Diarrheic Calves Research Articles

A one health study on phylogenetics and risk of pathogenic intestinal parasites at a ranch in Inner Mongolia

Cryptosporidium, Giardia duodenalis, and Enterocytozoon bieneusi are widespread zoonotic pathogens causing gastrointestinal diseases in humans and various animal species. Inner Mongolia, a major beef production region in China, there is a notable absence of comprehensive research on intestinal parasitism. Thus, timely and comprehensive diagnosis is essential to mitigate disease spread and minimize economic losses in the livestock industry. In this study, we collected fecal samples from cattle and humans, as well as soil and water samples, and all samples were tested for pathogenic intestinal protozoa at the Simmental cattle ranch in Wengniute, Chifeng City, Inner Mongolia. Among the 393 samples tested, 76/371 (20.5 %) cattle, 6/11 (54.5 %) ranch workers, 1/7 (14.3 %) water, and 2/4 (50 %) soil samples were positive. Factors affecting the infection rate of intestinal protozoa were examined. Results showed that the infection rate was higher in June than in January, higher in calves than in adults, and higher in diarrheal calves than in healthy calves. Additionally, the infection rate of intestinal protozoa was higher in pathogen-contaminated water source sheds than in uncontaminated sheds. Genetic and evolutionary analyses revealed that the prevalent E. bieneusi subtypes are predominantly J, I, and BEB4, while the G. duodenalis subtypes are assemblages B and E. The Cryptosporidium species identified were C. bovis, C. andersoni, C. parvum, C. ryanae, and C. suis, with C. parvum being a notable zoonotic pathogen. The pathogen sequences from humans, cattle, water, and soil showed 99–100 % similarity, suggesting possible transmission or contamination between animals and the environment. This study contributes to the One Health approach by addressing the gap in research on intestinal protozoa in Inner Mongolia. It provides important data for other ranches in the region to understand the prevalence of such pathogens and develop effective control measures. Using the concept of One Health to analyze the spatiotemporal distribution of intestinal protozoa in pastures is of great significance for maintaining public health.

Pestivirus bovis is implicated in repeated abortions and subfertility of vaccinated cattle in Egypt

The study of Pestivirus bovis, formerly known as Bovine Viral Diarrhea Virus (BVDV), is of significant importance due to the economic challenges it poses in cattle herds in several countries. This virus leads to decreased productivity, reproductive failures, and increased susceptibility to secondary infections. The current study aimed to investigate the role of BVDV in abortion and infertility among cattle in Egypt using advanced diagnostic techniques. We employed a one-step multiplex real-time reverse transcription polymerase chain reaction (rRT-PCR) to detect BVDV, and the results showed an overall prevalence of 11.2% among 178 tested samples. Notably, 11.2% tested positive for BVDV-1, with higher detection rates in adult cows (12.1%) compared to calves (9.85%). Importantly, 13.8% of samples from dams with subfertility and repeated abortions were positive for BVDV-1. The results of rRT-PCR guided virus isolation using Madin–Darby bovine kidney (MDBK) cells. Identifying cytopathic effects (CPEs) in 15% of the samples, consistent with cytopathic-BVDV (CP-BVDV). An indirect fluorescent antibody assay (IFA) confirmed the presence of CP-BVDV in these samples. For non-cytopathic (NCP)-strains, the immunoperoxidase (IP) test using bovine turbinate (BT) cells was more effective, detecting NCP-BVDV in samples without CPE in MDBK cells. The presence of mixed infection was indicated by an isolate from a diarrheic calf, showing positive results for both CP-BVDV and NCP-BVDV. Plaque assays further confirmed CP-BVDV and NCP-BVDV isolation from mixed infections, highlighting the selective amplification of both biotypes. These findings underscore the significant role of BVDV-1 in reproductive disorders in cattle and the importance of employing comprehensive diagnostic methods for effective control and management strategies. Our study provides valuable insights that can guide future studies and improve herd health and productivity.

Prevalence and molecular characterization of Cryptosporidium spp. in pre-weaned diarrheic dairy calves and their bedding materials in northern China.

