Diagnostic performance of Mycoplasmopsis bovis antibody ELISA tests on bulk tank milk from dairy herds

BACKGROUND

Testing of bulk tank milk (BTM) for Mycoplasmopsis bovis (previously Mycoplasma bovis) antibodies is increasingly popular. However the performance of some commercially available tests is unknown, and cutoff values possibly need to be adjusted in light of the purpose. Therefore, the aim of this study was to compare the diagnostic performance of three commercially available M. bovis antibody ELISAs on BTM, and to explore optimal cutoff values for screening purposes. A prospective diagnostic test accuracy study was performed on 156 BTM samples from Belgian and Swiss dairy farms using Bayesian Latent Class Analysis. Samples were initially classified using manufacturer cutoff values, followed by generated values.

RESULTS

Following the manufacturer's guidelines, sensitivity of 91.4%, 25.6%, 69.2%, and specificity of 67.2%, 96.8%, 85.8% were observed for ID-screen, Bio K432, and Bio K302, respectively. Optimization of cutoffs resulted in a sensitivity of 89.0%, 82.0%, and 85.5%, and a specificity of 83.4%, 75.1%, 77.2%, respectively.

CONCLUSIONS

The ID-screen showed the highest diagnostic performance after optimization of cutoff values, and could be useful for screening. Both Bio-X tests may be of value for diagnostic or confirmation purposes due to their high specificity.

Dynamics of protozoal excretion in the faeces of calves during the first 28 days after arrival at the fattening farm indicate infection before regrouping and show poor temporal correlation with diarrhoea

BACKGROUND

Calves in dairy cattle production in Switzerland are transported to a fattening farm at the age of 3-5 weeks, and frequently suffer from diarrhoea within the first 14 days after arrival. To characterise the role of intestinal protozoa in this, we investigated the excretion dynamics of Eimeria, Cryptosporidium and Giardia during the first 28 days after the arrival and regrouping of calves at fattening farms.

METHODS

A total of 610 faecal samples from 122 calves (mean age 37.3 days; mean body weight 79.8 kg) were collected on seven different fattening farms during the first 28 days after the arrival and regrouping of the animals. The farms were visited between January and April (cold season; n = 4) and between June and August (warm season; n = 3). The samples were collected rectally on days 1, 4, 7, 14 and 28, assessed for consistency, and analysed using the McMaster method for quantitative determination of the number of Eimeria oocysts per gram of faeces (OPG), flotation for morphological differentiation of the unsporulated Eimeria oocysts, a concentration method for the semi-quantitative determination of Giardia cysts, and modified Ziehl-Neelsen staining for semi-quantitative determination of Cryptosporidium oocysts.

RESULTS

Overall, 50.8% (62/122) of the animals had diarrhoea during the study period. However, the faecal excretion of protozoal pathogens was neither associated with diarrhoea nor with body weight gain of the animals. Altogether, 90.2% (110/122) of the calves were Eimeria positive. Eimeria zuernii was excreted by 51 (41.8%) and Eimeria bovis by 68 (55.7%) animals. In the warm season more animals tested positive for Eimeria and OPGs were higher than in the cold season. There was no correlation between the age of the calves and the OPG values. Overall, 64.8% (79/122) of the calves excreted Eimeria oocysts within the first 7 days, indicating that they had been infected with the parasite on the dairy farm of origin. Eighty-nine calves (73.0%) excreted Giardia cysts, with more positive animals in the cold (80.3%) compared with the warm season (64.3%). Only Giardia duodenalis assemblage E was identified. Cryptosporidium oocysts were microscopically detected in 14 animals (11.5%) on five farms. Cryptosporidium spp. were present in a total of 12 animals, i.e. Cryptosporidium parvum in nine, Cryptosporidium ryanae in two, and Cryptosporidium bovis in one animal.

CONCLUSIONS

A better understanding of the temporal dynamics of protozoal infections in calves is helpful for the implementation of appropriate measures to protect the health of these animals at a critical phase in their lives. Our results indicate that factors other than those examined in the present study contributed to the onset of diarrhoea in the calves.

