Aims To investigate the association between gastrointestinal parasites (GIP) and animal behaviour in dairy calves under New Zealand pastoral conditions, using animal-mounted, accelerometer-based sensors. Methods Thirty-six, 5–6-month-old, Friesian-Jersey, heifer calves fitted with animal activity sensors to track behaviour were randomly allocated to one of two treatment groups. Half the animals were challenged with an oral dose of 20,000 larvae of Ostertagia ostertagi and Cooperia oncophera once a week for 3 weeks and half were unchallenged. Five weeks after the last dose, seven infected and nine uninfected animals were treated with an oral anthelmintic (AHC) and data collected for a further week. Accelerometer data were classified into minutes per day eating, ruminating, in moderate–high activity or in low activity. Live weight and faecal egg counts (FEC) were recorded weekly over the study period. All animals co-grazed a newly sown pasture not previously grazed by ruminants and were moved every week to fresh grazing. Treatment status was blinded to those managing the animals which were otherwise treated identically. Results Complete behavioural records were available from 30/36 calves, (13 challenged and 17 unchallenged). Before treatment with AHC, FEC increased in infected and un-treated calves over the study, while uninfected animals maintained a near zero FEC. There was no difference in live weight gain between the two groups over the study period. Bayesian, multinomial regression predicted differences in animal behaviour between infected and uninfected animals that were not treated with AHC over the 7 weeks following initial infection. Parasitised calves not treated with AHC were less active and spent up to 6 (95% highest density interval (HDI) = 1–11) minutes/day less in low level activity and up to 15 (95% HDI = 7–20) minutes/day less in moderate to high level activity. They ruminated up to 9 (95% HDI = 2–15) minutes/day more and ate up to 10 (95% HDI = 2–19) minutes/day more than control calves that were not treated with AHC. The effect of AHC on time spent in each behaviour differed between infected and uninfected calves and increased the coefficient of dispersion of the behavioural data. Conclusions and clinical relevance Small differences in animal behaviour can be measured in calves with GIP. However, to use this to target treatment, further validation studies are required to confirm the accuracy of behavioural classification and understand the complex drivers of animal behaviour in a dynamic and variable pasture-parasite–host environment.

PREVALENCE AND INTENSITY OF GASTROINTESTINAL PROTOZOAN INFECTION IN BALINESE CATTLE CALVES AT BERINGKIT ANIMAL MARKET, BADUNG REGENCY

Bali cattle are one of the indigenous cattle breeds in Indonesia that are the direct result of domestication from wild bulls. Gastrointestinal protozoan infection is still a factor that often disturbs the health of bali cattle. This study aimed to determine the prevalence and intensity of gastrointestinal protozoa infection in bali calves breeds in Beringkit Animal Market, Badung Regency. The examination was conducted using the floating method, with fecal samples from 100 bali cattle seedlings and the Mc Master method to determine protozoan infection. The results found 41% of the samples were infected with gastrointestinal protozoa. Based on gender, the prevalence of gastrointestinal protozoa infection in male bali calves was 41.1% and in female bali calves was 40.9%. The types of gastrointestinal protozoa found were Eimeria sp, and Balantidium sp. The average infection intensity of Eimeria sp, 36% with an infection intensity of 622.5 ± 2359.21 oocysts/gram of feces, and Balantidium sp, 17% with an infection intensity of 58.82 ± 75.99 cysts/gram of feces. The prevalence in this study was moderate. Male and female cattle have the same chance of being infected with gastrointestinal protozoa. The average infection intensity of Eimeria sp, and Balantidium sp, both protozoa were mild. It is recommended to improve environmental sanitation around bali breeding calves, routine feces cleaning and hygienic feeding methods

Designing a multiepitope mRNA-based vaccine against enterotoxigenic Escherichia coli infection in calves: Immunoinformatics and molecular modeling approach.