Cryptosporidiosis, primarily caused by Cryptosporidium parvum, is a significant cause of diarrhea in pre-weaned dairy calves. To investigate the prevalence of Cryptosporidium among pre-weaned diarrheic dairy calves and identify potential sources of infection in northern China, 234 fecal samples from 18 farms in six regions were analyzed for Cryptosporidium. Furthermore, 217 bedding samples from both occupied and unoccupied calf hutches, heating lamp pens, and individual calving pens in eight farms in Beijing were also examined for the presence of the parasite. All samples were screened for Cryptosporidium spp. using nested PCR targeting the SSU rRNA gene fragment, and C. parvum was subtyped with nested PCR targeting the 60kDa glycoprotein gene. The prevalence of Cryptosporidium was 33.3%, with C. parvum and C. bovis constituting 29.9% and 3.4% of cases, respectively. The positive rate of Cryptosporidium in 1- to 4-week-old calves ranged from 9.6 to 63.6%. Analysis of the gp60 fragment of C. parvum revealed four subtypes: IIdA15G1, IIdA17G1, IIdA19G1, and IIdA20G1. Besides the bedding samples in heating lamp pens, both C. parvum and C. bovis were detected in bedding samples throughout the other regions. A significant positive correlation between the detection rate of Cryptosporidium in fecal samples and that in the bedding materials of occupied calf hutches (R = 0.93, P = 0.002). These findings suggest that C. parvum is the predominant species among pre-weaned diarrheic dairy calves in northern China. Contaminated bedding materials may act as sources of infection for newborn calves.

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

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

Fecal microbiota of diarrheic calves: Before, during, and after recovering from disease.

It is unknown if gastrointestinal dysbiosis in diarrheic calves causes disease or is a consequence of the disease. Describe the fecal microbiota of calves before, during, and after recovering from diarrhea. Fifteen female Holstein calves of 0 to 21 days old from a single farm. Seven calves remained healthy throughout the study, and 8 developed diarrhea on Day 14. Longitudinal cohort study. Microbiota composition was characterized by amplifying the V4 region of the 16S rRNA gene. Diversity (Shannon index) increased with age in healthy and diarrheic calves from Day 3 to 21, but diarrheic calves had a lower diversity on the day diarrhea was first observed (Day 14). By Day 21, diversity increased in calves that recovered from diarrhea and was not significantly different from that of their healthy counterparts (P > .05). Weighted UniFrac distance showed significant differences in the fecal microbiota between diarrheic and healthy calves at Day 14 of age (PERMANOVA, P < .05), but not before or after diarrhea (PERMANOVA, P > .05). Lactobacillus, Clostridium Sensu Stricto 1, and Collinsella were differentially abundant on Day 10 in calves that developed diarrhea on Day 14 (P < .05). The fecal microbiota of healthy and diarrheic calves evolved similarly during the first 10 days of age but differed significantly on the day of onset of diarrhea. Enriching Lactobacillus, Clostridium Sensu Stricto 1, and Collinsella before diarrhea onset could have been contributed to the development of diarrhea.

Comparison between the dilution of electrolyte concentrate in milk or water for oral rehydration of diarrheal calves

The administration of oral electrolyte solution (OES) is the most used method to correct dehydration and electrolyte and acid-base imbalances in calves with diarrhea. To prepare OES, the electrolyte concentrate (EC) is diluted in water. Alternatively, it can be diluted in milk and the correction of dehydration depends on voluntary water intake. Although dilution in milk is used, its efficacy has not been fully proven. This study compared the effectiveness of two rehydration methods in correcting imbalances in diarrheal calves. Twenty-four neonatal calves with induced osmotic diarrhea were distributed into two treatment groups using a commercial EC: GM with EC diluted in the milk at meals; and GW with EC diluted in water (volumes of 5% BW, at 4 and 12 h). All were fed with milk (volumes of 4% BW, at 0, 8, and 16 h) and had free access to water. Clinical and laboratory variables were monitored over time up to 48 h. The calves presented moderate dehydration, hyponatremia, relative hyperchloremia and moderate strong ion metabolic acidosis. Both rehydration methods were effective in correcting imbalances and reestablishing plasma SID3 at the end of the day of treatment. Plasma volume expansion was faster in GW. Electrolyte-enriched milk is as efficient as OES for treating diarrheal calves.