A pilot study for the isolation of Eimeria spp. oocysts from environmental straw samples in comparison with individual faecal examination of fattening calves

The diagnosis of eimeriosis in calves mainly relies on the presence of diarrhoea and the excretion of Eimeria oocysts in the faeces. Restraining the animals to collect rectal samples for diagnostic purposes is stressful and time-consuming. The aim of this study was to evaluate a method for the quantification of oocysts in environmental barn straw samples. To investigate the recovery rate of the method, straw and Eimeria negative faeces were spiked with Eimeria oocysts in plastic bags and mixed with water and 0.05% Tween 20 (v/v); the liquids were filtered twice through sieves (mesh size 300 and 52 μm), centrifuged and the number of oocysts in the sediment determined using a McMaster counting chamber. A recovery rate of 52.4% (95% confidence interval: 48.2-56.5%) was obtained. In the following, field straw (n = 156) and individual faecal samples (n = 195, also analysed by McMaster counting chambers) were collected on four different farms. Eimeria oocysts were present on all farms in faecal (84/195, 43.1%) and straw samples (119/156, 76.3%). In 37 (23.7%) straw samples, sporulated oocysts were observed, with a sporulation rate ranging from 0 to 40%. Despite high variability between farms and examination days, mean numbers of oocysts in the straw positively correlated with mean numbers of oocysts excreted in the faeces (ρ_Spearman = 0.60). The examination of environmental straw samples may represent an easy-to-perform, non-invasive, inexpensive preliminary diagnostic approach for surveillance of eimeriosis at group level, having the potential to assess the infection pressure.

Sucking and drinking behaviour in preweaned dairy calves in the first five weeks of life

Background

Nursing and sucking are essential for adequate nourishment of preweaned calves and the relationship between sucking indices has not been studied. The goal of this study was to investigate the number of sucks per litre of milk and per minute of drinking and the amount of milk ingested per suck in healthy preweaned calves. Correlation coefficients were calculated for the relationships between these variables. Eighteen healthy calves were used from birth to 5 weeks of age, and five measurements were made at the end of weeks 1 to 5. The calves were randomly divided into three groups and offered milk twice daily in a bucket with a rubber nipple. The amount of milk offered per day was equal to 12% of body weight in group A and 16% of body weight in group B. Calves in group C were offered as much milk as they wanted during each feeding period. The duration of drinking was determined with a stopwatch, and the number of sucks was counted with a handheld tally counter. The variables drinking duration, total amount consumed and the number of sucks required were used to calculate the number of sucks/min, the number of sucks/L, the amount ingested per suck and drinking speed.

Results

The number of sucks/min ranged from 113 to 133 and increased significantly during the study period. The mean number of sucks/L decreased from 204 in week 1 to 141 in week 5 and drinking speed increased from 0.6 to 1.0 L/min. There were significant correlations between the number of sucks/L of milk and the amount of milk ingested per suck, drinking duration, total amount consumed and drinking speed. Drinking speed was positively correlated with the amount of milk ingested per suck and the total amount of milk consumed, and negatively correlated with drinking duration.

Conclusions

These findings show that drinking variables of calves offered different amounts of milk vary little and significant changes occur during the same period with respect to the number of sucks/L of milk and the amount of milk ingested per suck. Several drinking variables are significantly correlated with other variables.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03280-x.

[Repeated drenching of calves - -Ultra-sonographic findings of the -reticulum and abomasum and -short-term -effects on pH and -D-lactate in rumen fluid and blood]