Escherichia coli is one of the serious pathogens causing various infections in the animal field, such as neonatal calf diarrhea, which is responsible for mortality associated with diarrhea during the first days of life. Current work is aimed at designing an effective and safe multiepitope vaccine candidate against E. coli infection in calves based on the fimbrial protein K99 of Enterotoxigenic E. coli (ETEC) and Immuno-informatics. A conserved sequence of K99 protein was generated, and then highly antigenic, nonallergic, and overlapped epitopes were used to construct a multiepitope vaccine. Five THL, six MHC II, and four beta cell epitopes were targeted to create the candidate. The candidate vaccine was produced utilizing 15 epitopes and three types of linkers, two types of untranslated region (UTR) human hemoglobin subunit beta (HBB), UTR beta-globin (Rabb), and RpfE protein as an immunomodulation adjuvant. Immuno-informatics analysis of the constructed protein showed that the protein was antigenic (antigenic score of 0.8841), stable, nonallergen, and soluble. Furthermore, the Immuno-informatics and physiochemical analysis of the constructed protein showed a stable, nonallergic, soluble, hydrophilic, and acidic PI (isoelectric point). of 9.34. Docking of the candidate vaccine with the toll-like receptor TLR3 was performed, and results showed a strong interaction between the immune receptor and the vaccine. Finally, the expression efficiency of the construct in E. coli was estimated via computational cloning of the vaccine sequence into Pet28a. Results of immunoinformatics and in silico approaches reveal that the designed vaccine is antigenic, stable, and able to bind to the immune cell receptors. Our results interpret the proposed multiepitope mRNA vaccine as a good preventive option against E. coli infection in calves.

Interferon-gamma producing CD4+ T cells quantified by flow cytometry as early markers for Mycobacterium avium ssp. paratuberculosis infection in cattle

Current diagnostic methods for Johne’s disease in cattle allow reliable detection of infections with Mycobacterium avium ssp. paratuberculosis (MAP) not before animals are 2 years of age. Applying a flow cytometry-based approach (FCA) to quantify a MAP-specific interferon-gamma (IFN-γ) response in T cell subsets, the present study sought to monitor the kinetics of the cell-mediated immune response in experimentally infected calves. Six MAP-negative calves and six calves, orally inoculated with MAP at 10 days of age, were sampled every 4 weeks for 52 weeks post-inoculation (wpi). Peripheral blood mononuclear cells (PBMC) were stimulated with either purified protein derivatives (PPD) or whole cell sonicates derived from MAP (WCSj), M. avium ssp. avium or M. phlei for 6 days followed by labeling of intracellular IFN-γ in CD4+ and CD8+ T cells. No antigen-specific IFN-γ production was detectable in CD8+ cells throughout and the responses of CD4+ cells of MAP-infected and control calves were similar up to 12 wpi. However, the mean fluorescence intensity (MFI) for the detection of IFN-γ in CD4+ cells after WCSj antigen stimulation allowed for a differentiation of animal groups from 16 wpi onwards. This approach had a superior sensitivity (87.8%) and specificity (86.8%) to detect infected animals from 16 wpi onwards, i.e., in an early infection stage, as compared to the IFN-γ release assay (IGRA). Quantification of specific IFN-γ production at the level of individual CD4+ cells may serve, therefore, as a valuable tool to identify MAP-infected juvenile cattle.

Analysis of the parasitological situation regarding eimeriosis in cattle in the Russian Federation

The purpose of the study is to review the spread of bovine eimeriosis in the territory of the Russian Federation. Objectives of the study: to analyze the epizootic situation of bovine eimeriosis in the territory of the Russian Federation. Bovine coccidiosis is widespread in many regions of Russia and in other countries of the world. The pathogens are more than 10 species of eimeria, which have a specific localization in the body of animals, as well as morphological differences from each other. Three species (E. zuernii, E. bovis and E. alabamensis) are characterized by the highest pathogenicity and are most often associated with the clinical manifestation of the disease. Mostly young animals aged from 2 weeks to 1 year are ill, and adult animals have an asymptomatic form of invasion. In many animals, eimeria causes dangerous diseases, accompanied by a decrease in productivity, the birth of weak offspring, often the death of young animals, and additional feed costs per unit of production. In livestock complexes, the incidence of calves with eimeriosis is 10–100%, and mortality is 25–60%. The maximum infection of calves and adult animals is observed in the spring and autumn periods, and in some regions in the autumn-winter period. It was found that with an increase in the density of calves in the machine, their infection with eimeria increases significantly. The invasion of calves was minimal when kept in individual machines. Given that parasites have a complex developmental biology, one of the most importantmeasures in the complex of measures ensuring the prevention and elimination of animal diseases with coccidiosis is currently still pharmacotherapy and prevention, contributing not only to the liberation of animals from parasites, but also to prevent the dispersion of the invasive origin in the environment and to prevent the threat of new infection.