Detection and molecular characterization of major enteric pathogens in calves in central Ethiopia

BackgroundCalf diarrhea is a major cause of morbidity and mortality in the livestock sector worldwide and it can be caused by multiple infectious agents. In Ethiopia, cattle are the most economically important species within the livestock sector, but at the same time the young animals suffer from high rates of morbidity and mortality due to calf diarrhea. However, studies including both screening and molecular characterization of bovine enteric pathogens are lacking. Therefore, we aimed to both detect and molecularly characterize four of the major enteric pathogens in calf diarrhea, Enterotoxigenic Escherichia coli (E. coli K99 +), Cryptosporidium spp., rotavirus A (RVA), and bovine coronavirus (BCoV) in calves from central Ethiopia. Diarrheic and non-diarrheic calves were included in the study and fecal samples were analyzed with antigen-ELISA and quantitative real-time PCR (qPCR). Positive samples were further characterized by genotyping PCRs.ResultsAll four pathogens were detected in both diarrheic and non-diarrheic calves using qPCR and further characterization showed the presence of three Cryptosporidium species, C. andersoni, C. bovis and C. ryanae. Furthermore, genotyping of RVA-positive samples found a common bovine genotype G10P[11], as well as a more unusual G-type, G24. To our knowledge this is the first detection of the G24 RVA genotype in Ethiopia as well as in Africa. Lastly, investigation of the spike gene revealed two distinct BCoV strains, one classical BCoV strain and one bovine-like CoV strain.ConclusionsOur results show that Cryptosporidium spp., E. coli K99 + , RVA and BCoV circulate in calves from central Ethiopia. Furthermore, our findings of the rare RVA G-type G24 and a bovine-like CoV demonstrates the importance of genetic characterization.

Determining lactate concentrations in Korean indigenous calves and evaluating its role as a predictor for acidemia in calf diarrhea

BackgroundCalf diarrhea leads to high mortality rates and decreases in growth and productivity, causing negative effects on the livestock industry. Lactate is closely associated with metabolic acidosis in diarrheic calves. However, there have been no reports on lactate concentrations in Korean indigenous (Hanwoo) calves, especially those with diarrhea. This study aimed to determine the reference range of L-lactate and D-lactate concentrations in Hanwoo calves and to better understand the utility of lactate as predictive factors for acidemia in diarrheic calves.ResultsL-lactate and D-lactate concentrations were measured in healthy (n = 44) and diarrheic (n = 93) calves, and blood gas analysis was performed on diarrheic calves. The reference range in healthy calves was 0.2–2.25 mmol/L for L-lactate and 0.42–1.38 mmol/L for D-lactate. Diarrheic calves had higher concentrations of L-lactate and D-lactate than healthy calves. In diarrheic calves, L-lactate and D-lactate each had weak negative correlation with pH (r = − 0.31 and r = − 0.35). In diarrheic calves with hyper-L-lactatemia, the combined concentrations of L-lactate and D-lactate had moderate correlation with pH (r = − 0.51) and anion gap (r = 0.55). Receiver operating characteristic analysis showed D-lactate had fair predictive performance (AUC = 0.74) for severe acidemia, with an optimal cut-off value of > 1.43 mmol/L. The combined concentrations of L-lactate and D-lactate showed fair predictive performance for predicting acidemia (AUC = 0.74) and severe acidemia (AUC = 0.72), with cut-off values of > 6.05 mmol/L and > 5.95 mmol/L.ConclusionsThe determined reference ranges for L-lactate and D-lactate in Hanwoo calves enable the identification of hyper-L-lactatemia and hyper-D-lactatemia. Diarrheic calves exhibited increased lactate concentrations correlated with acid-base parameters. While the concentrations of L-lactate and D-lactate have limitations as single diagnostic biomarkers for predicting acidemia or severe acidemia, their measurement remains important, and L-lactate has the advantage of being measurable at the point-of-care. Assessing lactate concentrations should be considered by clinicians, especially when used alongside other clinical indicators and diagnostic tests. This approach can improve calf diarrhea management, contributing positively to animal welfare and providing economic benefits to farms.

Dynamic Analysis of Stool Microbiota of Simmental Calves and Effects of Diarrhea on Their Gut Microbiota.