INTRODUCTION

An oesophageal tube feeder was used to administer milk to six clinically healthy calves every 12 hours for a total of three feedings. The calves were seven to nine days of age, and each feeding consisted of a volume of milk that was 6 % of the body weight of the calves. The reticulum and abomasum were scanned ultrasonographically before, during and after drenching. Blood samples for D-lactate determination and venous blood gas analysis were collected at -12, 0 (first drenching), 6, 12 (second drenching), 18, 24 (third drenching), 30 and 36 hours. Ruminal fluid was collected for measurement of pH and D-lactate concentration at -12 and 36 hours. Based on simultaneous ultrasonographic examinations of the reticulum and abomasum, some of the force-fed milk flowed into the reticulum and some directly into the abomasum; both organs contained milk immediately after drenching. Drenching led to ruminal acidosis evidenced by a significant decrease in median pH from 7,0 (6,0 - 7,0) to 4,5 (3,0 - 5,0) and a 93-fold increase in median D-lactate concentration from 0,39 (0,14 - 1,33) to 36,3 (17,9 - 53,3) mmol/l but it did not cause metabolic acidosis. Based on these findings, we concluded that milk administered to calves via an oesophageal tube feeder flows into the reticulum and abomasum simultaneously and three force feedings 12 hours apart cause acute ruminal acidosis, which was not accompanied by metabolic acidosis in the short term.

[Usage of antimicrobials on seven farms of beef producers in Switzerland]

INTRODUCTION

It was the objective of this study to evaluate morbidity, mortality, use of veterinary drugs and production output on seven representative Swiss beef fatteners, who bought on a regular basis batches of calves from traders (mean age and weight: 31 day, 75 kg) and practised an all in-all out system. From March 2015 until May 2016, 51 batches with a total of 1307 calves were included. The use of drugs during the first eight weeks following delivery of calves from the trader, casualty rate and carcass performance of 837 bulls. The administration of antimicrobials was calculated per calf as the number of days with effective therapeutic concentrations (daily doses per animal; DD/A). The average weight of the calves at arrival on the fattening unit was 75 kg and the age 31 days. The group size was between 13 to 47 calves (median 22, Q1 = 21, Q2 = 30). In 36 batches (70,6 %), a veterinary entry examination was performed which demonstrated that at admission 20 % of the calves suffered from a relevant disease. The median for the number of DD/A was 16 for the first 56 days on the farm (Q1 = 11, Q3 = 21); 68 % of these DD/A were attributed to metaphylactic medications after delivery. Thereafter, pneumonia (54 %), diarrhea (33 %) and otitis (10 %) were the most frequent indications for subsequent therapeutic interventions. Over all batches, a median of 71 % (Q1 = 47, Q3 = 85) of all DD/A were due to critically important antimicrobials (CIM) and drugs containing several antibiotics including a CIM. The losses due to death or euthanasia averaged 3,7 % of all calves. The median for daily weight gain for the total fattening period (median 354 days; Q1 = 328, Q3 = 379) accounted for 1325 g (Q1 = 1216, Q3 = 1425). The profound variation between the farms in respect to the results of drug use and production output reveals evidence for the strong impact of farm-specific factors (such as pen space per calf, barn climate, vaccination protocol, supervision). Concurrently, the remarkable differences between the results of different batches on one farm depict that there are further important risk factors which are beyond the control of the farmer (in particular season of the year, transport). It is concluded that a systematic minimization of risk factors as part of a continuous veterinary consultation is useful two improve herd health and to reduce the input of drugs in the production of beef.

Short communication: Variance and autocorrelation of deviations in daily milk yield are related with clinical mastitis in dairy cows

Daily milk production, and fluctuations therein, can provide information on health and resilience of dairy cows. We studied variance and autocorrelation of deviations in daily milk yield in relation to the occurrence of clinical mastitis (no, early or later in lactation). Individual lactation curves were fitted to 305-d lactations of 414 dairy cows using quantile regression. Log-transformed variance (lnVar) and autocorrelation of the quantile residuals of daily milk yield (predicted - observed) were evaluated for intervals until 30 and until 305 days in milk (DIM). Cows were classified as having no mastitis (n = 249), early mastitis that first occurred before 30 DIM (n = 29); or later mastitis (n = 136). Subsequently, linear models were used to assess effects of mastitis and parity class (primiparous or multiparous) on lnVar and autocorrelations; and logistic regression analyses were performed to predict mastitis from lnVar or autocorrelation and parity. From 10 to 30 DIM, lnVar was greater for cows with early mastitis than for cows with no or late mastitis, and autocorrelation tended to be lower for cows with early mastitis than for cows with no mastitis. The lnVar and autocorrelation from 10 to 30 DIM were not predictive of late mastitis. From 10 to 305 DIM, lnVar was greater and autocorrelation was lower for both cows with early and late mastitis than for cows with no mastitis; and both were predictive of having mastitis in the 305-d lactation. Primiparous cows had lower lnVar than multiparous cows. In cows without mastitis, autocorrelation values were positively correlated with lnVar. Results confirm that increased lnVar is associated with clinical mastitis.

