Disease In Calves Research Articles

Contagious acquisition of antimicrobial resistance is critical for explaining emergence in western Canadian feedlots—insights from an agent-based modelling tool

IntroductionAntimicrobial resistance (AMR) is a growing threat to the efficacy of antimicrobials in humans and animals, including those used to control bovine respiratory disease (BRD) in high-risk calves entering western Canadian feedlots. Successful mitigation strategies require an improved understanding of the epidemiology of AMR. Specifically, the relative contributions of antimicrobial use (AMU) and contagious transmission to AMR emergence in animal populations are unknown.Materials and methodsA stochastic, continuous-time agent-based model (ABM) was developed to explore the dynamics of population-level AMR in Mannheimia haemolytica in pens of high-risk cattle on a typical western Canadian feedlot. The model was directly informed and parameterized with proprietary data from partner veterinary practices and AMU/AMR surveillance data where possible. Hypotheses about how AMR emerges in the feedlot environment were represented by model configurations in which detectable AMR was impacted by (1) only selection arising from AMU; (2) only transmission between animals in the same pen; and (3) both AMU-linked selection and transmission. Automated calibration experiments were used to estimate unknown parameters of interest for select antimicrobial classes. Calibrated parameter values were used in a series of Monte Carlo experiments to generate simulated outputs at both the pen and feedlot levels. Key model outputs included the prevalence of AMR by class at multiple time points across the feeding period. This study compared the relative performances of these model configurations with respect to reproducing empirical AMR data.ResultsAcross all antimicrobial classes of interest, model configurations which included the potential for contagious acquisition of AMR offered stronger fits to the empirical data. Notably, sensitivity analyses demonstrated that model outputs were more robust to changes in the assumptions underscoring AMU than to those affecting the likelihood of transmission.DiscussionThis study establishes a feedlot simulation tool that can be used to explore questions related to antimicrobial stewardship in the context of BRD management. The ABM stands out for its unique hierarchical depiction of AMR in a commercial feedlot and its grounding in robust epidemiological data. Future experiments will allow for both AMU-linked selection and transmission of AMR and can accommodate parameter modifications as required.

Evaluating case definitions of respiratory disease in dairy calves: a scoping review.

Bovine respiratory disease (BRD) is one of the most common diseases observed in dairy calves in both the pre- and post-weaning periods. Despite its common occurrence, there has been no formal synthesis (e.g., scoping review) of the scientific literature surrounding diagnosing BRD in dairy calves. As such, the objective of this scoping review was to describe what case definitions for diagnosing BRD in dairy calves have been used in research. An initial search of peer-reviewed journals and the gray literature yielded 12,001 unique articles, of which 307 records containing 358 case definitions were included. Seven categories of diagnostic methods were used to categorize case definitions: (1) clinical scoring systems alone were the most used diagnostic method (n = 148, 41%) followed by (4) physical exam parameters alone (i.e., the study did not provide a detailed description of how the calf was assessed for each component of the physical exam [i.e., no description or scoring options reported]), n = 91, 25%), (5) physical exam parameters in combination with other diagnostic methods (n = 40, 11%), (6) thoracic ultrasound alone (n = 31, 9%), (2) clinical scoring system in combination with other diagnostic methods (n = 23, 7%), (3) clinical scoring system in combination with thoracic ultrasound (n = 10, 3%), and (7) other diagnostic methods (n = 15, 4%). Only 2-thirds of publications provided a citation for their case definition (n = 230, 64%), of which the Wisconsin clinical scoring system was most referenced (n = 100, 43%), followed by the California clinical scoring system (n = 19, 8%). An attempt was made to compare entire case definitions within each diagnostic method; however, they displayed substantial diversity which limited the ability to compare them at this level. Instead, counts of individual factors within each case definition (e.g., individual clinical signs) were reported for each diagnostic method. From all case definitions across the 7 diagnostic method categories (n = 358), common factors assessed included cough (n = 224, 63%), nasal discharge (n = 213, 60%), and body temperature (n = 142, 54%). Across all case definitions, additional parameters such as validity were frequently not reported - only 4 (1.1%) were referred to as validated, 9 (2.5%) were being validated in the study, and 28 (7.8%) modified existing case definitions. Additionally, assessment of severity of disease when present (e.g., mild, moderate or severe) was frequently not reported (n = 336, 93.9%). Further, 106 (29.0%) reported assessments of accuracy, 66 (18.4%) of which were reports of qualitative oversight (e.g., training of assessors) and 40 (11.1%) of which were related to a quantitative assessment of accuracy (e.g., sensitivity and specificity). Parameters surrounding conducting the assessment were also extracted, for example how often (most common: at least daily, n = 120, 33.5%) and who conducted it (most common: information not reported, n = 144, 40.2%). The findings of this scoping review highlighted the need for a validated, standardized set of criteria for BRD diagnosis in dairy calves, achievable through following the methodology of developing a core outcome set.

