Experimental co-infection of calves with SARS-CoV-2 Delta and Omicron variants of concern

Since emerging in late 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has repeatedly crossed the species barrier with natural infections reported in various domestic and wild animal species. The emergence and global spread of SARS-CoV-2 variants of concern (VOCs) has expanded the range of susceptible host species. Previous experimental infection studies in cattle using Wuhan-like SARS-CoV-2 isolates suggested that cattle were not likely amplifying hosts for SARS-CoV-2. However, SARS-CoV-2 sero- and RNA-positive cattle have since been identified in Europe, India, and Africa. Here, we investigated the susceptibility and transmission of the Delta and Omicron SARS-CoV-2 VOCs in cattle. Eight Holstein calves were co-infected orally and intranasally with a mixed inoculum of SARS-CoV-2 VOCs Delta and Omicron BA.2. Twenty-four hours post-challenge, two sentinel calves were introduced to evaluate virus transmission. The co-infection resulted in a high proportion of calves shedding SARS-CoV-2 RNA at 1- and 2-days post-challenge (DPC). Extensive tissue distribution of SARS-CoV-2 RNA was observed at 3 and 7 DPC and infectious virus was recovered from two calves at 3 DPC. Next-generation sequencing revealed that only the SARS-CoV-2 Delta variant was detected in clinical samples and tissues. Similar to previous experimental infection studies in cattle, we observed only limited seroconversion and no clear evidence of transmission to sentinel calves. Together, our findings suggest that cattle are more permissive to infection with SARS-CoV-2 Delta than Omicron BA.2 and Wuhan-like isolates but, in the absence of horizontal transmission, are not likely to be reservoir hosts for currently circulating SARS-CoV-2 variants.

Identification of miR-29a as a novel biomarker for lumpy skin disease virus exposure in cattle

Micro RNAs (miRNAs) have been implicated in the regulation of maturation, proliferation, differentiation, and activation of immune cells. In this study, we demonstrated that miR-29a antagonizes IFN-γ production at early times post-LSDV infection in cattle. miR-29a was predicted to target upstream IFN-γ regulators, and its inhibition resulted in enhanced IFN-γ production in sensitized peripheral blood mononuclear cells (PBMCs). Further, stimulation of PBMCs with LSDV antigen exhibited lower levels of miR-29a, concomitant with a potent cell-mediated immune response (CMI), characterized by an increase in LSDV-specific CD8+ T cell counts and enhanced levels of IFN-γ, which eventually facilitated virus clearance. In addition, a few immunocompromised cattle (developed secondary LSDV infection at ~ 6 months) that failed to mount a potent cell-mediated immune response, were shown to maintain higher miR-29a levels. Furthermore, as compared to the sensitized crossbred cattle, PBMCs from sensitized Rathi (a native Indian breed) animals exhibited lower levels of miR-29a along with an increase in CD8+ T cell counts and enhanced levels of IFN-γ. Finally, we analysed that a ≥ 60% decrease in miR-29a expression levels in the PBMCs of sensitized cattle correlated with a potent CMI response. In conclusion, miR-29a expression is involved in antagonizing the IFN-γ response in LSDV-infected cattle and may serve as a novel biomarker for the acute phase of LSDV infection, as well as predicting the functionality of T cells in sensitized cattle. In addition, Rathi cattle mount a more potent CMI response against LSDV than crossbred cattle.

Copy number variations within fibroblast growth factor 13 gene influence growth traits and alternative splicing in cattle

Previous researches revealed a copy number variation (CNV) region in the bovine fibroblast growth factor 13 (FGF13) gene. However, its effects remain unknown. This study detected the various copy number types in seven Chinese cattle breeds and analysed their population genetic characteristics and effects on growth traits and transcription levels. Copy number Loss was more frequent in Caoyuan Red cattle and Xianan cattle than in the other breeds. Association analysis between CNV and growth traits of Qinchuan indicated that the CNV was significantly related to chest depth, hip width and hucklebone width (P < 0.05). Additionally, the growth traits of individuals with copy number Loss were significantly inferior to those with copy number Gain or Median (P < 0.05). Besides, we found two splicing isoforms, AS1 and AS2, in FGF13 gene, which resulted from alternative 5' splicing sites of intron 1. These isoforms showed varied expression levels in various tissues. Moreover, CNV was significantly and negatively associated with the mRNA expression of AS1 (r = -0.525, P < 0.05). The CNVs in bovine FGF13 gene negatively regulated growth traits and gene transcription. These observations provide new insights into bovine FGF13 gene, delivering potentially useful information for future Chinese cattle breeding programs.

Functional analysis of the GPAT4 gene mutation predicted to affect splicing

The GPAT4 gene is considered as a potential functional candidate for single nucleotide polymorphism (SNP) studies in dairy cattle breeding due to its association with dairy performance in cattle by encoding an enzyme responsible for the presence of diacylglycerols and triacylglycerols in milk. Using the example of the GPAT4 gene, we applied the minigene splicing assay to analyze the functional consequences of its variant that was predicted to affect normal splicing. The results of functional analysis revealed the sequence variations (rs442541537), transfection experiments in a wild type and mutant cell line model system demonstrated that the investigated mutation in the second intron of the GPAT4 gene was responsible for the presence of a second exon in mature messenger RNA (mRNA). The cases of its absence in the spliced mature mRNA transcript resulted in a truncated dysfunctional protein due to the appearance of a stop codon. Thus, the discovered SNP led to alternative splicing in pre-mRNA by the 'cassette exon' ('exon skipping') mechanism. The studied mutation can potentially be a molecular genetic marker for alternative splicing for the GPAT4 gene and, therefore contributes to economic benefits in cattle breeding programs.

Lumpy jaw caused by Nocardia farcinica in a Holstein cow

A 3-year-old Holstein cow was examined in an intensive system due to unilateral swelling in the mandible. A right mandibular mass was associated with painful mastication and Ptyalism. In palpation, the mass was raised, ulcerated, attached to the mandible bone and firm, approximately 17 × 12 × 10 cm3 in size. The lesion was sampled, and after routine bacteriology and histopathology procedures, the occurrence of lumpy jaw caused by Nocardia farcinica was confirmed. The bacterium was analysed using genome sequencing and new strain called Najm 114. Due to the risk of zoonosis of the isolated agent, the cow was euthanized. This is the first report of lumpy jaw caused by N. farcinica in a cow. This study showed that N. farcinica should be considered a possible etiological agent for lumpy jaw in cattle.

An in-depth investigation of the microbiota and its virulence factors associated with severe udder cleft dermatitis lesions

Udder cleft dermatitis (UCD) is a skin condition affecting the anterior parts of the udder in dairy cattle. In the present study, we aimed to shed light on the microbiota in severe UCD lesions versus healthy udder skin by putting forward a taxonomic and functional profile based on a virulence factor analysis. Through shotgun metagenomic sequencing, we found a high proportion of bacteria in addition to a low abundance of archaea. A distinct clustering of healthy udder skin versus UCD lesion samples was shown by applying principal component analysis and (sparse) partial least squares analysis on the metagenomic data. Proteobacteria, Bacillota, and Actinomycetota were among the most abundant phyla in healthy udder skin samples. In UCD samples, Bacteroidota was the most abundant phylum. At genus level, Bifidobacterium spp. had the highest relative abundance in healthy skin samples, whereas Porphyromonas spp. and Corynebacterium spp. had the highest relative abundance in UCD samples. In the differential abundance analysis, Porphyromonas spp. and Bacteroides spp. were significantly differentially abundant in UCD samples, whereas Bifidobacterium spp., Staphylococcus sp. AntiMn-1, and Staphylococcus equorum were more commonly found in healthy samples. Moreover, the abundance of several treponeme phylotypes was significantly higher in lesion samples. The streptococcal cysteine protease speB was among the most abundant virulence factors present in severe UCD lesions, while a plethora of virulence factors such as the antitoxin relB were downregulated, possibly contributing to creating the ideal wound climate for the dysbiotic community. Network analysis showed healthy lesion samples had a large network ofpositive, correlations between the abundances of beneficial species such as Aerococcus urinaeequi and Bifidobacterium angulatum, indicating that the healthy skin microbiome forms an active protective bacterial network, which is disrupted in case of UCD. In UCD samples, a smaller microbial network mainly consisting of positive correlations between the abundances of Bacteroides fragilis and anaerobic Bacteroidota was exposed. Moreover, a high correlation between the taxonomic data and virulence factors was revealed, concurrently with 2 separate networks of microbes and virulence factors. One network, matching with the taxonomic findings in the healthy udder skin samples, showcased a community of harmless or beneficial bacteria, such as Bifidobacterium spp. and Butyrivibrio proteoclasticus, associated with hcnB, hcnC, relB, glyoxalase, and cupin 2. The other network, corresponding to UCD samples, consisted of pathogenic or facultative pathogenic and mainly anaerobic bacteria such as Treponema spp., Mycoplasmopsis spp., and bovine gammaherpesvirus 4, that correlated with virulence factors SpvB, fhaB, and haemagglutination activity domain-associated factor. Our results point toward a dysbiotic community with a notable decrease in diversity and evenness, with a loss of normal skin inhabitants and innocuous or useful species making way for predominantly anaerobic, facultative pathogens. The shift in the abundance of virulence factors such as fhaB and SpvB could play a role in the manifestation of a local micro-environment favorable to the microbiome associated with udder skin lesions. Lastly, the presence of specific networks between microbial species, and between microbes and virulence factors was shown.

Detection of selected antimicrobial residues in red meat and kidney of beef cattle slaughtered at Nekemte municipal abattoir, Ethiopia

BACKGROUND

Antibiotics are commonly used drugs in farm animals for therapeutic, prophylactic and diagnosis purposes. As a result of the use of antibiotics in livestock, residues of antibiotics may be present in animal-derived foods, especially in meat. This study aimed at determining the antibiotic residues in cattle slaughtered at Nekemte municipal abattoir and assessing the knowledge, attitude and practice (KAP) level of the community about antibiotic residue in food of cattle origin.

MATERIALS AND METHODS

A cross-sectional study was conducted on randomly selected kidney and muscle samples slaughtered at Nekemte municipal abattoir. The samples were collected aseptically and analysed using liquid chromatography mass spectrometer. In addition the KAP of cattle handlers, butcher men and meat users were collected using structured questionnaire. The data was analysed by SPSS and intercooled Stata version 7.0, 2001.

