Risk factors for calf mortality in large Swedish dairy herds

α-Tocopherol and β-carotene concentrations in feed, colostrum, cow and calf serum in Swedish dairy herds with high or low calf mortality

BACKGROUND

A study of herd-level risk factors for calf mortality in large Swedish dairy herds showed low serum concentrations of α-tocopherol and β-carotene in 1-7 day old calves to be more common in high mortality herds. Therefore, we aimed to investigate if calf mortality risk at herd level is associated with concentrations of α-tocopherol and/or β-carotene at individual level in feed, colostrum, cow and calf serum, while controlling for herd level covariates. Inclusion criteria were affiliation to the Swedish official milk recording scheme, herd size of ≥ 120 milking cows/year, calf mortality risk (day 1-90) of at least 6% (high mortality; HM) or less than 1% (low mortality; LM) and located within one of two regions in southern Sweden. This cross-sectional study was performed in 2010 in 19 (n_HM = 9; n_LM = 10) dairy herds. Questionnaires were used to collect information about feed and routines for colostrum feeding. Feed (n = 57), colostrum (n = 162), cow serum (n = 189) and calf serum samples (n = 187) were collected and analysed for α-tocopherol and β-carotene. Other analyses e.g. total serum protein, fat content, and total solids in colostrum were also performed. Linear regression models with vitamin concentrations in feed, colostrum, cow and calf serum as outcome were performed.

RESULTS

Calves in HM herds had lower concentrations of α-tocopherol in serum than calves in LM herds, but the effect depended on total protein status in serum of the calf (P = 0.036). Calves from herds that fed transition milk for 3 days or more had higher α-tocopherol concentrations in serum than calves from herds feeding transition milk up to 2 days (P = 0.013). Fat percentage in colostrum was positively associated with α-tocopherol (P < 0.001) and β-carotene concentrations in colostrum (P < 0.001). A diet containing ≥ 20% (in kg dry matter) maize silage of the total ration was negatively associated with β-carotene concentration in cow serum (P = 0.001).

CONCLUSIONS

High calf mortality risks were associated with lower concentrations of α-tocopherol in calf serum for calves with failure of passive transfer. Feeding transition milk longer was associated with higher concentrations of α-tocopherol in calf serum. In HM herds, evaluation of the calves' α-tocopherol status is recommended.

Prospective cohort study to assess rates of contagious disease in pre-weaned UK dairy heifers: management practices, passive transfer of immunity and associated calf health

Dairy calves are vulnerable to infectious diseases, particularly diarrhoea and bovine respiratory disease (BRD), causing mortality and reducing welfare and growth. A prospective cohort study was performed on 11 UK dairy farms to determine the underlying causes for calf disease. This first paper describes the incidence, timing and duration of infectious disease, mortality rates, passive transfer of immunity and key management practices that may contribute to disease incidence. Heifer calves were recruited in the first week of life (n=492) and a blood sample taken to measure IgG and total protein (TP). Each animal was examined weekly for nine weeks using a standardised health scoring system. Recruitment of calves occurred between August and February. Four farms provided supplementary colostrum to more than 75 per cent of calves born, whereas on the remainder only 0 to 19 per cent were supplemented. Mean serum IgG and TP were 19.0±10 and 56.7±10.3 mg/ml respectively, with 20.7 per cent (95CI: 17.2 to 24.7 per cent) of all calves classified as having failure of passive transfer (IgG <10 mg/ml). The overall preweaning mortality rate was 4.5 per cent. (95 per cent CI: 2.9 to 6.8 per cent). During this period,48.2 per cent of all calves (range 24.1 to 74.4 per cent between farms) were diagnosed with diarrhoea and 45.9 per cent (range 20.4 to 77.8 per cent) with BRD. The incidence rates were 7.8 cases of diarrhoea and 10.1 cases of BRD per 100 calf weeks at risk, respectively. Rates of infectious disease were therefore high despite relatively good passive transfer.

Effect of colostrum quantity and quality on neonatal calf diarrhoea due to Cryptosporidium spp. infection

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Cryptosporidium spp. is a common pathogen participating in neonatal calf diarrhoea.

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Effect of colostrum quality and quantity on Cryptosporidium spp. calf diarrhoea.

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Colostrum management and season influence the number of Cryprosporidium spp. oocysts and faecal consistency.

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Novel risk factors for the strategic approaches to control cryptosporidiosis in newborn calves.