Characterization of circulating miRNA in cow milk and colostrum.

MicroRNAs (miRNAs) are short RNA molecules, typically 21-25 nucleotides long, synthesized within eukaryotic cells. They play a crucial role in coordinating complex gene expression regulatory networks. The miRNAs are involved in post-transcriptional regulation, either by degrading target mRNA or suppressing their transcription, thereby influencing protein translation. Also, the variation of miRNAs expression in different milk components suggests diverse metabolic pathways. Additionally, characteristics of farm production systems exert a noticeable influence on miRNAs profiles, shaping the functional properties of bovine milk. In this study, milk and colostrum samples of Holstein cows (Bos taurus) were collected for RNA extraction and sequencing. Sequencing data underwent quality controls, and short non-coding RNA reads were analyzed to identify and compare miRNAs profiles. The sequencing runs yielded 73,567,661 and 44,283,978 reads for milk and colostrum samples, respectively. Following trimming, 8,335,860 and 7,778,212 reads for milk and colostrum samples were retained. A total of 4.3% milk and 37.8% colostrum reads were identified as miRNAs. Overall, 157 miRNAs were common to milk and colostrum, 2 were unique to milk, and 90 were unique to colostrum. After applying a minimal cutoff of 100 reads per miRNA, 146 miRNAs were considered as expressed. In milk, bta-miR-101 was unique; in colostrum, bta-miR-18a, bta-miR-262-3p, bta-miR-130a, and bta-miR-224 were unique; and 141 miRNAs were common to colostrum and milk. Chromosome distribution of these miRNAs varied, with higher representation on autosome 19 and sexual chromosome X. Overall, colostrum contained a greater number of miRNAs, although specific miRNAs such as miR-11-988b, miR-140, and miR-146b were more abundant in milk. Conversely, miRNAs such as miR-7a-5p, let-7e, and miR-16a were more prevalent in colostrum. Validation through qPCR confirmed the expression levels of selected miRNAs from RNA sequencing, establishing concordance between the methods. Analysis of gene regulation by specific miRNAs identified key miRNAs (e.g., miR-223, miR-181a, and miR-155) involved in regulating various genes. Distinct miRNAs profiles in milk and colostrum suggest various functionalities, potentially influencing calf development and immune responses. The study unveils a comprehensive map of miRNAs in milk and colostrum and highlights their potential roles in regulating biological processes, as they play an essential role in calf development, disease resistance, and metabolism.

Virulotyping, Antimicrobial Resistance Profiling and DNA Fingerprinting of Escherichia coli Isolates from Neonatal Calves

Escherichia coli harbors various virulence factors responsible for diarrhea and other diseases in neonatal calves. The antimicrobial resistance (AMR) among the diarrheagenic and non-diarrheagenic E. coli may impose a potential health hazard among the calves and make the antibacterial therapy ineffective. The virulence gene expression among AMR strains plays a crucial role in establishing diarrheal disease with therapeutic complications. This study investigates the diversity of E. coli isolates from neonatal calves. E. coli isolated from the fecal samples were subsequently subjected to pathotyping and virulotyping using the PCR technique. AMR profiling was done by phenotypic and genotypic methods. The ERIC pattern of E. coli pathotypes was compared and correlated with the pattern of AMR and virulence traits. 179 isolates were obtained from 158 fecal samples collected from neonatal calves. Forty-two isolates were pathotypable; predominated by shigatoxigenic E. coli. Seventy-four isolates were ESBL producers. Nineteen isolates were carbapenem resistant and 68 isolates exhibited quinolone resistance. blaAmpC, blaVIM and qnrS were the predominant genes detected among ESBL, carbapenem and quinolone resistance genes, respectively. The present study indicated diverse virulence profiles and the presence of significant ESBL, carbapenem and fluoroquinolone resistance among E. coli pathotypes from calves. The analysis of resistance profiling indicates the risks associated with the indiscriminate antibiotic use among farm animals, which may pose a potential health hazard to livestock owners.

Hematologic, Histopathological, and Inflammatory Biomarkers associated with Bovine Respiratory Disease in Calves

Hematologic, Histopathological, and Inflammatory Biomarkers associated with Bovine Respiratory Disease in Calves

The Safety and Efficacy of New DIVA Inactivated Vaccines Against Lumpy Skin Disease in Calves.