RESULTS

Results are presented as percentages and frequency distributions in tabular and graphical form. From 120 individuals interviewed, only 25.83% knew about withdrawal time and had limited knowledge on effect of antibiotic residue on human health, whereas about 47.5% did not heard about antibiotic residue in meat. Tetracycline was detected in all the sampled meat 60 (100%), whereas oxytetracycline residues were detected in half 15 (50%) of the samples. In the current study doxycycline, sulphadiazine, penicillin G and enrofloxacin were not detected in all samples. Oxytetracycline residue levels ranged from 0.00 to 463.35 µg/kg for the kidney and 0.00 to 354.55 µg/kg for muscle samples. About 10% of kidney and 3.33% muscle samples collected had oxytetracycline residues above maximum residue limits.

CONCLUSION

In general, the study revealed that oxytetracycline residues were prevalent among antimicrobial residues analysed from the study area. The study indicated the presence of high antimicrobial residue and hence exposes for antimicrobial resistance of pathogens warranting coordinated effort to mitigate its health effect on the animal and hence human being.

Suspected intoxication by Kikuyu grass (Cenchrus clandestinus) of dairy cattle in the Azores, Portugal

CASE HISTORY

An outbreak of suspected Kikuyu grass (Cenchrus clandestinus) intoxication among dairy cattle occurred on the island of Terceira in the Azores (Portugal), in October 2022. The animals affected were non-lactating dairy cows and heifers from five small farms grazing (free or tethered) a Kikuyu-dominant pasture. Of the 29 animals exposed, 17 were affected, and eight (five heifers and three adult cows) died, resulting in a morbidity rate of 58%, a mortality rate of 28% and a case mortality rate of 47%.

CLINICAL FINDINGS AND TREATMENT

The clinical signs were non-specific and inconsistent, and included dry faeces, some with dark red blood; apathy and prostration; abdominal dilatation; tachycardia; tachypnoea; pale or jaundiced mucous membranes; sham drinking; sialorrhoea; and moderate to severe dehydration. Symptomatic treatment was provided but was ineffective. Haematology and serum biochemistry revealed an acute inflammatory leukogram, increased alkaline phosphatase (ALP) activity, decreased gamma-glutamyl transferase (GGT) activity, and azotaemia.The most consistent necropsy findings were haemorrhages in the epicardium and endocardium, an enlarged liver with rounded edges, non-perforated abomasal ulcers, and haemorrhagic lesions in the small and large intestines. Histopathology indicated myocarditis, hepatitis, interstitial nephritis, enteritis and colitis.Several fungal species were isolated from grass samples taken from affected pastures including several Fusarium spp., the genus implicated in Kikuyu toxicosis. Immediate removal of the animals from the pasture with Kikuyu was the only measure that prevented new cases and resulted in the recovery of some of the less affected animals.

DIAGNOSIS

The epidemiological features of this outbreak and the clinical signs and micro- and macroscopic lesions observed were highly suggestive of Kikuyu grass poisoning.

CLINICAL RELEVANCE

Although the weather conditions varied from other published cases, the grazing conditions (almost exclusive Kikuyu grass) and the post-mortem findings were very similar to those described in the literature, particularly the haemorrhages in the epicardium and endocardium. Kikuyu grass is very invasive and presents many desirable characteristics as cattle feed. Thus, an increase in cases of intoxication may be expected. Practitioners and farmers in areas where Kikuyu grass is abundant should be aware of the potential risks of grazing cattle exclusively on these pastures. They should also be aware of the early and subtle signs of Kikuyu intoxication to allow for timely removal of the animals from pasture.

Impact of herd mobility on brucellosis seroprevalence and spread risk resulting from cross-border transhumance

BACKGROUND

Cross-border livestock mobility through transhumance is mainly practiced in West African countries for seasonal access to resources and market. Cross-border herds are involved in the dynamic of transboundary animal diseases among them brucellosis taken as model. Brucellosis is a zoonotic disease causing abortion.

OBJECTIVES

This study explores the seroprevalence of brucellosis according to mobility and infection spread between Mali and Côte d'Ivoire in the context of seasonal cross-border transhumance.

METHODS

From February to April 2021, a transversal serological survey of brucellosis was conducted on 521 cattle from 111 transhumant herds and 283 cattle from 59 sedentary herds, all from Mali.

RESULTS

The global individual seroprevalence for Brucella spp. in transhumant and sedentary cattle from Mali was 8.2% (95% CI = 6.0-10.5). At herd level, seroprevalence was 21.2% with a significant variation between transhumant (11.7%) and sedentary (39.0%) herds. For herds in transhumance, cattle seropositivity was associated with a previous infection suspected by herdsmen odds ratio (OR = 4.4; 95% CI = 1.1-18.1) and unknown abortion aetiology (OR = 4.3; 95% CI = 1.0-17.3). The departure region (coming from Sikasso) and previous brucellosis infection or unexplained abortion could be used to predict Brucella infection in transhumant herds with a probability of around 60%. The risk of brucellosis introduction in host regions was high despite the individual animal seroprevalence of 3.6% and a low sale rate in transhumant cattle.

CONCLUSIONS

The findings suggest that testing transhumant during border control and survey of cattle markets and sales could improve risk control of the spread of disease at regional scale.

Graduate Student Literature Review: Hemotropic mycoplasmas in cattle

The objective of this narrative literature review is to better understand bovine hemoplasmosis, an emerging disease that threatens dairy animal health. Several species of hemotropic mycoplasma are known to infect both animals and humans, and Mycoplasma wenyonii and Candidatus Mycoplasma haemobos are the species that infect red blood cells of cattle. These microorganisms are associated with clinical signs in dairy cattle, but the effects of infection on health and productivity of dairy cows are poorly understood. In this paper, we review information about the epidemiology of bovine hemoplasmosis in different countries, including clinical signs associated with hemoplasmosis in cattle, methods of diagnosis, treatment, possible routes of transmission, risk factors for infection, and disease progression. Although hemoplasmas have been reported to infect cattle in many countries, and methods used to detect these organisms have improved, numerous gaps in knowledge were identified. The pathogenesis of the disease and potential effect on animal health and productivity remain unclear. With this review, we seek to contribute to the understanding of hemoplasmosis in cattle and provide insights for further research to improve disease management strategies and overall animal health in the dairy industry.

Exploring precision-cut liver slices for comparative xenobiotic metabolism profiling in swine and cattle

In vitro systems are useful tools for unravelling species differences in xenobiotic metabolism.The current work aimed to validate the technique of precision-cut liver slices (PCLS) for comparative studies on xenobiotic metabolism in swine and cattle.PCLS from swine (n = 3) and cattle (n = 3) were produced using a Brendel-VitronTM Tissue Slicer and cultured for 6 h. Tissue viability was preserved throughout the whole culture period.Metabolic viability was evaluated using the anthelmintics albendazole (ABZ) and fenbendazole (FBZ) as model drugs, as well as other substrates of hepatic monooxygenases: benzydamine (BZ) N-oxygenase (FMO-dependent), and the O-dealkylations of 7-ethoxyresorufin (EROD, CYP1A1-dependent) and 7-methoxyresorufin (MROD, CYP1A2-dependent).ABZ S-oxygenation resulted 6-fold (cattle) and 13.6-fold (swine) higher (p = 0.001) compared to FBZ S-oxygenation.Similar BZ N-oxygenation and EROD activities were observed in PCLS cultures from both species. MROD was 2.5-fold higher (p = 0.033) in swine than in cattle. Similarly, ABZ S-oxygenation was 1.7-fold higher (p = 0.0002) in swine than in cattle. Conversely, a 82% higher (p = 0.0003) rate of FBZ S-oxygenation was evidenced in PCLS cultures from cattle compared to those from swine.Overall, this work shows that PCLS cultures are useful to obtain relevant information on species differences in xenobiotic metabolism.

Comparison of 4 laboratory tests for the detection of bovine rabies viral infection in Paraguay: fluorescent antibody test, rapid detection test, histologic lesions, and RT-PCR

Rabies virus (RABV; Lyssavirus rabies) is a neurotropic virus that can be transmitted to mammals by the hematophagous bat Desmodus rotundus. An accurate, accessible method for the detection of RABV in cattle is necessary in Paraguay; thus, we evaluated the detection of RABV using 4 techniques: fluorescent antibody test (FAT), immunochromatography rapid detection test (RDT; Anigen Rapid Rabies Ag test kit; Bionote), a reverse-transcription PCR (RT-PCR) assay, and histologic lesions in different portions of the CNS of 49 Paraguayan cattle to determine the most sensitive and specific technique. By FAT and RDT, 15 of 49 (31%) samples were positive. By RT-PCR amplification of N and G genes, 13 of 49 (27%) and 12 of 49 (25%) were positive, respectively. RDT had high agreement with FAT (kappa = 1); sensitivity was 100% (95% CI: 97-100%) and specificity was 100% (95% CI: 99-100%). The amplification of the N and G genes resulted in substantial agreement (kappa of 0.9 and 0.8, respectively) compared with FAT, and the sensitivity and specificity of the N gene were 87% (95% CI: 66-100%) and 100% (95% CI: 98-100%), respectively, and those of the G gene were 80% (95% CI: 56-100%) and 100% (95% CI: 98-100%), respectively. Histologic lesions observed were lymphoplasmacytic meningoencephalitis, gliosis, and neuronophagia. The agreement observed between the FAT and RDT tests suggests that RDT is an accurate tool for the detection of RABV. Histopathology can be used to confirm lesions caused by RABV and to rule out other conditions; the RT-PCR assay is useful for molecular epidemiology studies.

The effectiveness of a virtual fencing technology to allocate pasture and herd cows to the milking shed

Virtual fencing technology provides an opportunity to rethink the management of intensive grazing systems in general, yet most studies have used products developed and applied to more extensive livestock systems. This research aimed to assess the application of a virtual fencing technology developed for the intensive pastoral dairy industry. The Halter system uses 2 primary cues, sound and vibration, and one aversive secondary cue, a low energy electrical pulse, to confine cows to a pasture allocation and remotely herd cows. Two groups of 40 mid-lactation multiparous dairy cows were studied (Bos taurus, predominantly Friesian and Friesian × Jersey, parity 1-8). Cows were milked twice per day and provided 9 kg pasture DM/day in a 24-h allocation, supplemented with 7 kg silage and 6 kg grain DM/day. Training to the Halter system occurred over 10 d after which cows were managed with the technology for a further 28 d. The type and time of cues delivered was recorded by each collar and communicated via a base-station to cloud data storage. Cows took less than a day to start responding to the sound cues delivered while held on a pasture allocation and were moving to the milking parlor without human intervention by d 4 of training. On training d 1, at least 60% of sound cues resulted in an electrical pulse. Across training d 2-10, 6.4% of sound cues resulted in a pulse. After the 10-d training period, 2.6% of sound cues resulted in a pulse. During the management period, 90% of cows spent ≤1.7 min/d beyond the virtual fence, received ≤ 0.71 pulse/d in the paddock and received ≤ 1 pulse/d during virtual herding to the parlor. By the final week of the management period, 50% of cows received zero pulses/week in the paddock and 35% received zero pulses/week during virtual herding. The number of pulses delivered per day and the pulse:sound cue ratio was lower in this study than that previously reported using other virtual fencing technologies. We conclude that the Halter technology is successful at containing lactating dairy cows in an intensive grazing system as well as at remotely herding animals to the milking parlor.