[Laboratory diagnostic examinations as part of «Pathocalf» in case of herd problems on Swiss calf rearing and fattening farms]

INTRODUCTION

«PathoCalf» represents a project promoted by the Swiss Federal Food Safety and Veterinary Office. It was the aim of this project to use laboratory diagnostic services for farms raising calves (dairy farms, fattening units, beef cow operations) and dealing with a herd health issue in order to obtain an overview about the spectrum of infectious agents and bacterial resistance patterns in Switzerland. From January 2015 to March 2018, the Bovine Health Service and the farm veterinarian straightened out 148 stock problems on 125 farms. For this, samples were collected from 342 animals. In addition, 98 necropsies were performed. The service related to «PathoCalf» was utilized most frequently related to stock problems with respiratory disease (40,5%; 60/148), gastrointestinal disease (37,2%, 55/148) and fatalities with unknown causation (8,8%, 13/148). The majority of all investigated animals (71,8%) were younger than 10 weeks of age. In calves suffering from respiratory disease, most frequently Pasteurella (P.) multocida was found (40,6%, 67/165), followed by mycoplasmen (35,8%, 59/165) and Mannheimia (M.) haemolytica (13,3%, 22/165). The proportion of tested P. multocida and M. haemolytica strains being resistant against oxytetracyline was 67,7% (42/62), 21,1% (4/19) for tilmicosine and 11,3% (7/62) for danofloxacine. For calves suffering from gastrointestinal problems, most frequently Rotavirus (57,6%, 19/33), E. coli (47,7%, 74/155) and Campylobacter spp. (27,7%, 43/155) were found. A resistance against tetracycline was evident for 95,0% (19/20) of all isolated E. coli, and for 80,0% (16/20) in respect to sulfonamides and for 57,1% (12/21) against enrofloxacine. For fatalities with unknown causation, a perforated abomasal ulcer was the most important finding (33,3%, 7/21), followed by diarrhea (28,6%, 6/21) and indigestion related to ruminal acidosis (19,1%, 4/21). The results indicate that aetiological investigations facilitate the evaluation of stock problems. The systematic assessment of abiotic risk factors remains, however, indispensable for the factorial diseases most frequently found on farms raising calves.

Postoperative wound assessment in cattle: How reliable is the back hand palpation?

Background

As part of clinical wound assessment in bovine surgery, discrepancies in skin temperature are evaluated by placing the back of the hand on the area to be examined. Generally, an increased skin temperature at the wound site for a prolonged period is considered as an indicator of impaired wound healing.

The aim of this study was to verify the reliability of palpation under bovine practice conditions using laparotomy as an example. Fourteen cows (German Holstein) with a left displacement of the abomasum (LDA) without other severe concurrent diseases were examined preoperatively and once daily for ten days after surgery. The skin temperature of the wound site in the right flank was assessed by palpation, followed by thermographic evaluation using an infrared camera after a 45-min acclimatisation period, under standardised conditions in a closed examination room daily for 10 days.

Results

All the incisions healed without clinical detectable perturbances. The ambient temperature range during the study period was 7.8 − 24.1 °C. Two groups were retrospectively defined according to the ambient temperature: high ambient temperature (HT group; median: 20.2 °C 25/75 quartile: 18.5 °C / 21.7 °C; n = 6) and low ambient temperature (LT group; 10.8 °C; 9.4 °C / 12.8 °C; n = 8). The temperature differences (Δϑ) between the mean skin temperature of the wound site and a defined reference area cranial to the wound were assessed. A significant negative correlation was found between the ambient temperature (ϑ_Amb) and Δϑ (r=-0.51; P < 0.001). The Δϑ was postoperatively higher in the cows in the LT group (median of the individual animals 0.8–2.5 °C) than in the HT group (0.1–0.5 °C; P < 0.05). In contrast to the thermographic findings, manual palpation rarely detected local hyperthermia (> 1 °C) at the wound site (sensitivity 0.20; specificity 0.96).