Background: Lumpy skin disease virus (Poxviridae family-Capripoxvirus genus) is the aetiological agent of LSD, a disease primarily transmitted by hematophagous biting, affecting principally cattle. Currently, only live attenuated vaccines are commercially available, but their use is limited to endemic areas. There is a need for safer vaccines, especially in LSD-free countries. This research aims to develop and test a safe and efficacious inactivated vaccine. Moreover, in this study, we used keyhole limpet hemocyanin (KLH) as a positive marker to distinguish infected from vaccinated animals (DIVA). Methods: Lumpy skin disease virus was propagated on primary lamb testis cells and Madin-Darby bovine kidney cells (PLT and MDBK, respectively), and four inactivated vaccines were produced. The vaccines differed from each other with the addition or not of KLH and in cells used for virus propagation. To evaluate the safety and immunogenicity, the vaccines and two placebos were administered to six groups comprising six male calves each, and antibody response was investigated using both an enzyme-linked immunosorbent assay (ELISA) and a serum neutralization (SN) test. In addition, the LSD/γ-interferon test and KLH (IgM-IgG) ELISA were performed on the collected samples. Furthermore, the use of KLH allowed us to distinguish vaccinated animals in the ELISA results, without any interference on the strength of the immune response against the LSDV. Finally, the efficacy of one of four vaccines was investigated through a challenge, in which one group of vaccinated animals and one animal control group were infected with a live field strain of LSDV. Results: Four out of the six control animals showed severe clinical signs suggestive of LSD, and, therefore, were euthanized for overcoming the predetermined limit of clinical score. By contrast, the vaccinated animals showed only mild symptoms, suggesting a reduction in severe disease notwithstanding the incapability of the vaccine in reducing the virus shedding. Conclusion: The vaccines produced were safe and able to elicit both a humoral and a cellular immune response, characteristics that, together with the demonstrated efficacy, make our vaccine a good candidate for countering the LSD spread in disease-free countries, thus also facilitating disease containment throughout the application of a DIVA strategy.

Growth Promotion and Economic Benefits of the Probiotic Lactiplantibacillus plantarum in Calves

Objectives: Various measures have been attempted to prevent infectious diseases in calves, such as environmental improvement and vaccine administration. Probiotics are commonly used to improve the body condition of newborn calves and prevent disease. In our previous research, Lactiplantibacillus plantarum RGU-LP1 (LP1) suppressed the expression of inflammatory cytokines in PBMCs of cattle fed it in the diet. In this study, we evaluated the effect of LP1 on the weights and number of treatments of the calves. Methods: Twenty-six one-week-old Holstein bull calves were divided into two groups (thirteen each), the LP1 group (LP1-treated) and the CN group (no LP1 fed), and tested as follows. The LP1 group was fed lyophilized LP1 (109 CFU/head/day) in milk replacer for 40 days. The CN group was fed the same diet only. Calves were followed for 63 days. The average treatment costs for the LP1 during the period were recorded. Feces and blood were collected from each calf during this period. Feces were examined for gut microbiota, and blood for immune assay and cytokine gene expression. Results: The LP1-treated group showed a decrease in disease incidence and an increase in body weights compared to controls. The average treatment cost during the observation period was significantly reduced compared to the CN group. The expression of TGFβ and IL10, inhibitory cytokines of inflammation, was significantly increased. The simultaneous expression of this set of inhibitory molecules resulted in low serum IL1β levels during the growth period. Conclusions: The Th1-type cytokine IFNγ was also significantly increased in LP1-treated calves. By reducing the amount of disease treatments and increasing dairy gain, LP1 is effective in preventing infectious diseases in calves. In addition, the increase in IFNγ by LP1 indicates improved Th1-type immunity in calves. These results show that LP1 has effects on the regulated inflammatory response and growth of calves.

Effects of the Prenatal Maternal Health Status on Calf Disease Prevalences and Respective Genetic Parameter Estimates in German Holstein Cattle.

