Diagnostics of dairy and beef cattle diarrhea

Stable flies are bona fide carriers of mastitis-associated bacteria

Hematophagous Stomoxys (stable) fly populations in dairy barns are sustained by a constant availability of cattle hosts and manure, which serve as major reservoirs of both zoonotic and opportunistic bacterial pathogens. However, the composition of the Stomoxys fly microbiota, the mechanisms by which flies acquire their microbiome, and the ability of potentially pathogenic bacteria to colonize and persist in fly hosts remain to be investigated. Here, we longitudinally collected fly and manure samples from two connected dairy facilities. High throughput 16S rRNA gene amplicon sequencing was then used to characterize and compare bacterial communities present on or within flies and in manure collected from the same facility, while culture-dependent methods were used to verify the viability of clinically relevant bacteria. Bacterial alpha diversity was overall higher in manure samples as compared to fly samples, with manure-associated bacterial communities being dominated by members of the Bacteroidales, Eubacteriales, and Oscillospirales. In contrast, flies harbored relatively low-complexity communities dominated by members of the Enterobacterales, Staphylococcales, and Lactobacillales. Clinically relevant bacterial strains, including Escherichia spp. and other taxa associated with mastitic cows housed in the same facilities, were detected in paired fly and manure samples but exhibited dramatically elevated abundances in fly samples as compared to manure samples. Viable colonies of Escherichia, Klebsiella, and Staphylococcus spp. were also readily isolated from fly samples, confirming that flies harbor culturable mastitis-associated bacteria. This study identifies biting flies as bona fide carriers of opportunistically pathogenic bacterial taxa on dairy farms.

IMPORTANCE

Disease prevention on dairy farms has significant implications for cattle health, food security, and zoonosis. Of particular importance is the control of bovine mastitis, which can be caused by diverse bacteria, including Klebsiella, Escherichia coli, Streptococcus, and Staphylococcus spp. Despite being one of the most significant and costly cattle diseases worldwide, the epidemiology of bovine mastitis is not well understood. This study provides parallel culture-independent and culture-dependent evidence to support the carriage of opportunistically pathogenic bacteria by Stomoxys flies on dairy farms. We further show that the fly microbiota is enriched in clinically relevant taxa-the vast majority of which can be traced to the manure habitats in which flies breed. Altogether, our results identify biting flies as underrecognized carriers of bacterial taxa associated with environmental bovine mastitis and other opportunistic infections in vertebrates and offer important insights into mechanisms of microbial acquisition by these and other medically important insects.

Salmonellosis in adult cattle in Central Argentina: case series

Salmonellosis is an infectious disease caused by bacteria belonging to the Salmonella genus. Bovine salmonellosis is more frequent in young cattle under intensive overcrowd husbandry conditions, and therefore uncommon in adults. We report four outbreaks of clinical salmonellosis due to Salmonella Typhimurium, Salmonella Newport and Salmonella Dublin provoking outbreaks of diarrheic/septicemic disease in adult cattle of Central Argentina. Anamnesis information, clinical, pathological, and bacteriological findings were retrospective analyzed. This report emphasizes the importance to include salmonellosis among the differential diagnosis of clinical enteric/septicemic disease in adult cattle under different husbandry conditions in Argentina. The source of Salmonella could not be established in these outbreaks.

Chloride and lactate as prognostic indicators of calf diarrhea from eighty-nine cases

IMPORTANCE

Deaths due to neonatal calf diarrhea are still one of the most critical problems of cattle breeding worldwide. Determining the parameters that can predict diarrhea-related deaths in calves is especially important in terms of prognosis and treatment strategies for the disease.

OBJECTIVE

The primary purpose of this study was to determine mortality rates and durations, survival status, and predictive prognosis parameters based on vital signs, hematology, and blood gas analyses in neonatal diarrheic calves.

METHODS

The hospital automation system retrospectively obtained data from 89 neonatal diarrheic calves.

RESULTS

It was found that 42.7% (38/89) of the calves brought with the complaint of diarrhea died during hospitalization or after discharge. Short-term and long-term fatalities were a median of 9.25 hours and a median of 51.50 hours, respectively. When the data obtained from this study is evaluated, body temperature (°C), pH, base excess (mmol/L), and sodium bicarbonate (mmol/L) parameters were found to be lower, and hemoglobin (g/dL), hematocrit (%), lactate (mmol/L), chloride (mmol/L), sodium (mmol/L) and anion gap (mmol/L) parameters were found to be higher in dead calves compared to survivors. Accordingly, hypothermia, metabolic acidosis, and dehydration findings were seen as clinical conditions that should be considered. Logistic regression analysis showed that lactate (odds ratio, 1.429) and CI- (odds ratio, 1.232) concentration were significant risk factors associated with death in calves with diarrhea.

CONCLUSIONS AND RELEVANCE

According to the findings obtained from this study, the determination of lactate and Cl- levels can be used as an adjunctive supplementary test in distinguishing calves with diarrhea with a good prognosis.

Investigating the potential for genetic selection of dairy calf disease traits using management data

Genetic selection could be a tool to help improve the health and welfare of calves; however, to date, there is limited research on the genetics of calfhood diseases. This study aimed to understand the current impact of calf diseases, by investigating incidence rates, estimating genetic parameters, and providing industry recommendations to improve calf disease recording practices on farms. Available calf disease data composed of 69,695 Holstein calf disease records for respiratory problems (RESP) and diarrhea (DIAR), from 62,361 calves collected on 1,617 Canadian dairy herds from 2006 to 2021. Single- and multiple-trait analysis using both a threshold and linear animal model for each trait were evaluated. Furthermore, each trait was analyzed using 2 scenarios with respect to minimum disease incidence threshold criterion (herd-year incidence of at least 1% and 5%) to highlight the effect of different filtering thresholds on selection potential. Observed scale heritability estimates for RESP and DIAR ranged from 0.02 to 0.07 across analyses, while estimated genetic correlations between the traits ranged from 0.50 to 0.62. Sires were compared based on their estimated breeding value and their diseased daughter incidence rates. On average, calves born to the bottom 10% of sires were 1.8 times more likely to develop RESP and 1.9 times to develop DIAR compared with daughters born to the top 10% of sires. Results from the current study are promising for the inclusion of both DIAR and RESP in Canadian genetic evaluations. However, for effective genetic evaluation, standardized approaches on data collection and industry outreach to highlight the importance of collecting and uploading this information to herd management software is required. In particular, it is important that the herd management software is accessible to the national milk recording system to allow for use in national genetic evaluation.

Forensic investigations of suspected livestock depredation by vultures: scientific tools for compensation programmes

Human-wildlife conflicts may have devastating consequences for fauna due to targeting by humans of wildlife populations suspected to have predated livestock. Suspicion of depredation of extensively raised livestock by vultures in Europe has triggered public administration-led forensic investigations intended to distinguish between predation and scavenging in order to compensate farmers for attacks on their livestock. In this study, gross and histological analyses were carried out on suspected cases of domestic animal depredation by griffon vultures (Gyps fulvus) over a 1-year period. Fifty-eight animals were affected (n = 41, suspected depredation), including domestic cattle (75.9%), sheep (22.4%) and a goat (1.7%). All the adults affected were female and most cases of suspected depredation occurred during the peripartum period (56%). Histological investigations distinguished between post-mortem (84% of diagnostic samples) and ante-mortem (16% of diagnostic samples) cases, and gross examinations revealed significant differences (P ≤ 0.002) between ante-mortem, post-mortem and non-diagnostic samples. This study highlights the need to optimize sampling protocols to increase the success of forensic studies. The forensic investigations presented here may be applied to resolve human-wildlife conflicts involving not only vultures but other endangered carnivores and contribute to human-wildlife coexistence in rural areas by protecting the interests of both the livestock sector and endangered species.

Competitive Analysis of Rumen and Hindgut Microbiota Composition and Fermentation Function in Diarrheic and Non-Diarrheic Postpartum Dairy Cows

Postpartum dairy cows can develop nutritional diarrhea when their diet is abruptly changed for milk production. However, it is unclear whether nutritional diarrhea develops as a result of gut acidosis and/or dysbiosis. This study aimed to uncover changes in the gastrointestinal microbiota and its fermentation parameters in response to nutritional diarrhea in postpartum dairy cows. Rumen and fecal samples were collected from twenty-four postpartum cows fed with the same diet but with different fecal scores: the low-fecal-score (LFS: diarrheic) group and high-fecal-score (HFS: non-diarrheic) group. A microbiota difference was only observed for fecal microbiota, with the relative abundance of Defluviitaleaceae_UCG-011 and Lachnospiraceae_UCG-001 tending (p < 0.10) to be higher in HFS cows compared to LFS cows, and Frisingicoccus were only detected in HFS cows. The fecal bacterial community in LFS cows had higher robustness (p < 0.05) compared to that in HFS cows, and also had lower negative cohesion (less competitive behaviors) and higher positive cohesion (more cooperative behaviors) (p < 0.05) compared that in to HFS cows. Lower total volatile fatty acids and higher ammonia nitrogen (p < 0.05) were observed in LFS cows' feces compared to HFS cows. The observed shift in fecal bacterial composition, community networks, and metabolites suggests that hindgut dysbiosis could be related to nutritional diarrhea in postpartum cows.