Validation of a commercial ELISA kit to measure 11-oxoetiocholanolone in equine and bovine feces

Feces are a noninvasive and easily collectible matrix that may help determine cumulative hormone metabolite concentrations over medium-to-long times. To date, 11-oxoetiocholanolone, an important metabolite of cortisol, has been measured in equine and bovine feces solely by an in-house enzyme immunoassay (EIA). Therefore, we validated the use of a commercial ELISA kit (11-oxoetiocholanolone ELISA kit; Cayman Chemical), which had been validated on sheep feces and human urine, to measure 11-oxoetiocholanolone in feces from 42 horses and 32 bulls. The ELISA kit had good precision (intra- and inter-assay CVs: 5.8% and 11.2% for equine feces; 9.9% and 11.2% for bovine feces, respectively), analytical sensitivity (0.186 ng/mL for both equine and bovine feces), and accuracy (parallelism and recovery tests) in determining 11-oxoetiocholanolone concentrations in feces from both species. We found ranges of 11-oxoetiocholanolone concentrations of 1-109 ng/g in equine feces and 40-302 ng/g in feces of bulls. The Cayman Chemical ELISA kit offers a simple and accessible means of analysis of 11-oxoetiocholanolone in equine and bovine fecal samples.

In vitro efficacy testing of ivermectin against Tritrichomonas foetus trophozoites

There are no recommended drugs to treat cattle infected with the protozoan Tritrichomonas foetus (TF). Ivermectin, widely used in the treatment of intestinal parasites, was found effective against some protozoa growing in vitro. Here, its effectiveness against a TF line was investigated. Trophozoites were incubated in media with increasing concentrations of ivermectin and mortality was determined after 24 h. Ivermectin killed cells with a mean maximum effective concentration (EC50) of 2.47 μg mL-1. The effective concentration of ivermectin was rather high for a formulation suitable for systemic treatment. However, topical treatment of animals against TF could still be considered and tested.

strain YE332, isolated from a cattle rumen fermentation of Leucaena leaf

We report the 2.78-Mb circular genome sequence of Pyramidobacter sp. strain YE332, isolated from a fermentation of bovine rumen fluid, supplied with leaf material from Leucaena leucocephala cv. Cunningham. This genome sequence consists of 2,795,328 bp with 60% G + C content, 2,573 predicted coding DNA sequences, and 70 RNAs.

Effects of oral calcium on reproduction and postpartum health in cattle: a meta-analysis and quality assessment

Postpartum blood calcium (Ca) concentration is related to the reproduction and health of cattle. Oral calcium supplements were given to dairy cows after calving to increase blood Ca concentration and reduce the risk of hypocalcemia. However, studies have shown that oral Ca has different effects in preventing disease. The purposes of this study were (i) to conduct a meta-analysis to evaluate the expected effect of oral Ca on incidence of calving-related diseases, pregnancy risk and milk yield in dairy cows, and (ii) to make a quality assessment of these related studies. In total, 22 eligible studies were included in this review. Meta-analysis showed that oral Ca could significantly reduce the incidence of hypocalcemia (clinical hypocalcemia: relative risk (RR) = 0.67, 95% confidence interval (CI) = [0.52, 0.87]; subclinical hypocalcemia: RR = 0.81, CI = [0.72, 0.91]), and incidence of retained placenta (RR = 0.77, CI = [0.62, 0.95]), improved blood Ca concentrations: mean difference (MD) = 0.08; 95% CI = [0.04, 0.11]. For other results, the meta-analysis revealed a lack of evidence of the correlation between oral Ca and serum magnesium (Mg) / phosphorus (P) concentration (Mg: MD = -0.04; 95% CI = [-0.10, 0.02]; P: MD = 0.05; 95% CI = [-0.10, 0.21]) or incidence of other calving-related disorders (metritis: RR = 1.06, CI = [0.94, 1.19]; ketosis: RR = 1.04, CI = [0.91, 1.18]; mastitis: RR = 1.02, CI = [0.86, 1.21]; displacement of the abomasum: RR = 0.81, CI = [0.57, 1.16]) or pregnancy risk (pregnancy risk at first service: RR = 0.99, CI = [0.94, 1.05]; overall pregnancy rate: RR = 1.03, CI = [0.98, 1.08]) or milk yield (MD = 0.44; 95% CI = [-0.24, 1.13]). The distribution of the funnel plot formed by the included studies was symmetrical, and the Egger's test had a p > 0.05, indicating that there was no significant publication bias. Sensitivity analyses results suggested that the results of meta-analysis are robust. Quality assessment of the included studies revealed that the risk of bias was focused on selection bias, performance bias, detection bias and other sources of bias, and the future research should focus on these aspects.

Dogs' ability to detect an inflammatory immune response in cattle via olfaction

Introduction

Canine olfaction is a potential means for detection of respiratory disease in beef cattle. In a prior study, two dogs were trained to discriminate between nasal swabs from healthy cattle and cattle that developed Bovine Respiratory Disease. Dogs had some ability to identify samples from BRD-affected cattle, but results were ambiguous. The purpose of this study was to evaluate more dogs using better-controlled training and testing procedures.

Methods

Nasal and saliva swabs were collected from 96 cattle before and after administering a vaccine to induce an inflammatory immune response. Samples were stored at -80°C for up to 11 months before use, and samples from animals with an elevated body temperature at baseline were omitted. An automated olfactometer apparatus was constructed to improve blinding procedures and reduce opportunities for odor contamination. Four dogs were trained to distinguish between swabs from healthy and sickness-model cattle, including the two dogs from the previous study ("Runnels" and "Cheaps") and two inexperienced dogs ("Molokai" and "Amy"). During a seven-month training period, dogs were exposed to samples from 28 animals. Dogs were tested on 59 sets of unfamiliar samples.

Results

Performance varied among dogs (χ2 = 10.48, p = 0.02). Molokai's performance was above chance (0.73 ± 0.06, p = 0.0006), while Amy (0.44 ± 0.06, p = 0.43), Cheaps (0.53 ± 0.07, p = 0.79), and Runnels (0.56 ± 0.06, p = 0.43) did not respond correctly at a rate different from chance. Accuracy did not differ between nasal swabs (0.63 ± 0.08) and saliva swabs (0.53 ± 0.08, χ2 = 0.81, p = 0.37).

Discussion

The results of this study indicate that canine olfaction may be an effective means of detecting illness in beef cattle. However, individual dogs' aptitude for this detection task varies.

The landscape of allelic expression and DNA methylation at the bovine SGCE/PEG10 locus

Genomic imprinting is an epigenetic regulation in mammals in which a small subset of genes is monoallelically expressed dependent on their parental origin. A large imprinted domain, SGCE/PEG10 locus, is located on human chromosome 7q21s and mouse proximal chromosome 6. However, genomic imprinting of bovine SGCE/PEG10 cluster has not been systematically studied. In this study, we investigated allele expression of 14 genes of the SGCE/PEG10 locus in bovine somatic tissues and term placenta using a single nucleotide polymorphism (SNP)-based sequencing method. In addition to SGCE and PEG10, two conserved paternally expressed genes in human and mice, five other genes (TFPI2, GNG11, ASB4, PON1, and PON3) were paternally expressed. Three genes, BET1, COL1A2, and CASD1, exhibited tissue-specific monoallelic expression. CALCR showed monoallelic expression in tissues but biallelic expression in the placenta. Three genes, GNGT1, PPP1R9A, and PON2, showed biallelic expression in cattle. Five differentially methylated regions (DMRs) were found to be associated with the allelic expression of TFPI2, COL1A2, SGCE/PEG10, PON3, and ASB4 genes, respectively. The SGCE/PEG10 DMR is a maternally hypermethylated germline DMR, but TFPI2, COL1A2, PON3, and ASB4 DMRs are secondary DMRs. In summary, we identified five novel bovine imprinted genes (GNG11, BET1, COL1A2, CASD1, and PON1) and four secondary DMRs at the SGCE/PEG10 locus.

Pleomorphic adenoma gene (PLAG1) in reproduction and implication for embryonic survival in cattle: A review

The pleomorphic adenoma gene (PLAG1) encodes a DNA-binding, C2H2 zinc finger protein which acts as a transcription factor that regulates the expression of diverse genes across different organs and tissues; hence, the name pleomorphic. Rearrangements of the PLAG1 gene, and/or overexpression, are associated with benign tumors and cancers in a variety of tissues. This is best described for pleomorphic adenoma of the salivary glands in humans. The most notable expression of PLAG1 occurs during embryonic and fetal development, with lesser expression after birth. Evidence has accumulated of a role for PLAG1 protein in normal early embryonic development and placentation in mammals. PLAG1 protein influences the expression of the IGF2 gene and production of IGF2 protein. IGF2 is an important mitogen in ovarian follicles/oocytes, embryos, and fetuses. The PLAG1-IGF2 axis, therefore, provides one pathway whereby PLAG1 protein can influence embryonic survival and pregnancy. PLAG1 also influences over 1,000 other genes in embryos including those associated with ribosomal assembly and proteins. Brahman (Bos indicus) heifers homozygous for the PLAG1 variant, rs109815800 (G>T), show greater fertility than contemporary heifers with either one, or no copy, of the variant. Greater fertility in heifers homozygous for rs109815800 could be the result of early puberty and/or greater embryonic survival. The present review first looks at the broader roles of the PLAG1 gene and PLAG1 protein and then focuses on the emerging role of PLAG1/PLAG1 in embryonic development and pregnancy. A deeper understanding of factors which influence embryonic development is required for the next transformational increase in embryonic survival and successful pregnancy for both in vivo and in vitro derived embryos in cattle.

Comparison of Machine Learning Tree-Based Algorithms to Predict Future Paratuberculosis ELISA Results Using Repeat Milk Tests

Machine learning algorithms have been applied to various animal husbandry and veterinary-related problems; however, its use in Johne's disease diagnosis and control is still in its infancy. The following proof-of-concept study explores the application of tree-based (decision trees and random forest) algorithms to analyze repeat milk testing data from 1197 Canadian dairy cows and the algorithms' ability to predict future Johne's test results. The random forest models using milk component testing results alongside past Johne's results demonstrated a good predictive performance for a future Johne's ELISA result with a dichotomous outcome (positive vs. negative). The final random forest model yielded a kappa of 0.626, a roc AUC of 0.915, a sensitivity of 72%, and a specificity of 98%. The positive predictive and negative predictive values were 0.81 and 0.97, respectively. The decision tree models provided an interpretable alternative to the random forest algorithms with a slight decrease in model sensitivity. The results of this research suggest a promising avenue for future targeted Johne's testing schemes. Further research is needed to validate these techniques in real-world settings and explore their incorporation in prevention and control programs.