This study was conducted to assess the effect of colostrum quality and quantity on Cryptosporidium spp. calf diarrhoea in an intensive dairy cattle farm in Greece. Faecal samples were collected from 100 dairy calves randomly selected and born during all 4 seasons (March 2015 to May 2016) of the year. In total, 71% of the selected calves were positive for Cryptosporidium spp. oocysts. The statistical analysis revealed influence of colostrum quality on faecal score. Linear regression showed that the colostrum quantity during the first day of life was negatively associated with the number of Cryptosporidium spp. oocysts in faeces. During multivariable analysis, the variables representing the quality of colostrum and the season of the calf’s birth were identified as confounders. Cryptosporidium spp. is a common pathogen participating in neonatal calf diarrhoea. Colostrum management and season influence the number of Cryprosporidium spp. oocysts and faecal consistency. The above findings demonstrate novel risk factors that should be included in the strategic approaches to control cryptosporidiosis in newborn calves.

A retrospective epidemiological analysis of risk factors for a primary necropsy diagnosis of bovine respiratory disease

Bovine respiratory disease (BRD) is a multifactorial disease and the primary cause of both bovine morbidity and mortality in Ireland. The risk factors associated with a primary necropsy diagnosis of BRD among cattle in the traditional (non-feedlot) husbandry systems prevalent in Ireland have not been investigated previously. The aim of this case-control study was to investigate those risk factors among cattle of all ages over an 8 year period. A total of 3,090 BRD cases and 5,236 controls were matched by submitting veterinary practitioner. Univariable and multivariable analyses were performed to examine the association of selected animallevel, herd-level and environmental risk factors with case or control status using a conditional logistical regression model. Male cattle aged more than 31 days were significantly more likely to record a primary necropsy diagnosis of BRD than female cattle. Older cattle of both sexes were at increased odds of a BRD necropsy diagnosis than younger calves with the exception of female cattle aged greater than 165 days. The risk of a primary necropsy diagnosis of BRD increased with increasing herd size and decreased with increasing time in days since the last animal movement into the submitting herd. There were significantly reduced odds of a primary necropsy diagnosis of BRD in the summer (June to August) when compared with the autumn (September to November). These findings identify significant risk factors for a necropsy diagnosis of BRD under non-feedlot-type husbandry conditions.

Management factors associated with mortality of dairy calves in Finland: A cross sectional study

Mortality at herd level is an indicator of overall calf welfare on dairy farms. The aim of this cross sectional study was to identify management factors associated with calf mortality on dairy farms in Finland. Calf mortality data and information on management practices collected during farm visits and farmer interviews were analysed using linear models. The average size of 82 herds enrolled in the study was 125 ± 41 cows. The mortality risk of calves <7 days of age was 5 (or 5.2) ± 2.3% and was associated with larger herd size and the practice of not separating sick calves from other calves (6.0 ± 0.4 vs. 4.7 ± 0.3%; P < 0.05). The mortality risk of calves aged 7-180 days was 6 (or 5.7) ± 6.2% and increased with a shorter whole milk feeding period, longer period in the calving pen and lower average herd production level (P < 0.05). The mortality risk of calves was lower on farms where a veterinarian disbudded calves instead of farmer. Longer milk feeding and improved management of sick calves are recommended to reduce calf mortality. Specific management practices associated with lower mortality risk should be emphasised when advising farmers on how to enhance calf welfare.

An observational study using blood gas analysis to assess neonatal calf diarrhea and subsequent recovery with a European Commission-compliant oral electrolyte solution

An observational study was conducted on dairy calves (51 healthy, 31 with neonatal diarrhea) during outbreaks of diarrhea on 4 dairy farms. Clinical assessment scores (CAS) were assigned to each healthy and diarrheic calf [from 0 (healthy) to 4 (marked illness)]. Blood gas analysis [pH, base excess (BE), Na(+), K(+), Ca(2+), Cl(-), glucose, total hemoglobin, standard HCO3(-), strong ion difference (SID), and anion gap (AG)] was completed for each calf. Repeated measurements were taken in healthy animals, and pre- and postintervention measurements were taken for diarrheic calves. The mean CAS of diarrheic calves was 1.7, with 51, 30, 17, and 2% of calves scoring 1, 2, 3, and 4, respectively. The mean value for blood pH, BE, AG, and SID was 7.26, -4.93mM, 16.3mM, and 38.59mM, respectively. Calves were administered an oral rehydration and buffering solution (ORBS; Vitalife for Calves, Epsilion Ltd., Cork, Ireland) and reassessed. The mean CAS decreased to 0.38 (65% of calves scored 0 and 35% scored 1) at 6 to 18h posttreatment and to 0.03 (98% of calves scored 0 and 2% scored 1) within 24 to 48h. Significant increases in mean value for pH, BE, HCO3(-), Na(+), and SID, and significant decreases in AG, K(+), Ca(2+), and total hemoglobin were recorded posttreatment. The correlation estimates indicated that pH, HCO3(-), and BE were strongly correlated with CAS, with values exceeding 0.60 in all cases. Administration of an ORBS with a high SID and bicarbonate buffer demonstrated rapid recovery from a diarrheic episode in dairy calves.