Conclusions

The infrared thermography provides a more reliable assessment of temperature changes at the wound site in comparison to manual palpation. The ambient temperature markedly affects the extent of local hyperthermia at the wound site.

Effects of an oral hydro-ethanolic purple coneflower extract on performance, clinical health and immune parameters in calves

The objective of this randomized, placebo-controlled, double-blinded field trial was to investigate the effects of oral administration of purple coneflower (Echinacea purpurea L. (EP)) on performance, health and immune parameters in calves. Calves (n = 27) were enrolled to three groups (9 calves per group): 0.5 g EP/calf per day (ECL), 5 g EP/calf per day (ECH) or placebo. Calves were vaccinated with Bluetongue-Virus (BTV) serotype 4 vaccine to investigate EPs effects on seroconversion. Clinical and performance parameters, inter alia body weight, health and milk intake were recorded for 57 days. Blood samples were analyzed for BTV antibodies and IgG by ELISA, white and red blood cell counts by flow cytometry and mRNA abundance of various inflammatory markers in leukocytes (IL-1β, IL-8, tumor necrosis factor α (TNFα), cyclooxygenase 2 (Cox-2) and prostaglandin E synthase) was studied. The findings demonstrated no differences between groups regarding performance parameters. In all groups, calves suffered from diarrhea for a minimum of 2 days, but EP reduced the number of diarrhea days by 44% in ECL and increased the body temperature. Interestingly, ECL resulted in an increased number of respiratory disease days during the follow-up period. EP did not change blood cell and IgG counts, whereas eosinophil granulocytes were reduced in ECL. Decreased levels of hemoglobin and hematocrit were found in ECH. Prostaglandin E synthase levels in leukocytes were higher in ECL and ECH, whereas no differences were obtained for IL-1β, IL-8, TNFα and Cox-2. Due to the unexpected occurrence of BTV seropositive calves before the first vaccination, 13 calves were excluded from the evaluation on seroconversion and no statistical analyses could be performed regarding antibody production. BTV-4 antibodies were not produced in 4 placebo-calves, whereas 4 of 5 and 1 of 6 ECL- and ECH-calves produced antibodies. Further investigations are needed to draw final conclusions on mode of action and efficacy of EP in calves.

[Economic importance of antibiotic sale for private food animal practices in Switzerland - example veal production]

INTRODUCTION

The use of antibiotics in Swiss veal production is considered an established method for controlling bacterial infectious diseases. Although the veterinary profession aims to ensure animal welfare, the veterinary business income needs to be ensured at the same time. Against the background of increasing problems with resistant pathogens in human and veterinary medicine, the use of antibiotics should be significantly reduced and used more selectively. The associated economic consequences for food animal practitioners are unknown. The aim of this study was to determine the economic importance of antibiotic sale volume for private food animal practitioners in veal production. An anonymized questionnaire was sent to 120 mixed veterinary practices in Switzerland, which offered services to veal and beef cattle farmers. Questions involved the pharmaceutical sale volume, details on veterinary invoices from three farms with average, below and above average animal health throughout 2017. Twenty-nine complete questionnaires (response rate: 24.2%) and veterinary invoices of 84 farms were returned. The study is not representative, but it allows a rough assessment of the economic framework in Swiss livestock practice. The majority of the total turnover with livestock farms was generated by the sale of antibiotics (54%). Antibiotic sales per animal were higher as expected in farms with a below-average animal health than in farms with an average or above-average animal health. Consulting services turnover contributed only 0.5% to the total sale volume in veal farming. The results document, that antibiotic reduction measurements in veal and beef production will have economic consequences for veterinary livestock practices. In the medium term, the profitable existence of livestock veterinary practice requires a change to cost based consulting services.

[Interventions and treatments of farm animals by non-veterinarians: quo vadis?]