Movements after Captive Bolt Stunning in Cattle and Possible Animal- and Process-Related Impact Factors-A Field Study

Movements in cattle after captive bolt stunning cause problems in the slaughter process and lead to uncertainties in assessing stunning effectiveness. The objective of this study was to categorize and quantify these movements and determine animal- and process-related impact factors, as well as connections to stunning effectiveness and shooting position. In total 2911 cows, heifers, and bulls (dairy, beef, and crossbreeds) were examined (mean age 3.02 years). Movements from landing until at least four minutes after sticking were recorded by action cams (Apeman® A100). Nine movement categories were defined ("kicking hind limb", "twitching", "bending and stretching hind limb", "lifting and bending forelimb", "body arching laterally", "body arching ventrally", and "arching backwards"). According to the movement severity, a score was assigned to each category. The scores were summed, either for certain process intervals, e.g., LANDING (ejection from the stunning box), HOISTING, or STICKING, or for the total time between LANDING and end of the FOURTH MINUTE OF BLEEDING (sum score). Statistical analysis (ANOVA) was performed on the scores. Only 6.6% of cattle showed no movement. Most movements occurred during STICKING and FIRST MINUTE OF BLEEDING, occurring rarely up to 8 min after sticking. While cows moved most at LANDING, bulls and heifers moved more if all process intervals were considered. The sum score was highest in German Angus, Charolais, and Limousin and lowest in Brown Swiss and Simmental. The score at LANDING was highest in German Angus and Black Holstein. The use of pneumatic stunners and an increase in bolt-exit length significantly reduced movements. No impact of stunning effectiveness on movements was found, but only 19 cattle showed reduced effectiveness.

Whole-genome sequencing-based antimicrobial resistance and shedding dynamics of Escherichia coli isolated from calves before and after antimicrobial group treatments

The fattening of calves is often associated with high antimicrobial use and the selection of antimicrobial resistance (AMR). The objective of this observational longitudinal study was to describe the AMR and strain dynamics, using whole-genome sequencing (WGS), of fecal Escherichia coli in a cohort of 22 calves. All calves received antimicrobial group treatments on Day (D) 1 (oxytetracycline, intramuscularly) and on D4 through D12 (doxycycline, in-feed). Additionally, eight calves received individual parenteral treatments between D7 and D59, including florfenicol, amoxicillin, marbofloxacin, and gamithromycin. Rectal swabs were collected from all calves on D1 (prior to treatment), D2, D9, and D82. The swabs were spread onto Enterobacterales-selective agar, and three E. coli colonies per plate were subjected to WGS. Out of 264 isolates across all calves and sampling times, 80 unique strains were identified, a majority of which harbored genes conferring resistance to tetracyclines, streptomycin, and sulfonamides. The diversity of strains decreased during the in-feed antimicrobial group treatment of the calves. On D82, 90% of isolates were strains that were not isolated at previous sampling times, and the median number per strain of AMR determinants to tetracyclines, florfenicol, β-lactams, quinolones, or macrolides decreased compared to D9. Additionally, clonal dissemination of some strains represented the main transmission route of AMR determinants. In this study, WGS revealed important variations in strain diversity and genotypic AMR of fecal E. coli over time in calves subjected to group antimicrobial treatments.

IMPORTANCE

The continued emergence and spread of antimicrobial resistance (AMR) determinants are serious global concerns. The dynamics of AMR spread and persistence in bacterial and animal host populations are complex and not solely driven by antimicrobial selection pressure. In calf fattening, both antimicrobial use and carriage prevalence of antimicrobial-resistant bacteria are generally recognized as high. This study provides new insights into the short-term, within-farm dynamics and transmission of AMR determinants in Escherichia coli from the dominant fecal flora of calves subjected to antimicrobial group treatments during the rearing period. The diversity of E. coli strains decreased over time, although, in contrast to previous observations in extended-spectrum β-lactamase-producing Enterobacterales, the predominance of a few clones was not observed. The spread of AMR determinants occurred through the dissemination of clonal strains among calves. The median number per strain of AMR determinants conferring resistance to selected antimicrobials decreased toward the end of the rearing period.

Comparison of serum very low-density lipoprotein concentrations during transition in primiparous and multiparous cows

This study was carried out as an observational study in order to examine the difference of change in serum very low-density lipoprotein (VLDL) between primiparous and multiparous cows. Twenty-one clinically healthy cows (10 primiparous and 11 multiparous) were selected at 21 days prior to expected calving. Blood samples were collected in the morning (before feeding) on days -21, -7, 7, 21 and 56 days in milk (DIM). At 7 and 21 DIM, the serum non-esterified fatty acid concentration of multiparous cows was significantly higher than that of primiparous cows. The serum β-hydroxybutyrate concentration was also markedly higher in multiparous cows than in primiparous cows at 21 DIM. These results suggested that the degree of negative energy balance was greater in multiparous cows than in primiparous cows during this period. In both, serum VLDL concentrations decreased at over 7 DIM, increased at 21 DIM, and then decreased at 56 DIM. On the other hand, triglyceride and total protein concentrations of VLDL in multiparous cows were significantly lower than in primiparous cows at 21 DIM. This suggests that multiparous cows have poor triglyceride secretion from the liver and that they become more susceptible to hepatic lipidosis.

Cow key point detection in indoor housing conditions with a deep learning model

Lameness in dairy cattle is a costly and highly prevalent problem that affects all aspects of sustainable dairy production, including animal welfare. Automation of gait assessment would allow monitoring of locomotion in which the cows' walking patterns can be evaluated frequently and with limited labor. With the right interpretation algorithms, this could result in more timely detection of locomotion problems. This in turn would facilitate timely intervention and early treatment, which is crucial to reduce the effect of abnormal behavior and pain on animal welfare. Gait features of dairy cows can potentially be derived from key points that locate crucial anatomical points on a cow's body. The aim of this study is 2-fold: (1) to demonstrate automation of the detection of dairy cows' key points in a practical indoor setting with natural occlusions from gates and races, and (2) to propose the necessary steps to postprocess these key points to make them suitable for subsequent gait feature calculations. Both the automated detection of key points as well as the postprocessing of them are crucial prerequisites for camera-based automated locomotion monitoring in a real farm environment. Side-view video footage of 34 Holstein-Friesian dairy cows, captured when exiting the milking parlor, were used for model development. From these videos, 758 samples of 2 successive frames were extracted. A previously developed deep learning model called T-LEAP was trained to detect 17 key points on cows in our indoor farm environment with natural occlusions. To this end, the dataset of 758 samples was randomly split into a train (n = 22 cows; no. of samples = 388), validation (n = 7 cows; no. of samples = 108), and test dataset (n = 15 cows; no. of samples = 262). The performance of T-LEAP to automatically assign key points in our indoor situation was assessed using the average percentage of correctly detected key points using a threshold of 0.2 of the head length (PCKh0.2). The model's performance on the test set achieved a good result with PCKh0.2: 89% on all 17 key points together. Detecting key points on the back (n = 3 key points) of the cow had the poorest performance PCKh0.2: 59%. In addition to the indoor performance of the model, a more detailed study of the detection performance was conducted to formulate postprocessing steps necessary to use these key points for gait feature calculations and subsequent automated locomotion monitoring. This detailed study included the evaluation of the detection performance in multiple directions. This study revealed that the performance of the key points on a cows' back were the poorest in the horizontal direction. Based on this more in-depth study, we recommend the implementation of the outlined postprocessing techniques to address the following issues: (1) correcting camera distortion, (2) rectifying erroneous key point detection, and (3) establishing the necessary procedures for translating hoof key points into gait features.

Gas exchange, rumen hydrogen sinks, and nutrient digestibility and metabolism in lactating dairy cows fed 3-nitrooxypropanol and cracked rapeseed

Fat in the form of cracked rapeseed and 3-nitrooxypropanol (3-NOP, market as Bovaer) were fed alone or in combination to 4 Danish Holstein multicannulated dairy cows, with the objective to investigate effects on gas exchange, dry matter intake (DMI), nutrient digestion, and nutrient metabolism. The study design was a 4 × 4 Latin square with a 2 × 2 factorial treatment arrangement with 2 levels of fat supplementation; 33 g of crude fat per kg of dry matter (DM) or 64 g of crude fat per kg of DM for low and high fat diets, respectively, and 2 levels of 3-NOP; 0 mg/kg DM or 80 mg/kg DM. In total, 4 diets were formulated: low fat (LF), high fat (HF), 3-NOP and low fat (3LF), and 3-NOP and high fat (3HF). Cows were fed ad libitum and milked twice daily. The adaptation period lasted 11 d, followed by 5 d with 12 diurnal sampling times of digesta and ruminal fluid. Thereafter, gas exchange was measured for 5 d in respiration chambers. Chromic oxide and titanium dioxide were used as external flow markers to determine intestinal nutrient flow. No interactions between fat supplementation and 3-NOP were observed for methane yield (g/kg DM), total-tract digestibility of nutrients or total volatile fatty acid (VFA) concentration in the rumen. Methane yield (g/kg DMI) was decreased by 24% when cows were fed 3-NOP. In addition, 3-NOP increased carbon dioxide and hydrogen yield (g/kg DM) by 6% and 3,500%, respectively. However, carbon dioxide production was decreased when expressed on a daily basis. Fat supplementation did not affect methane yield but tended to reduce methane in percent of gross energy intake. A decrease (11%) in DMI was observed, when cows were fed 3-NOP. Likely, the lower DMI mediated a lower passage rate causing the tendency to higher rumen and total-tract neutral detergent fiber digestibility, when the cows were fed 3-NOP. Total VFA concentrations in the rumen were negatively affected both by 3-NOP and fat supplementation. Furthermore, 3-NOP caused a shift in the VFA fermentation profile, with decreased acetate proportion and increased butyrate proportion, whereas propionate proportion was unaffected. Increased concentrations of the alcohols methanol, ethanol, propanol, butanol, and 2-butanol were observed in the ruminal fluid when cows were fed 3-NOP. These changes in rumen metabolites indicate partial re-direction of hydrogen into other hydrogen sinks, when methanogenesis is inhibited by 3-NOP. In conclusion, fat supplementation did not reduce methane yield, whereas 3-NOP reduced methane yield, irrespective of fat level. However, the concentration of 3-NOP and diet composition and resulting desired mitigation effect must be considered before implementation. The observed reduction in DMI with 80 mg 3-NOP/kg DM was intriguing and may indicate that a lower dose should be applied in a Northern European context; however, the mechanism behind needs further investigation.