The objective of this study was to explore the dynamic changes in the gut microbiota of Simmental calves before weaning and to compare the microbial composition and functionality between healthy calves and those with diarrhea. Fourteen neonatal Simmental calves were divided into a healthy group (n = 8) and a diarrhea group (n = 6). Rectal stool samples were collected from each calf on days 1, 3, 5, 7, 9, 12, 15, 18, 22, 26, 30, 35, and 40. High-throughput sequencing of the 16S rRNA gene V1-V9 region was conducted to examine changes in the gut microbiota over time in both groups and to assess the influence of diarrhea on microbiota structure and function. Escherichia coli, Bacteroides fragilis, and B. vulgatus were the top three bacterial species in preweaning Simmental calves. Meanwhile, the major functions of the fecal microbiota included "metabolic pathways", "biosynthesis of secondary metabolites", "biosynthesis of antibiotics", "microbial metabolism in diverse environments", and "biosynthesis of amino acids". For calves in the healthy group, PCoA revealed that the bacterial profiles on days 1, 3, 5, 7, and 9 differed from those on days 15, 18, 22, 26, 30, 35, and 40. The profiles on day 12 clustered with both groups, indicating that microbial structure changes increased with age. When comparing the relative abundance of bacteria between healthy and diarrheic calves, the beneficial Lactobacillus johnsonii, Faecalibacterium prausnitzii, and Limosilactobacillus were significantly more abundant in the healthy group than those in the diarrhea group (p < 0.05). This study provides fundamental insights into the gut microbiota composition of Simmental calves before weaning, potentially facilitating early interventions for calf diarrhea and probiotic development.

Multi-omics strategy reveals potential role of antimicrobial resistance and virulence factor genes responsible for Simmental diarrheic calves caused by Escherichia coli.

Escherichia coli (E. coli) is reported to be an important pathogen associated with calf diarrhea. Antibiotic resistance genes (ARGs) and virulence factor genes (VFGs) pose a considerable threat to both animal and human health. However, little is known about the characterization of ARGs and VFGs presented in the gut microbiota of diarrheic calves caused by E. coli. In this study, we used multi-omics strategy to analyze the ARG and VFG profiles of Simmental calves with diarrhea caused by E. coli K99. We found that gut bacterial composition and their microbiome metabolic functions varied greatly in diarrheic calves compared to healthy calves. In total, 175 ARGs were identified, and diarrheal calves showed a significantly higher diversity and abundance of ARGs than healthy calves. Simmental calves with diarrhea showed higher association of VFGs with pili function, curli assembly, and ferrienterobactin transport of E. coli. Co-occurrence patterns based on Pearson correlation analysis revealed that E. coli had a highly significant (P < 0.0001) correlation coefficient (>0.8) with 16 ARGs and 7 VFGs. Metabolomics analysis showed that differentially expressed metabolites in Simmental calves with diarrhea displayed a high correlation with the aforementioned ARGs and VFGs. Phylotype analysis of E. coli genomes showed that the predominant phylogroup B1 in diarrheic Simmental calves was associated with 10 ARGs and 3 VFGs. These findings provide an overview of the diversity and abundance of the gut microbiota in diarrheic calves caused by E. coli and pave the way for further studies on the mechanisms of antibiotic resistance and virulence in the calves affected with diarrhea.IMPORTANCESimmental is a well-recognized beef cattle breed worldwide. They also suffer significant economic losses due to diarrhea. In this study, fecal metagenomic analysis was applied to characterize the antibiotic resistance gene (ARG) and virulence factor gene (VFG) profiles of diarrheic Simmental calves. We identified key ARGs and VFGs correlated with Escherichia coli isolated from Simmental calves. Additionally, metabolomics analysis showed that differentially expressed metabolites in Simmental calves with diarrhea displayed a high correlation with the aforementioned ARGs and VFGs. Our findings provide an insight into the diversity and abundance of the gut microbiota in diarrheic calves caused by Escherichia coli and pave the way for further studies on the mechanisms of antibiotic resistance and virulence in the diarrheal calves from cattle hosts.

