G and P genotype profiles of rotavirus a field strains circulating in a vaccinated bovine farm as parameters for assessing biosecurity level

After improvement of hygiene protocols on boots in a bovine operation (farm A) in Ibaraki, Japan in September 2017, mortality of calves and the detection of 4 viral pathogen indicators, including bovine rotavirus A (RVA), became significantly low for one year. Subsequently, in the present study, these indicators and mortality were monitored and confirmed all were still low, except for the detection rate of bovine RVA in calves less than 3 weeks old. The present study aimed to investigate G and P genotypic profiles of RVAs in farm A from 2018 to 2020. Molecular analysis using semi-nested multiplex RT-PCR of positive RVAs (n=122) and sequencing of selected samples revealed the presence of G6, G8, G10, P[1], P[5] and P[11] genotypes and the prevalence of G and/or P combination and mixed infections. The most common combination of G and P types was G10P[11] (41.8%), followed by mixed infection with G6+G10P[5] (11.5%). Phylogenetic analysis of RVAs showed clustering with bovine and other animal-derived RVA strains, suggesting the possibility of multiple reassortant events with strains of bovine and others animal origins. Noteworthy as well is that vaccinated cattle might fail to provide their offspring with maternal immunity against RVA infections, due to insufficient colostrum feeding. Our findings further highlight the importance of RVA surveillance in bovine populations, which may be useful to improving effective routine vaccination and hygiene practices on bovine farms.     

Bovine Viral Diarrhea Virus in Swine: Characteristics of Virus Recovered from Naturally and Experimentally Infected Swine

A noncytopathogenic field strain of bovine viral diarrhea virus (BVDV) was isolated from an Iowa farm brood sow and from her hysterectomy-derived, colostrum-deprived (HDCD) piglets. This field isolant was fully virulent for a neonatal calf. The NADL strain of BVDV was passaged through a series of HDCD piglets with no resultant loss of virulence for neonatal calves. Most of the BVD viral isolants recovered from pigs had been changed from a cytopathogenic biotype to a noncytopathogenic biotype. Circumstantial evidence points to swine as “carrier” hosts of BVDV.     

Measures of herd health and productivity in Ontario cow-calf herds

A cohort of cows and heifers in 180 separate breeding herds from 170 randomly sampled farms was followed from the 1986 breeding season through to the weaning of their calves in 1987. Data were collected from farm records, survey information collected during farm visits, and provincial government weaning-weight records.

“Kilograms of calf weaned per female-exposed-to-breeding” was calculated as a summary measure of herd productivity. The lowest 25% of cow-herds produced less than 160 kg of calf weaned per cow-exposed-to-breeding, while the highest 25% exceeded 205 kg.

Overall calf crop was 78.1% for cows and 78.5% for heifers. The 25th, 50th, 75th, and 90th percentile estimates for rates, which were components of calf crop (e.g. calving rate), were estimated. The component rates that most influenced calf crop were culling rate for cows and stillbirth rate for heifers.

     

Genetically diverse group C rotaviruses cause sporadic infection in Korean calves

This study examined the prevalence and genetic diversity of the bovine group C rotaviruses (GCRVs) in a total of 127 diarrhea fecal samples of calves from 52 Korean native beef calf herds using RT-PCR and nested PCR. Overall, seven of the 127 fecal samples (5.5%) from seven of the 52 herds (13.5%) tested positive for bovine GCRVs only by nested PCR. Sequence and phylogenetic analyses of a partial VP6 gene showed that Korean bovine GCRVs had marked genetic diversity; two Korean strains belonged to the bovine lineage, whereas five Korean strains belonged to the porcine lineage. These results suggest that the genetically diverse bovine GCRVs cause sporadic infections in diarrheic calves in South Korea.     