Prevalence and molecular characterization of Cryptosporidium spp. in dairy and beef cattle in Shanxi, China

Cryptosporidium spp. are key gastrointestinal protists in humans and animals worldwide. Infected cattle are considered the main source of cryptosporidiosis outbreaks in humans. However, little is known about the genetic makeup of Cryptosporidium populations in Shanxi province, China. We analyzed 858 fecal samples collected from farms in Shanxi. The presence of Cryptosporidium spp. was determined via polymerase chain reaction and subsequent sequence analysis of the small subunit rRNA gene as well as restriction fragment length polymorphism analysis. Cryptosporidium parvum was subtyped following sequence analysis of the 60 kDa glycoprotein gene (gp60). The overall prevalence of Cryptosporidium in cattle was 11.19%, with a prevalence of 13.30% and 8.67% in Lingqiu and Yingxian, respectively. The overall prevalence of Cryptosporidium in dairy and beef cattle was 10.78% and 11.50%, respectively. Cryptosporidium infection was detected across all analyzed age groups. The overall prevalence of Cryptosporidium in diarrhea and nondiarrhea samples was 18.24% and 9.72%, respectively, whereas that in intensively farmed and free-range cattle was 17.40% and 3.41%, respectively. We identified five Cryptosporidium species, with C. andersoni being the dominant species. Further, two cases of mixed infections of Cryptosporidium species were detected. All identified C. parvum isolates belonged to the subtype IIdA17G1.

Diversity and probiotic characterisation of yeast isolates in the bovine gastrointestinal tract

The use of yeasts as a feed supplement for cattle can promote animal development and performance. However, for the positive results to be consistent, strains with probiotic properties must be selected. The objective of this study was to isolate and identify yeasts present in the bovine feces and evaluate their probiotic potential together with strains previously isolated from the rumen (preliminary study). A total of 193 isolates were studied, including 139 isolates (19 species) from fecal samples from 11 different animals (Bos taurus and Bos indicus) and 54 strains previously isolated from rumen fluid (Bos taurus). The yeast population in the feces ranged from 3.51 to 4.99 log CFU/g, with Candida pararugosa being the most abundant (isolated from the feces of six samples analysed). Isolates were selected that had negative results in the safety tests (hemolytic activity, DNAse, and gelatinase) and had percentages greater than 35 and 70% for hydrophobicity and auto-aggregation, respectively. In addition, selected isolates had percentages greater than 77.7 and 74.7% for coaggregation with pathogenic strains of Escherichia coli and Clostridium perfringens, respectively. The isolates with percentage growth at 39 °C greater than 64.6% and viability greater than 96.7% were selected for survival testing under bovine gastrointestinal conditions. After the tests, the seven best isolates were selected, belonging to the species Candida pararugosa (L60, CCMA 928 and CCMA 930) and Pichia kudriavzevii (L97, L100, CCMA904, CCMA 907). The selected isolates were exopolysaccharide producers. Based on the results of the evaluated properties, the seven selected isolates were classified as potential probiotics for cattle.

Study of the economic impact of cryptosporidiosis in calves after implementing good practices to manage the disease on dairy farms in Belgium, France, and the Netherlands

Cryptosporidium spp. are widespread parasitic protozoans causing enteric infections in humans and animals. The parasites cause neonatal diarrhoea in calves, leading to a high mortality rate in the first three weeks. Losses are significant for farmers, but the cost of cryptosporidiosis remains poorly documented. In the absence of a vaccine, only preventive measures are available to farmers to combat the infection. This study, conducted between 2018 and 2021, aimed to evaluate the economic impact of Cryptosporidium spp. on European dairy farms and monitor changes in costs after implementing disease management measures. First, a field survey was carried out and questionnaires administered to 57 farmers in Belgium, France, and the Netherlands. The aim of the survey was to assess the losses associated with the occurrence of diarrhoea in calves aged between 3 days and 3 weeks. The economic impact of diarrhoea was calculated based on mortality losses, health expenditures, and additional labour costs. To refine the cost estimation specifically for Cryptosporidium spp., stool samples were collected from 10 calves per farm. The prevalence of Cryptosporidium spp. was determined, and the economic impact of diarrhoea was adjusted accordingly. The assumption was made that a certain percentage of costs was attributed to cryptosporidiosis based on the prevalence. These protocols were repeated at the end of the study to observe changes in costs. In the three years, the cost of diarrhoea for the 28 farms that stayed in the panel all along the study improved from €140 in 2018 to €106 on average per diarrhoeic calf in 2021. With a stable prevalence at 40%, the cost of cryptosporidiosis per infected calf decreased from €60.62 to €45.91 in Belgium, from €43.83 to €32.14 in France, and from €58.24 to €39.48 in the Netherlands. This represented an average of €15 saved per infected calf. The methodology employed in this study did not allow us to conclude that the improvement is strictly due to the implementation of preventive measures. However, with 11 million calves raised in the Interreg 2 Seas area covered by the study, it provided valuable insights into the economic burden of Cryptosporidium spp.

Multi-resistant diarrheagenic Escherichia coli identified by FTIR and machine learning: a feasible strategy to improve the group classification

The identification of multidrug-resistant strains from E. coli species responsible for diarrhea in calves still faces many laboratory limitations and is necessary for adequately monitoring the microorganism spread and control. Then, there is a need to develop a screening tool for bacterial strain identification in microbiology laboratories, which must show easy implementation, fast response, and accurate results. The use of FTIR spectroscopy to identify microorganisms has been successfully demonstrated in the literature, including many bacterial strains; here, we explored the FTIR potential for multi-resistant E. coli identification. First, we applied principal component analysis to observe the group formation tendency; the first results showed no clustering tendency with a messy sample score distribution; then, we improved these results by adequately selecting the main principal components which most contribute to group separation. Finally, using machine learning algorithms, a predicting model showed 75% overall accuracy, demonstrating the method's viability as a screaming test for microorganism identification.

The Effect of Capsaicin on Growth Performance, Antioxidant Capacity, Immunity and Gut Micro-Organisms of Calves

Capsaicin is the active ingredient of the red pepper plant of the genus Capsicum. The aim of this study was to investigate the effects of different doses of capsaicin on growth performance, antioxidant capacity, immunity, fecal fermentation parameters and gut microbial composition in nursing calves. Twenty-four newborn Holstein calves were randomly assigned to three treatment groups, which each consisted of eight calves. The milk replacer was supplemented with 0, 0.15 or 0.3 mL/d of capsaicin in each of the three treatment groups. During the 4-week experiment, intake was recorded daily, body weight and body size parameters were measured at the beginning and end of the trial and serum samples and rectal fecal samples were collected at the end of the trial to determine serum parameters, fecal fermentation parameters and fecal microbiome compartments. The results showed that both doses of capsaicin had no negative effect on the growth performance or the fecal fermentation parameters of calves, and the higher dose (0.3 mL/d) of capsaicin significantly improved the antioxidant capacity and immunity of calves. The calves in the high-dose capsaicin-treated group had lower fecal scores than those recorded in the control group. High doses of capsaicin increased glutathione antioxidant enzyme, superoxide dismutase, immunoglobulin A, immunoglobulin G, immunoglobulin M and interleukin-10 levels and decreased malondialdehyde and bound bead protein levels. In addition, capsaicin regulated the gut microbiota, reducing the abundance of diarrhea-associated bacteria, such as Eggerthella, Streptococcus, Enterococcus and Enterobacteriaceae, in the gut of calves in the treated group. Therefore, high doses of capsaicin can improve the antioxidant and immune capacity of calves without affecting growth performance, as well as improve the gut microbiological environment, which enables the healthy growth of calves.

Development of an IgY-Based Treatment to Control Bovine Coronavirus Diarrhea in Dairy Calves

Bovine Coronavirus (BCoV) is a major pathogen associated with neonatal calf diarrhea. Standard practice dictates that to prevent BCoV diarrhea, dams should be immunized in the last stage of pregnancy to increase BCoV-specific antibody (Ab) titers in serum and colostrum. For the prevention to be effective, calves need to suck maternal colostrum within the first six to twelve hours of life before gut closure to ensure a good level of passive immunity. The high rate of maternal Ab transfer failure resulting from this process posed the need to develop alternative local passive immunity strategies to strengthen the prevention and treatment of BCoV diarrhea. Immunoglobulin Y technology represents a promising tool to address this gap. In this study, 200 laying hens were immunized with BCoV to obtain spray-dried egg powder enriched in specific IgY Abs to BCoV on a large production scale. To ensure batch-to-batch product consistency, a potency assay was statistically validated. With a sample size of 241, the BCoV-specific IgY ELISA showed a sensitivity and specificity of 97.7% and 98.2%, respectively. ELISA IgY Abs to BCoV correlated with virus-neutralizing Ab titers (Pearson correlation, R2 = 0.92, p < 0.001). Most importantly, a pilot efficacy study in newborn calves showed a significant delay and shorter duration of BCoV-associated diarrhea and shedding in IgY-treated colostrum-deprived calves. Calves were treated with milk supplemented with egg powder (final IgY Ab titer to BCoV ELISA = 512; VN = 32) for 14 days as a passive treatment before a challenge with BCoV and were compared to calves fed milk with no supplementation. This is the first study with proof of efficacy of a product based on egg powder manufactured at a scale that successfully prevents BCoV-associated neonatal calf diarrhea.