Characterization of the preweaned Holstein calf fecal microbiota prior to, during, and following resolution of uncomplicated gastrointestinal disease

Little is known about shifts in the fecal microbiome of dairy calves preceding and following the incidence of gastrointestinal disease. The objective of this cohort study was to describe the fecal microbiome of preweaned dairy calves before, during, and after gastrointestinal disease. A total of 111 Holstein dairy calves were enrolled on 2 dairies (D1 and D2) and followed until 5 weeks old. Health assessments were performed weekly and fecal samples were collected every other week. Of the 111 calves, 12 calves from D1 and 12 calves from D2 were retrospectively defined as healthy, and 7 calves from D1 and 11 calves from D2 were defined as diarrheic. Samples from these calves were sequenced targeting the 16S rRNA gene and compared based on health status within age groups and farms: healthy (0–1 week old) vs. pre-diarrheic (0–1 week old), healthy (2–3 weeks old) vs. diarrheic (2–3 weeks old), and healthy (4–5 weeks old) vs. post-diarrheic (4–5 weeks old) calves. Healthy and diarrheic samples clustered together based on age rather than health status on both farms. Based on linear discriminant analysis, a few species were identified to be differently enriched when comparing health status within age groups and farm. Among them, Bifidobacterium sp. was differently enriched in pre-diarrheic calves at D1 (0–1 week old) whereas healthy calves of the same age group and farm showed a higher abundance of Escherichia coli. Bifidobacterium sp. was identified as a biomarker of fecal samples from healthy calves (2–3 weeks old) on D1 when compared with diarrheic calves of the same age group and farm. Feces from diarrheic calves on D2 (2–3 weeks old) were characterized by taxa from Peptostreptococcus and Anaerovibrio genera whereas fecal samples of age-matched healthy calves were characterized by Collinsella aerofaciens and Bifidobacterium longum. After resolution of uncomplicated diarrhea (4–5 weeks old), Collinsella aerofaciens was more abundant in D2 calves whereas Bacteriodes uniformis was more abundant in D1 calves. Taken together, these findings suggest that the age of the preweaned calf is the major driver of changes to fecal microbiome composition and diversity even in the face of uncomplicated gastrointestinal disease.

Detection and Genetic Characterization of Bovine Torovirus in Uruguay.

Bovine torovirus (BToV) is an enteric pathogen that may cause diarrhea in calves and adult cattle, which could result in economic losses due to weight loss and decreased milk production. This study aimed to report the presence, the genetic characterization and the evolution of BToV in calves in Uruguay. BToV was detected in 7.9% (22/278) of fecal samples, being identified in dairy (9.2%, 22/239) but not beef (0.0%, 0/39) calves. BToV was detected in both diarrheic (14%, 6/43) and non-diarrheic (13.2%, 5/38) dairy calves. In addition, BToV was detected in the intestinal contents of 14.9% (7/47) of naturally deceased dairy calves. A complete genome (28,446 nucleotides) was obtained, which was the second outside Asia and the first in Latin America. In addition, partial S gene sequences were obtained to perform evolutionary analyses. Nucleotide and amino acid substitutions within and between outbreaks/farms were observed, alerting the continuous evolution of the virus. Through Bayesian analysis using BEAST, a recent origin (mid-60s) of BToV, possibly in Asia, was estimated, with two introductions into Uruguay from Asia and Europe in 2004 and 2013, respectively. The estimated evolutionary rate was 1.80 × 10-3 substitutions/site/year. Our findings emphasize the importance of continued surveillance and genetic characterization for the effective management and understanding of BToV's global epidemiology and evolution.

Fecal shedding of Clostridioides difficile in calves in Sao Paulo state, Brazil

ObjectiveThis study aimed to evaluate the fecal shedding of C. difficile in calves on farms in Sao Paulo State, Brazil. Materials and methodsFecal samples (n = 300) were collected from diarrheic (n = 78) and nondiarrheic (n = 222) calves less than 60 days of age from 20 farms. Fecal samples were inoculated into enrichment broth supplemented with taurocholate and cultured under anaerobic conditions. Colonies suspected to be C. difficile were harvested for DNA extraction and then multiplex PCR for the detection of genes encoding toxins A and B and binary toxins. All toxigenic isolates were ribotyped and tested for antimicrobial susceptibility, and five selected strains were subjected to whole-genome sequencing to determine their sequence type. Results and discussionC. difficile was isolated from 29.3 % (88/300) of the samples. All toxigenic isolates (17/88, 19.3 %) were classified as ribotypes RT046 (13/17–79.47 %, A+B+ CDT−) and RT126 (4/17 = 20.53 %, A+B+ CDT+). The sequenced strains from RT046 were classified as ST35 (Clade 1), while those from RT126 were classified as ST11 (Clade 5). No associations between the epidemiological factors in any of the groups and C. difficile isolation were observed. Most of the toxigenic isolates (16/17 = 94.41 %) were classified as multidrug-resistant. Calves can be an important source of toxigenic C. difficile strains, including multidrug-resistant isolates from ribotypes commonly observed in humans.