Influences on the assessment of resource- and animal-based welfare indicators in unweaned dairy calves for usage by farmers

Consumers, industrial stakeholders, and the legislature demand a stronger focus on animal welfare of all livestock at the farm level by using suitable indicators in self-assessments. In order to deduce farms’ animal welfare status reliably, factors that influence indicators’ results need to be identified. Hence, this study aimed to apply possible animal welfare indicators for unweaned dairy calves on conventional dairy farms with early cow–calf separation and evaluate influencing factors such as age and sex of calves or climatic conditions on the applied indicators’ results. An animal welfare assessment using 7 resource-based and 14 animal-based indicators was conducted at 42 typical Western German dairy farms (844 calves) in 2018 and 2019 by two observers. The effect of influencing factors was calculated by binary and ordinal logistic regressions and expressed as odds ratios. Although every unweaned calf was assessed during the farm visits, most farms had relatively few unweaned calves (average number of calves ± standard deviation = 20.1 ± 6.7 calves), with six farms having not more than 10 calves. The small sample sizes question the usage of those indicators to compare between farms and to set thresholds at the farm level. Only one assessed indicator (cleanliness core body) was not statistically affected by the evaluated influencing factors. Calf age was identified as the most decisive factor, as it affected 16 of 21 evaluated indicators, and calf age distribution on-farm varied greatly. Climatic conditions (ambient temperature and rainfall) influenced resource-based indicators such as access to concentrate and water or the cleanliness of feeding implements and bedding as well as animal-based cleanliness indicators and the occurrence of health-related impairments such as coughing and diarrhea. The authors found differences between calves on farms assessed by the different observers not only in resource-based hygiene indicators but also in animal-based indicators such as hyperthermia or hypothermia, highlighting the need for further evaluation of quality criteria in dairy calf welfare assessments. Nevertheless, animal welfare assessments by farmers themselves could be useful tools to sensitize farmers to animal welfare and thereby improve calves’ welfare.     

Associations between health and productivity in cow-calf beef herds and persistent infection with bovine viral diarrhea virus, antibodies against bovine viral diarrhea virus, or antibodies against infectious bovine rhinotracheitis virus in calves

OBJECTIVE: To measure associations between health and productivity in cow-calf beef herds and persistent infection with bovine viral diarrhea virus (BVDV), antibodies against BVDV, or antibodies against infectious bovine rhinotracheitis (IBR) virus in calves. ANIMALS: 1,782 calves from 61 beef herds. PROCEDURES: Calf serum samples were analyzed at weaning for antibodies against type 1 and type 2 BVDV and IBR virus. Skin biopsy specimens from 5,704 weaned calves were tested immunohistochemically to identify persistently infected (PI) calves. Herd production records and individual calf treatment and weaning weight records were collected. RESULTS: There was no association between the proportion of calves with antibodies against BVDV or IBR virus and herd prevalence of abortion, stillbirth, calf death, or nonpregnancy. Calf death risk was higher in herds in which a PI calf was detected, and PI calves were more likely to be treated and typically weighed substantially less than herdmates at weaning. Calves with high antibody titers suggesting exposure to BVDV typically weighed less than calves that had no evidence of exposure. CONCLUSIONS AND CLINICAL RELEVANCE: BVDV infection, as indicated by the presence of PI calves and serologic evidence of infection in weaned calves, appeared to have the most substantial effect on productivity because of higher calf death risk and treatment risk and lower calf weaning weight.     

牛病毒性腹泻病毒BVDV-JL株的分离与鉴定

本研究从吉林某牛场表现严重腹泻症状濒死牛的胸腺病料样品中分离一株病毒,该病毒在MDBK细胞中盲传4代无细胞病变产生,而通过RT-PCR和间接免疫荧光试验、微量血清中和试验检测表明该分离病毒株为牛病毒性腹泻病毒(BVDV),并命名为BVDV-JL.将BVDV-JL株F4代细胞培养液(10<'7.13>TCID<,50>/...     

Hygiene management in newborn individually housed dairy calves focusing on housing and feeding practices