INTRODUCTION

The increasing professionalization and the cost pressure on farms combined with a decreasing availability of veterinary expertise procures the demand for treatments and interventions performed by non-veterinarians. A current survey resulting in 56 responses of food animal practitioners showed that a majority delivered pour-on anthelmintics, drugs for oral application and ointments after respective instruction to farmers. Udder injectors, antimicrobials and vaccines were handled more restrictively, but even hormones were committed by more than half of the veterinarians to livestock owners. In respect to interventions, most practitioners supported that farmers perform functional foot trimming, administration of boli, inseminations, dehorning and castrations of calves. By contrast, many veterinarians refused that farmers apply intravenous injections, insert a trocar or treat sole ulcers. In respect to the future development, implications of non-veterinarian interventions on animal welfare, consumer protection and drug safety have to be considered. Indispensable are qualification and skills of the person performing interventions which can be acquired by certificated training courses. Moreover, a basic conception and taking responsibility in particular for application of veterinary drugs is mandatory - in this respect, at present marked deficits exist among many farmers. Based on the current legal situation, several interventions can be delegated to non-veterinarians, but the technical responsibility for the proper implementation is due to the veterinarian. This includes an evaluation of interventions and treatments on a regular basis together with the farmer. On this basis, the assessment of clinical symptoms as well as the initial treatment can be useful and appropriate to ensure a rapid therapy especially in animals suffering from factorial diseases. Having in mind profound differences in respect to the competence of non-veterinarians, general procedures to deliver drugs and to delegate interventions have to be rejected. Advanced diagnostic procedures and the prescription of veterinary drugs remain an exclusive mission of the veterinarian.

Stakeholders' perceptions of the challenges to improving calf health and reducing antimicrobial use in Swiss veal production

Large quantities of antimicrobials are used in Swiss veal production. To develop strategies to reduce antimicrobial use, it is important to understand how stakeholders along the veal production chain perceive the current situation and to find the key issues that challenge them about calf health management and antimicrobial use. However, there has been insufficient research into the individual contexts of the supply chain actors, and the central themes that they perceive to enable or limit their actions remain largely unknown. The aim of this study is to investigate the perceptions of the current situation of the Swiss veal production system, in terms of calf health management and antimicrobial use held by industry stakeholders, i.e. dairy farmers, veal producers, traders, slaughterhouse managers, advisors and veterinarians. Qualitative interviews were conducted with 27 respondents and analyzed using content analysis. The results show that stakeholders are aware of the current need to minimize resistance development and the related risks for public health by reducing antimicrobial use. The main reason for high antimicrobial use was nominated as the practice of purchasing calves from many different dairy farms and bringing them together in large groups at a young age, which exposes them to a variety of pathogens that their still developing immune systems are not able to cope with. To prevent and combat infectious diseases which are a frequent consequence of this practice, antimicrobial group treatments are commonly administered, which significantly raises the total amount of antimicrobials used. Group level treatments with antimicrobials were associated directly with the large-scale veal farming system, which uses excess calves from specialized dairy farms, and which the respondents perceive to cause financial pressure and mutual dependencies among participants. In addition, disunity between actors was perceived as a further challenge to find strategies for the reduction of antimicrobial use. The respondents suggested downscaling the production system so that calves can be treated individually but conceded that the current system may be very difficult to change, so also suggested various improvement measures within the existing system. The results of this study provide a basis for further research to investigate possible interventions that could considerably reduce antimicrobial use in veal production.

Extended lactation in high-yielding dairy cows. I. Effects on reproductive measurements