Development and validation of a fully automated 2-dimensional imaging system generating body condition scores for dairy cows using machine learning

Monitoring body condition score (BCS) is a useful management tool to estimate the energy reserves of an individual cow or a group of cows. The aim of this study was to develop and evaluate the performance of a fully automated 2-dimensional imaging system using a machine learning algorithm to generate real-time BCS for dairy cows. Two separate datasets were used for training and testing. The training dataset included 34,150 manual BCS (MAN_BCS) assigned by 5 experienced veterinarians during 35 visits at 7 dairy farms. Ordinal regression methods and deep learning architecture were used when developing the algorithm. Subsequently, the testing dataset was used to evaluate the developed BCS prediction algorithm on 4 of the participating farms. An experienced human assessor (HA1) visited these farms and performed 8 whole-milking-herd BCS sessions. Each farm was visited twice, allowing for 30 d (±2 d) to pass between visits. The MAN_BCS assigned by HA1 were considered the ground truth data. At the end of the validation study, MAN_BCS were merged with the stored automated BCS (AI_BCS), resulting in a testing dataset of 9,657 single BCS. A total of 3,817 cows in the testing dataset were scored twice 30 d (±2 d) apart, and the change in their BCS (ΔBCS) was calculated. A subset of cows at one farm were scored twice on consecutive days to evaluate the within-observer agreement of both the human assessor and the system. The manual BCS of 2 more assessors (HA2 and HA3) were used to assess the interobserver agreement between humans. Finally, we also collected ultrasound measurements of backfat thickness (BFT) from 111 randomly selected cows with available MAN_BCS and AI_BCS. Using the testing dataset, intra- and interobserver agreement for single BCS and ΔBCS were estimated by calculating the simple percentage agreement (PA) at 3 error levels and the weighted kappa (κw) for the exact agreement. A Bland-Altman plot was constructed to visualize the systematic and proportional bias. The association between MAN_BCS and AI_BCS and the BFT was assessed with Passing-Bablok regressions. The system had an almost perfect repeatability with a κw of 0.99. The agreement between MAN_BCS and AI_BCS was substantial, with an overall κw of 0.69. The overall PA at the exact, ± 0.25-unit, and ± 0.50-unit BCS error range between MAN_BCS and AI_BCS was 44.4%, 84.6%, and 94.8%, respectively, and greater than the PA obtained between HA1 and HA3. The Bland-Altman plot revealed a minimal systematic bias of -0.09 with a proportional bias at the extreme scores. Furthermore, despite the low κw of 0.20, the overall PA at the exact and ± 0.25-unit of BCS error range between MAN_BCS and AI_BCS regarding the ΔBCS was 45.7 and 88.2%, respectively. A strong linear relationship was observed between BFT and AI_BCS (ρ = 0.75), although weaker than that between BFT and MAN_BCS (ρ = 0.91). The system was able to predict single BCS and ΔBCS with satisfactory accuracy, comparable to that obtained between trained human scorers.

Comparative Metabolomic Profiling of L-Histidine and NEFA Treatments in Bovine Mammary Epithelial Cells

Non-esterified fatty acids (NEFAs) are pivotal in energy metabolism, yet high concentrations can lead to ketosis, a common metabolic disorder in cattle. Our laboratory observed lower levels of L-histidine in cattle suffering from ketosis, indicating a potential interaction between L-histidine and NEFA metabolism. This relationship prompted us to investigate the metabolomic alterations in bovine mammary epithelial cells (BMECs) induced by elevated NEFA levels and to explore L-histidine's potential mitigating effects. Our untargeted metabolomic analysis revealed 893 and 160 metabolite changes in positive and negative models, respectively, with VIP scores greater than 1 and p-values below 0.05. Notable metabolites like 9,10-epoxy-12-octadecenoic acid were upregulated, while 9-Ethylguanine was downregulated. A pathway analysis suggested disruptions in fatty acid and steroid biosynthesis pathways. Furthermore, L-histidine treatment altered 61 metabolites in the positive model and 34 in the negative model, with implications for similar pathways affected by NEFA. Overlaying differential metabolites from both conditions uncovered a potential key mediator, 1-Linoleoylglycerophosphocholine, which was regulated in opposite directions by NEFA and L-histidine. Our study uncovered that both NEFA L- and histidine metabolomics analyses pinpoint similar lipid biosynthesis pathways, with 1-Linoleoylglycerophosphocholine emerging as a potential key metabolite mediating their interaction, a discovery that may offer insights for therapeutic strategies in metabolic diseases.

Susceptibility, Immunity, and Persistent Infection Drive Endemic Cycles of Coxiellosis on Dairy Farms

Coxiella (C.) burnetii, a zoonotic bacterium, is prevalent in dairy farms. Some cows develop a persistent infection and shed C. burnetii into milk and occasionally by amniotic fluid at calving. Serological diagnosis of Q fever in humans is performed by phase (Ph)-specific antibody tests; PhII antibodies usually indicate an acute infection, while the development of a chronic infection is characterised by elevated PhI antibody titres. Phase-specific tests have now been established for diagnosis of coxiellosis in cattle. Additionally, an interferon-γ (IFN-γ) recall assay has been implemented to assess cellular immunity to C. burnetii in cattle. Milk samples from all lactating cows (n = 2718) of 49 Bavarian dairy farms were collected through a convenience sample and analysed for phase-specific antibodies. Antibody profiles were evaluated by age. Based on the seropositivity of first-lactation cows, three distinct herd profiles were observed: an 'acute' state of herd infection was characterised by a PhI-/PhII+ pattern. The detection of PhI antibodies (PhI+/PhII+) characterised the 'chronic' state, and seronegative results defined the 'silent' state of herd infection. If antibodies had not been detected in multiparous cows, the herd was considered as probably free of coxiellosis. The analysed cattle herds were noted to have an 'acute' (n = 12, 24.5%), 'chronic' (n = 18, 36.8%), or 'silent' state of herd infection (n = 16, 32.6%). Only three farms (6.1%) were classified as 'free' of C. burnetii. The detection of these herd states over a time period of 4 years in one farm indicated that the described states occur in a cyclical manner. Frequently, a wave-like profile was seen, i.e., a circumscribed seronegative age group was flanked by seropositive age groups. In seronegative animals, IFN-γ reactivity was demonstrated. Seroconversion after vaccination was observed by day 7 post-vaccination in chronically infected herds, whereas in the case of silent infection, it started by day 14. These data indicated a pre-existing immunity in seronegative animals in chronically infected herds. Additionally, IFN-γ reactivity was detected in seronegative calves (>3 months) and heifers from chronically infected farms compared to a negative farm. An infection prior to 3 months of age resulted in cellular immunity in the absence of detectable antibodies. An infection around calving would explain this. The aforementioned circumscribed seronegative age groups are, therefore, explained by an infection early in life during active shedding at calving. Based on these results, an endemic cycle of coxiellosis is proposed: Susceptible young heifers get infected by persistently infected cows. Subsequently, shedding of C. burnetii at calving results in infection and then in cellular immunity in offspring. When these calves enter the cow herd two years later, a maximum of herd immunity is achieved, shedding ceases, and new susceptible animals are raised. In an acutely infected dairy farm, the PhI+/PhII+ serological pattern prevailed in second-lactation cows. In this study, stored sera collected since birth were analysed retrospectively. From the earliest seroconversion, the peak of seroconversion took about 33 months. These data suggested a slow spread of infection within herds. The classification of dairy cow herds is a promising basis for further analysis of the clinical impact of coxiellosis.

Propaedeutic and Therapeutic Practices Used for Retained Fetal Membranes by Rural European Veterinary Practitioners

The present study aimed to monitor the practices of European veterinarians for the diagnosis and treatment of retained fetal membranes in cattle. A questionnaire was established and distributed to veterinarians from five European countries. A total of 700 veterinarians participated in the survey. A vaginal examination, general examination and uterine palpation are carried out by 71%, 38% and 23% of veterinarians, respectively. Moreover, half of the veterinarians attempt to remove the placenta manually, 70% of them administer a combined local and general treatment if the cow has a fever (more than 39.5 °C), and 50% of them only administer IU treatment if no fever is observed. Tetracyclins, cefapirin and penicillins are the most used intrauterine (IU) antibiotics, whereas penicillin is the most used parenteral one. All other European veterinarians were less likely to use cefapirin and more likely to use oxytocin, Ca perfusion and NSAID than French and Walloon veterinarians. In conclusion, our study confirms the necessity of improving and rationalizing the diagnostic and therapeutic approach of the RFM, mainly to reduce the important problem of antibiotic resistance.

Effect of Addition of a Mixture of Ethyl Esters of Polyunsaturated Fatty Acid of Linseed Oil to Liquid Feed on Performance and Health of Dairy Calves

This study aimed to determine the effect of supplementing liquid feeds with a mixture of ethyl esters of polyunsaturated fatty acid of linseed oil (EEPUFA; α-linolenic acid-64.5%, linoleic acid-16.1%, and oleic acid-19.4%) on feed intake, body weight gain, feed efficiency, and health of dairy calves. Thirty-six healthy female Holstein-Friesian calves (7 d of age, 41.2 ± 4.0 kg) were assigned to one of two treatment groups (18 calves per group), i.e., control or EEPUFA, and fed liquid feed (whole milk (WM) or milk replacer (MR)) either without or with 10 mL/d of EEPUFA supplementation, respectively, for 56 days (till 63 d of age). Average daily intake of WM and MR was similar between treatments (p = 0.94). Average daily total DM intake and average daily starter feed DM intake were higher for the EEPUFA group (p = 0.05 and p = 0.01, respectively). The average daily body weight gain was also higher for the EEPUFA group (55 g/d; p = 0.03), although final body weight turned out not to be significantly different between groups (75.6 kg vs. 79.0 kg, control vs. EEPUFA, respectively; p = 0.20). Supplementation of liquid feeds with EEPUFA did not affect feed efficiency (p = 0.37) and most of investigated health parameters. However, the percentage of days with diarrhea relative to the number of days receiving treatment was higher in the control group than the EEPUFA group (76 vs. 42, respectively; p = 0.04). Although the results of this preliminary study are promising, further research is needed to establish the dose effect of EEPUFA on the performance and health of calves.