In calf rearing, the first weeks of life are critical and associated with the highest mortality due to enteric and respiratory diseases. A well-implemented hygiene management can help to protect calves’ health preventively by reducing the load of pathogenic bacteria and interrupting infection chains. The aim of this study was to identify deficiencies in hygiene management of individually housed dairy calves by surveying current practice and examining feeding and housing equipment with different hygiene indicators. On 11 farms, different locations in 2 pens or hutches for individual calf rearing prepared for restocking and 2 feeding buckets per farm, including the inner and outer surfaces of artificial teats, were visually scored for cleanliness and sampled with swabs (housing equipment: n = 167; feeding equipment: n = 120). The sanitation of floors was tested with sock samples (n = 41). A total of 328 samples were analyzed for adenosine triphosphate (ATP) and protein residues, aerobic total viable count (TVC), total coliform count (TCC), Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum β-lactamase-producing bacteria (ESBL), and Salmonella spp. After evaluation of these results, the farmers were informed about the findings and trained on improvement in hygiene management personally. The sampling was repeated after 1 year to detect possible changes in hygiene management. The highest bacterial loads (TVC, TCC, and E. coli) were observed in feeding equipment, especially the inner teat of milk feeding buckets. Environmental samples, primarily the sidewalls and back walls of tested pens and hutches, exhibited the lowest bacterial counts and ATP and protein residues. All samples were negative for MRSA and Salmonella spp. In 10.5% of all samples, ESBL was detected, and in 6.8%, ESBL E. coli was detected, predominately in sock samples, followed by feeding equipment samples. Training in hygiene management showed only limited effects. In conclusion, there is still great potential to improve the implementation of hygiene measures in individual calf housing. In particular, more attention should be paid to the cleaning of feeding buckets and artificial teats, as this is a simple means of interrupting the possible spread of pathogens among calves.     

Prevalence of bovine viral diarrhea virus (BVDV) in persistently infected cattle and BVDV subtypes in affected cattle in beef herds in south central United States

The prevalence of bovine viral diarrhea virus (BVDV) in persistently infected (PI) cattle in beef breeding herds was determined using 30 herds with 4530 calves. The samples were collected by ear notches and tested for BVDV antigens using immunohistochemistry (IHC) and antigen capture enzyme-linked immunosorbent assay (ACE). Animals with initial positives on both IHC and ACE were sampled again using both tests and serums were collected for viral propagation and sequencing of a viral genomic region, 5′-untranslated region (5′-UTR) for viral subtyping. Samples were also collected from the dams of PI calves. There were 25 PI calves from 4530 samples (0.55%) and these PI calves were from 5 of the 30 herds (16.7%). Two herds had multiple PI calves and 3 herds had only 1 PI calf. Only 1 of the 25 dams with a PI calf was also PI (4.0%). The subtype of all the PI isolates was BVDV1b. Histories of the ranches indicated 23 out of 30 had herd additions of untested breeding females. Twenty-four of the 30 herds had adult cowherd vaccinations against BVDV, primarily using killed BVDV vaccines at pregnancy examination.     

牛冠状病毒、牛轮状病毒和致病性大肠杆菌混合感染致犊牛腹泻的研究

为了明确新疆石河子某规模化奶牛场犊牛腹泻病死率较高的原因。本研究对腹泻犊牛的粪样及病死犊牛肠道内容物进行病原检测,并对分离菌株进行毒力基因检测、耐药基因检测、动物致病性试验及药敏试验。最终明确病因主要由牛冠状病毒(BCoV)和牛轮状病毒(BRV)和大肠杆菌混合感染引起。药敏试验表明,分离到的大肠杆菌对28种抗生素产生了严重的耐药,仅对多粘菌素和呋喃妥因敏感,并且发现该菌同时携带2种毒力基因和10种耐药基因。本研究分离的一株大肠杆菌携带有丰富的耐药基因,具有多重耐药性,为该奶牛场上临床治疗加大了难度。而本试验结果为该养殖场提供科学的临床药物指导,为该牛场治疗此次犊牛腹泻提供了依据,同时为新疆犊牛腹泻混合感染的防控提供了病例参考和技术资料。     

Prevalence of Giardia spp. infection in pre-weaned and weaned calves in relation to management factors

Two hundred and forty calf faecal samples from 16 Malaysian farms were screened by PCR for Giardia spp. The overall prevalence was 12.5% and the overall farm prevalence was 68.8% (11/16 farms). The prevalence in pre-weaned and weaned calves was 16.7% and 8.3%, respectively. Sequence analysis of 25 isolates identified all as G. duodenalis assemblage E. Management factors associated with an increased risk of infection with Giardia spp. included keeping weaned calves in pens with sand floors and calf age. Keeping pre-weaned calves in pens with concrete floors and calving in single cow calving areas decreased the risk.     

A bovine virus diarrhea calfhood vaccination trial in a persistently infected herd: effects on titres, health and growth.

