Genetic diversity and phylogenetic relationships of Clostridium perfringens strains isolated from mastitis and enteritis in Egyptian dairy farms.

BACKGROUND: Clostridium perfringens, a common environmental bacterium, is responsible for a variety of serious illnesses including food poisoning, digestive disorders, and soft tissue infections. Mastitis in lactating cattle and sudden death losses in baby calves are major problems for producers raising calves on dairy farms. The pathogenicity of this bacterium is largely mediated by its production of various toxins. RESULTS: The study revealed that Among the examined lactating animals with a history of mastitis, diarrheal baby calves, and acute sudden death cases in calves, C. perfringens was isolated in 23.5% (93/395) of the total tested samples. Eighteen isolates were obtained from mastitic milk, 59 from rectal swabs, and 16 from the intestinal contents of dead calves. Most of the recovered C. perfringens isolates (95.6%) were identified as type A by molecular toxinotyping, except for four isolates from sudden death cases (type C). Notably, C. perfringens was recovered in 100% of sudden death cases compared with 32.9% of rectal swabs and 9% of milk samples. This study analyzed the phylogeny of C. perfringens using the plc region and identified the plc region in five Egyptian bovine isolates (milk and fecal origins). Importantly, this finding expands the known data on C. perfringens phospholipase C beyond reference strains in GenBank from various animal and environmental sources. CONCLUSION: Phylogenetic analyses of nucleotide sequence data differentiated between strains of different origins. The plc sequences of Egyptian C. perfringens strains acquired in the present study differed from those reported globally and constituted a distinct genetic ancestor.

Molecular investigation of Blastocystis in children and calves in Bangladesh.

BACKGROUND: Blastocystis, a widely distributed zoonotic protozoan infecting both humans and numerous animals, remains poorly understood with its potential medical and veterinary significance. This study examined the molecular occurrence and genetic variation of Blastocystis in children and calves in Bangladesh to explore cross-species transmission and disease burden. METHODS: In total, 998 DNA samples were investigated, comprising 299 stool DNA from children and 699 fecal DNA from calves, using polymerase chain reaction and sequencing of the small subunit ribosomal RNA (SSU rRNA) gene. RESULTS: This study detected Blastocystis in 5.35% of the children and 14.74% of the calves. While slight variations in occurrence rates were observed across different study variables, none were statistically significant. The occurrence was highest among children under 5 years and calves aged 1-3 months. Regarding breed, the Holstein Friesian cross and the Jersey cross exhibited higher rates of infection. Conversely, occurrences were lower among children and calves in Gazipur district. The remaining parameters displayed nearly equivalent percentages of Blastocystis. The subtypes identified in children included ST1, ST3, and ST4, with ST1 comprising 50% of them. ST3 and ST4 were also found in calves, alongside ST10 (55.34%) being the most prevalent. Other subtypes found in calves were ST14, ST21, and ST24-ST26. CONCLUSIONS: This study found that Blastocystis is more common in calves than in children in Bangladesh, with genetic diversity of nine subtypes. The common occurrence of identical variants of two subtypes in both populations suggests potential zoonotic transmission, highlighting the necessity for further molecular investigations and comprehensive measures within the One Health framework to mitigate public health risks.

Impacts of intake of trichothecenes (Fusarium sporotrichioides) for dairy calves: Effects on animal growth, oxidative and inflammatory response.

The objective of the present study was to evaluate the impacts of trichothecenes (Fusarium sporotrichioides) for dairy calves on animal growth, oxidative and inflammatory responses in the presence or absence of essential oils. Twelve calves weaned at 70 days of age were divided into 2 groups: T-C (control) and T-EO (essential oils - oregano, thyme, basil and rosemary) in the period of 40 days consuming ration contaminated by trichothecenes (500 ppb). The animals in the T-EO group received a mixture of EOs via feed at a dosage of 0.75 mL per/kg of feed. Blood collections were performed on days 1, 20 and 40 for hematological and biochemical analyses; the fecal score was performed every 2 days on a scale of 1-5 and clinical examinations were performed 3 times during the experiment period. The animals were weighed at the beginning and at the end of the experiment; euthanasia of two calves per group for macroscopic and microscopic evaluation of several tissues (spleen, liver, duodenum, jejunum, ilium, cecum and colon) was performed at the end of the experiment. The calves in the T-EO group had a tendency (P = 0.07) of higher body weight when compared to the T-C. Treatment effect and treatment vs day interaction was detected for leukocytes and granulocytes variables, demonstrating a higher count of these cells in the T-EO group on both days (20 and 40), and the same behavior occurred for the distribution amplitude of erythrocytes (RDW). The enzymes alanine transferase (ALT), aspartate transferase (AST) and gamma glutamyl-transferase (GGT) showed higher serum activity in the T-C group (days 20 and 40). The levels of thiobarbituric acid reactive substances (TBARS) were lower in the serum of animals in the T-EO group. For calves in the T-EO group, glutathione S-transferase activity was higher in serum. Haptoglobulin and C-reactive protein levels were lower on days 20 and 40 in T-EO animals when compared to the T-C group. In the macroscopic and microscopic evaluations, which were collected at the end of the experiment after slaughtering the animals, liver and intestine did not show changes for the animals in the T-EO group, unlike the animals in the T-C group, which had moderately firm diffuse consistency of the liver and edema in the mesentery, as well as oxidative stress in tissues (liver, duodenum, jejunum, ileum, cecum and colon). The results concluded that the consumption of a mixture of EOs (essential oils - oregano, thyme, basil and rosemary) minimized the negative effects caused by trichothecenes in dairy calves, thus being an alternative to improving the immunological and antioxidant condition, as well as a possible adsorbent alternative.