Diagnosis of fasciolosis antibodies in Brazilian cattle through ELISA employing both native and recombinant antigens

Bovine fasciolosis is a parasitic disease with a global reach. Coprological based on egg detection in fecal samples and liver inspection to evaluate the presence of the parasite is currently the gold standard for diagnosing chronic fasciolosis in cattle. However, these techniques are labor-intensive and ineffective during the acute phase of the disease. Serodiagnosis using native and recombinant antigens has become an interesting alternative in efforts to identify cattle fasciolosis. We evaluated cattle from abattoir (n = 139) and farms (n = 500) through liver inspection and coprological examination, respectively. Our laboratory team optimized and validated enzyme-linked immunosorbent assay tests based on somatic antigen, excretory/secretory proteins, and the recombinant antigen cathepsin L-1 to detect serum antibodies against fasciolosis in cattle. For animals from abattoir, 10 were positive for fasciolosis according to liver inspection. Both FhES and FhrCL-1 presented an area under the receiver operating characteristic (AUROC) curve of 0.80, with a sensitivity of 0.80 (95% CI: 0.46-0.95) and 0.70 (95% CI: 0.38-0.90) and specificity of 0.81 (95% CI: 0.73-0.87) and 0.87 (95% CI: 0.80-0.92), respectively. For those cattle from farms, 28 were positive only for fasciolosis according to coprological examination. In this scenario, FhES gave the best performance, with an AUROC of 0.84, sensitivity of 0.79 (95% CI: 0.60-0.90), and specificity of 0.86 (95% CI: 0.82-0.89). In conclusion, our study highlights the potential of serodiagnosis for accurately screening cattle fasciolosis. The promising sensitivity and specificity values of FhES when compared to liver inspection or coprological examination enhance its importance for cattle fasciolosis diagnosis.

IMPORTANCE

The aim of this article was to identify antibodies against fasciolosis in cattle in Brazil. The methodology was reproduced in our laboratory and applied for the first time to the Brazilian cattle herd. The antigens tested can be used as a screening test and thus speed up the diagnosis of bovine fascioliasis.

Influence of BOVAMINE DEFEND Plus on growth performance, carcass characteristics, estimated dry matter digestibility, rumen fermentation characteristics, and immune function in finishing beef steers

One hundred and eighty crossbred beef steers (406.0 ± 2.2 kg) were used to determine the impact of a novel direct-fed microbial (DFM) on growth performance, carcass characteristics, rumen fermentation characteristics, and immune response in finishing beef cattle. Steers were blocked by body weight (BW) and randomly assigned, within block, to 1 of 2 treatments (3 replicates/treatment: 30 steers/replicate). Treatments included: (1) no DFM (control) and (2) DFM supplementation at 50 mg ∙ animal-1 ∙ d-1 (BOVAMINE DEFEND Plus). All steers were fed a high-concentrate finishing diet and individual feed intake was recorded daily via the GrowSafe system. BWs were collected every 28 d. On day 55, 10 steers per pen were injected with ovalbumin (OVA). Jugular blood samples were collected from each steer on days 0, 7, 14, and 21 post injection. On day 112, the same steers were injected again with OVA and intramuscularly with a pig red blood cell solution. Jugular blood samples were collected from each steer on days 0, 7, 14, and 21 post injection. On day 124, rumen fluid was collected from 3 steers per treatment and used to estimate in vitro rumen fermentation characteristics. Equal numbers of steers per treatment were transported to a commercial abattoir on days 145, 167, and 185 of the experiment, harvested, and carcass data were collected. Initial BW was similar across treatments. On days 28 and 55, steers receiving DFM had heavier BW (P < 0.01) compared to controls. The average daily gain was greater in DFM-supplemented steers from days 0 to 28 (P < 0.01) and days 0 to 55 (P < 0.01) of the experiment compared to controls. Overall dry matter intake (DMI) was greater (P < 0.04) and overall feed efficiency was similar in DFM-supplemented steers compared to controls. Dressing percentage (P < 0.02) was greater in steers receiving DFM compared to controls. Antibody titers to injected antigens were similar across treatments. However, red blood cell superoxide dismutase activity was greater (P < 0.05) in DFM-supplemented steers compared to controls. In vitro molar proportions of isobutyric and butyric acid were greater (P < 0.01) and dry matter (DM) digestibility tended (P < 0.07) to be greater in rumen fluid obtained from steers supplemented with DFM. These data suggest that BOVAMINE DEFEND Plus supplementation improves growth performance during the initial period of the finishing phase, increases overall DMI and dressing percentage, and may impact antioxidant status in beef cattle.

Profile of uterine flush lipid mediators in cows with subclinical endometritis: pilot study

Subclinical endometritis affects reproductive outcomes and causes economic losses in dairy cows, thus, it is important to understand disease progression mechanisms and develop diagnostic procedures for better disease management. We measured the levels of 146 lipid mediators in uterine flush samples using lipid chromatography-mass spectrometry. We detected 25 lipid mediators in the uterine flush of both the control and subclinical endometritis cows; 15 of the 25 lipid mediators were AA-derived metabolites. Among the AA-derived metabolites, cyclooxygenase (COX)-generated mediators were the most abundant. Specifically, levels of 11β-13,14-dihydro-15-keto prostaglandin (PG)F2α, PGE2, PGA2, 13-hydroxyoctadecadienoic acid, and PGD1 were elevated in all the cows with subclinical endometritis. This study may provide new insights for the management of subclinical bovine endometritis.

Evaluation of the Antimicrobial, Cytotoxic, and Physical Properties of Selected Nano-Complexes in Bovine Udder Inflammatory Pathogen Control

Purpose

Mastitis in dairy cows is a worldwide problem faced by dairy producers. Treatment mainly involves antibiotic therapy, however, due to widespread antibiotic resistance among bacteria, such treatments are no longer effective. For this reason, scientists are searching for new solutions to combat mastitis, which is caused by bacteria, fungi, and algae. One of the most promising solutions, nanotechnology, is attracting research due to its biocidal properties. The purpose of this research was to determine the biocidal properties of nanocomposites as a potential alternative to antibiotics in the control of mastitis, as well as to determine whether the use of nanoparticles and what concentration is safe for the breeder and the animal.

Patients and Methods

In this study, the effects of Ag, Au, Cu, Fe, and Pt nanoparticles and their complexes were evaluated in relation to the survival of bacteria and fungi isolated from cattle diagnosed with mastitis, their physicochemical properties, and their toxicity to bovine and human mammary epithelial cells BME-UV1 and HMEC (human microvascular endothelial cells). Moreover, E. coli, S. aureus, C. albicans, and Prototheca sp. invasion was assessed using the alginate bead (bioprinted) model. The NPs were tested at concentrations of 25, 12.5, 6.25, 3.125, 1.56 mg/l for Au, Ag, Cu and Fe NPs, and 10, 5, 2.5, 1.25, 0.625 mg/l for Pt.

Results

With the exception of Fe and Pt, all exhibited biocidal properties against isolates, while the AgCu complex had the best effect. In addition, nanoparticles showed synergistic effects, while the low concentrations had no toxic effect on BME-UV1 and HMEC cells.

Conclusion

Synergistic effects of nanoparticles and no toxicity to bovine and human cells might, in the future, be an effective alternative in the fight against microorganisms responsible for mastitis, and the implementation of research results in practice would reduce the percentage of dairy cows suffering from mastitis. The problem of increasing antibiotic resistance is posing a global threat to human's and animal's health, and requires comprehensive research to evaluate the potential use of nanoparticles - especially their complexes - as well as to determine whether nanoparticles are safe for the breeders and the animals. The conducted series of studies allows further consideration of the use of the obtained results in practice, creating a potentially new alternative to antibiotics in the treatment and prevention of mastitis in dairy cattle.

Genomic epidemiology of third-generation cephalosporin-resistant Escherichia coli from Argentinian pig and dairy farms reveals animal-specific patterns of co-resistance and resistance mechanisms

Control measures are being introduced globally to reduce the prevalence of antibiotic resistance (ABR) in bacteria on farms. However, little is known about the current prevalence and molecular ecology of ABR in bacterial species with the potential to be key opportunistic human pathogens, such as Escherichia coli, on South American farms. Working with 30 dairy cattle farms and 40 pig farms across two provinces in central-eastern Argentina, we report a comprehensive genomic analysis of third-generation cephalosporin-resistant (3GC-R) E. coli, which were recovered from 34.8% (cattle) and 47.8% (pigs) of samples from fecally contaminated sites. Phylogenetic analysis revealed substantial diversity suggestive of long-term horizontal and vertical transmission of 3GC-R mechanisms. CTX-M-15 and CTX-M-2 were more often produced by isolates from dairy farms, while CTX-M-8 and CMY-2 and co-carriage of amoxicillin/clavulanate resistance and florfenicol resistance were more common in isolates from pig farms. This suggests different selective pressures for antibiotic use in these two animal types. We identified the β-lactamase gene blaROB, which has previously only been reported in the family Pasteurellaceae, in 3GC-R E. coli. blaROB was found alongside a novel florfenicol resistance gene, ydhC, also mobilized from a pig pathogen as part of a new composite transposon. As the first comprehensive genomic survey of 3GC-R E. coli in Argentina, these data set a baseline from which to measure the effects of interventions aimed at reducing on-farm ABR and provide an opportunity to investigate the zoonotic transmission of resistant bacteria in this region.

IMPORTANCE

Little is known about the ecology of critically important antibiotic resistance among bacteria with the potential to be opportunistic human pathogens (e.g., Escherichia coli) on South American farms. By studying 70 pig and dairy cattle farms in central-eastern Argentina, we identified that third-generation cephalosporin resistance (3GC-R) in E. coli was mediated by mechanisms seen more often in certain species and that 3GC-R pig E. coli were more likely to be co-resistant to florfenicol and amoxicillin/clavulanate. This suggests that on-farm antibiotic usage is key to selecting the types of E. coli present on these farms. 3GC-R E. coli and 3GC-R plasmids were diverse, suggestive of long-term circulation in this region. We identified the de novo mobilization of the resistance gene blaROB from pig pathogens into E. coli on a novel mobile genetic element, which shows the importance of surveying poorly studied regions for antibiotic resistance that might impact human health.