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.

Cryptosporidium parvum infection and associated risk factors in dairy calves in western France

This study was conducted to determine the prevalence and risk factors for Cryptosporidium infection in calf neonates on dairy farms in Normandy.

Fecal samples were randomly collected between July 2010 and September 2011 from 968 calves (7–21 days old) on 97 farms. Up to 10 calves were selected and sampled per farm, and feces examined for oocysts by microscopy. C. parvum oocyst shedding was scored semi-quantitatively (0–5). A questionnaire about calf-level care and management was completed, and mortality rates were obtained from the French national registration database (BDNI). Bivariable and multivariable analyses of potential risk factors for C. parvum oocyst shedding were conducted using generalized estimating equation (GEE) models (family = Binomial).Overall, 402 out of 968 calves (41.5%) were positive for oocysts, and 25.1% of animals had a shedding score >2. Seven of the 97 farms (7%) were negative for oocysts in all fecal samples. At the time of collection, 375 calves (39%) had diarrhea, and its prevalence strongly correlated with the score for C. parvum oocyst shedding (p < 0.0001). The mortality rate at 90 days was significantly greater for calves with high combined scores of diarrhea and shedding. Factors associated with the shedding of C. parvum were the Normande breed (odds ratio = 1.49; 95% confidence interval (CI): 0.93–2.37), dispensing of colostrum using a bucket (odds ratio = 1.37; 95% CI: 1.00–1.89), treatment with halofuginone (odds ratio = 0.46; 95% CI: 0.19–1.15) and feeding with fermented milk (odds ratio = 0.32; 95% CI: 0.17–0.63).

C. parvum is widespread among calves under 21 days old in dairy herds of western France. Shedding of C. parvum is associated with a high incidence of diarrhea and increased risk of mortality in young calves. This study identified some associated calf-level factors, although further investigations are necessary to determine appropriate measures that farmers and veterinary practitioners should take to reduce the prevalence of C. parvum.

Prevalence and genotyping of Cryptosporidium spp. in farm animals in Egypt

In this study, we examined the prevalence and molecular characteristics of Cryptosporidium in buffalo, dairy cattle and sheep in different farms at Kafr El Sheikh Province, Egypt. Rectal fecal samples, including 466 samples from buffalo, 1697 from cattle and 120 from sheep, were collected from different ages and screened by modified Ziehl-Neelsen acid-fast microscopy for detection of Cryptosporidium oocysts. All studied farms were positives with an overall prevalence of 1.29% in buffalo (4.17% in claves versus 0.48% in adults), 7.07% in cattle (6.90% in calves versus 10.20% and 6.10% in heifers and adults, respectively) and 2.50% in sheep (4.40% in lambs versus 1.30% in adults). PCR-RFLP analyses of small-subunit rRNA genes from positive specimens revealed the occurrence of C. parvum and C. ryanae in buffalo; C. parvum, C. ryanae, C. bovis and C. andersoni in cattle and only C. xiaoi in sheep. Genotypes distribution showed that C. ryanae was the dominant species (60.0%) followed by C. parvum (40.0%) in buffalo calves. Meanwhile, in cattle calves, C. parvum was the commonest species (74.23%) followed by C. ryanae (16.10%) and C. bovis (9.70%). Subtyping of C. parvum based on sequence analysis of the polymorphic 60 kDa glycoprotein gene locus showed the presence of subtypes IIdA20G1 and IIaA15G1R1 in both buffalo and cattle calves, addressing the potential role of calves in zoonotic cryptosporidiosis in Egypt.