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

BACKGROUND: 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. METHODS AND RESULTS: A total of 340 fecal swab samples were obtained from diarrheic (n = 170) and healthy (n = 170) calves for 12 months 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. CONCLUSIONS: 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.

Comparison of plasma substance P concentrations in the blood of healthy male and female German Simmental calves.

BACKGROUND: The recognition of pain is a major problem in cattle, as they are stoic animals which strongly mask their pain. Among objective parameters to assess pain in cattle is substance P (SP), a neurotransmitter which is involved in the pain pathways. Research about SP concentration in calves focus on painful procedures, such as castration and dehorning. Basic research work is lacking; evaluation of SP concentrations in healthy calves and possible differences between sexes have not been published yet. The objectives of this study were to (1) describe SP concentrations in healthy male and female calves of the German Simmental breed to establish benchmarks of orientation, (2) compare SP concentrations between male and female calves, and (3) assess differences in SP concentrations between calves and adult cows. A total of 44 male and 49 female calves aged 14 to 21 days (17.1 ± 2.2 days) were included in this study. Blood samples were taken at 06:00 a.m. from the jugular vein, followed by a clinical examination. SP concentrations were analyzed using a commercial ELISA kit. Differences in SP concentrations according to laboratory parameters, and correlation of SP concentrations with different parameters were assessed. RESULTS: Median SP concentrations in the blood plasma were 516 pg/ml (Interquartile Range 320 pg/ml, range 229-1615 pg/ml) in calves. Median SP concentrations differed significantly between male and female calves (554 pg/ml for male, and 489 pg/ml for female calves, respectively). There was no significant difference in animals with laboratory findings within reference ranges and those with mild deviations from reference ranges. There was a positive correlation between SP concentrations and leucocyte count, which was significant. SP concentrations were significantly lower in calves compared with a dataset of adult cows, which has been published previously. CONCLUSION: Due to the high interindividual differences in SP concentrations, it is hard to establish benchmarks for orientation. Sex has a significant influence on SP concentrations. Research work should preferably be done in animals of the same sex. Also, animals should be within the same age range (adults or calves), as age seems to have an influence on SP concentrations.

Effect of parenteral micronutrient supplementation at birth on immunity, growth, and health in preweaning dairy heifers.

This randomized clinical trial aimed to determine the extent to which injectable micronutrient supplementation at birth can improve intranasal vaccine response by ameliorating oxidative stress in dairy calves from birth to weaning. For this, 120 Holstein heifer calves were enrolled at birth and randomly allocated into one of 4 groups. The 4 groups included 3 commercially available micronutrient supplements (selenium, copper, zinc, and manganese; selenium and vitamin E; and vitamins E, A, and D) and one control (saline). Calves received an intranasal vaccine against the respiratory viruses parainfluenza 3, bovine herpesvirus type 1 (BHV-1), and bovine respiratory syncytial virus (BRSV) within the first week of life. Body weight and hip height (HH) were recorded, and a blood sample and nasal secretion sample were collected at birth before treatment and vaccine administration, as well as weekly until weaning at 8 wk. Health scores, including thoracic ultrasound assessment, were recorded weekly from wk 1 to wk 8. Farm treatment records were collected after the completion of the study. Serum micronutrient concentrations were determined from birth to weaning to identify micronutrient status, and serum blood metabolites were analyzed as markers of nutrient utilization. Redox balance was determined in serum as a ratio of reactive oxygen and nitrogen species to antioxidant capacity, known as the oxidant status index (OSi). Intranasal vaccine response was quantified as anti-BRSV and anti-BHV-1 IgA concentrations in nasal secretions. Linear mixed models with repeated measures were built for micronutrient concentrations, blood metabolites, redox balance, IgA concentrations, BW, and HH. Pre-planned contrasts of the control and supplemented groups were also built for the primary outcome of IgA concentrations. A logistic regression mixed model was built for health events and treatment of disease. Serum selenium concentrations were greater in calves receiving supplements containing Se throughout the first 4 wk of life. However, we did not observe any consistent differences in the other micronutrients. The metabolic biomarkers indicate that supplemented calves had better energy status, as suggested by lower BHB and nonesterified fatty acids concentrations. Supplemented calves showed improved redox balance, as indicated by lower OSi throughout the first week of life. Calves supplemented with antioxidants at birth had higher anti-BRSV IgA than control calves. Our results indicate an improved immune response to vaccines in calves supplemented with antioxidants at birth. However, this did not translate to growth and health performance, as we did not find any differences in average daily gain or incidence of health events throughout the preweaning period. This study provides evidence that improving the antioxidant capacity might improve vaccine response, and further research is required to investigate the appropriate frequency and dose of supplementation to improve calf growth and health.