A cell cycle regulator, E2F2, and glucocorticoid receptor cooperatively transactivate the bovine alphaherpesvirus 1 immediate early transcription unit 1 promoter.

Bovine alpha-herpesvirus 1 (BoHV-1) acute infection in cattle leads to establishment of latency in sensory neurons in the trigeminal ganglia (TG). A synthetic corticosteroid dexamethasone consistently initiates BoHV-1 reactivation in latently infected calves. The BoHV-1 immediate early transcription unit 1 (IEtu1) promoter regulates expression of infected cell protein 0 (bICP0) and bICP4, two viral transcriptional regulators. Hence, the IEtu1 promoter must be activated for the reactivation to occur. The number of TG neurons expressing E2F2, a transcription factor and cell cycle regulator, increased during early stages of reactivation from latency. The glucocorticoid receptor (GR) and E2F2, but not E2F1, E2F3a, or E2F3b, cooperatively transactivated a 436-bp cis-regulatory module (CRM) in the IEtu1 promoter that contains two GR responsive elements. Chromatin immunoprecipitation studies revealed that E2F2 occupies IEtu1 promoter sequences in cultured cells. GR and E2F2 mediate cooperative transactivation of IEtu1 promoter activity, which is predicted to stimulate viral replication following stressful stimuli.

Prevalence of Salmonella spp. in Neonatal Calves with Acute Diarrhea: A Study in Şanlıurfa Province, Southeastern Anatolia, Türkiye

Diarrhea is one of the most important health problems in neonatal calves. Salmonellosis, one of the causes of diarrhea in neonatal calves, continues to be one of the major health problems worldwide. Prevalence data on enteropathogens can provide basic information for control and prevention strategies. The aim of this study was to determine the prevalence of Salmonella spp. in neonatal calves with acute diarrhoea in Şanlıurfa province located in the Southeastern Anatolia Region of Türkiye. The animal material of the study consisted of 100 neonatal calves with acute diarrhoea aged 1-28 days. The presence of Salmonella spp. was determined by PCR method from rectal fecal samples taken from the calves included in the study. As a result of the study, 5% prevalence of Salmonella spp. was determined. This study showed that there is a potential risk of zoonotic Salmonella spp. infection in neonatal calves with acute diarrhoea in the region and an original contribution was made to determine the prevalence of Salmonella spp. in Türkiye. It was emphasized that treatment for the causative agent and necessary protective measures should be taken in the region. In addition, further studies with multifocal serotyping in human and animal populations living in this region and other regions of Türkiye are needed in terms of the epidemiology of zoonotic Salmonella spp.

Necrosis plays a role in the concentration of mycobacterial antigens in granulomas from Mycobacterium bovis naturally infected cattle

The dynamics that develop between cells and molecules in the host against infection by Mycobacterium bovis, leads to the formation of granulomas mainly present in the lungs and regional lymph nodes in cattle. Cell death is one of the main features in granuloma organization, however, it has not been characterized in granulomatous lesions caused by M. bovis. In this study we aimed to identify the profiles of cell death in the granuloma stages and its relationship with the accumulation of bacteria. We identified necrosis, activated caspase-3, LC3B/p62 using immunohistochemistry and digital pathology analysis on 484 granulomatous lesions in mediastinal lymph nodes from 23 naturally infected cattle. Conclusions: greater amounts of mycobacterial antigens were identified in granulomas from calves compared with adult cattle. The highest percentage of necrosis and quantity of mycobacterial antigens were identified in granuloma stages (III/IV) from adults. The LC3B/p62 profile was heterogeneous in granulomas between adults and calves. Our data suggest that necrosis is associated with a higher amount of mycobacterial antigens in the late stages of granuloma and the development of autophagy appears to play an heterogeneous effector response against infection in adults and calves. These results represent one of the first approaches in the identification of cell death in the four stages of granulomas in bovine tuberculosis.