The aim of the present study was to infer phenotypic responses and genetic parameters of the F1 calf diseases diarrhoea (DIAR) and pneumonia (PNEU) in dependency of the prenatal maternal health status (PMHS) of the dam and of the herd-calving year. The PMHS considered diagnoses for the cow disease mastitis (MAST) and claw disorders (CD) during gestation of F0 dams. Furthermore, 305-d milk production traits of F1 offspring from either healthy or diseased dam groups were compared. The study comprised 20,045 female calves (F1 = generation 1) and their corresponding dams (F0 = parental generation 0), kept in 41 large-scale herds. All F1 calves were from their dams' 2nd parity, implying that all dam (maternal) diseases were recorded during the first lactation and dry period of the dams. The F1 calves were phenotyped for DIAR up to 30 days post-partum, and for PNEU up to 180 days of age. At least one entry for the respective disease implied a score = 1 = sick, otherwise, a score = 0 = healthy, was assigned. Production records of the 10,129 F1 cows comprised 305-d records in first lactation for milk yield (MY), protein yield (PY) and fat yield (FY). Linear and generalised linear mixed models were applied to infer phenotypic responses of F1 traits in dependency of the PMHS for CD and MAST. A diagnosis for MAST or CD in F0 cows during gestation was significantly (p ≤ 0.05) associated with an increased prevalence for DIAR and PNEU, with pairwise differences of least-squares-means between calves from healthy and diseased cow groups up to 3.61%. The effects of PMHS on 305-d production traits in offspring were non-significant (p > 0.05). In bivariate genetic analyses, DIAR and PNEU were defined as different traits according to the PMHS, i.e., DIAR-MASThealthy and DIAR-MASTdiseased, DIAR-CDhealthy and DIAR-CDdiseased, PNEU-MASThealthy and PNEU-MASTdiseased, and PNEU-CDhealthy and PNEU-CDdiseased. The direct heritabilities for DIAR and PNEU were quite similar in the healthy and respective diseased dam group. Slightly larger direct heritabilities in the diseased dam groups were due to increased genetic variances. Maternal heritabilities were quite stable and smaller than the direct heritabilities. In random regression models, genetic parameters for DIAR and PNEU were estimated along the continuous herd-calving-year prevalence scale, considering a prevalence for MAST and CD (based on the 20,045 dam records plus 16,193 herd contemporary records) in the range from 0% to 30%. Direct heritabilities for PNEU were quite stable along the herd-calving-year gradient for MAST and CD. For DIAR, we observed stronger estimate fluctuations, especially increasing direct heritabilities in dependency of the herd-calving-year prevalence for MAST from 0.13 (at a MAST prevalence of 0%) to 0.30 (at a MAST prevalence of 30%). Consequently, obvious genotype x herd-calving-year PMHS interactions were observed for DIAR on the prenatal MAST scale, with a minimal correlation of 0.48 between direct genetic effects at 0% MAST prevalence and at 30% MAST prevalence. The correlations between direct genetic and maternal genetic effects were antagonistic at all herd-calving-year prevalence levels, displaying strongest fluctuations for "DIAR-MAST." The genotype x herd-calving-year PMHS interactions for DIAR suggest consideration of specific sires according to the herd health status for CD and for MAST.

The efect of phytometabiotic "Phytolysat Gastro" on parameters gomeostaza and changes in the populations of the microfora of the large intestine of calves with gastrointestinal disease syndrome

Among the diseases of young cattle, the most common are lesions of the gastrointestinal tract. Most often they are manifested by diarrhea, which leads to dehydration of the body and severe metabolic disorders. Often sick calves lose a lot of weight, and then lag behind in growth compared to healthy animals, cases of death are not uncommon. With such diseases, the microflora inhabiting the digestive tract is subject to great changes. At the same time, it is populated by pathogenic species whose vital activity complicates the course of the disease. We have studied the therapeutic effect of the use of phytometabiotic drug “Phytolizat Gastro” in gastrointestinal diseases in calves. For the study, experimental and control groups of black-and-white calves aged 10-14 days were formed by the method of analogues. All the calves studied had a clinical sign of gastrointestinal tract damage - diarrhea. According to the results of the study, the effect of the drug on the body was established. Blood counts vary in intervals close to the average values of norms. According to the results of the study, the recovery of calves of the experimental group in a shorter time, greater preservation of body weight during recovery and further increase in calves of the experimental group (by 85 g) compared to calves of the control group was established. Microbiota studies have shown that the amount of Lactobacillus spp. the calves of the experimental group decreased by 8.5% less compared to the control group, and the amount of Bifidobacterium spp. the calves of the experimental group increased by 48%. At the same time, the total number of lacto- and bifidobacteria prevails in calves of the experimental group, which indicates a positive effect of the studied drug on the microflora of the gastrointestinal tract of calves.

Encephalomyelitis and serositis caused by Chlamydia pecorum in buffalo calves from Brazil.

Chlamydia pecorum causes subclinical infections in cattle, but sporadic, bovine encephalomyelitis cases have been reported in calves and documented in two instances in European buffalo. An outbreak of Chlamydia pecorum-induced encephalomyelitis and serositis occurred in 3-month-old buffalo calves from Brazil. Initially presenting with pelvic limb incoordination, the calves progressed to lateral recumbency, depression, and death. Necropsies of two calves revealed encephalomyelomalacia, fibrin deposition on the external surface of the pericardium (case 1) and pleural and pericardial fibrosis (case 2). Microscopically, a multifocal to coalescing, necrotizing, neutrophilic and lymphocytic meningoencephalomyelitis with fibrinoid vasculitis and thrombosis was present. Anti-Chlamydia antibody labeling was demonstrated by immunohistochemistry. Bacteriological examination yielded no pathogenic bacteria in the brain or lungs. Chlamydia pecorum was confirmed by PCR. This work describes the gross, histopathological, microbiological, and molecular findings in two cases from an outbreak of Chlamydia pecorum-induced disease in buffalo calves.