A multidisciplinary approach to determine factors associated with calf rearing practices and calf mortality in dairy herds

In the Netherlands, an increase in ear-tagged calf mortality (3 days to 1 year of age) in dairy farms was observed. The aim was to determine why calf mortality increased and how to reduce calf mortality in herds with structural high rates. A multi-disciplinary approach was chosen to study this phenomenon. First analysis of census data revealed that the majority of the calves died in the first month of life. In addition, a panel of 236 farmers indicated that the increase in calf mortality might be related to priority, time management and the mind-set of farmers. For that reason a questionnaire was carried out to detect risk factors for mortality among young calves (<1 month) in 100 dairy farms with increased calf mortality compared to 100 dairy farms with stable and below average calf mortality. The results showed that, besides management factors such as IBR and BVDV control, and purchase of cattle, also the answers to statements giving an indication on the farmers' mind-set, were associated with calf mortality. Therefore, a qualitative sociological study on the farmers' identity was conducted by performing in-depth interviews among 30 farmers with structurally high calf mortality rates. Afterwards, the results were communicated with a veterinary advisor who visited the farmers and gave tailored advice. Most of the interviewed farmers believed to have sufficient knowledge and skills regarding calf rearing. The farmers did not share their calf rearing problems with colleagues and advisors but they mentioned to be open to receive advice if not communicated in a reproaching or pedantic way. The sociologist distinguished three different phases of awareness concerning calf mortality among the farmers: (1) farmers who were only partly, or not at all, aware of high calf mortality; (2) farmers who felt powerless because of their inability to find a solution to their problems; and (3) farmers who knew they can be inaccurate when it comes to rearing calves, but were reluctant to change this. With the background information of the farmers' identity it was easier for the veterinary advisor to provide tailored advice resulting in a higher probability of following up. A first evaluation in which calf mortality rates in the six months after providing the advice were monitored, indicated that the advice resulted in reduced mortality. The combination of census data, epidemiological and qualitative sociological research revealed that advisors should be aware of the attitude and mind-set of the farmer and adapt their approach and advice accordingly.

Farm characteristics and calf management practices on dairy farms with and without diarrhea: a case-control study to investigate risk factors for calf diarrhea

Calf diarrhea is one of the most important problems in calf rearing on dairy farms worldwide. Besides pathogens, several noninfectious management factors, especially management around birth, colostrum management, calf housing, feeding, and hygiene are important in the pathogenesis of diarrhea. To date, few data are available concerning calf rearing management on small and medium-sized dairy farms that are typical for Austria and the alpine region. Consequently, the objectives of this case-control study were to evaluate routine calf management practices on Austrian dairy farms and to examine differences in management between farms with and without the presence of calf diarrhea to identify risk factors. Overall, 100 dairy farms were visited. Of these farms, 50 were chosen based on the history and presence of calf diarrhea (case farms). Another 50 farms with no presence of calf diarrhea were chosen to serve as a standard of comparison (control farms). On farms, management was evaluated by face-to-face interview, and health status and hygiene were surveyed. Several calf rearing management procedures were similar on all of the visited farms, especially in areas regulated by national and European law. These factors include colostrum management and feeding. Consequently, no influence of these factors on the appearance of calf diarrhea could be detected. In contrast, other areas such as hygiene measures differed between farms and showed a partial association with the presence of calf diarrhea on farm. Variables related to diarrhea on farm were farm size; that is, the number of cows on farm. Farms with diarrhea cases were larger (median 40 cows, interquartile range 24.5 to 64.0) compared with farms with no presence of diarrhea (median 28 cows, interquartile range 18.8 to 44.0). Other risk factors that influenced the presence of diarrhea were the presence of other farm animal species on the farm [odds ratio (OR) 26.89, 95% confidence interval (CI): 2.64 to 273.5], frequency of cleaning of the calving area (OR 0.12, 95% CI: 0.02 to 0.79), the placement of individual calf housings (barn vs. outdoors; OR 0.02, 95% CI: 0.00 to 0.47), and the presence of respiratory tract disease (OR 52.49, 95% CI: 1.26 to 2,181.83). The possible influence of these factors on the appearance of calf diarrhea should be considered when farmers are advised.