306 Awardee Talk: Characterization and surveillance testing of problematic pathogens within the livestock industry using metagenomic and long read sequencing

Abstract With increased intensification of livestock production, the rate of disease susceptibility and emergence of pathogens has increased. Currently in the beef cattle industry, infectious bovine keratoconjunctivitis (IBK), is a problematic disease that is not well understood where vaccines have shown to have low efficacy. This is partly due to the lack of understanding of the ocular microbiome, where IBK disease progression may be a result of a polymicrobial disease due to certain bacterial and/or viral taxa predisposing the animal to infection. To understand the microbial ecology of IBK we used metagenomic shotgun sequencing to characterize the bovine ocular microbiome and virome. Infected and healthy beef calves were sampled before, during, and after IBK infection and shotgun metagenomic sequencing was performed to identify microbial changes during IBK infection. Preliminary data showed that we were able to identify 230 contigs consisting of bacteriophages such as Escherichia virus, Bacillus virus, Corynebacterium virus, and Mycoplasma virus. Out of the 230 bacteriophages, 213 of them are lytic phages. Additionally, preliminary data showed bacteria contigs such as Moraxella bovoculi, and Mycoplasma bovoculi Like IBK, the rate of disease emergence has increased in the last decade. As such, rapid in-field surveillance tools are greatly needed to monitor the emergence of known and unknown pathogens for early intervention. Current tools such as RT-PCR and enzyme linked immunosorbent assay (ELISA) require previous genomic knowledge to detect pathogens and are limited to the pathogen of interest. We have developed a long-read sequencing-based surveillance tool that eliminates the need of prior knowledge to detect both bacterial and viral pathogens simultaneously. The approach we developed can rapidly and accurately identify pathogens within clinical samples in as short as 12 h from sample collection to results. Here we present sequence-based microbiome studies and tools to help understand disease etiology and develop novel surveillance tools to improve food security within the livestock industry.

The Establishment of a Novel γ-Interferon In Vitro Release Assay for the Differentiation of Mycobacterial Bovis-Infected and BCG-Vaccinated Cattle.

BCG vaccination is increasingly reconsidered in the effective prevention of bovine tuberculosis (bTB). However, the primary challenge in BCG vaccination for cattle is the lack of a technique for differentiating between infected and vaccinated animals (DIVA). This study aimed to establish a novel DIVA diagnostic test based on an interferon-gamma in vitro release assay (IGRA). The plasmid encoding three differential antigens (Rv3872, CFP-10, and ESAT-6) absent in BCG genes but present in virulent M. bovis was previously constructed. Thus, a recombinant protein called RCE (Rv3872, CFP-10, and ESAT-6) was expressed, and an RCE-based DIVA IGRA (RCE-IGRA) was established. The RCE concentration was optimized at 4 μg/mL by evaluating 97 cattle (74 of which were bTB-positive, and 23 were negative) using a commercial IGRA bTB diagnostic kit. Further, 84 cattle were tested in parallel with the RCE-IGRA and commercial PPD-based IGRA (PPD-IGRA), and the results showed a high correlation with a kappa value of 0.83. The study included BCG-vaccinated calves (n = 6), bTB-positive cattle (n = 6), and bTB-negative non-vaccinated calves (n = 6). After 3 months post-vaccination, PPD-IGRA generated positive results in both vaccinated and infected calves. However, RCE-IGRA developed positive results in infected calves but negative results in vaccinated calves. In conclusion, this DIVA method has broad prospects in differentiating BCG vaccination from natural infection to prevent bTB.