Signatures of positive selection after the introduction of genomic selection in the Finnish Ayrshire population

The Finnish Ayrshire (FAY) belongs to the Nordic Red breeds and is characterized by high milk yield, high milk components, good fertility, and functional conformation. The FAY breeding program is based on genomic selection. Despite the benefits of selection on breeding values, autozygosity in the genome may increase due to selection, and increased autozygosity may cause inbreeding depression in selected traits. However, there is lack of studies concerning selection signatures in the FAY after genomic selection introduction. The aim of this study was to identify signatures of selection in FAY after the introduction of genomic selection. Genomic data included 45,834 SNPs. The genotyped animals were divided into 2 groups: animals born before genomic selection introduction (6,108 cows) and animals born after genomic selection introduction (47,361 cows). We identified the selection signatures using 3 complementary methods: 2 based on identification of selection signatures from runs of homozygosity (ROH) islands and one based on the decay of site-specific extended haplotype between populations at SNP sites (Rsb). In total, we identified 34 ROH islands on chromosomes 1, 3, 6, 8, 12-15, 17, 19, 22, and 26 in FAY animals born before genomic selection (between 1980 and 2011) and 30 ROH islands on chromosomes 1-3, 13-17, 22, and 25-26 in FAY animals born after genomic selection introduction (between 2015 and 2020). We additionally detected 22 ΔROH islands on chromosomes 2-3, 11, 13, 14, 16, 18, 20, and 25-26. Finally, a total of 31 Rsb regions on chromosomes 2, 3, 14, 18, 20, and 25 were identified. Based on the results, genomic selection has favored certain alleles and haplotypes on genomic regions related to traits relevant in the FAY breeding program: milk production, fertility, growth, beef production traits, and feed efficiency. Several genes related to these traits, e.g., PLA2G4A, MECR, CHUK, COX15, RICTOR, SHISA9, and SEMA4G overlapped or partially overlapped the observed selection signature regions. The association of genotypes within these regions and their effects on traits relevant in the FAY breeding program should be studied and genetic regions undergoing selection monitored in the FAY population.

Evaluating the liver abscess microbiota of beef cattle during a reduction in tylosin supplementation shows differences according to abscess size and fraction

Liver abscesses (LA) resulting from bacterial infection in cattle pose a significant global challenge to the beef and dairy industries. Economic losses from liver discounts at slaughter and reduced animal performance drive the need for effective mitigation strategies. Tylosin phosphate supplementation is widely used to reduce LA occurrence, but concerns over antimicrobial overuse emphasize the urgency to explore alternative approaches. Understanding the microbial ecology of LA is crucial to this, and we hypothesized that a reduced timeframe of tylosin delivery would alter LA microbiomes. We conducted 16S rRNA sequencing to assess severe liver abscess bacteriomes in beef cattle supplemented with in-feed tylosin. Our findings revealed that shortening tylosin supplementation did not notably alter microbial communities. Additionally, our findings highlighted the significance of sample processing methods, showing differing communities in bulk purulent material and the capsule-adhered material. Fusobacterium or Bacteroides ASVs dominated LA, alongside probable opportunistic gut pathogens and other microbes. Moreover, we suggest that liver abscess size correlates with microbial community composition. These insights contribute to our understanding of factors impacting liver abscess microbial ecology and will be valuable in identifying antibiotic alternatives. They underscore the importance of exploring varied approaches to address LA while reducing reliance on in-feed antibiotics.

Genome assembly of antimicrobial-resistant Escherichia coli HMVC1 isolated from healthy Mogosane village cattle, South Africa

Here, we present the genome assembly of E. coli strain HMVC1 isolated from rectal fecal samples of healthy cattle in South Africa. The genome size of HMVC1 consisted of 5,043,843 bp, with G + C content of 50.5%. The strain harbors marA, mdtM, acrF, acrD, and other antimicrobial resistance genes.

VPBrowse: Genome-based representation of MS/MS spectra to quantify 10,000 bovine proteins

SWATH is a data acquisition strategy acclaimed for generating quantitatively accurate and consistent measurements of proteins across multiple samples. Its utility for proteomics studies in nonlaboratory animals, however, is currently compromised by the lack of sufficiently comprehensive and reliable public libraries, either experimental or predicted, and relevant platforms that support their sharing and utilization in an intuitive manner. Here we describe the development of the Veterinary Proteome Browser, VPBrowse (http://browser.proteo.cloud/), an on-line platform for genome-based representation of the Bos taurus proteome, which is equipped with an interactive database and tools for searching, visualization, and building quantitative mass spectrometry assays. In its current version (VPBrowse 1.0), it contains high-quality fragmentation spectra acquired on QToF instrument for over 36,000 proteotypic peptides, the experimental evidence for over 10,000 proteins. Data can be downloaded in different formats to enable analysis using popular software packages for SWATH data processing whilst normalization to iRT scale ensures compatibility with diverse chromatography systems. When applied to published blood plasma dataset from the biomarker discovery study, the resource supported label-free quantification of additional proteins not reported by the authors previously including PSMA4, a tissue leakage protein and a promising candidate biomarker of animal's response to dehorning-related injury.

Genetic diversity and recombination of bovine enterovirus strains in China

Bovine enterovirus (BEV) consisting of enterovirus species E (EV-E) and F (EV-F) is the causative agent associated with respiratory and gastrointestinal diseases in cattle. Here, we reported the characterization, genetic diversity, and recombination of novel BEV strains isolated from the major cattle-raising regions in China during 2012-2018. Twenty-seven BEV strains were successfully isolated and characterized. Molecular characterization demonstrated that the majority of these novel BEV strains (24/27) were EV-E, while only few strains (3/27) were EV-F. Sequence analysis revealed the diversity of the circulating BEV strains such as species and subtypes where different species or subtype coinfections were detected in the same regions and even in the same cattle herds. For the EV-E, two novel subtypes, designated as EV-E6 and EV-E7, were revealed in addition to the currently reported EV-E1-EV-E5. Comparative genomic analysis revealed the intraspecies and interspecies genetic exchanges among BEV isolates. The representative strain HeN-B62 was probably from AN12 (EV-F7) and PS-87-Belfast (EV-F3) strains. The interspecies recombination between EV-E and EV-F was also discovered, where the EV-F7-AN12 might be from EV-E5 and EV-F1, and EV-E5-MexKSU/5 may be recombined from EV-F7 and EV-E1. The aforementioned results revealed the genetic diversity and recombination of novel BEV strains and unveiled the different BEV species or subtype infections in the same cattle herd, which will broaden the understanding of enterovirus genetic diversity, recombination, pathogenesis, and prevention of disease outbreaks.

IMPORTANCE

Bovine enterovirus (BEV) infection is an emerging disease in China that is characterized by digestive, respiratory, and reproductive disorders. In this study, we first reported two novel EV-E subtypes detected in cattle herds in China, unveiled the coinfection of two enterovirus species (EV-E/EV-F) and different subtypes (EV-E2/EV-E7, EV-E1/EV-E7, and EV-E3/EV-E6) in the same cattle herds, and revealed the enterovirus genetic exchange in intraspecies and interspecies recombination. These results provide an important update of enterovirus prevalence and epidemiological aspects and contribute to a better understanding of enterovirus genetic diversity, evolution, and pathogenesis.

Enhancing bovine abortion surveillance: A learning experience

Abortions and perinatal mortalities (APM) substantially affect cattle industry efficiency. Various infectious and noninfectious factors have been associated with bovine APM worldwide. Infections are often considered pivotal due to their abortifacient potential, leading laboratories to primarily investigate relevant infectious agents for APM cases. Some infectious causes, such as Brucella abortus, have also a zoonotic impact, necessitating monitoring for both animal and human health. However, underreporting of bovine APM is a global issue, affecting early detection of infectious and zoonotic causes. Previous studies identified factors influencing case submission, but regional characteristics may affect results. In Belgium, farmers are obliged to report cases of APM within the context of a national brucellosis monitoring program. The inclusion criteria for this monitoring program cover abortions (gestation length of 42-260 d) and perinatal mortalities of (pre)mature calves following a gestation length of more than 260 d, which were stillborn or died within 48 h after birth. The objective of the present study was to describe the evolution in submission of APM cases within a mandatory abortion monitoring program in relation to subsidized initiatives in the northern part of Belgium. Based on the proportion of APM submissions versus the proportion of bovine reproductive females, an APM proportion (APMPR) was calculated, and factors at both animal and herd level that may influence this APMPR were explored by using linear models. This evaluation revealed that the APMPR increased with the introduction of an extensive analytical panel of abortifacient agents and a free on-farm sample collection from 0.44% to 0.94%. Additionally, an increase of the APMPR was associated with an outbreak of an emerging abortifacient pathogen (Schmallenberg virus; 1.23%), and the introduction of a mandatory eradication program for bovine viral diarrhea virus (BVDv; 1.20%). The APMPR was higher in beef compared with dairy cattle, and it was higher in winter compared with fall, spring, and summer. Smaller herds categorized in the first quartile had a higher APMPR compared with larger herds. Herds that submitted an APM in the previous year had a higher APMPR in the next year compared with herds without an APM submission. Finally, herds for which there was evidence of the presence of BVDv had a higher APMPR compared with herds without evidence of the presence of BVDv. In conclusion, the number of APM submissions increased after the introduction of a free on-farm sample collection and an extensive pathogen screening panel. Production type (beef), season (winter), smaller herd size, previous APM, and presence of BVDv seemed to have a positive effect on APMPR. However, even under mandatory circumstances, APM still seems to be underreported, since the APMPR was lower than the expected minimal rate of 2%. Therefore, further research is necessary to identify the drivers that convince farmers to submit APM cases to improve submission rates and ensure an efficient monitoring program for APM and eventually associated zoonotic pathogens.

cattle

Bovine hepacivirus (BoHV) is closely related to the hepatitis C virus (HCV) in humans and can cause both acute and chronic liver infections in cattle. BoHV was first identified in Ghana and Germany in 2015 and since then it has been detected and characterized in other countries around the world, but no strains have been sequenced from U.S. cattle. To date, BoHV has been classified into 2 genotypes (1 and 2), with genotype 1 being further divided into 11 subtypes (A-K). However, the true genetic diversity of BoHV is likely underestimated given limited surveillance and a lack of published genome sequences. Here, we sequenced 2 nearly complete BoHV genomes from serum samples collected in 2019 from beef cattle in Missouri. Sequence comparisons and phylogenetic analysis showed that isolate MARC/2019/60 had high sequence homology with genotype 1, subtype E isolates from China. In contrast, isolate MARC/2019/50 represented a novel BoHV subtype within genotype 2. Thus, we report the first genomic characterization of BoHV isolates from U.S. cattle, and the second complete BoHV2 genome worldwide. This work increases our knowledge of the global genetic diversity of BoHV and demonstrates the co-circulation of divergent BoHV strains in U.S. cattle.