First isolation of bovine coronavirus with a three-amino-acid deletion in the N gene causing severe respiratory and digestive disease in calve.

Bovine coronavirus (BCoV), a persistent threat to global cattle industry, has caused significant economic losses worldwide. In this study, a viral strain was isolated from the intestinal content of a diseased calve, and identified by cytopathic effects observation, indirect immunofluorescence assay and electron microscopy. Results showed that BCoV NXWZ2310 belonging to the GIIb genotype and has a three-amino-acid deletion in the serine-rich region of the N gene. Importantly, the BCoV NXWZ2310 strain exhibited strong pathogenicity, causing nasal discharge and watery diarrhea in calves for 8 and 10 days, respectively. Viral shedding was detected in nasal, throat and rectal swabs at levels reaching 106.228 copies/mL, 105.0 copies /mL and 106.692 copies/mL, respectively. Pathological examination showed that NXWZ2310 resulted in parenchymal lesions of the pulmonary lobe and significant intestinal lesions. Both the lungs and intestines displayed marked microscopic lesions with clear viral antigens present. BCoV NXWZ2310 strain with N-gene deletion mutations, caused severe respiratory and digestive disease in calves. Therefore, effective strategies are needed for the prevention and control of this isolate.

Investigation of the diagnostic and prognostic importance of Tumor Necrosis Factor-alfa (TNF-α), Procalcitonin (PCT), Interleukin-6 (IL-6) and Haptoglobin (HP) in calves with neonatal diarrhea

This study aims to investigate the effects of Procalcitonin, Tumor Necrosis Factor-alpha, Interleukin-6, and Haptoglobin levels on the prognosis of calves classified according to the severity of diarrhea. The animal material comprised 48 diarrheic calves of different breeds and sexes, aged 1‐30 days, and 16 healthy calves aged 1–30 days. The 48 diarrheic calves used were divided into 3 groups, each consisting of 16 calves. Group 1 was designed as Viral (Rota + Corona n = 16), Group 2 as Bacterial (E. coli n = 16), and Group 3 as Parasitic (Cryptosporidiosis n = 16). Each of these groups was further divided into 2 subgroups (moderate and severe subgroups). Blood samples were taken from the diarrheic calves before treatment (0 h) and at 24 and 72 h after treatment. Complete blood count, biochemical, blood gas analyses, and ELISA tests were performed.It was determined that 18.75 % (9/48) of the 48 diarrheic calves included in the study died, while 81.25 % (39/48) survived. The highest mortality rate among the patient groups was observed in the severe rota + corona group (37.5 %).The average PCT concentration in the diarrheic calves in the Rota-corona and E. coli groups at 0 and 24 hours was found to be higher than both the healthy calves and the diarrheic calves in the Cryptosporidium spp. group (P<0.001). This increase was also observed in the Cryptosporidium spp. group at 72 h (P<0.001). A positive and moderate correlation was observed between Procalcitonin and TNF-α (r = 0.603, P<0.001). As a result, it was concluded that the Procalcitonin value, along with other tests, could be used as a biomarker to determine the prognosis of the disease in diarrheic calves, regardless of the etiological agent. This study was evaluated as an original study in which cytokines and acute phase proteins were investigated before and after treatment, with diarrhea divided into subgroups.

How control and eradication of BVDV at farm level influences the occurrence of calf diseases and antimicrobial usage during the first six months of calf rearing

BackgroundBovine viral diarrhoea (BVD) is one of the major cattle diseases causing economic losses worldwide. Nowadays the disease manifests mainly as virus-induced immunosuppression and early embryonic death, impacting overall herd performance and contributing to increased antibiotic usage in calf rearing.MethodsIn our study we investigated the effect of rapid BVDV control measures on calf diseases and antimicrobial usage after weaning on a large industrial dairy farm. Persistently infected (PI) animals were identified and removed from the herd within a short period of time, and all susceptible animals were vaccinated against BVDV. Recorded herd parameters and AB usage were monitored retrospectively and compared with data collected after starting the BVD control program.Results and discussionThe programme began in January 2023 with identifying and eliminating PI animals from the farm. Twenty-one PI animals were found by using RT-qPCR testing of blood sera out of the 1571 animals tested (1.33%). Subsequent testing (January and December 2023) identified further 28 PI animals amongst the 542 calves tested shortly after birth, and all were instantly removed from the farm. In parallel with the BVDV eradication measures, AB usage dropped by more than 50% compared to previous years. Calf mortality also decreased from 7.45 to 4.38% as the control program progressed. Correspondingly, both the number of respiratory and diarrhoea cases decreased dramatically on the farm while the eradication measures were in place.ConclusionOur study clearly demonstrated the positive effects of BVDV eradication on the improvement of calf health and importantly, a reduction of AB usage, contributing to the One Health perspective of farm animal production.