Detection of haptoglobin and serum amyloid A as biomarkers in naturally infected Mycoplasma bovis calves

The livestock sector of Pakistan is increasing rapidly and it plays important role both for rural community and national economy. It is estimated that almost 8 million rural people are involved in livestock rearing and earning about 35–40 % of their income from the livestock sector. Mycoplasma bovis (M. bovis) infection causes significant economic losses in dairy animals especially young calf in the form of clinical illnesses such as pneumonia, poly-arthritis, respiratory distress and mortality. M. bovis is hard to diagnose and control because of uneven disease appearance and it is usually noticed in asymptomatic animals. For the identification of M. bovis in sub-clinical and clinical samples, determination of acute phase proteins i.e., haptoglobin (Hp) and serum amyloid A (SAA) are important tools for the timely diagnosis of disease. Therefore, early diagnosis of disease and hemato-biochemical changes are considered beneficial tools to control the infectious agent to uplift the economy of the dairy farmers. For this purpose, blood samples were collected from 200 calves of Bovidae family. Serum was separated from blood samples to determine the concentration of Hp and SAA, while blood samples were processed to determine hematological changes in blood from calves by using hematological analyzer. The blood plasma obtained from the blood samples was processed to measure oxidative stress factors. Lungs tissues from slaughterhouses/ morbid calves were collected to observe histopathological changes. The results of present study indicated that level of SAA and Hp remarkably increased (P < 0.05) in M. bovis infected calves in comparison to healthy calves. The oxidative stress markers indicated that nitric oxide and MDA levels in the infected calves increased significantly (P < 0.05), while infected claves had considerably lower levels of superoxide dismutase, catalase and glutathione. These findings indicate that oxidative stress play role to increase the level of APPs, while monitoring of APPs levels may serve as a valuable addition to the clinical evaluation of naturally infected calves with M. bovis. The hematological parameters were decreased significantly (P < 0.05). Altogether, this study suggests that Hp and SAA are proposed as promising biomarkers for detecting naturally occurring M. bovis infection in calves.

Impact of Limosilactobacillus fermentum probiotic treatment on gut microbiota composition in sahiwal calves with rotavirus diarrhea: A 16S metagenomic analysis study”

BackgroundDiarrhea poses a major threat to bovine calves leading to mortality and economic losses. Among the causes of calf diarrhea, bovine rotavirus is a major etiological agent and may result in dysbiosis of gut microbiota. The current study was designed to investigate the effect of probiotic Limosilactobacillus fermentum (Accession No.OR504458) on the microbial composition of rotavirus-infected calves using 16S metagenomic analysis technique. Screening of rotavirus infection in calves below one month of age was done through clinical signs and Reverse Transcriptase PCR. The healthy calves (n = 10) were taken as control while the infected calves (n = 10) before treatment was designated as diarrheal group were treated with Probiotic for 5 days. All the calves were screened for the presence of rotavirus infection on each day and fecal scoring was done to assess the fecal consistency. Infected calves after treatment were designated as recovered group. Fecal samples from healthy, recovered and diarrheal (infected calves before sampling) were processed for DNA extraction while four samples from each group were processed for 16S metagenomic analysis using Illumina sequencing technique and analyzed via QIIME 2.ResultsThe results show that Firmicutes were more abundant in the healthy and recovered group than in the diarrheal group. At the same time Proteobacteria was higher in abundance in the diarrheal group. Order Oscillospirales dominated healthy and recovered calves and Enterobacterials dominated the diarrheal group. Alpha diversity indices show that diversity indices based on richness were higher in the healthy group and lower in the diarrheal group while a mixed pattern of clustering between diarrheal and recovered groups samples in PCA plots based on beta diversity indices was observed.ConclusionIt is concluded that probiotic Limosilactobacillus Fermentum N-30 ameliorate the dysbiosis caused by rotavirus diarrhea and may be used to prevent diarrhea in pre-weaned calves after further exploration.