Current and Emerging Diagnostic Approaches to Bacterial Diseases of Ruminants

The diagnostic approaches and methods to detect bacterial pathogens in ruminants are discussed, with a focus on cattle. Conventional diagnostic methods using culture, isolation, and characterization are being replaced or supplemented with new methods. These include molecular diagnostics such as real-time polymerase chain reaction and whole-genome sequencing. In addition, methods such as matrix-assisted laser desorption ionization-time-of-flight mass spectrometry enable rapid identification and enhanced pathogen characterization. These emerging diagnostic tools can greatly enhance the ability to detect and characterize pathogens, but performance and interpretation vary greatly across sample and pathogen types, disease syndromes, assay performance, and other factors.

Evaluation of the immunogenic properties of the recombinant Histophilus somni outer membrane protein 40 kDa (rOMP40)

Background

Gram-negative bacterial infections are a serious problem in beef and dairy cattle. Bacterial outer membrane proteins (OMPs) play a pivotal role in cellular survival and the host-bacterium interaction. Histophilus somni OMP40 was identified as a porin with homology between its N-terminal amino acid sequence and the sequences of porins of other gram-negative bacteria The aim of this study was to produce recombinant H. somni OMP40 (rOMP40), optimize its production and evaluate its immunogenic properties in calves. The cross-reactivity of anti-rOMP40 antibodies were also checked.

Results

The highest overexpression of rOMP40 was demonstrated by Escherichia coli C41 using the autoinduction process. Double immunization of calves (20 μg rOMP40 per animal) induced a significant increase of anti-rOMP40 antibodies in the IgG1 (P ≤ 0.01) and IgG2 (P ≤ 0.01, after first immunization only) subclasses, but not IgM. ELISA revealed increased reactivity of the IgG against surface antigens of E. coli and Pasteurella multocida after the second immunization (P < 0.01). Cross reactivity of anti-rOMP40 antibodies with ~ 40 kDa antigens of most common gram-negative pathogens was shown by Western blotting.

Conclusion

Immunization with H. somni rOMP40 induced a humoral response in cattle with broad cross-reactivity with similar antigens of other species of Pasteurellaceae and Enterobacteriaceae families and the delayed-type hypersensitivity reaction. The obtained results encourage further study to evaluate the protective effect of the produced protein as a subunit vaccine in cattle.

Clinical, hematological and some biochemical alterations during diarrhea in Friesian calves naturally infected with E. coli and Salmonella

Background

This study aimed to assess the clinical and hemato-biochemical changes associated with diarrhea in E. coli and Salmonella pathogens in Friesian bovine calves less than one month old as well as to examine the relationship between Vit D₃ and cardiac biomarkers.

Results

The study was carried out on 43 Friesian calves from a private farm in Ash Sharqia Governorate, 33 diarrheic calves aged 1–14 days with an average body weight 43.7 ± 1.2 kg, and 10 apparently healthy calves were kept as a control group to investigate the clinical and hemato-biochemical profiles. E. coli and Salmonella pathogens were isolated from the diarrheic calves where 76% were E. coli and 24% were Salmonella. Diarrheic calves showed signs of anorexia, weakness, dullness, staggering gait, pale mucous membranes with sunken eyes and dehydration. Analysis of clinical and hemato-biochemical profile of the diarrheic calves revealed significant increase in body temperature, respiratory rate, heart rate, white blood cells, neutrophils, serum potassium, urea, creatinine, ALT, AST, cardiac NT-proBNP and cardiac troponin I with significant decrease in hemoglobin, packed cell volume, erythrocytes, serum Vit D₃, sodium, glucose, total protein and albumin concentrations.

Conclusions

It could be concluded that bacterial diarrhea has a severe negative impact on the clinical and hemato-biochemical profile of the neonatal calves with diarrhea. Serum cardiac biomarkers such as cardiac troponin I (cTn-I) and NT-proBNP were significantly higher in neonatal calves with diarrhea, and there is an important relationship between cardiac biomarkers and vitamin D levels.

Detection and genome characterization of bovine kobuvirus (BKV) in faecal samples from diarrhoeic calves in Quebec, Canada

Kobuviruses are known to infect the gastrointestinal tract of different animal species. Since its discovery in 2003, bovine kobuvirus (BKV) has been identified in faecal samples from diarrhoeic cattle in many countries, but only recently in North America. Although its possible role as an agent of calf diarrhoea remains to be determined, evidence is mounting. Our study reports for the first time the detection of BKV in faecal samples from diarrhoeic calves raised in Quebec, Canada. BKV was more commonly identified than eight known and common enteric calf pathogens. Further sequence analysis revealed that Canada BKV strain 1,043,507 was more closely correlated with the US BKV IL35164 strain than other BKV strains with complete genome. Continued surveillance and genomic characterization are needed to monitor BKV in the cattle around the world.

A comparison of assays for the detection of Cryptosporidium parvum in the feces of scouring calves

Cryptosporidium parvum is a zoonotic, protozoan parasite that causes potentially life-threatening diarrhea in the host and can be transmitted via the fecal-oral route. C. parvum can infect cattle and may be detected in their feces using a variety of tests. We compared the level of agreement, ease of procedure, and cost among PCR, lateral flow immunoassay, fluorescent antibody, and Kinyoun acid-fast stain direct smear tests. Over the course of 9 mo, 74 calf fecal samples were submitted and tested for C. parvum using all 4 tests. A Fleiss kappa value of 0.813 was obtained, indicating an excellent level of agreement among tests. Overall, the best test based on cost and ease of procedure was the Kinyoun acid-fast stain direct smear.

Implementation of a pre-calving vaccination programme against rotavirus, coronavirus and enterotoxigenic Escherichia coli (F5) and association with dairy calf survival

Background

Diarrhea is one of the most common diseases and causes of death in calves during the first month of life. Pre-calving vaccination programme (PVP) against the most common diarrhea-causing pathogens could help to avoid this threat if hyperimmune transition milk (TM) is fed to calves throughout the whole susceptibility period. The aim of this retrospective cohort study was to reveal the implementation practices of PVPs in large commercial dairy farms and to compare calf-level mortality hazards during the first year of vaccination (V+ period) and a year before implementing the vaccination programme (V- period). A questionnaire was filled out in 15 large-scale dairy farms in Estonia that used PVP. The farms were assigned into three groups based on compliance with the vaccine directions for use and TM feeding practices. Calf-level time-to-event data was analyzed with an observation period of 21 days and on-farm mortality due to diarrhea being the event of interest.

Results

During the V+ period, a significant decline in diarrhea-induced calf mortality was identified in three out of six herds that followed vaccination instructions and fed TM for at least 14 days. On average, calf mortality hazard due to diarrhea decreased among these herds (hazard rate ratio (HR) = 0.72, 95% confidence interval (CI) 0.63; 0.81). In the group of correctly vaccinating herds where TM was fed for less than 14 days, diarrhea-induced calf mortality decreased in two herds and remained unchanged in two herds with average diarrhea-induced calf mortality hazard declining significantly during the vaccination period (HR = 0.24, 95% CI 0.14; 0.41). Among the three farms that deviated from the vaccination instructions, the average calf mortality hazard increased in the V+ period (HR = 1.61, 95% CI 1.21; 2.14).

Conclusions

This study revealed that implementing a PVP might aid to reduce diarrhea-induced calf mortality in large commercial dairy farms. There is a need to increase veterinarians´ and farmers´ awareness about the importance of including pregnant heifers into the vaccination programme and emphasize the importance of prolonged feeding of hyperimmune TM to calves.

Literature Review: Coinfection in Young Ruminant Livestock-Cryptosporidium spp. and Its Companions

The protozoan Cryptosporidium parvum is one of the major causative pathogens of diarrhoea in young ruminants; therefore, it causes economic losses and impairs animal welfare. Besides C. parvum, there are many other non-infectious and infectious factors, such as rotavirus, Escherichia coli, and Giardia duodenalis, which may lead to diarrhoeic disease in young livestock. Often, more than one infectious agent is detected in affected animals. Little is known about the interactions bet-ween simultaneously occurring pathogens and their potential effects on the course of disease. In this review, a brief overview about pathogens associated with diarrhoea in young ruminants is presented. Furthermore, information about coinfections involving Cryptosporidium is provided.

Comparative evaluation of various diagnostic techniques for detection of Cryptosporidium infection from the faecal samples of diarrhoeic bovine calves

BACKGROUND

Cryptosporidium, an opportunistic, zoonotic, apicomplexan parasite, is one of the most common causes of diarrhea in neonatal bovine calves around the globe. Bovine calves act as a major source of infection by excreting huge numbers of highly resistant oocysts in faeces, which can survive for a long time in extreme environmental conditions. As low as ten oocysts can cause disease and mortality, leading to the requirement of an early and accurate diagnosis for proper and favorable prognosis, management, and control.

AIMS

The current study was conducted with the objective to evaluate various diagnostic techniques (acid fast staining, negative staining, fluorescent, ELISA, PCR, nested PCR, and qPCR) for the detection of Cryptosporidium in the faecal samples of diarrheic bovine calves.