Genetic characterization and clinicopathological features of &lt;em&gt;Escherichia coli&lt;/em&gt; in neonatal septicemic calves

Due to severe diarrhea associated with calf scour and septicemia, colibacillosis is one of the leading causes of neonatal mortality in calves. This study investigated the clinical and hematological manifestations as well as the genetic composition of Shiga toxin-producing E. coli (STEC) strains in septicemic neonatal calves. In this study, 47 fecal specimens were collected from diarrheic calves aged between one and three weeks on dairy farms that are unorganized around Basra, Iraq, while twenty age-matched calves were tested as controls. Of the 47 tested samples, 28 fecal samples were tentatively identified as STEC, with a prevalence of 60%. STEC-affected calves had variable rectal temperatures ranging from subnormal to fever, tachycardia, hyperpnea, diarrhea, partial or complete cessation of suckling, mucous membrane congestion, depression, incoordination and rough hair coat conditions. Significant changes were observed in the hemogram and the leukogram during the analysis of blood samples from calves with diarrhea. Molecular analysis of fecal samples demonstrated that local STEC isolates are more closely related to other strains obtained from both human and animal samples worldwide. Based on the results of the current study, we can conclude that the septicemic calves were likely infected by human or environmental resources and could play a major role in further spreading STEC infection.

Prevalence of rotavirus, coronavirus, Cryptosporidium spp, Escherichia coli K99 and Giardia lamblia in neonatal calves with diarrhea in Burdur and its districts

TThe aim of this study is to determine the prevalence of pathogens such as Rotavirus, Coronavirus, Cryptosporidium spp, Escherichia coli K99, and Giardia lamblia in neonatal calves with diarrhea in Burdur and its districts. The study material consisted of 96 diarrheic calves aged between 1 and 28 days from different cattle farms in the Burdur region. Fecal samples were collected, and the causative agents were identified using rapid diagnostic kits (BoviD-5 Ag Test Kit- BIONOTE). In the study, among the 96 diarrheic calves, a single enteropathogen was detected in 61 (63.54%), and 25 (26.04%) of these calves were positive for Cryptosporidium, 12 (12.5%) for E. coli K99, 11 (11.45%) for Rotavirus, 7 (7.29%) for Coronavirus, and 6 (6.25%) for Giardia lamblia, respectively. Multiple enteropathogens were responsible for diarrhea in 18 calves, and 2 (2.08%) of them were Cryptosporidium spp.+Giardia lamblia, 8 (8.33%) Cryptosporidium spp.+Rotavirus, 3 (3.12%) Coronavirus+Rotavirus, with 1 (1.04%) Coronavirus+Cryptosporidium spp., 2 (2.08%) Rotavirus+E. coli, and 1 (1.04%) of them was E. coli+Cryptosporidium spp.+Rotavirus. Among the 96 diarrheic calves with mixed infections or a single enteropathogen, 38 (39.58%) had Cryptosporidium, 15 (15.62%) had E. coli K99, 26 (27.08%) had Rotavirus, 12 (12.50%) had Coronavirus, and 8 (8.33%) had Giardia lamblia. However, in 17 of the 96 diarrheic calves, neither mono- nor multiple enteropathogens were detected, suggesting that other factors might have caused diarrhea. Finally, this research provides valuable information for faster diagnosis, prevention, control, and treatment of enteropathogens causing diarrhea in neonatal calves in the Burdur region, contributing to reducing calf losses. It is believed that the research findings will shed light on future studies.

Health-associated changes of the fecal microbiota in dairy heifer calves during the pre-weaning period.