Evaluation of risk factors of omphalitis in newborn beef calves with indoor housing

BackgroundOmphalitis is the third most common cause for diseases and infections in newborn calves. Its risk factors are well described in dairy production, but data in beef production is limited. ObjectiveTo identify and quantify the risk factors of omphalitis in cow-calf operations with seasonal indoor calving period. AnimalsNine hundred sixty-four calves included from 22 cow–calf operations in central France were included. MethodsA prospective cohort study involved data collection during two visits for each calf. Simple and multivariable logistic regression analyses evaluated the association between omphalitis and the variables. ResultsAmong 964 included calves, 311 (32.3%) calves had an omphalitis. Accounting for farms’ random effect, risk factors for omphalitis highlighted by the univariable analysis were: absence of navel disinfection (odds ratio (OR) = 2.3, [1.45–3.04]), wetness of bedding calving area (OR = 1.8–2.1, [0.78–2.83]-[0.63–3.57]), cleanliness of calves’ pen (OR =1.6–2.8, [1.22–2.27]-[2.02–3.84]), wetness of calves’ pen bedding (OR = 1.7–3.2, [1.12–2.06]-[3.08–3.84]), calf weight at birth >50 kg (OR = 2.0–5.0, [1.02–2.38]-[1.51–11.1]), umbilical cord length <3 cm (OR = 2.2–2.3, [1.53–3.11]-[1.24–4.38]), and sex (male vs female) (OR = 2.6, [2.08–3.69]). The multivariable analysis, accounting for farms’ random effect, showed that the absence of navel disinfection (OR= 2.2, [1.44–3.09]), wetness of bedding calving area (OR = 1.9–2.4, [0.55–2.83]-[0.59–3.28]), calf weight at birth >50 kg (OR = 1.9–2.6, [1.03–2.56]-[1.43–12.5]) and sex (male vs female) (OR =2.4, [2.09–3.49]) were risk factors for omphalitis. Conclusions and clinical importanceThese observations may help identify animals at early risk (>50 kg, male, short umbilical cord) and pay particular attention to the wetness of bedding and cleanliness of housing. This study highlights the importance of calving-pen bedding, calf characteristics and navel disinfection.

Outbreak of persistently infected heifer calves with bovine viral diarrhea virus subgenotypes 1b and 1d in a BVDV-vaccinated open dairy herd

Bovine viral diarrhea virus (BVDV) infection has a significant economic impact on beef and dairy industries worldwide. Fetal infection with a non-cytopathic strain may lead to the birth of persistently infected (PI) offspring, which is the main event in the epidemiological chain of BVDV infection. This report describes the birth of 99 BVDV-PI heifer calves within 52 days of birth in a regular BVDV-vaccinated Brazilian dairy cattle herd and the subgenotypes of the infecting field strains. This study was conducted in a high-yielding open dairy cattle herd that frequently acquired heifers from neighboring areas for replacement. The farm monitors the birth of PI calves by screening all calves born using an ELISA (IDEXX) for BVDV antigen detection. All calves aged 1–7 days were evaluated. For positive and suspected results, the ELISA was repeated when the calves were close to one month old. A total of 294 heifer calves were evaluated between February and March 2021. Of these, 99 (33.7 %) had positive ELISA results and were considered PI calves. To evaluate the predominant BVDV species and subgenotypes in this outbreak, whole blood samples were collected from 31 calves born during the study period. All samples were submitted to the RT-PCR assay for the partial amplification of the BVDV 5′-UTR region, and these amplicons were subjected to nucleotide sequencing. Phylogenetic analysis identified BVDV-1b and BVDV-1d in 16 and 13 heifer calves, respectively. In two calves, it was not possible to determine the BVDV-1 subgenotype. Detection of PI animals and monitoring of circulating BVDV subgenotype strains are central to disease control. This study shows that regular BVDV vaccination alone may be insufficient to prevent BVDV infection in high-yielding open dairy cattle herds. Other biosecurity measures must be adopted to avoid the purchase of cattle with acute infections by BVDV or BVDV-PI, which can cause a break in the health profile of the herd and economic losses.