METHODS

Two hundred diarrheic faecal samples from bovine calves were collected and subjected to these techniques for Cryptosporidium diagnosis. Results of these were evaluated for diagnostic comparison.

RESULTS

Out of 200 faecal samples evaluated, 24% (48/200) were detected positive for Cryptosporidium using a combination of two techniques as gold standard criteria. Cohen's kappa value indicated moderate to almost perfect agreement (0.616 to 0.986) among all the techniques used in the present study. Leishman staining showed the lowest sensitivity (54.17%), while nested PCR and qPCR showed the highest sensitivity (97.92%). Diagnostic specificity of all these tests ranged from 98.68 to 100%.

CONCLUSION

Auramine stain was used for the first time in the bovine calves in India for the detection and diagnostic comparison of Cryptosporidium. It showed strong agreement with the molecular as well as classical diagnostic techniques, and can be used for primary screening for better diagnosis.

Interactions between Cryptosporidium parvum and bovine corona virus during sequential and simultaneous infection of HCT-8 cells

Neonatal diarrhoea in calves is one of the major health problems in the cattle industry. Although co-infections are often associated with greater severity of disease, there is limited information on any impact on the pathogens themselves. Herein, we studied Cryptosporidium parvum and bovine coronavirus (BCoV) in human HCT-8 cells, inoculated either sequentially or simultaneously, to investigate any influence from the co-infections. Quantitative results from (RT)-qPCR showed that prior inoculation with either of the two pathogens had no influence on the other. However, the results from simultaneous co-inoculation showed that entry of viral particles was higher when C. parvum sporozoites were present, although elevated virus copy numbers were no longer evident after 24 h. The attachment of BCoV to the sporozoites was probably due to specific binding, as investigations with bovine norovirus or equine herpes virus-1 showed no attachment between sporozoites and these viruses. Flow cytometry results at 72 h post inoculation revealed that C. parvum and BCoV infected 1-11% and 10-20% of the HCT-8 cells, respectively, with only 0.04% of individual cells showing double infections. The results from confocal microscopy corroborated those results, showing an increase in foci of infection from 24-72 h post inoculation for both pathogens, but with few double infected cells.

Viral Enteritis in Cattle: To Well Known Viruses and Beyond

Livestock products supply about 13 percent of energy and 28 percent of protein in diets consumed worldwide. Diarrhea is a leading cause of sickness and death of beef and dairy calves in their first month of life and also affecting adult cattle, resulting in large economic losses and a negative impact on animal welfare. Despite the usual multifactorial origin, viruses are generally involved, being among the most important causes of diarrhea. There are several viruses that have been confirmed as etiological agents (i.e., rotavirus and coronavirus), and some viruses that are not yet confirmed as etiological agents. This review summarizes the viruses that have been detected in the enteric tract of cattle and tries to deepen and gather knowledge about them.

RETRACTED ARTICLE: Molecular detection of pathogenic Escherichia coli strains and their antibiogram associated with risk factors from diarrheic calves in Jimma Ethiopia

Diarrheagenic Escherichia coli are a number of pathogenic E. coli strains that cause diarrheal infection both in animal and human hosts due to their virulence factors. A cross sectional study was conducted between November, 2016 and April, 2017 to isolate and molecularly detect pathogenic E. coli from diarrheic calves to determine the pathogenic strains, antibiogram and associated risk factors in Jimma town. Purposive sampling technique was used to collect 112 fecal samples from diarrheic calves. Conventional culture and biochemical methods were conducted to isolate E. coli isolates. Molecular method was followed to identify virulence factors of pathogenic E. coli strains. Antimicrobial sensitivity patterns of the isolates were tested using the Kirby-Bauer disk diffusion method. A structured questionnaire was also used to collect information from dairy farms and socio-demographic data. The overall isolation rate of E. coli in calves was 51.8% (58/112) (95% CI 42.0-61.0). The occurrence of the bacterium differed significantly by age, colostrum feeding time, amount of milk given per time and navel treatment (P < 0.05). Multivariable analysis revealed that the odds of being infected was significantly highest in calves which fed 1-1.5 L amount of milk per a time (OR 5.38, 95% CI 1.66-17.45, P = 0.005). The overall virulence genes detection rate was 53.5% (95% CI 40.0-67.0). Eleven (19.6%) of eaeA, 6 (10.7%) of Stx1 and 13 (23.2%) of Stx2 genes were detected from calves isolates. Except ciprofloxacillin, all isolates were resistant to at least one drug. Multi drug resistance was recorded in 68.0% (38/56) of calves isolates. Neomycin, 83.3% (25/30), followed by amoxicillin, 53.3% (16/30) were the highest resisted virulence genes. The study demonstrated considerable isolation rate, multiple antimicrobial resistant isolates and high resistant virulent genes in diarrheic calves. It also indicated that the potential importance of calves as source of pathogenic E. coli strains and resistant genes for human diarrhea infection. Improving the hygienic practice of farms and wise use of antimicrobials could help to reduce the occurrence of pathogenic E. coli in farms. Hence, further studies are needed to describe all virulent factors and serotypes associated with the emergence of drug resistant pathogenic E. coli strains in calves.

The Specific Immune Response after Vaccination against Neonatal Calf Diarrhoea Differs between Apparent Similar Vaccines in a Case Study

Simple Summary

Neonatal calf diarrhoea (NCD) is a complex, multifactorial disease involving pathogens but also environmental, nutritional and management factors. Enterotoxigenic Escherichia coli (ETEC), rotavirus (BoRV) and coronavirus (BoCV) are the main enteric pathogens involved. NCD is a major health challenge that impacts on farm profitability, calf welfare and antimicrobial usage. Thus, a key part of prevention is optimisation of preventive programs for NCD such as vaccinating cows to increase passive immunity transfer for their offspring during the neonatal period. In this study, it was demonstrated that dam vaccination against NCD is an excellent tool to increase specific immunity; how different vaccines differ in their specific immune response and, consequently, in the amount of specific passive transfer of antibodies to their calves. One of the most relevant findings is the importance of inducing a specific immune response for the three NCD pathogens.

Abstract

Neonatal calf diarrhoea (NCD) is a major health challenge with a negative impact on farm profitability, calf welfare and antimicrobial use. Neonatal calves are particularly sensitive to enteric infections. Thus, a key point for prevention is minimising infectious pressure and maximising specific immune responses. An amount of 120 dams not previously vaccinated against NCD were randomly allocated to one of three study groups: negative control versus two vaccinated groups (A and B). In the control group, the average level of antibodies was significantly low for both BoCV and ETEC (15.6 and 13.9% in the colostrum samples, respectively), demonstrating the importance of dam vaccination. Indeed, the level of specific immunity was significantly increased for BoCV and ETEC with dam vaccination using both one-shot vaccines versus the control group. Moreover, the statistical analysis revealed a significantly higher level of antibodies for BoCV and ETEC in colostrum samples in vaccine A versus vaccine B and the control group. In accordance, the calf serum demonstrated a significantly higher level and greater homogeneity of antibodies against BoCV and ETEC in the Vaccine A group versus other experimental groups (p < 0.05). In conclusion, this study demonstrated a different specific immune response for the pathogens depending on the vaccine used to control NCD in cows.

Causes of neonatal calf diarrhea and mortality in pasture-based dairy herds in Uruguay: a farm-matched case-control study

Neonatal calf diarrhea (NCD) and mortality cause significant losses to the dairy industry. The preweaning dairy calf mortality risk in Uruguay is high (15.2%); however, causes for these losses are largely unknown. This study aimed to assess whether various pathogens were associated with NCD and death in Uruguayan dairy calves and whether these infections, diarrhea, or deaths were associated with the failure of transfer of passive immunity (FTPI). Contemporary diarrheic (n = 264,) and non-diarrheic (n = 271) 1- to 30-day-old calves from 27 farms were sampled. Feces were analyzed by antigen-capture ELISA for Cryptosporidium spp., rotavirus, bovine coronavirus, and Escherichia coli F5+, RT-PCR for bovine astrovirus (BoAstV), and bacterial cultures for Salmonella enterica. Blood/serum was analyzed by RT-PCR or antigen-capture ELISA for bovine viral diarrhea virus (BVDV). Serum of ≤ 8-day-old calves (n = 95) was assessed by refractometry to determine the concention of serum total proteins (STP) as an indicator of FTPI. Whether the sampled calves died before weaning was recorded. At least one pathogen was detected in 65.4% of the calves, and this percentage was significantly higher in diarrheic (83.7%) versus non-diarrheic (47.6%) calves. Unlike the other pathogens, Cryptosporidium spp. and rotavirus were associated with NCD. Diarrheic calves, calves infected with any of the pathogens, and calves infected with rotavirus had significantly lower concentrations of STP. Diarrheic calves had higher chances of dying before weaning than non-diarrheic calves. Diarrheic calves infected with S. enterica were at increased risk of mortality. Controlling NCD, salmonellosis, cryptosporidiosis, and rotavirus infections, and improving colostrum management practices would help to reduce calf morbi-mortality in dairy farms in Uruguay.