Macrolide resistance in Mannheimia haemolytica isolates associated with bovine respiratory disease from the German national resistance monitoring program GERM-Vet 2009 to 2020

Data collected from the German national resistance monitoring program GERM-Vet showed slowly increasing prevalence of macrolide resistance among bovine respiratory disease (BRD)-associated Pasteurellacae from cattle over the last decade. The focus of this study was to analyze the genetic basis of antimicrobial resistance (AMR) and the prevalence of multidrug-resistance (MDR)-mediating integrative and conjugative elements (ICEs) in 13 German BRD-associated Mannheimia haemolytica isolates collected between 2009 and 2020 via whole-genome sequencing. Antimicrobial susceptibility testing (AST) was performed via broth microdilution according to the recommendations of the Clinical and Laboratory Standards Institute for the macrolides erythromycin, tilmicosin, tulathromycin, gamithromycin, tildipirosin, and tylosin as well as 25 other antimicrobial agents. All isolates either had elevated MICs or were resistant to at least one of the macrolides tested. Analysis of whole-genome sequences obtained by hybrid assembly of Illumina MiSeq and Oxford Nanopore MinION reads revealed the presence of seven novel Tn7406-like ICEs, designated Tn7694, and Tn7724- Tn7729. These ICEs harbored the antimicrobial resistance genes erm(T), mef (C), mph(G), floR, catA3, aad(3")(9), aph(3')-Ia, aac(3)-IIa, strA, strB, tet(Y), and sul2 in different combinations. In addition, mutational changes conferring resistance to macrolides, nalidixic acid or streptomycin, respectively, were detected among the M. haemolytica isolates. In addition, four isolates carried a 4,613-bp plasmid with the β-lactamase gene blaROB - 1. The detection of the macrolide resistance genes erm(T), mef (C), and mph(G) together with other resistance genes on MDR-mediating ICEs in bovine M. haemolytica may explain the occurrence of therapeutic failure when treating BRD with regularly used antimicrobial agents, such as phenicols, penicillins, tetracyclines, or macrolides. Finally, pathogen identification and subsequent AST is essential to ensure the efficacy of the antimicrobial agents applied to control BRD in cattle.

Interaction of talus and calcaneus morphometric values and estimation of carcass weight in cattle

In this study, the calcaneus and talus bones of 20 male and female adult Simmental and Angus cattle were used. The age and sex of these animals were recorded before slaughter, and carcass weights were taken after slaughter. Calcaneus and talus morphometric measurements were used to obtain multipliers that allow the estimation of the carcass weight. These multipliers were found to be mean values of 3.346 and 4.642, respectively. Thus, multipliers were obtained that can be used in the evaluation of chronological differences in archaeological cattle size and consequently carcass weight. LSM (Least Square Means) analysis of calcaneus and talus GL values revealed the effect of sex but not of breed. Proportional factors were obtained for calcaneus and talus pairings and associated bone size (GL) estimates.

Serum vitamin D3 (25-OH vit D3) concentrations and hemogram changes in calves with enzootic pneumonia

BACKGROUND

Enzootic pneumonia is an important disease complex associated with insufficient colostrum intake after birth, adverse environmental conditions, and stress. Vitamin D deficiency may be an important predisposing factor for this disease.

OBJECTIVE

This study aimed to investigate in calves with enzootic pneumonia.

METHODS

A total of 30 calves, aged 3-5 months, under the same care and feeding conditions were used. Groups were formed according to Clinical Respiratory Scoring as the group with mild/moderate enzootic pneumonia (n = 10), the group with severe enzootic pneumonia (n = 10), and the healthy control group (n = 10) without any disease. Blood samples were collected from the jugular vein of animals in all groups on Day 0; a complete blood count was performed, and serum vitamin D levels were measured using the Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) method.

RESULTS

Although no statistical differences were observed in total leukocyte, lymphocyte, eosinophil, basophil, hemoglobin, and hematocrit levels between groups, statistically significant differences in blood neutrophil, monocyte, and erythrocyte counts were found between the groups. Monocyte counts were statistically decreased in the mild/moderate group compared with the control group. Neutrophil counts were significantly higher in the mild/moderate and severe groups than in the control group. Erythrocyte counts were increased in the mild/moderate and severe groups compared with the control group. Vitamin D concentrations were statistically lower in the mild/moderate and severe groups than in the control group. However, no statistical differences in Vitamin D concentrations were observed between the mild/moderate and severe groups. There was a negative and significant correlation between erythrocyte counts and vitamin D concentrations (r = -0.64, P < .0001). While erythrocyte counts increased in the severe group compared with the mild/moderate group, vitamin D concentrations decreased. Also, a negative and significant correlation was observed between platelet counts and vitamin D concentrations (r = -0.74, P < .0001).

CONCLUSIONS

The results of this study determined that serum vitamin D concentrations in calves with pneumonia were lower than those in healthy calves. Detailed studies on the etiologic and prognostic importance of low vitamin D levels in calves with enzootic pneumonia may provide valuable data for prevention and treatment.

Plasma pharmacokinetics of clorsulon following administration of a single subcutaneous or intravenous injection to cattle

The benzenedisulfonamide derivative clorsulon is a potent fasciolicide which is marketed in fixed combination injectables, typically combined with the macrocyclic lactone ivermectin. In the presented pharmacokinetic study, the plasma profile of clorsulon in 32 healthy, young Brown Swiss cattle was administered a single intravenous dose at 3 mg/kg body weight or subcutaneously at 3, 6 or 12 mg/kg body weight (4 intact male and 4 female animals per treatment) as a 30% w/v clorsulon injection formulation. Serial blood samples were collected up to 24 days after administration to establish the pharmacokinetics, bioavailability and dose proportionality of clorsulon. Following a single intravenous injection of clorsulon at 3 mg/kg body weight, the area under the concentration versus time curve from the start of dose administration to the time of the last quantifiable concentration (AUClast ) was 4830 ± 941 day*ng/mL, and half-live was 2.37 ± 0.98 days. The back extrapolated concentration at time 0 was 38,500 ± 6070 ng/mL. The volume of distribution at steady state and clearance were 685 ± 107 mL/kg and 664 ± 127 mL/day/kg, respectively. In the groups dosed at 3, 6 or 12 mg/kg body weight by subcutaneous injection, clorsulon plasma concentrations rose to maximum within 0.5 day and decreased to the last sample point. For these groups, the maximum plasma clorsulon concentrations were 3100 ± 838, 5250 ± 1220 and 10,800 ± 1730 ng/mL, respectively, and the AUClast was 5330 ± 925, 9630 ± 1300 and 21,500 ± 3320 day*ng/mL, respectively. Half-lives, 2.01 ± 0.62, 3.84 ± 1.42 and 5.36 ± 0.60 days, respectively, increased significantly with dose, likely related to increasing dose volume. Clorsulon was well absorbed and fully bioavailable (103%-114%) after subcutaneous injection. No gender-related difference in systemic exposure was observed. Assessment of Cmax and AUClast demonstrated a proportional increase in systemic exposure to the clorsulon subcutaneous doses over the range of 3-12 mg/kg body weight.

Fertilization with follicular fluid reduces HSP70 and BAX expression on bovine in vitro embryos

The in vivo fertilization process occurs in the presence of follicular fluid (FF). The aim of this study was to evaluate the effect of in vitro fertilization medium supplementation with 5% or 10% bovine follicular fluid (BFF) on the production of in vitro bovine embryos. FF was collected from ovarian follicles with a diameter of 8-10 mm, and cumulus-oocyte complexes (COCs) were co-incubated with sperm for 24 h in the commercial medium BotuFIV® (BotuPharma©), being distributed among the experimental groups: oocytes fertilized in a control medium; oocytes fertilized in a medium supplemented with 5% BFF; and oocytes fertilized in a medium supplemented with 10% BFF. After fertilization, the zygotes were cultured in vitro for 8 days. Embryo development was assessed through cleavage rates (day 2) and blastocyst formation rates (day 8). The relative expression of the genes OCT4, IFNT2, BAX, HSP70 and SOD2 was measured using the real-time polymerase chain reaction method. There was no difference (p > .05) among the different experimental groups in terms of cleavage rates and blastocyst formation rates. Regarding the gene expression results, only the blastocysts from oocytes fertilized with 10% BFF showed significantly lower expression of IFNT2 (p = .003) and SOD2 (p = .01) genes compared to blastocysts from oocytes fertilized in control medium alone, while there was no difference between blastocyst from oocytes fertilized in control medium and the ones from oocytes fertilized with 5% BFF. In addition to this, the blastocysts from oocytes fertilized with 5% BFF showed significantly reduced levels of expression of the heat shock protein HSP70 (p < .001) and the pro-apoptotic protein BAX (p = .015) compared to blastocysts from oocytes fertilized with control medium. This may indicate that lower supplementation of BFF to the IVF medium creates a more suitable environment for fertilization and is less stressful for the zygote.

Clinical, pathologic, and molecular characterization of a non-metastatic multicentric cutaneous mast cell tumor in a cow

Cutaneous mast cell tumors are rarely reported in cattle. Although mutations in the c-KIT gene have been shown to play a central role in the oncogenesis of canine mast cell tumors, few data are available in cattle. This report describes the clinical, histologic, immunohistochemical, and genetic features of a multicentric cutaneous mast cell tumor in an adult cow. An 11-year-old Prim'Holstein cow was presented for a 5-month history of multiple skin nodules. Cytologic and histologic analyses of the nodules led to a diagnosis of mast cell tumors. Immunohistochemical analysis for KIT expression showed a moderate to strong signal in neoplastic mast cells with a cytoplasmic and membranous pattern. Sequencing of the c-KIT gene coding sequence revealed no mutation. Despite partial response after corticosteroid treatment, euthanasia was elected. No metastases to the lymph nodes, spleen, and liver were identified at post-mortem and histologic examinations.

Macrophage polarization in lymph node granulomas from cattle and pigs naturally infected with Mycobacterium tuberculosis complex

Tuberculosis in animals is caused by members of the Mycobacterium tuberculosis complex (MTC), with the tuberculous granuloma being the main characteristic lesion. The macrophage is the main cell type involved in the development of the granuloma and presents a wide plasticity ranging from polarization to classically activated or pro-inflammatory macrophages (M1) or to alternatively activated or anti-inflammatory macrophages (M2). Thus, this study aimed to analyze macrophage polarization in granulomas from cattle and pig lymph nodes naturally infected with MTC. Tuberculous granulomas were microscopically categorized into four stages and a panel of myeloid cells (CD172a/calprotectin), M1 macrophage polarization (iNOS/CD68/CD107a), and M2 macrophage polarization (Arg1/CD163) markers were analyzed by immunohistochemistry. CD172a and calprotectin followed the same kinetics, having greater expression in late-stage granulomas in pigs. iNOS and CD68 had higher expression in cattle compared with pigs, and the expression was higher in early-stage granulomas. CD107a immunolabeling was only observed in porcine granulomas, with a higher expression in stage I granulomas. Arg1+ cells were significantly higher in pigs than in cattle, particularly in late-stage granulomas. Quantitative analysis of CD163+ cells showed similar kinetics in both species with a consistent frequency of immunolabeled cells throughout the different stages of the granuloma. Our results indicate that M1 macrophage polarization prevails in cattle during early-stage granulomas (stages I and II), whereas M2 phenotype is observed in later stages. Contrary, and mainly due to the expression of Arg1, M2 macrophage polarization is predominant in pigs in all granuloma stages.