Status of vitamins E and A and β-carotene and health in organic dairy cows fed a diet without synthetic vitamins

Synthetic vitamin supplementation is not consistent with organic production, so it is important to investigate whether dairy cows can maintain their health and production without synthetic vitamins being added to their diet. In basic dairy cow diets, provitamin A (β-carotene) and vitamin E are mainly found in pasture and in grass and legume silages, but the concentrations are highly variable. This study compared the vitamin status and health of cows without synthetic vitamin supplementation (NSV group) with control cows (CON group) fed synthetic vitamins according to Swedish recommendations (600 IU of vitamin E and 80,000 IU of vitamin A per cow per day) to investigate whether dairy cows can fulfill their requirements of vitamins A and E without supplementation with synthetic vitamins. Vitamin concentrations in blood plasma and milk, health, fertility, milk yield, and milk composition were measured in Swedish Holstein cows (n=28) during 2 complete lactations. All cows were fed a 100% organic diet containing grass-legume silage, cold-pressed rapeseed cake, peas, cereal grains, and minerals. Blood samples were collected from each cow 3 wk before expected calving, at calving, and 3 wk, 3 to 5 mo, and 7 to 9 mo after calving. Samples of colostrum were taken and milk samples were collected 4d after calving and at the same time as the 3 blood samplings after calving. The only difference in vitamin status between groups was found in colostrum in yr 1, when CON cows tended to have a higher concentration of α-tocopherol, and their β-carotene concentration was higher compared with NSV cows. The NSV cows tended to have more cases of mastitis than CON cows in yr 2. Within the NSV group, fewer cows were healthy and more cases of mastitis were observed in yr 2 than in yr 1. The groups did not differ in production parameters. In conclusion, the vitamin status in blood and milk of the studied cows indicated that cows in organic dairy production can fulfill their requirements of vitamins A and E without any supplementation of synthetic vitamins, except at the time around calving, when the requirements are high. However, the impaired health of NSV cows in yr 2 may indicate a long-term negative health effect in cows fed no synthetic vitamins.

Pre-Calving and Calving Management Practices in Dairy Herds with a History of High or Low Bovine Perinatal Mortality

Simple Summary

Mortality of full-term calves at calving is an increasing problem in dairy industries internationally. Multiple herd management factors contribute to such losses. This case-control study identified factors which differed between herds with high and low calf mortality. These included breeding, dietary, health and calving factors. It was concluded that calving, not pre-calving, management appears to be the most important area of concern in herds with high perinatal mortality. This indicates that farmers and their veterinarians need to focus on calving management when investigating such problems and when attempting to reduce losses in herds with high rates of bovine perinatal mortality.

Abstract

Bovine perinatal mortality is an increasing problem in dairy industries internationally. The objective of this study was to determine the risk factors associated with high and low herd-level calf mortality. Thirty herds with a history of either high (case) or low (control) calf mortality were recruited. A herd-level questionnaire was used to gather information on management practices likely to impact bovine perinatal mortality. The questionnaire was divided into four subsections dealing with pre-calving (breeding, diet and body condition score, endemic infectious diseases) and calving factors. Most of the significant differences between case and control herds were found in calving management. For example, in case herds, pregnant cattle were less likely to be moved to the calving unit two or more days and more likely to be moved less than 12 hours pre-calving, they were also less likely to calve in group-calving facilities and their calves were more likely to receive intranasal or hypothermal resuscitation. These management procedures may cause social isolation and periparturient psychogenic uterine atony leading to dystocia, more weak calves requiring resuscitation and high perinatal calf mortality. The key finding is that calving, not pre-calving, management appears to be the most important area of concern in herds with high perinatal mortality.

Tracing the transmission of bovine coronavirus infections in cattle herds based on S gene diversity

Bovine coronavirus (BCoV) is found worldwide and causes respiratory infections and diarrhoea in calves and adult cattle. In order to investigate the molecular epidemiology of BCoV, 27 reverse transcription polymerase chain reaction (RT-PCR) positive samples from 25 cattle herds in different parts of Sweden were analysed. A 1038-nucleotide fragment was PCR amplified and directly sequenced.

The analysed BCoV strains showed a high sequence identity, regardless of whether they were obtained from outbreaks of respiratory disease or diarrhoea or from calves or adult cattle. Circulation of an identical BCoV strain during a 4-month period was demonstrated in calves in one dairy herd. In a regional epizootic of winter dysentery in Northern Sweden, highly similar BCoV strains were detected. In the Southern and Central regions, several genotypes of BCoV circulated contemporaneously, indicating that in these regions, which had a higher density of cattle than the Northern regions, more extensive transmission of the virus was occurring. Identical BCoV sequences supported the epidemiological data that inter-herd contact through purchased calves was important. Swedish BCoV strains unexpectedly showed a high homology with recently detected Italian strains. This study shows that molecular analysis of the spike (S) glycoprotein gene of BCoV can be a useful tool to support or rule out suspected transmission routes.