Effect of trehalose supplementation in milk replacer on the incidence of diarrhea and fecal microbiota in preweaned calves

Trehalose, a nonreducing disaccharide consisting of d-glucose with α,α-1,1 linkage, was evaluated as a functional material to improve the gut environment in preweaned calves. In experiment 1, 173 calves were divided into two groups; the trehalose group was fed trehalose at 30 g/animal/d with milk replacer during the suckling period, and the control group was fed nonsupplemented milk replacer. Medication frequency was lower in the trehalose group (P < 0.05). In experiment 2, calves (n = 20) were divided into two groups (control group [n = 10] and trehalose group [n = 10]) based on their body weight and reared under the same feeding regimens as in experiment 1. Fresh feces were collected from individual animals at the beginning of the trial (average age 11 d), 3 wk after trehalose feeding (experimental day 22), and 1 d before weaning, and the fecal score was recorded daily. Fecal samples were analyzed for fermentation parameters and microbiota. The fecal score was significantly lower in the trehalose group than in the control group in the early stage (at an age of 14 to 18 d; P < 0.05) of the suckling period. Calves fed trehalose tended to have a higher proportion of fecal butyrate on day 22 than calves in the control group (P = 0.08). Population sizes of Clostridium spp. were significantly lower (P = 0.036), whereas those of Dialister spp. and Eubacterium spp. tended to be higher in the feces of calves in the trehalose group on day 22 (P = 0.060 and P = 0.083). These observations indicate that trehalose feeding modulated the gut environment and partially contributed to the reduction in medication frequency observed in experiment 1.

Effect of the administration of Lactobacillus spp. strains on neonatal diarrhoea, immune parameters and pathogen abundance in pre-weaned calves

Neonatal calf diarrhoea is one of the challenges faced by intensive farming, and probiotics are considered a promising approach to improve calves' health. The objective of this study was to evaluate the effect of potential probiotic lactobacilli on new-born dairy calves' growth, diarrhoea incidence, faecal score, cytokine expression in blood cells, immunoglobulin A (IgA) levels in plasma and faeces, and pathogen abundance in faeces. Two in vivo assays were conducted at the same farm in two annual calving seasons. Treated calves received one daily dose of the selected lactobacilli (Lactobacillus reuteri TP1.3B or Lactobacillus johnsonii TP1.6) for 10 consecutive days. A faecal score was recorded daily, average daily gain (ADG) was calculated, and blood and faeces samples were collected. Pathogen abundance was analysed by absolute qPCR in faeces using primers directed at Salmonella enterica, rotavirus, coronavirus, Cryptosporidium parvum and three Escherichia coli virulence genes (eae, clpG and Stx1). The faecal score was positively affected by the administration of both lactobacilli strains, and diarrhoea incidence was significantly lower in treated calves. No differences were found regarding ADG, cytokine expression, IgA levels and pathogen abundance. Our findings showed that oral administration of these strains could improve gastrointestinal health, but results could vary depending on the calving season, which may be related to pathogen seasonality and other environmental effects.

Phylogenetic Analyses of Rotavirus A from Cattle in Uruguay Reveal the Circulation of Common and Uncommon Genotypes and Suggest Interspecies Transmission

Uruguay is one of the main exporters of beef and dairy products, and cattle production is one of the main economic sectors in this country. Rotavirus A (RVA) is the main pathogen associated with neonatal calf diarrhea (NCD), a syndrome that leads to significant economic losses to the livestock industry. The aims of this study are to determine the frequency of RVA infections, and to analyze the genetic diversity of RVA strains in calves in Uruguay. A total of 833 samples from dairy and beef calves were analyzed through RT-qPCR and sequencing. RVA was detected in 57.0% of the samples. The frequency of detection was significantly higher in dairy (59.5%) than beef (28.4%) calves (p < 0.001), while it did not differ significantly among calves born in herds that were vaccinated (64.0%) or not vaccinated (66.7%) against NCD. The frequency of RVA detection and the viral load were significantly higher in samples from diarrheic (72.1%, 7.99 log₁₀ genome copies/mL of feces) than non-diarrheic (59.9%, 7.35 log₁₀ genome copies/mL of feces) calves (p < 0.005 and p = 0.007, respectively). The observed G-types (VP7) were G6 (77.6%), G10 (20.7%), and G24 (1.7%), while the P-types were P[5] (28.4%), P[11] (70.7%), and P[33] (0.9%). The G-type and P-type combinations were G6P[11] (40.4%), G6P[5] (38.6%), G10P[11] (19.3%), and the uncommon genotype G24P[33] (1.8%). VP6 and NSP1-5 genotyping were performed to better characterize some strains. The phylogenetic analyses suggested interspecies transmission, including transmission between animals and humans.

Serum Metabolomics Revealed the Differential Metabolic Pathway in Calves with Severe Clinical Diarrhea Symptoms

Simple Summary

The present study focuses on the metabolic changes in the diarrhea of calves, which are manifested with the following symptoms: a thin water-like stool, cold ears and nose, throbbing bowels, oliguria, a pale or yellowish complexion, a smooth mouth, and a slow pulse. The differential metabolic pathways in calves with diarrhea were screened by metabolomics. There were nine biomarkers in the serum of healthy calves and calves with diarrhea. On the basis of these biomarkers, their associated mineral absorption, protein digestion and absorption, and other metabolic pathways, the targeted regulation of the metabolic differences of calves with diarrhea may contribute to the diagnosis, treatment, and discussion of the mechanism of calf diarrhea.

Abstract

The complex etiology, higher morbidity and mortality, poor prognosis, and expensive cost of calf diarrhea have made it a catastrophic disease in the dairy industry. This study aims to assess the biomarkers in calves with diarrhea and to predict the biomarkers related to the pathway. As subjects, nine calves with diarrhea and nine healthy calves were enrolled, according to strict enrollment criteria. The serum metabolites were detected by a liquid chromatographic tandem mass spectrometry (LC-MS/MS), and then analyzed by online multivariate statistical analysis software to further screen the biomarkers. In addition, the biomarkers involved in the metabolic pathways of calves with diarrhea and healthy calves were analyzed. In the serum of calves with diarrhea, nine biomarkers were found to which several biomarkers exhibited a certain relation. Moreover, these biomarkers were involved in important metabolic pathways, including protein digestion and absorption, ABC transporters, aminoacyl-tRNA biosynthesis, mineral absorption, and fatty acid biosynthesis. All these findings suggested that the imbalance of these markers was closely related to the occurrence and development of calf diarrhea. The targeted regulation of metabolic pathways involved in these biomarkers may facilitate the diagnosis, treatment, and discussion of the mechanism of calf diarrhea.

Long-term production effects of clinical cryptosporidiosis in neonatal calves

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Cryptosporidium parvum is a major cause of enteric disease in neonatal calves.

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Clinically severe cryptosporidiosis in neonatal calves significantly reduces weight gain.

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The impact of reduced weight gain in calves is seen over a 6 month period.

Cryptosporidiosis can have a devastating effect in neonatal calves, resulting in diarrhoea, dehydration and, in severe cases, death of the animal. The disease is caused by Cryptosporidium spp. and is one of the most common causes of calf enteritis in the UK. The parasite is very difficult to remove from the farm, as the oocysts have a tough outer wall which enables the parasite to survive for several months in moist temperate environmental conditions and it is difficult to kill oocysts with common disinfectants used on a farm. If appropriate management practises are applied, the disease is usually self-limiting and most calves will recover. It has been shown, in studies with children and in lambs, that severe clinical cryptosporidiosis can result in long-term growth and cognitive impairment compared with individuals with no obvious signs of the disease. This study measured the long-term growth rate of beef calves on farm by comparing groups of animals that had suffered differing degrees of clinical severity of cryptosporidiosis as neonates. A group of 27 beef calves were enrolled in the study and monitored from birth to 6 months of age. The calves were scored for severity of cryptosporidiosis and weighed at regular intervals. The average difference in weight gain, at 6 months, between a group of calves that had severe cryptosporidiosis as neonates and a group of calves with no clinical signs of infection was 34 kg. Those calves that had experienced severe cryptosporidiosis as neonates showed a significantly reduced live weight gain compared with those calves showing no clinical signs of infection (P = 0.034). Therefore, the impact of severe cryptosporidiosis in neonatal calves has longer term effects on weight gain and production efficiency, resulting in the parasite having a greater impact on cattle production than previously thought.

Cryptosporidium Prevalence in Calves and Geese Co-Grazing on Four Livestock Farms Surrounding Two Reservoirs Supplying Public Water to Mainland Orkney, Scotland

The parasite Cryptosporidiumparvum represents a threat to livestock health and production, water quality and public health. Cattle are known to be significant reservoirs of C. parvum, but transmission routes are complex and recent studies have implicated the potential role of wildlife in parasite transmission to cattle and water sources. On the Orkney Isles, high densities of Greylag geese (Anser anser) cause widespread faecal contamination of cattle pastures, where cryptosporidiosis is known to be the main cause of neonatal calf diarrhoea and Cryptosporidium contamination frequently occurs in two reservoirs supplying Mainland Orkney’s public water. This study aimed to determine the Cryptosporidium species and subtypes present in geese and calves co-grazing on four farms surrounding two reservoirs on Mainland Orkney. Results indicated a high level of C. parvum prevalence in calves, geese and water samples. gp60 analysis illustrated that higher genotypic diversity was present in the goose population compared with calves, but did not yield sequence results for any of the water samples. It can be concluded that the high levels of C. parvum evident in calves, geese and water samples tested represents a significant risk to water quality and public health.