Bovine Respiratory Disease (BRD) in Post-Weaning Calves with Different Prevention Strategies and the Impact on Performance and Health Status

Our study aimed to compare Bovine Respiratory Disease (BRD) morbidity, mortality, and growth in dairy and dairy beef cross-bred calves during the commingle period, 81–120 days of age, using two different BRD prevention strategies. The calves (n = 1799) were randomly assigned into groups: (1) Control (CON; received no vaccine or metaphylaxis); (2) Tulathromycin metaphylaxis (TUL; IncrexxaTM, Elanco Animal Health Inc., Greenfield, IN, USA); and (3) Mannheimia haemolytica vaccine (VACC; Nuplura® PH, Elanco Animal Health Inc., Greenfield, IN, USA). Calves were individually weighed three times during the study to estimate average daily gain (ADG). Deep nasopharyngeal swabs, thoracic ultrasonography, health scores, and treatment records were collected during the study. Ultrasound and health score results were not different across treatments. In this study, the TUL group had a lower cumulative BRD incidence than CON. The cumulative incidence and 95% CI of BRD during the commingle period, 81–120 days of age for CON, TUL, and VACC were 0.43 (0.38 to 0.47), 0.36 (0.38 to 0.40), and 0.39 (0.35 to 0.43), respectively. The ADG for CON, TUL, and VACC were 0.25 ± 0.15, 0.32 ± 0.15, and 0.17 ± 0.15 kg, respectively. There was no difference among the treatment groups for ADG. Management and environmental conditions were variable at this operation throughout the study period and likely impacted the calves. Earlier interventions may be needed when the BRD incidence is elevated in high-risk calves.

PSV-16 Evaluation of upper respiratory and fecal microbiomes in neonatal beef calves

Abstract There is a critical lack of information on the timing of colonization of bovine respiratory disease-related bacteria in the upper respiratory tract, potentially affecting calf health and disease onset. The objective of this study was to evaluate the upper respiratory tract and fecal microbiomes of neonatal beef calves during the first 24 h of life compared with their dams at the time of birth. Late-gestation commercial beef cows (n = 28) were assigned to individual, soil-surfaced pens (6.25 x 2.29 m) fitted with canvas tarps on shared fences to limit contact between unrelated pairs. Left nasal (LN), right nasal (RN), fecal, and vaginal swab samples were collected from cows at a single time point promptly after parturition. Swabs of the LN, RN, and rectum were collected from calves at birth (0 h), 6, 12, and 24 h post-parturition. Samples were flash-frozen and stored at -80°C until processing. DNA was extracted from swabs using Power Soil Pro kit. Extracted DNA was used to prepare DNA libraries for full-length 16S rRNA gene sequencing on a MinION Mk1C device. Sequenced reads were classified using Centrifuge and used in microbiome analyses conducted in R to estimate the changes in the microbiome according to animal type (cow versus calf), time of collection, and sample type (nasal, fecal, or vaginal). Upper respiratory microbiomes significantly differed (P &amp;lt; 0.005) between cows and their offspring at birth. In nasal microbiomes, animal type explained 12.6% (P = 0.002) and 18.5% (P = 0.001) of variance in beta diversity in left and right cavities, respectively. Animal type explained 42.1% of the beta diversity variance in fecal microbiomes (P = 0.001). Nasal microbiomes at birth were significantly more dispersed in dams compared with their calves in both the LN (P = 0.03) and RN (P = 0.03). Similarly, fecal microbiomes of dams were significantly more dispersed (P &amp;lt; 0.0001) than those of their offspring. There was a clear transition of the microbial communities associated with calf age in the upper respiratory and fecal niches. Calf age accounted for 2% (P = 0.02), 3.5% (P = 0.001), and 28% (P = 0.001) of the variance in the beta diversity of the LN, RN, and fecal microbiomes, respectively. After adjusting for calf age, the laterality of nasal microbiomes was not significantly (P = 0.682) associated with the composition of microbial communities. In conclusion, calf microbial communities were dissimilar to that of their dam at birth. Additionally, microbial community transition was evident with each subsequent sampling time point, potentially influenced by the presence of the dam.