Scientific Opinion on the welfare of cattle kept for beef production and the welfare in intensive calf farming systems

Information given in previous Opinions "Welfare of cattle kept for beef production" (SCAHAW, 2001) and "The risks of poor welfare in intensive calf farming systems" (EFSA, 2006) is updated and recent scientific evidence on the topics reviewed. Risks of poor welfare are identified using a structured analysis, and issues not identified in the SCAHAW (2001) beef Opinion, especially effects of housing and management on enteric and respiratory diseases are reviewed. The Opinion covers all systems of beef production, although the welfare of suckler cows or breeding bulls is not considered. The Chapter on beef cattle presents new evidence and recommendations in relation to heat and cold stress, mutilations and pain management, digestive disorders linked to high concentrate feeds and respiratory disorders linked to overstocking, inadequate ventilation, mixing of animals and failure of early diagnosis and treatment. Major welfare problems in cattle kept for beef production, as identified by risk assessment, were respiratory diseases linked to overstocking, inadequate ventilation, mixing of animals and failure of early diagnosis and treatment, digestive disorders linked to intensive concentrate feeding, lack of physically effective fibre in the diet, and behavioural disorders linked to inadequate floor space, and co-mingling in the feedlot. Major hazards for white veal calves were considered to be iron-deficiency anaemia, a direct consequence of dietary iron restriction, enteric diseases linked to high intakes of liquid feed and inadequate intake of physically effective fibre, discomfort and behavioural disorders linked to inadequate floors and floor space.

Antimicrobial resistance and virulence factors in Escherichia coli from Swedish dairy calves

Background

In Sweden, knowledge about the role of enteropathogenic Escherichia coli in neonatal calf diarrhea and the occurrence of antimicrobial resistance in E. coli from young calves is largely unknown. This has therapeutic concern and such knowledge is also required for prudent use of antimicrobials.

Methods

In a case control study Esherichia coli isolated from faecal samples from dairy calves were phenotyped by biochemical fingerprinting and analyzed for virulence genes by PCR. Antimicrobial susceptibility was tested by determination of minimum inhibitory concentration (MIC). Farm management data were collected and Fisher's exact test and univariable and multivariable logistic regression analysis were performed.

Results

Of 95 E. coli tested for antimicrobial susceptibility 61% were resistant to one or more substances and 28% were multi-resistant. The virulence gene F5 (K99) was not found in any isolate. In total, 21 out of 40 of the investigated virulence genes were not detected or rarely detected. The virulence genes espP, irp, and fyuA were more common in resistant E. coli than in fully susceptible isolates (P < 0.05). The virulence gene terZ was associated with calf diarrhea (P ≤ 0.01).

The participating 85 herds had a median herd size of 80 lactating cows. Herds with calf diarrhea problems were larger (> 55 cows; P < 0.001), had higher calf mortality (P ≤ 0.01) and calf group feeders were more in use (P < 0.05), compared to herds without calf diarrhea problems.

There was no association between calf diarrhea and diversity of enteric E. coli.

Conclusions

Antimicrobial resistance was common in E. coli from pre-weaned dairy calves, occurring particularly in calves from herds experiencing calf diarrhea problems. The results indicate that more factors than use of antimicrobials influence the epidemiology of resistant E. coli.

Enteropathogenic E. coli seems to be an uncommon cause of neonatal calf diarrhea in Swedish dairy herds. In practice, calf diarrhea should be regarded holistically in a context of infectious agents, calf immunity, management practices etc. We therefore advice against routine antimicrobial treatment and recommend that bacteriological cultures, followed by testing for antimicrobial susceptibility and for virulence factors, are used to guide decisions on such treatment.

Lactic acid bacteria isolated from young calves--characterization and potential as probiotics

Lactic acid bacteria (LAB) are widely used as probiotics in humans and animals to restore the ecological balance of different mucosa. They help in the physiological functions of newborn calves that are susceptible to a variety of syndromes. The criteria for the selection of strains for the design of probiotic products are not available. Based in the host-specificity of the indigenous microbiota, 96 LAB isolates from faeces and oral cavity of calves were obtained. The surface properties were screened showing a small number of highly hydrophobic or autoagglutinating isolates. Also, a group produced H(2)O(2) and were able to inhibit pathogens, and two strains were bacteriocin-producers. Some grew at very low pH and high bile concentrations. The strains sharing some of the specific properties evaluated were identified genetically, assayed their compatibility and exopolysaccharide production. The results allow going further in the establishment of criteria to select strains to be included in a multi-strain-probiotic-product to be further assayed in animals.