Prevalence and molecular characterization of Cryptosporidium and Giardia in pre-weaned native calves in the Republic of Korea

Cryptosporidium spp. and Giardia duodenalis are protozoan parasites that cause diarrhea in humans and animals. Molecular data on Cryptosporidium spp. and G. duodenalis in calves in the Republic of Korea (ROK) is limited; thus, we investigated the prevalence of Cryptosporidium and Giardia in pre-weaned calves, analyzed the association between these parasites and diarrhea, and identified their zoonotic potential for human infection. Fecal samples were collected from 315 pre-weaned calves aged 1-60 days from 10 different regions in the ROK and screened for Cryptosporidium spp. and G. duodenalis using PCR. Overall prevalence of Cryptosporidium spp. and G. duodenalis was 4.4% (n = 14) and 12.7% (n = 40), respectively. Co-infection was not detected. All Cryptosporidium-positive samples were identified as C. parvum after sequence analysis of a small subunit rRNA fragment and further subtyped into zoonotic IIaA15G2R1 (n = 13) and IIaA18G3R1 (n = 1) by DNA sequencing of the 60-kDa glycoprotein gene. To our knowledge, this is the first report of C. parvum IIaA15G2R1 subtype in calves in the ROK. Based on β-giardin (bg) gene, G. duodenalis-positive samples belonged to assemblages E (n = 36) and A (n = 4), with the latter belonging to subtype A1, the zoonotic genotype. Six subtypes of assemblage E were identified at the bg locus: E1 (n = 6), E2 (n = 3), E3 (n = 13), E5 (n = 1), E8 (n = 1), and E11 (n = 1). The occurrence of C. parvum and G. duodenalis was not associated with diarrhea in pre-weaned Korean native calves. The present results suggest that the prevalence of C. parvum is not related to calf age; in contrast, the prevalence of G. duodenalis was significantly higher in 41-50-day-old calves (odds ratio = 9.90, 95% confidence interval 2.37-41.34; P = 0.001) than in 1-10-day-old calves. Therefore, calves are a potential source of zoonotic transmission, which may have significant public health implications.

Antibiogram, virulotyping and genetic diversity of Escherichia coli and Salmonella serovars isolated from diarrheic calves and calf handlers

Antimicrobial resistance profile of E. coli and Salmonella serovars isolated from diarrheic calves and handlers in Egypt is unknown due to the absence of monitoring. Therefore, this study aimed to determine the virulence, genetic and antimicrobial resistance profiles of E. coli and Salmonella serovars associated with diarrhea in calves and handlers in intensive dairy farms in Egypt. A total of 36 bacterial strains (20 E. coli and 16 Salmonella) were isolated from fecal samples of 80 diarrheic Holstein dairy calves (10 E. coli and 13 Salmonella) and hand swabs of 35 handlers (10 E. coli and 3 Salmonella) in two intensive dairy farms in Sharkia Governate in Egypt. E. coli strains belonged to six different serogroups and O114:K90 was the most prevalent serogroup (30%). However, Salmonella strains were serotyped into four different serogroups and S. Kiel was the most prevalent serotype (50%). Thirteen (65%) E. coli isolates were harbouring either stx2, eaeA and/or astA virulence-associated genes. However, stn and spvC virulence genes were detected in 2 (12.5%) and 4 (25%) of Salmonella isolates, respectively. E. coli isolates showed marked resistance to ampicillin (75%), while Salmonella strains exhibited high resistance to amikacin (100%), gentamicin (93.75%) and tobramycin (87.5%). Results of the present study showed that E. coli and Salmonella serovars isolated from diarrheic calves and handlers in intensive dairy farms in Egypt exhibited resistance to multiple classes of antimicrobials, which may pose a public health hazard. Thus, the continuous monitoring of antimicrobial resistance is necessary for both humans and veterinary medicine to decrease the economic losses caused by antimicrobial-resistant strains in animals as well as the zoonotic risk.

Bovine coronavirus in Uruguay: genetic diversity, risk factors and transboundary introductions from neighboring countries

Bovine coronavirus (BCoV) is a recognized cause of severe neonatal calf diarrhea, with a negative impact on animal welfare, leading to economic losses to the livestock industry. Cattle production is one of the most important economic sectors in Uruguay. The aim of this study was to determine the frequency of BCoV infections and their genetic diversity in Uruguayan calves and to describe the evolutionary history of the virus in South America. The overall detection rate of BCoV in Uruguay was 7.8% (64/824): 7.7% (60/782) in dairy cattle and 9.5% (4/42) in beef cattle. The detection rate of BCoV in samples from deceased and live calves was 10.0% (6/60) and 7.6% (58/763), respectively. Interestingly, there was a lower frequency of BCoV detection in calves born to vaccinated dams (3.3%, 8/240) than in calves born to unvaccinated dams (12.2%, 32/263) (OR: 4.02, 95%CI: 1.81–8.90; p = 0.00026). The frequency of BCoV detection was higher in colder months (11.8%, 44/373) than in warmer months (1.5%, 3/206) (OR: 9.05, 95%CI: 2.77–29.53, p = 0.000013). Uruguayan strains grouped together in two different lineages: one with Argentinean strains and the other with Brazilian strains. Both BCoV lineages were estimated to have entered Uruguay in 2013: one of them from Brazil (95%HPD interval: 2011–2014) and the other from Argentina (95%HPD interval: 2010–2014). The lineages differed by four amino acid changes, and both were divergent from the Mebus reference strain. Surveillance should be maintained to detect possible emerging strains that can clearly diverge at the antigenic level from vaccine strains.

Effectiveness of zinc supplementation on diarrhea and average daily gain in pre-weaned dairy calves: A double-blind, block-randomized, placebo-controlled clinical trial

The objective of this clinical trial was to evaluate the effectiveness of zinc supplementation on diarrhea and average daily weight gain (ADG) in pre-weaned dairy calves. A total of 1,482 healthy Holstein heifer and bull calves from a large California dairy were enrolled at 24 to 48 hours of age until hutch exit at approximately 90 days of age. Calves were block-randomized by time to one of three treatments: 1) placebo, 2) zinc methionine (ZM), or 3) zinc sulfate (ZS) administered in milk once daily for 14 days. Serum total protein at enrollment and body weight at birth, treatment end, and hutch exit were measured. Fecal consistency was assessed daily for 28 days post-enrollment. For a random sample of 127 calves, serum zinc concentrations before and after treatment and a fecal antigen ELISA at diarrhea start and resolution for Escherichia coli K99, rotavirus, coronavirus, and Cryptosporidium parvum were performed. Linear regression showed that ZM-treated bull calves had 22 g increased ADG compared to placebo-treated bulls (P = 0.042). ZM-treated heifers had 9 g decreased ADG compared to placebo-treated heifers (P = 0.037), after adjusting for average birth weight. Sex-stratified models showed that high birth weight heifers treated with ZM gained more than placebo-treated heifers of the same birth weight, which suggests a dose-response effect rather than a true sex-specific effect of ZM on ADG. Cox regression showed that ZM and ZS-treated calves had a 14.7% (P = 0.015) and 13.9% (P = 0.022) reduced hazard of diarrhea, respectively, compared to placebo-treated calves. Calves supplemented for at least the first five days of diarrhea with ZM and ZS had a 21.4% (P = 0.027) and 13.0% (P = 0.040) increased hazard of cure from diarrhea, respectively, compared to placebo-treated calves. Logistic regression showed that the odds of microbiological cure at diarrhea resolution for rotavirus, C. parvum, or any single fecal pathogen was not different between treatment groups. Zinc supplementation delayed diarrhea and expedited diarrhea recovery in pre-weaned calves. Additionally, zinc improved weight gain differentially in bulls compared to heifers, indicating a research need for sex-specific dosing.

Outbreak of cryptosporidiosis due to Cryptosporidium parvum subtype IIdA19G1 in neonatal calves on a dairy farm in China

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An outbreak of severe diarrhea was caused by Cryptosporidium parvum IIdA19G1 in dairy calves.

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Concurrence of rotavirus was present, but not as a significant cause of diarrhea in the investigation.

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Cryptosporidium parvum infection was associated with the occurrence of watery diarrhea in calves.

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Cryptosporidium ryanae and Cryptosporidium bovis infections were associated with the occurrence of moderate diarrhea.