346 Investigating the potential of incorporating indirect genetic effects into genetic evaluations of dairy calf disease traits

Abstract The goal of infectious disease control is often local eradication, but this is theoretically impossible to achieve based on classical quantitative genetic theory. Current methods focus on the susceptibility of individuals to disease and assume that exposure to a pathogen is 1) constant over time, 2) equal among individuals, and (3) due entirely to the environment. For this reason, it is likely that conventional genetic methods are capturing only a fraction of genetic variation in disease occurrence. The incorporation of epidemiological theory into quantitative genetics provides an opportunity to better determine the level of genetic variation in infectious disease traits. This stems from the ability to include the positive feed-back dynamics of infectious disease transmission. From an epidemiolocal perspective, both susceptibility and infectivity also have indirect genetic effects (IGE), because the genotype of one individual impacts the risk of infection of other individuals, and this can drastically affect the rate and direction of response to selection. Epidemiological models unravel the genetic heterogeneity in both susceptibility and infectivity traits, and account for the impact each animal has on its contemporaries compared with conventional quantitative genetic approaches. From a calf health perspective, there is a shift towards group housing dairy calves, primarily due to welfare and social acceptability. In turn, this will lead to increased animal interactions from a young age. Therefore, the aim of this study was to investigate the potential of incorporating IGE into current quantitative approaches to determine its impact on selection potential. Our study looked at two common infectious diseases in calves on dairy farms: respiratory problems (RESP) and diarrhea (DIAR). Producer-recorded data comprised of 19,445 records collected on 34 herds that group housed calves between 2007 and 2020. Calves were allocated into pen groups based on birth dates and herd specific housing practices. Original phenotypes were split into 10 records, each representing a week of life, to determine when exactly calves became sick and infective. Several scenarios were investigated with respect to the time an animal was infective for following a disease case (1 or 2 wk), and the maximum difference in weeks between animal birth dates to be included within the same pen (2 to 5 wk). Variance components were estimated using a generalized linear mixed model fitting a complementary-log-log link function with offset for exposure. Initial heritability estimates for susceptibility on the observed scale for DIAR ranged from 0.03 to 0.07, and from 0.02 to 0.03 for RESP across scenarios. While heritability estimates for infectivity are currently being investigated, the results for susceptibility highlight the potential for incorporating IGE into genetic evaluation of disease traits and provide an introduction towards incorporating epidemiological theory into classical quantitative approaches to better respect the transmission dynamics of infections.

19 Strategies to optimize the trace mineral status of weaned beef calves

Abstract Trace mineral nutrition of pre-weaned beef calves is derived from 1) tissue stores at birth, 2) milk, 3) forage, and 4) supplement. In most production systems, calves are born with adequate trace mineral status, namely Cu, Zn, Mn and Se. One exception, however, is severe Se deficiency in the dam which may result in White Muscle Disease in Se-deficient calves shortly after birth. Despite general adequacy at birth, tissue concentrations of these elements often decrease during the pre-weaning period due to inadequacies in milk and trace mineral deficiency of forages. Trace mineral losses are further exacerbated by a variety of stressors naturally occurring throughout the production system, including, but not limited to, environmental, social, and immunological. Weaning, which is unavoidable in modern production systems, is the most stressful experience a beef animal will experience in their lifetime. To avoid deficiency at weaning, trace mineral deficits must be addressed through supplementation during the pre-weaning period. One of the most common supplementation methods involves the blending of supplemental trace minerals with common salt, offered free choice. This system assumes that cattle have a “nutritional wisdom” to consume salt at a level that meets their requirement for Na. Although largely effective in most grazing situations, this management system is not without complications. Notably, salt-based, free-choice mineral supplements are offered simultaneously to cow/calf pairs with known variation in voluntary intake. The necessity to understand and manage free-choice intake is the basic principle behind all successful free-choice mineral supplementation systems. In tropical and subtropical climates, where a large percentage of the world’s beef is produced, cattle are typically enrolled in year-long grazing schedules that are characterized by dry and wet seasons. In these environments, the craving for salt increases as forage DM decreases resulting in large seasonally impacted reductions in voluntary intake of salt-based, free-choice mineral supplements. During the dry season, when forage moisture is low, free-choice, salt-based mineral consumption often does not meet anticipated target levels due to a reduced natural craving for salt. There are other examples where seasonal variation in salt craving impacts the effectiveness of targeting appropriate voluntary intake of free-choice mineral supplements. For example, in some coastal regions of the world, salt-water intrusion will impact the Na content of forages and drinking water. In these regions, cattle may avoid salt-fortified supplements because of excessive Na intake from other sources. Fortunately, if we understand these regional and climatic impacts, there are effective management interventions that may be adopted to protect against trace mineral deficiency resulting from inadequate free-choice intake. This symposium presentation will review multiple pre-weaning mineral supplementation systems that have been shown to be effective for optimizing the mineral status of weaned beef calves.