Exploring the effects of transport duration on the fecal microbial communities of surplus dairy calves.

Transportation significantly affects the health and welfare of surplus dairy calves, largely due to the various stressors and pathogen exposures encountered during the process. Concurrently, an animal's microbiome is known to correlate with its health status, with stress-induced alterations in the microbiota potentially precipitating various diseases. This study aimed to compare the effects of transportation durations of 6, 12, or 16 h on the fecal microbiota in young surplus dairy calves. We used a randomized controlled design in which surplus dairy calves aged 1 to 19 d from 5 commercial dairy farms in Ontario were allocated into 1 of 3 transportation groups (6, 12, and 16 h of continuous transportation). Health assessments were conducted before, immediately after, and for 2 wk following transportation. Fecal samples were collected before, immediately after, and at 24 and 72 h after transportation and subjected to 16S rRNA sequencing. Alpha diversity metrics showed no significant differences between the 3 transportation groups at any of the sampling time points. Although ß diversity metrics revealed no clustering by transportation groups, they indicated significant differences across sampling time points within each group. The overall analysis revealed a total of 22 phyla and 353 genera, with Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria, and Fusobacteria being the most abundant phyla. Bacteroides, Escherichia/Shigella, Lactobacillus, Collinsella, and Bifidobacterium were the most abundant genera. The reduction in Fusobacteria abundance before and after transport was significantly larger in the 16-h transportation group when compared with the 6-h transportation group. We also identified several genus-level and amplicon sequence variation-level taxa that displayed significant differences in their abundances across various transportation groups, observed at all sampling time points investigated. This research identifies microbiota changes due to varying transportation durations in surplus dairy calves, providing a broad understanding of the microbial shifts in surplus dairy calves after transportation across varying durations. Although these variations may not directly correlate with overall calf health or indicate dysbiosis, these results emphasize the importance of further investigating transportation practices to enhance calf health and well-being. Further studies are warranted to elucidate the relationship between microbiota and calf health.

Retrospective cohort study investigating the relationship between diarrhea during the preweaning period and subsequent survival, health and production in dairy cows.

The primary objective of this study was to evaluate the association between preweaning diarrhea and measures of survival, health and production. The measures of interest included survival (mortality before first calving and time to removal from the herd), health (retained fetal membranes, metritis, mastitis and somatic cell count), and production (305d mature equivalent milk yield and time to first calving). A secondary objective was to investigate if these associations varied according to the age of the calf when the case of diarrhea occurred. Herd records from a farm located in Southern Australia were used to conduct a retrospective cohort study where subjects (calves) with diarrhea were enrolled at the time of their first case along with 2 subjects without diarrhea, matched for age (±3 d) and date of birth (±15 d), amounting to 9833 calves in the data set. Survival analysis was conducted to determine if preweaning diarrhea was associated with death in the short term (first 20 d after enrollment), medium term (21 to 100 d after enrollment) and long-term (101 d after enrollment to first calving). Crude incidence rate ratios, Kaplan-Meier curves and hazard ratios (HR, Cox regression) were derived for each event-based outcome (e.g., death, calving, mastitis). Multivariable linear models were used for continuous outcomes. Calves with preweaning diarrhea had greater mortality rates in the short term (hazard ratio, HR = 2.48, 95% CI: 1.87-3.29) and medium term (HR = 1.89, 95% CI: 1.41-2.55) but not in the long term (HR = 0.98, 95% CI: 0.79-1.22). A small negative association between preweaning diarrhea and time to first calving was found, with calves with diarrhea calving 4 d later than calves without diarrhea (HR = 0.95, 95% CI: 0.91-1.00). Rates of post-calving removal from the herd (death or culling) were higher in calves with a history of preweaning diarrhea (HR = 1.13, 95% CI: 1.01 to 1.26), as were peak lactation log somatic cell count (+0.08, 95% CI: 0.02 to 0.14). Further research is needed to replicate these novel findings as they are based on exploratory analyses and could be spurious findings. No substantial associations were observed for the other measures of interest. Our study findings support existing research demonstrating the significance of preweaning diarrhea as a significant cause of calf mortality, and raises new hypotheses about other potential impacts during lactation.