Neonatal diarrhea is one of the most important syndromes in dairy cattle. Among enteropathogens, Cryptosporidium spp. are primary causes of diarrhea, but outbreaks due to cryptosporidiosis are rarely reported in cattle. From January to April in 2016, severe diarrhea was observed in over 400 neonatal dairy calves on a large dairy farm in Jiangsu Province of East China. Approximately 360 calves died due to watery diarrhea despite antibiotic therapy. In this study, 18 fecal specimens were collected from seriously ill calves on this farm during the diarrhea outbreak, and analysed for common enteropathogens by enzymatic immunoassay (EIA). In a post-outbreak investigation, 418 and 1372 specimens collected from animals of various age groups were further analysed for rotavirus and Cryptosporidium spp. by EIA and PCR, respectively, to assess their roles in the occurrence of diarrhea on the farm. Cryptosporidium spp. were genotyped using established techniques. Initial EIA tests showed that 15/18 seriously ill calves during the outbreak were positive for Cryptosporidium parvum, while 8/18 were positive for rotavirus. The overall infection rate of Cryptosporidium in pre-weaned calves on the farm was 22.7%, with odds of the Cryptosporidium infection during the outbreak 4.4–23.5 times higher than after the outbreak. Four Cryptosporidium spp. were identified after the outbreak including C. parvum (n = 79), Cryptosporidium ryanae (n = 48), Cryptosporidium bovis (n = 31), and Cryptosporidium andersoni (n = 3), with co-infections of multiple species being detected in 34 animals. Infection with C. parvum (73/79) was found in the majority of calves aged ≤3 weeks, consistent with the age of ill calves during the outbreak. All C. parvum isolates were identified as subtype IIdA19G1. In the post-outbreak investigation, C. parvum infection was associated with the occurrence of watery diarrhea in pre-weaned calves, C. ryanae infection was associated with moderate diarrhea in both pre- and post-weaned calves, while no association was identified between rotavirus infection and the occurrence of diarrhea. Results of logistic regression analysis further suggested that C. bovis infection might also be a risk factor for moderate diarrhea in calves. Thus, we believe this is the first report of a major outbreak of severe diarrhea caused by C. parvum IIdA19G1 in dairy calves. More attention should be directed toward preventing the dissemination of this virulent subtype in China.

[Detection of serovars of Salmonella in artificially reared calves in Mar y Sierras Dairy Basin, Argentina]

La salmonelosis es una de las enfermedades bacterianas que afectan el tracto digestivo de los terneros y provocan en ellos diarrea. Con el objetivo de estudiar la prevalencia de los distintos serovares de Salmonella en terneros de crianza artificial y determinar la asociación con signos diarreicos, se realizó un estudio epidemiológico con diseño transversal en la región lechera Mar y Sierras, ubicada en la Provincia de Buenos Aires (Argentina). Mediante hisopado de mucosa rectal, se muestrearon 726 terneros en período de crianza distribuidos en 50 establecimientos lecheros de dicha zona, se incluyeron animales con signos diarreicos y sin estos. Los aislamientos identificados como Salmonella spp. fueron tipificados utilizando antisueros poli- y monovalentes dirigidos contra antígenos somáticos, flagelares y capsulares (Vi). Salmonella spp. se detectó en el 36% de los establecimientos y los serovares hallados fueron S. Mbandaka, S. Anatum, S. Typhimurium, S. Dublin, S. Montevideo, S. Meleagridis, S. Newport, S. Seftemberg, S. subesp.16,7:z1, S. Infantis y S. Give. El 5,5% de los terneros fueron positivos y aquellos terneros con signología diarreica presentaron 5,9 veces más probabilidad de estar infectados con Salmonella spp. que aquellos que no tuvieron signos. La edad de los terneros positivos osciló desde un día hasta 53 días de vida; la mayor frecuencia se detectó al segundo día de nacidos. Se concluye que 11 serovares de Salmonella están presentes en más de un tercio de los establecimientos lecheros de la región lechera Mar y Sierras y que estos serovares mostraron estar asociados a la existencia de signos diarreicos en los terneros, sobre todo a la presencia de moco en las heces. La prevalencia de Salmonella fue mayor en terneros de menos de 21 días de vida.

Disinfection with hydrated lime may help manage cryptosporidiosis in calves

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Disinfection of calf pens with slaked lime delayed onset of diarrhea.

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Lime disinfection improved body condition in the calves.

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Lime disinfection did not affect diarrhea incidence or duration.

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Lime disinfection may help manage Cryptosporidium-associated diarrhea in problem herds.

Diarrhea is common in young calves and is often caused by Cryptosporidium parvum infection. The aim of this study was to investigate if disinfection of calf pens with hydrated lime would reduce contamination of C. parvum oocysts and improve calf health in herds with C. parvum associated diarrhea problems. Four dairy herds with ongoing C. parvum associated calf diarrhea problems each participated in the study over six to seven months. During the study period, all pens/huts for young calves were cleaned according to the usual farm routine before a new calf entered. Hydrated lime was then used to disinfect half of the pens/huts. Diarrhea incidence was recorded by the farmers and by veterinarians, who clinically examined the calves every second month. In total, 402 calves participated in the study. The farmers detected diarrhea in 214 (53%) calves, with similar proportions in calves kept in lime disinfected and control pens. Age at diarrhea onset was significantly higher in lime disinfected pens than in control pens, 9.0 days and 7.6 days, respectively. There was no difference between the groups regarding duration or severity index recorded by the farmers. The body condition score in 6–8 week old calves was significantly higher in calves that had been kept in lime disinfected pens during their first weeks of life, indicating that calves in disinfected pens/huts were less affected by their infections.

Faecal samples from 5 to 21 day old calves, were collected on four occasions at each farm (n = 95). Cryptosporidium positive samples were found at all samplings in all four herds. Cryptosporidium spp. was detected in 79 (83%) samples with no difference between lime disinfected and control pens. C. parvum was the dominant species. Two different C. parvum subtypes were found; IIaA16G1R1b in three herds and IIaA16G1R1b_variant in one herd. Only one subtype was found in each herd.

Disinfection of calf pens with slaked lime delayed onset of diarrhea and improved the body condition in the calves, but did not affect diarrhea incidence or duration. Although lime disinfection alone will not be sufficient to control Cryptosporidium associated diarrhea in herds with extensive calf diarrhea problems, these results suggest that it can be a valuable complement to other measures.

Dysbiosis of the fecal microbiota in feedlot cattle with hemorrhagic diarrhea

The bovine gastrointestinal microbiota is a complex polymicrobial ecosystem that plays an important role in maintaining mucosal health. The role of mucosal microbial populations in the pathogenesis of gastrointestinal diseases has been well established in other species. However, limited information is available about changes in the fecal microbiota that occur under disease conditions, such as hemorrhagic diarrhea in feedlot cattle. The objectives of this study were to characterize the differences in fecal microbiota composition, diversity and functional gene profile between feedlot calves with, and without, hemorrhagic diarrhea. Deep fecal swabs were collected from calves with hemorrhagic diarrhea (n = 5) and from pen matched healthy calves (n = 5). Genomic DNA was extracted, and V1-V3 hypervariable region of 16S rRNA gene was amplified and sequenced using the Illumina MiSeq sequencing. When compared to healthy calves, feedlot cattle with hemorrhagic diarrhea showed significant increases in the relative abundance of Clostridium, Blautia and Escherichia, and significant decreases in the relative abundance of Flavobacterium, Oscillospira, Desulfonauticus, Ruminococcus, Thermodesulfovibrio and Butyricimonas. Linear discriminant analysis effect size (LEfSe) also revealed significant differences in bacterial taxa between healthy calves and hemorrhagic diarrhea calves. This apparent dysbiosis in fecal microbiota was associated with significant differences in the predictive functional metagenome profiles of these microbial communities. In summary, our results revealed a bacterial dysbiosis in fecal samples of calves with hemorrhagic diarrhea, with the diseased calves exhibiting less diversity and fewer observed species compared to healthy controls. Additional studies are warranted in a larger cohort of animals to help elucidate the trajectory of change in fecal microbial communities, and their predictive functional capacity, in calves with other gastrointestinal diseases.

Evaluation of the in-field efficacy of oregano essential oil administration on the control of neonatal diarrhea syndrome in calves

The objective of this study was to evaluate under field conditions, whether daily administration of oregano essential oil is effective in preventing and/or diminishing the severity of neonatal diarrhea syndrome in calves aged less than 15days. Ninety-one newborn calves from three dairy farms were assigned into two groups; "Eco" group (n=46) calves were drenched with Greek oregano (Origanum vulgare ssp. Hirtum) essential oil (ECODIAR® liquid 5%) at the dose of 12.5mg/kg body weight once per day until the age of 10days. "Conts" group (n=45) calves were left untreated and served as controls. All animals were monitored daily for the incidence of diarrhea until the age of 15days and their fecal score was recorded. Fecal samples were collected on days 3, 6 and 10 for microbiological and parasitological evaluation. Average fecal score throughout the experiment, incidence of diarrhea, duration and severity of diarrhea episodes were significantly lower in Eco group compared to the controls. Daily administration of oregano essential oil in calves for the first 10days of their life effectively diminishes the severity of naturally acquired diarrhea under field conditions and, under certain hygiene practices, possess a preventive effect against neonatal diarrhea syndrome.