A controlled calfhood vaccination trial to prevent bovine virus diarrhea was conducted in a 100 head cow-calf operation with a three year history of annual calf losses due to enteric bovine virus diarrhea (persistently infected herd). Approximately 50% of the calves were vaccinated at six, 12 and 24 weeks of age. Paired serum samples and growth data were collected on three occasions for comparison between vaccinates and controls. Three vaccinated calves died of enteric bovine virus diarrhea in the first year of the trial and one nonvaccinated calf died in the second year. Two of the three vaccinated calves had developed bovine virus diarrhea virus neutralization antibody titres of 2048 or greater before developing clinical signs. The control and third vaccinated calf failed to seroconvert before dying of enteric bovine virus diarrhea. Approximately 90% of the vaccinated calves seroconverted compared to approximately 40% of the controls. Paired serum samples collected from 75% of the cows in the spring, summer and fall of each year of the trial, showed persistent high bovine virus diarrhea virus neutralization titres in all samples. Calf vaccination before 12 weeks of age had little effect on seroconversion due to high levels of passive antibody to bovine virus diarrhea. Growth data showed that there was no improvement in weight gain or rate of growth in the vaccinated calves.     

Molecular epidemiology of bovine noroviruses in South Korea

Since the prevalence of bovine norovirus (BNoV) and their genetic diversity have only been reported in the USA, England, Germany and The Netherlands, this study examined the prevalence and genetic diversity of BNoVs in diarrheic calves in South Korea using 645 diarrheic fecal specimens from calves by RT-PCR and nested PCR assays. Overall, 9.3% of the diarrheic fecal samples tested positive for BNoVs by either RT-PCR or nested PCR, of which 5.9% samples also tested positive for other enteric pathogens including the bovine coronavirus, bovine viral diarrhea virus, bovine torovirus, bovine groups A, B and C rotaviruses, bovine enteric Nebraska-like calicivirus and Escherichia coli. The genetic diversity was determined by direct sequencing of the partial RdRp region of 12 BNoVs detected from the fecal samples by nested PCR. Among the BNoVs examined, one Korean BNoV strain had the highest nucleotide (86.8%) and amino acid (99.1%) identity with the genotype 1 BNoV (GIII-1) strain, while the remaining 11 Korean BNoVs shared a higher nucleotide (88.0-90.5%) and amino acid (93.5-99.1%) identity with the genotype 2 BNoV (GIII-2) strains. The phylogenetic data for the nucleotide and amino acid sequences also demonstrated that one Korean BNoV strain clustered with GIII-1 but the remaining eleven strains clustered with GIII-2. In conclusion, BNoV infections are endemic and there are two distinct genotypes with GIII-2 being the main genotype circulating in the calf population in South Korea.     

Picobirnavirus detection in bovine and buffalo calves from foothills of Himalaya and Central India

The present study describes detection of picobirnavirus (PBV) in faecal samples from bovine and buffalo calves employing the polyacrylamide gel electrophoresis (PAGE). A total of 136 faecal samples from buffalo (n = 122) and cow calves (n = 14) exhibiting clinical signs of diarrhoea and from healthy calves were collected during 2007–2010 from subtropical (central India) and tarai area of western temperate Himalayan foothills (Uttarakhand). The dsRNA nature of the virus was confirmed by nuclease treatment (RNase A, RNaseT1 and DNase 1). PAGE results confirmed 3.67% (5/136) positivity for PBV, showing a typical genomic migration pattern with two discrete bands with size of approximately 2.4 and 1.7 kbps for the larger and smaller segments, respectively. Among the five PBV samples identified, three were from buffalo calves and one from cow calf exhibiting clinical signs of acute diarrhoea, while one sample from non-diarrhoeic buffalo calf also showed the presence of PBV. None of the samples showed dual infection of rotavirus and PBV. The preliminary findings indicate sporadic incidences of PBV in bovine calves and emphasize the need for the development of better diagnostics for early detection and genetic characterization of these emerging isolates of farm animals of economic significance.     

Results of an online questionnaire to survey calf management practices on dairy cattle breeding farms in Austria and to estimate differences in disease incidences depending on farm structure and management practices

Background

Calf disease may result in great economic losses. To implement prevention strategies it is important to gain information on management and to point out risk factors. The objective of this internet based survey was to describe calf management practices on registered dairy breeding farms in Austria and to estimate differences in calf disease incidences depending on farm structure and management practices.