Graduate Student Literature Review: Social and feeding behavior of group-housed dairy calves in automated milk feeding systems.

Automated milk feeders (AMF) allow farmers to raise calves in groups while generating individual records on milk consumption, drinking speed, and frequency of visits. Calves raised in groups benefit from social interaction, which facilitates learning and adapting to novelty. However, calves in large groups (>12 calves/feeder) experience a higher risk of disease transmission and competition than those housed individually or in smaller groups. Therefore, if group size, grouping strategy, and disease detection are not optimal, the health and performance of calves can be compromised. The objectives of this narrative literature review, from publications available as of February 2023, are to (1) describe the use of AMF in group housing systems for calves and the associated feeding behavior variables they automatically collect, (2) linking feeding behavior collected from AMF to disease risk in calves, (3) describe research on social behavior in AMF systems, and (4) introduce social networks as a promising tool for the study of social behavior and disease transmission in group-housed AMF-fed calves. Existing research suggests that feeding behavior measures from AMF can assist in detecting bovine respiratory disease and enteric disease, which are common causes of morbidity and mortality for preweaning dairy heifers. Automated milk feeder records show reduced milk intake, drinking speed, or frequency of visits when calves are sick. However, discrepancies exist among published research about the sensitivity of feeding behavior measures as indicators of sickness, likely due to differences in feeding plans and disease-detection protocols. Therefore, considering the influence of milk allowance, group density, and individual variation on the analysis of AMF data is essential to derive meaningful information used to inform management decisions. Research using dynamic social networks derived from precision data show potential for the use of social network analysis to understand disease transmission and the effect of disease on social behavior of group-housed calves.

Producer perceptions of dairy calf management, behavior, and welfare.

Approaches for raising calves vary across commercial dairy farms and relate to behavioral opportunities and animal welfare. The objectives of this study were to evaluate how US dairy producers and calf managers perceive (1) the welfare implications of varying management practices (including social housing and milk allowance) and behaviors in dairy calves, and (2) aspects of the human-animal relationship in calf rearing and relationships with on-farm management and personal calf handling habits. Survey questions were primarily quantitative (e.g., Likert scales) and addressed how common calf management practices and observed calf behaviors were related to aspects of welfare, including calf health and comfort. We additionally posed questions addressing respondent habits, management protocols, and perceptions related to human-animal interaction. Responses from 93 dairy producers and calf managers were collected via digital surveys. Social housing was viewed as being generally positive for both calf comfort and health, although this view was stronger with respect to calf comfort. Respondents from farms using social housing (56%) had more positive perceptions of social housing, viewed social play as being associated with better calf comfort and health, and considered access to other calves and "freedom to express natural behavior" as being more important for calves, compared with respondents from farms not providing social housing. Providing greater milk allowances (>7.6 L/d) was viewed as being good for both calf comfort and health, although respondents from farms providing these milk allowances (59%) had more positive perceptions than those who provided lesser allowances. Abnormal oral behaviors were viewed as being associated with both poor calf comfort and health. The welfare importance of various resources which may reduce abnormal oral behaviors (including hay and brushes) was perceived more ambiguously, although respondents from farms providing these resources, compared with those who do not, generally viewed them as more preferred by calves. We observed a positive relationship between how respondents perceived the human-animal bond (i.e., that calves enjoy contact with humans) and stated personal behavior related to calf contact (frequency of contacting calves to scratch or pet them). Respondent demographics were not related to perceptions of the human-animal relationship, but respondents identifying as female described more frequent positive calf interactions. Described aspects of human-animal interactions were not related to implementation of social housing on-farm. Job satisfaction was positively related to perception of the human-animal relationship. Overall, these results suggest that most calf management personnel place a high value on calf welfare, although farms implementing social housing appear to place a greater value on subjective calf well-being, and individual perceptions of animal welfare may depend on practical experience.