Neonatal calf diarrhea is a multifactorial condition that occurs in early life when calves are particularly susceptible to enteric infection and dysbiosis of the gut microbiome. Good calf health is dependent on successful passive transfer of immunity from the dam through colostrum. There are limited studies on the developing gut microbiota from birth to weaning in calves. Therefore, the objective of this study was to examine the effect of immune status and diarrheal incidence on the development of the fecal microbiota in Jersey (n = 22) and Holstein (n = 29) heifer calves throughout the pre-weaning period. Calves were hand-fed a colostrum volume equivalent to 8.5% of their birthweight, from either the calf's dam (n = 28) or re-heated mixed colostrum (≤2 cows, ≤1d; n = 23) within 2 h of birth. All calves were clinically assessed using a modified Wisconsin-Madison calf health scoring system and rectal temperature at day (d) 0, d7, d21, or disease manifestation (DM) and weaning (d83). Weights were recorded at d0, d21, and d83. Calf blood samples were collected at d7 for the determination of calf serum IgG (sIgG). Fecal samples were obtained at d7, d21/DM [mean d22 (SE 0.70)], and at weaning for 16S rRNA amplicon sequencing of the fecal microbiota. Data were processed in R using DADA2; taxonomy was assigned using the SILVA database and further analyzed using Phyloseq and MaAsLin 2. Significant amplicon sequence variants (ASVs) and calf performance data underwent a Spearman rank-order correlation test. There was no effect (p > 0.05) of colostrum source or calf breed on serum total protein. An effect of calf breed (p < 0.05) was observed on sIgG concentrations such that Holstein calves had 6.49 (SE 2.99) mg/ml higher sIgG than Jersey calves. Colostrum source and calf breed had no effect (p > 0.05) on health status or the alpha diversity of the fecal microbiota. There was a relationship between health status and time interaction (p < 0.001), whereby alpha diversity increased with time; however, diarrheic calves had reduced microbial diversity at DM. No difference (p > 0.05) in beta diversity of the microbiota was detected at d7 or d83. At the genus level, 33 ASVs were associated (adj.p < 0.05) with health status over the pre-weaning period.

Antibiotic resistance profiling and phylotyping of human-diarrheagenic Escherichia coli pathotypes detected from diarrheic and non-diarrheic calves in Iran.

Escherichia coli (E. coli) serves as a common indicator of gut microbiota and is utilized for monitoring antimicrobial resistance determinants in food-producing animals. This study aimed to investigate antimicrobial resistance patterns in virulence gene-positive E. coli isolates obtained from 340 healthy and diarrheic calves. A total of 340 fecal swab samples were obtained from diarrheic (n = 170) and healthy (n = 170) calves for 12months from different farms in Kerman, Iran. The samples were phenotypically analyzed to detect E. coli isolates and antibiotic resistance. Also, antimicrobial resistance genes, diarrheagenic E. coli pathotypes, and phylogenetic background were screened by PCR. Fifteen percent (51/340) of E. coli isolates were positive for at least one of the examined virulence genes (VGs); the prevalence of VGs in E. coli isolates from healthy calves (36/170; 21.17%) was higher than that in diarrheic cases (15/170; 8.82%). Out of the 51 VG-positive isolates, six pathotypes including Shiga toxin-producing E. coli (STEC; 27.45%), enterotoxigenic E. coli (ETEC; 23.52%), enterohemorrhagic E. coli (EHEC; 19.6%), necrotoxigenic E. coli (NTEC; 19.6%), enteropathogenic E. coli (EPEC; 15.68%), enteroinvasive E. coli (EIEC; 1.96%) and three hybrid pathotypes including ETEC/STEC, ETEC/EHEC, and STEC/EIEC were detected among the strains. Antimicrobial resistance (AR) was observed in 98.03% of the VG-positive isolates, which was the same for both healthy and diarrheic calves. The maximum prevalence rate of AR was found against trimethoprim/sulfamethoxazole (49.01%; 3/51), while the minimum prevalence rate was against gentamycin (5.88%; 25/51). Among the VG-positives, phylotype A was found to be the most prevalent followed by B1 and D phylotypes. The prevalence of VG-positive E. coli isolates was higher in healthy calves compared to diarrheic cases. AR was widespread among VG-positive isolates. These findings suggest that calves may serve as potential reservoirs of antimicrobial-resistant hybrid pathotypes of E. coli.