Results

A total of 1287 questionnaires were finally analysed (response rate 12.2 %). Herd characteristics and regional distribution of farms indicated that this survey gives a good overview on calf management practices on registered dairy farms in Austria. The median number of cows per farm was 20 (interquartile range 13–30). Significant differences regarding farm characteristics and calf management between small and large farms (≤20 vs >20 cows) were present. Only 2.8 % of farmers tested first colostrum quality by use of a hydrometer. Storing frozen colostrum was more prevalent on large farms (80.8 vs 64.2 %). On 85.1 % of the farms, whole milk, including waste milk, was fed to the calves. Milk replacer and waste milk were more often used on large farms. In accordance with similar studies from other countries, calf diarrhoea was indicated as the most prevalent disease. Multivariable logistic regression analysis revealed that herd size was associated with calf diarrhoea and calf respiratory tract disease, with higher risk of disease on large farms. Furthermore, feeding waste milk to the calves was associated with increasing calf diarrhoea incidence on farm. In the final model with calf respiratory tract disease as outcome, respondents from organic farms reported less often a respiratory tract disease incidence of over 10 % compared with conventional farms [odds ratio (OR) 0.40, 95 % confidence interval (CI) 0.21–0.75] and farmers that housed calves individually or in groups after birth significantly reported more often to have an incidence of respiratory tract disease >10 % compared with farms where all calves were housed individually (OR 2.28, 95 % CI 1.16–4.48).

Conclusion

The results obtained in this study provide an overview on calf management on dairy breeding farms in Austria and may help to further point out areas to be improved on farm.

Electronic supplementary material

The online version of this article (doi:10.1186/s13028-015-0134-y) contains supplementary material, which is available to authorized users.     

Prevalence of calves persistently infected with bovine viral diarrhea virus in beef cow-calf herds enrolled in a voluntary screening project

OBJECTIVE: To report the prevalence of bovine viral diarrhea virus (BVDV) in calves and calf groups (ie, calves from the same farm) in beef breeding herds and evaluate the ability of biosecurity risk assessment questionnaires to identify calf groups with positive results for BVDV. DESIGN: Nonrandom survey. ANIMALS: 12,030 calves born in spring from 102 operations. PROCEDURES: Cow-calf producers that voluntarily enrolled in a screening project submitted ear notch specimens from calves and answered a 29-question survey instrument. Ear notch specimens were tested for BVDV with an antigen-capture ELISA (ACE), and ear notch specimens with positive ACE results for BVDV were immediately retested by performing immunohistochemistry (IHC). Follow-up testing, 3 to 4 weeks after initial positive ACE results, was done by use of a second IHC test and virus isolation on a subsequently submitted ear notch specimen from the same calves to identify those that were persistently infected (PI). RESULTS: 102 producers submitted ear notch specimens for BVDV screening. Initially, 24 of 12,030 calves had positive ACE results for BVDV. A second ear notch specimen was submitted for 20 of these 24 calves. Of 20 retested calves, 12 had positive ICH results for BVDV, confirming PI status. The 12 PI calves came from 4 calf groups (3 singletons and 1 calf group with 9 PI calves). CONCLUSIONS AND CLINICAL RELEVANCE: Prevalence of BVDV in calf groups was low, and questions designed to identify high-risk biosecurity behaviors had little value in identifying calf groups with positive results for BVDV.     

Livestock-associated MRSA prevalence in veal calf production is associated with farm hygiene, use of antimicrobials, and age of the calves

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is highly prevalent in pork and veal production chains. In this study, we used data from a cross-sectional survey on 2151 calves from 102 veal calf farms to identify potential risk factors, with the goal of reducing MRSA prevalence by developing intervention strategies. Overall, calves from rose veal farms had a lower risk of LA-MRSA carriage than calves from white veal farms. Data were analysed separately for white and rose veal calves, because management systems of the two production chains were largely different. Group treatment with antimicrobials appeared to be a risk factor for MRSA carriage in white veal calves in univariate analyses, but was not included in the final multiple regression model that included age of the calves and rodent control. Number of start treatment days was positively associated with LA-MRSA carriage in rose veal calves, and was the only risk factor selected for the final multiple regression model for this group. Interpretation of the results from this cross-sectional study is complicated by the strong correlation between antimicrobial use, LA-MRSA carriage and age of the calves. Other age-related factors may be more influential. However, taken together these findings emphasize the need for prudent use of antimicrobials, and point to improvement of farm hygiene as a control measure.