The objective of this prospective field study was to evaluate the effects of extending the lactation period on various reproductive measurements of high-yielding Holstein cows. On 40 d in milk (DIM), cows were gynecologically examined (transrectal palpation, sonography, vaginoscopy). Cows without signs of clinical endometritis were blocked by parity and were randomly allocated to 1 of 3 experimental groups with a voluntary waiting period (VWP) of 40, 120, and 180 d, respectively (G40, n = 135; G120, n = 141; G180, n = 139). Cows of G120 and G180 were reexamined at the end of the VWP. If natural estrus was detected within 46 d after the end of the VWP, an artificial insemination was performed. If no estrus was detected, the respective cows were synchronized by applying the classical Ovsynch protocol. We found no difference in the proportion of cows in which estrus was detected between 40 to 86 DIM or in the days to first estrus between the 3 groups. Estrus detection in this period was lower in cows with body condition score <3 on 90 DIM compared with body condition score ≥3 (61.5 vs. 76.0%) and in cows with high energy-corrected milk production (ECM) on 92 DIM [58.6 vs. 70.1%, for cows with higher and lower than the median (39.9 kg) ECM, respectively]. The proportion of cows that estrus was detected within 46 d after the VWP was greater in G120 (88.9%) and G180 (90.8%) compared with G40 (70.4%). These effects were more apparent in cows with high ECM. The rate of estrus detection and of becoming pregnant in this period was greater for G120 (hazard ratio = 2.2 and 1.6, respectively) and for G180 (hazard ratio = 2.4 and 1.8) compared with G40. Cows in both groups with extended lactation had greater overall first service conception rates (G120 = 48.9%; G180 = 49.6%) and a lower number of services per pregnant cow (G120 = 1.56 ± 0.1; G180 = 1.51 ± 0.1) compared with G40 (36.6%; 1.77 ± 0.1). We observed no difference in pregnancy loss or in the proportion of cows culled up to 305 d of lactation between the 3 groups. The number of Ovsynch protocols per 1,000,000 kg of ECM was reduced by 75% in G180 and by 74% in G120 compared with G40 (5.9 vs. 7.1 vs. 25.1). In conclusion, extending the lactation of dairy cows can improve main reproductive measurements in high-yielding cows.

[AntibioticScout.ch: Decision support for the prudent use of antimicrobials: Application in cattle]

INTRODUCTION

The administration of antibiotics in livestock has been criticized for many years, in particular because of an inappropriate use and the appearance of antibiotic residues in the environment, which can promote the emergence and spread of resistant bacteria. However, antibiotics are essential for the successful and sustainable control of bacterial pathogens. With the aim of optimizing the use of antibiotics in food animals and minimizing the prevalence of resistant bacteria, AntibioticScout. ch provides a decision aid for the prudent use of antimicrobial drugs. This approach emphasizes the importance of supportive therapy and the hallmarks of preventive concepts. Procedures to improve animal health and animal welfare in accordance with the principles of good veterinary practice are primary and effective tools to reduce the use of antimicrobial drugs. The necessary reduction in the use of antibiotics must, therefore, be accompanied by appropriate management strategies in animal husbandry. In particular, hygiene, animal welfare and biosecurity measures are crucial to ensure an optimal health status in farm animals.

Impact of nutritional programming on the growth, health, and sexual development of bull calves

The growth, health, and reproductive performance of bull calves are important prerequisites for a successful cattle breeding program. Therefore, several attempts have been made to improve these parameters via nutritional programming. Although an increase in energy uptake during the postweaning period (7-8 mo of age) of the calves leads to a faster growing rate, it has no positive effects on sexual development. In contrast, a high-nutrition diet during the prepubertal period (8-20 wk of age) reduced the age at puberty of the bulls and increased the size and/or weight of the testis and the epididymal sperm reserves. This faster sexual development is associated with an increased transient LH peak, which seems to be mediated by an increase in serum IGF-I concentrations. However, the exact mechanisms responsible for the interaction between nutrition and the subsequent development of the calves are not clear. The sexual development of bull calves depends not only on the nutrition of the calves after birth but also on the feed intake of their mothers during pregnancy. In contrast to the effects of the feed intake of the bull calves, a high-nutrition diet fed to the mother during the first trimester has negative effects on the reproductive performance of their offspring. In conclusion, it has been clearly demonstrated that growth, health, and reproductive performance can be improved by nutritional programming, but further studies are necessary to obtain a better understanding about the mechanisms responsible for this phenomenon.