Experimental immunotherapy of association infections of the gastrointestinal tract of newborn calves using yolk melange enriched with specific Y class immunoglobulins

Mass gastrointestinal diseases of newborn calves manifested by symptoms of diarrhea are caused by various etiological factors and most often occur in the form of mixed infections. Mixed infections have a more severe diarrhea than mono-infections. The economic consequences of such infections due to the high prevalence, frequent mortality and loss of productivity during further exploitation of the animal can be significant. The most common causative agents of gastrointestinal diseases of newborn calves of viral etiology is rotavirus and coronavirus infections. Mixed (viral-bacterial) infection can lead to 100% mortality of the diseased calves. Specific vaccination of springer cows against gastrointestinal pathogens in calves, which is performed to increase the number of pathogen-specific immunoglobulins in the colostrum at calf birth, and ingestion of colostrum by the calves during the first 4 hours of life are the most important strategies to prevent severe diarrhea. But as practice shows, this is not always enough. The purpose of this work was to study the effectiveness of immunoprophylaxis of associative infections of the gastrointestinal tract of newborn calves with the use of melange prepared from chicken eggs previously immunized with the vaccine "Rotagal" (Pharmagal-BIO s.r.o., Slovakia), used for the prevention of colibacillosis, rotavirus and coronavirus infections of cattle. As a result of the study, it was established that the addition of yolk melange rich in specific immunoglobulins of Y class to the colostrum in the first hours of life of the calves has a pronounced prophylactic effect, facilitates the course of the infectious process in case of the disease, saves costs for the treatment of sick animals, increases survival rate, contributes to the acceleration of live weight gain. The use of an immunobiological preparation based on transovarial immunoglobulins has a positive effect on the indicators of nonspecific resistance of newborn calves compared to the calves with early postnatal disease and antibiotic treatment.

Study of Akabane disease in an Iranian dairy herd: a re-emerging disease.

Akabane virus is a teratogenic pathogen transmitted by Culicoides spp. to ruminants. The virus induces anomalies in the central nervous system in the developing fetus, resulting in arthrogryposis-hydranencephaly (A-H) syndrome. During three outbreaks of the disease (2002, 2013, and 2020), 77 calves were born in Varamin, Iran, with A-H syndrome. The presenting neurologic signs were categorized into three main groups, as common, less common, and uncommon signs. The common signs were unawareness of the surroundings, blindness, deep depression, partial failure of suckling, and unintelligent behavior. The less commonly noted signs were hyperexcitability, regurgitation, head pressing, compulsive walking, and kicking, while the uncommon signs comprised protrusion of the tongue, making sounds resembling barking, carnivore-like milk drinking, and deafness. Arthrogryposis, dome-shaped skull, kyphosis, torticollis, lordosis, scoliosis, and spina bifida were the diagnosed skeletal defects. Upon necropsy, hydranencephaly, hydrocephaly, and microencephaly were seen in the calves presenting neurologic signs, while astrocytosis, astrogliosis, focal gliosis, perivascular, perineuronal, and submeningeal edema, perivascular cuffing, non-suppurative meningitis, non-suppurative encephalitis and lymphoplasmacytic infiltration, and perivascular and parenchymal hemorrhage were seen in samples obtained from the brains. RT-PCR detected Akabane virus in the brain tissues of the affected calves. This is the first clinical study of Akabane disease in calves in Iran.

Detection of Disease in Calves using Artificial Intelligence

Background: Livestock farming is experiencing a digital transformation and is becoming more information-driven. However, this type of data is often kept in separate storage towers, making it incapable of practicing its potential to boost animal welfare. Lumpy Skin Disease (LSD) is a serious threat to the health of cattle worldwide and has caused financial problems for many cattle farming enterprises. It has been shown that combining machine learning (ML) and artificial intelligence (AI) with biosensor data and conventional visual inspections can improve the identification and diagnosis of this serious condition. Methods: This study presents an extremely precise livestock farming framework that combines data streams from a wide array of disciplines of dairy cattle to see if ever wider/vast data sources enhance the overall projections for diseases and if using the more complicated prediction models can reimburse for less diverse data to some extent. Using images from the farming landscape, this study highlights the utility of convolutional neural networks (CNNs) in the identification of the Lumpy Skin Disease Virus (LSDV) in animals. Result: An analysis of the relative weight given to individual factors in predicting accuracy shows that disease in dairy cattle results from the intricate interactions between many life domains/parameters, such as housing, nutrition and climate; that prediction performance is enhanced by incorporating a wider range of data sources; and that current information can be repurposed to produce useful information for vaccine development. The study highlights the potential of data-driven dairy interventions, focusing on artificial intelligence for disease prediction in cattle, to improve animal welfare and reduce the risk of disease. A Convolutional Neural Network (CNN) based model effectively classified skin conditions with an overall accuracy of 73.89% after 27 training epochs. This study demonstrates CNN’s useful applications in the field of veterinary medicine by highlighting its potential for early detection of Lumpy Skin Disease (LSD).