Molecular Epidemiology of Cryptosporidiosis in China

Molecular epidemiology of cryptosporidiosis is an active research area in China. The use of genotyping and subtyping tools in prevalence studies has led to the identification of unique characteristics of Cryptosporidium infections in humans and animals. Human cryptosporidiosis in China is exemplified by the high diversity of Cryptosporidium spp. at species and subtype levels, with dominant C. hominis and C. parvum subtypes being rarely detected in other countries. Similarly, preweaned dairy calves, lambs, and goat kids are mostly infected with non-pathogenic Cryptosporidium species (C. bovis in calves and C. xiaoi in lambs and goat kids), with C. parvum starting to appear in dairy calves as a consequence of concentrated animal feeding operations. The latter Cryptosporidium species is dominated by IId subtypes, with IIa subtypes largely absent from the country. Unlike elsewhere, rodents in China appear to be commonly infected with C. parvum IId subtypes, with identical subtypes being found in these animals, calves, other livestock, and humans. In addition to cattle, pigs and chickens appear to be significant contributors to Cryptosporidium contamination in drinking water sources, as reflected by the frequent detection of C. suis, C. baileyi, and C. meleagridis in water samples. Chinese scientists have also made significant contributions to the development of new molecular epidemiological tools for Cryptosporidium spp. and improvements in our understanding of the mechanism involved in the emergence of hyper-transmissible and virulent C. hominis and C. parvum subtypes. Despite this progress, coordinated research efforts should be made to address changes in Cryptosporidium transmission because of rapid economic development in China and to prevent the introduction and spread of virulent and zoonotic Cryptosporidium species and subtypes in farm animals.

Giardia and Cryptosporidium infections in neonatal reindeer calves: Relation to the acute phase response

This longitudinal observational study was conducted to investigate the spontaneous effect of Giardia and Cryptosporidium infections on acute phase response (APR) in reindeer calves (Rangifer tarandus tarandus) in Finnish Lapland. Serum (n=609) and faecal samples (n=366) were collected from 54 reindeer calves aged zero to 33days. The samples were analysed for Giardia, Cryptosporidium, acute phase proteins (APP) and γ-globulins. Linear regression models were used to investigate associations of early Giardia infection (before 12days of life) with the response of APPs and acquiring of passive immunity. Giardia was detected in 100% and Cryptosporidium in 23% of calves. There was a negative association between early Giardia infection and γ-globulin concentrations (p=0.032) and a positive association with serum amyloid A (SAA) concentrations (p=0.042). The results suggest a protective effect of colostrum against Giardia infection and that early infection may induce activation of APR.

Bovine cryptosporidiosis: impact, host-parasite interaction and control strategies

Gastrointestinal disease caused by the apicomplexan parasite Cryptosporidium parvum is one of the most important diseases of young ruminant livestock, particularly neonatal calves. Infected animals may suffer from profuse watery diarrhoea, dehydration and in severe cases death can occur. At present, effective therapeutic and preventative measures are not available and a better understanding of the host-pathogen interactions is required. Cryptosporidium parvum is also an important zoonotic pathogen causing severe disease in people, with young children being particularly vulnerable. Our knowledge of the immune responses induced by Cryptosporidium parasites in clinically relevant hosts is very limited. This review discusses the impact of bovine cryptosporidiosis and describes how a thorough understanding of the host-pathogen interactions may help to identify novel prevention and control strategies.

Antimicrobial susceptibility and phylotyping profile of pathogenic Escherichia coli and Salmonella enterica isolates from calves and pigs in Minas Gerais, Brazil

The aims of the present study were to determine (i) the profiles of phylogroup and (ii) the antimicrobial susceptibility of pathogenic Escherichia coli strains isolated from calves, and of Salmonella spp. strains isolated from calves and pigs in Minas Gerais State, Brazil. Sixty-one pathogenic E. coli strains and Salmonella spp. (n = 24) strains isolated from fecal samples of calves and Salmonella spp. (n = 39) strains previously isolated from fecal samples of growing/finishing pigs were tested. The minimum inhibitory concentration (MIC) using the agar dilution method was determined for nalidixic acid, amikacin, amoxicillin, ampicillin, cefoxitin, norfloxacin, gentamicin, tetracycline, and trimethoprim-sulfamethoxazole. All E. coli isolates were susceptible to amikacin. Tetracycline was the antimicrobial that presented the higher frequency of resistance among E. coli strains, followed by ampicillin, trimethoprim-sulfamethoxazole, amoxicillin, nalidixic acid, norfloxacin, gentamicin, and cefoxitin. E. coli (n = 61) strains isolated from calves belonged to different phylogroup namely, phylogroup A (n = 26), phylogroup B1 (n = 31), phylogroup E (n = 3), and phylogroup F (n = 1). Phylogroups B2, C, and D were not identified among the E. coli in the present study. All Salmonella spp. (n = 24) strains isolated from fecal samples of calves were susceptible to amikacin, amoxicillin, ampicillin, norfloxacin, gentamicin, tetracycline, and trimethoprim-sulfamethoxazole. Resistance to nalidixic acid and cefoxitin was detected in 16.66 and 8.33 % of the Salmonella spp. strains, respectively. Among the Salmonella spp. (n = 39) strains isolated from fecal samples of pigs, the higher frequency of resistance was observed to tetracycline, followed by amoxicillin, gentamicin, ampicillin, trimethoprim-sulfamethoxazole, nalidixic acid, cefoxitin, and norfloxacin. All strains were susceptible to amikacin. Forty-eight (78.68 %) of the E. coli strains were classified as multidrug-resistant, whereas among Salmonella spp. strains, the percentage of multidrug resistance was 57.14 %, being all multidrug-resistant strains isolated from pigs (92.30 %). The results from the present study indicate a high frequency of antimicrobial resistance among pathogenic E. coli strains isolated from calves and Salmonella spp. strains isolated from pigs and a high rate of susceptibility to most antimicrobials tested among Salmonella spp. strains isolated from calves. Our study highlights the presence of multidrug-resistant strains of E. coli and Salmonella spp. isolated from food-producing animals in Minas Gerais, Brazil.

A novel astrovirus species in the gut of yaks with diarrhoea in the Qinghai–Tibetan Plateau, 2013

The yak (Bos grunniens) is an iconic symbol in the high-altitude region of the Qinghai–Tibetan Plateau. Diarrhoea is a common disease in yaks, resulting in major economic losses. To investigate the diversity of viral species, we reported the metagenomics-derived virome in a pooled faecal sample of 20 diarrhoeic yaks. The nine viruses found in the pooled diarrhoeic samples, in order of abundance of nucleic acid sequence, were influenza A virus, bovine viral diarrhoea virus (BVDV), rotavirus, ungulate tetraparvovirus 1 (bovine hokovirus), astrovirus (AstV), bovine enterovirus, hepatitis E virus, kobuvirus and woodchuck hepatitis virus. Compared with healthy yaks, only AstV had a significantly higher prevalence rate in diarrhoeal samples, indicating a correlation with the clinical symptoms of diarrhoea in yaks. To further investigate the molecular characterization of yak AstV, a near-full genome was obtained from a diarrhoeic sample. It was 6243 bp in length and shared 46.4–66.2 % similarity with other related bovine AstVs from faeces. Phylogenetic analysis of the genome demonstrated that the yak AstV fell within the bovine AstVs cluster, but was located in a unique lineage, suggesting a novel AstV species was identified in yaks. Interestingly, the ORF2 region of yak AstV had closer similarity and genetically relationship with deer AstV strain CcAstV-2 than that of the bovine AstVs. Further analysis showed that one possible interspecies recombination event occurred in ORF2. In summary, this study expanded our understanding of the viral communities of diarrhoeal yaks and identified a novel AstV that was associated with diarrhoea in yaks.

Presence of antibodies but no evidence for circulation of MERS-CoV in dromedaries on the Canary Islands, 2015

In 2012, a new betacoronavirus, Middle East respiratory syndrome coronavirus (MERS-CoV), was identified in humans. Several studies confirmed dromedary camels to be a potential reservoir and a source for human infection. Camels located on the Canary Islands were included in those studies and ca 10% of them were positive for MERS-CoV-specific antibodies. However, these findings could not be correctly interpreted because epidemiological information was not provided. Thus, further investigations were necessary to clarify these results. A total of 170 camels were investigated in this survey, of which seven (4.1%) were seropositive by ELISA. Epidemiological information revealed that all seropositive camels had been imported from Africa 20 or more years prior. We conclude that seropositive camels had contact with MERS-CoV in Africa and that there is no shedding of the virus among camels or people around the farms on the Canary Islands. However, the presence of antibodies in the camel herds should be monitored.

Characterization of Escherichia coli isolated from calf diarrhea in and around Kombolcha, South Wollo, Amhara Region, Ethiopia

This study was carried out from October 2012 to end of February 2013 in and around Kombolcha, Amhara regional state, Ethiopia, using a total of 201 neonatal calves aged 1 day to 4 months and suffering from diarrhea. The objectives of the study were to isolate Escherichia coli from diarrheic calves, and to determine E. coli biotypes and risk factors associated with its isolation. The fecal samples were collected, transported, and processed following standard microbiological procedures. Seventy-four isolates of E. coli were identified. Yellowish diarrhea, younger age, and low-colostrum feeding were significantly associated with rate of E. coli isolation (P < 0.05). Then the 74 isolates of E. coli were biotyped using fermentation of 9 sugars and grouped into 12 biotypes; the most dominant was biotype III (36.8 %). Finally, by comparing with studies elsewhere, from the 12 isolated biotypes, 3 of them were suggested to be enteropathogenic E. coli (EPEC), entherotoxigenic E. coli (ETEC), and adhesion and effacing E. coli (AEEC) pathogenic strains. The present study showed that E. coli accounted for 37 % of calf diarrhea, with very diverse biotypes.