Identification of major protozoal enteropathogens causing calf diarrhea in dairy farms in and around Holeta Town, Oromia Special Zone, Ethiopia

Calf diarrhea can be caused by a variety of pathogens, including bacteria, viruses, protozoa, and intestinal parasites. Giardia, Eimeria, and Cryptosporidium are the most significant protozoan parasites and are all individually and ollectively infectious. A case-series study was carried out in and around Holeta dairy farms, Oromia Special Zone, Ethiopia, from November 2017 to April 2018 to identify the main protozoan enteropathogens from diarrheic calves. Samples were purposely collected from three dairy farms: Serkalem Dairy Farm (SDF), Holeta Agricultural Research Centre (HARC), and Ada Berga Agricultural Research Centre (ABARC). A total of 93 fecal samples were taken from diarrheic calves of up to 4 months of age. Protozoan enteropathogens were identified using flotation and modified Ziehl Neelsen staining methods. Cryptosporidium, Eimeria, and Giardia were detected in 44 (47.3%), 50 (53.8%), and 34 (36.6%) of the diarrheic fecal samples examined, respectively. The findings indicated that there were 17 (18.27%) cases of Cryptosporidium, Eimeria, and Giardia as mixed infections, 16 (17.2%) cases of Cryptosporidium and Eimeria, 5 (5.4%) cases of Cryptosporidium and Giardia, and 4 (4.3%) cases of Eimeria and Giardia, compared to 13 (13.97%), 6 (6.45%), and 5 (5.4%) cases of Cryptosporidium, Eimeria and Giardia as single infections, respectively. The selected farms had significant prevalence levels of three common protozoa: Eimeria, Giardia, and Cryptosporidium. Further molecular research is required to identify the species and genotype levels of protozoal enteropathogens and related risk factors.

Enterobacteria Isolated From Diarrheic Calves and their Phenotypic Resistance Pattern

Abstract Diarrhea is a prevalent and economically impactful ailment in cattle herds, resulting in substantial losses attributed to mortality, treatment expenses, and impaired calf growth. The aim of this study was to establish data about the occurrence of the main bacterial agents involved in diarrhea in dairy calves in the state of Maranhão, as well as to determine the most effective and/or resistant antibiotics, establishing a foundation for treatment and prevention protocols. The samples were collected with rectal swabs and initially cultivated on sheep blood agar (5%) and MacConkey agar and later on Salmonella-Shigella agar and eosin-methylene blue agar. Gram staining, biochemical tests, and antibiograms were performed on the obtained colonies. Ten municipalities were studied, with 230 calves evaluated from ten dairy farms. A total of 21 animals exhibited clinical signs of diarrhea, representing a frequency of 9.13%. The frequency of positive farms was 35%, and in 50% of municipalities. Bacteria isolated belonged to the Enterobacteriaceae family, with 71.4% Escherichia coli, 14.3% Enterobacter sp., 9.5% Proteus sp. and 4.8% Klebsiella sp. On the antibiogram, the bacteria that showed the highest resistance levels were those of the Proteus genus, followed by Enterobacter sp. and E. coli. The bacteria found are relevant for both animal and human health due to their zoonotic potential and serve as a public health alert since the isolates in this study showed in vitro resistance to several antibiotics, which predisposes them to the emergence of multidrug-resistant bacteria.

Exploring genetic polymorphisms and transcript levels of antioxidant and metabolic markers for prediction and monitoring diarrhea in Holstein dairy calves

ABSTRACT The objective of this study was to investigate the genetic polymorphisms and transcript levels of antioxidant and metabolic markers for diarrhea monitoring in Holstein dairy calves. For DNA and RNA extraction, blood samples were taken from 100 female calves (50 with diarrhea and 50 appearing healthy). DNA sequencing and real time PCR for and metabolic genes were performed to identify genetic variants linked to diarrhea susceptibility. Results revealed that there were nucleotide sequence variations in the investigated genes between healthy and diarrheal calves. Keap1, HMOX1, CMPK2, ASPG, FPGT, TNNI3 K, and LPCAT1 were considerably more highly expressed in diarrheic calves than resistant ones. The Nrf2, PRDX2, and PRDX6 genes, however, produced a different pattern. This study provides a practical control strategy to lessen newborn diarrhea in Holstein dairy calves and emphasizes the significance of nucleotide variations along with antioxidant and metabolic gene expression patterns as proxy markers of diarrhea susceptibility/resistance.