Medicinal plants--prophylactic and therapeutic options for gastrointestinal and respiratory diseases in calves and piglets? A systematic review

BACKGROUND

Gastrointestinal and respiratory diseases in calves and piglets lead to significant economic losses in livestock husbandry. A high morbidity has been reported for diarrhea (calves ≤ 35%; piglets ≤ 50%) and for respiratory diseases (calves ≤ 80%; piglets ≤ 40%). Despite a highly diverse etiology and pathophysiology of these diseases, treatment with antimicrobials is often the first-line therapy. Multi-antimicrobial resistance in pathogens results in international accordance to strengthen the research in novel treatment options. Medicinal plants bear a potential as alternative or additional treatment. Based on the versatile effects of their plant specific multi-component-compositions, medicinal plants can potentially act as 'multi-target drugs'. Regarding the plurality of medicinal plants, the aim of this systematic review was to identify potential medicinal plant species for prevention and treatment of gastrointestinal and respiratory diseases and for modulation of the immune system and inflammation in calves and piglets.

RESULTS

Based on nine initial sources including standard textbooks and European ethnoveterinary studies, a total of 223 medicinal plant species related to the treatment of gastrointestinal and respiratory diseases was identified. A defined search strategy was established using the PRISMA statement to evaluate 30 medicinal plant species starting from 20'000 peer-reviewed articles published in the last 20 years (1994-2014). This strategy led to 418 references (257 in vitro, 84 in vivo and 77 clinical trials, thereof 48 clinical trials in veterinary medicine) to evaluate effects of medicinal plants and their efficacy in detail. The findings indicate that the most promising candidates for gastrointestinal diseases are Allium sativum L., Mentha x piperita L. and Salvia officinalis L.; for diseases of the respiratory tract Echinacea purpurea (L.) MOENCH, Thymus vulgaris L. and Althea officinalis L. were found most promising, and Echinacea purpurea (L.) MOENCH, Camellia sinensis (L.) KUNTZE, Glycyrrhiza glabra L. and Origanum vulgare L. were identified as best candidates for modulation of the immune system and inflammation.

CONCLUSIONS

Several medicinal plants bear a potential for novel treatment strategies for young livestock. There is a need for further research focused on gastrointestinal and respiratory diseases in calves and piglets, and the findings of this review provide a basis on plant selection for future studies.

Efficiency of two commercial on-farm pasteurizers for inactivation of mastitis pathogens in milk intended for feeding of calves

Two commercially available pasteurizers for on farm pasteurization of milk intended for feeding calves were tested for their efficiency to inactivate mastitis pathogens. Raw bulk tank milk of the experimental farm Schaedtbek of the Max Rubner-Institute was artificially contaminated with twelve different strains of mastitis pathogens (intended level 7-8 log10 colony forming units [cfu]/ml). The average contamination level was 7.6 log10 cfu/ml in trials with pasteurizer 1 (P1) and 7.3 log10 cfu/ml in trials with pasteurizer 2 (P2), with lowest counts for yeasts (5.1 log10 cfu/ml for P1 and P2). Average reduction rates of > 5.8 log10 cfu/ml for P1 (72 degrees C, 12 s) and > 6.2 log10 cfu/ml for P2 (64 degrees C, 35 min) revealed an appropriate efficiency of both pasteurizers for practical purposes. Pathogens surviving pasteurization (enterococci in trials with both pasteurizers and of Staphylococcus aureus and Escherichia coli with P1) demonstrate the limits of pasteurization as a function of raw milk quality and emphasize the necessity for appropriate handling of pasteurized milk to prevent excessive multiplication of microbial pathogens.

Feeding untreated and pasteurized waste milk and bulk milk to calves: effects on calf performance, health status and antibiotic resistance of faecal bacteria

Non-saleable milk (waste milk, WM) is contaminated with an undefined spectrum of potentially harmful pathogens and antimicrobial residues. The objective of this study was to determine the impact of feeding bulk milk (BM) or WM - both pasteurized or not - on calf performance, health and the antibiotic resistance of specific faecal bacteria. A total of 114 calves from a large-scale dairy were housed outdoors in individual hutches and were randomly assigned to one of four feeding groups. The calves were fed either WM, pasteurized WM (pWM), BM or pasteurized BM (pBM) from day 3 to 56 of life. Milk samples taken from the pasteurizer and calves' nipple buckets were investigated at regular intervals for total plate count and counts of thermoduric bacteria, coliforms and mastitis pathogens. Faecal samples were taken on days 2, 14, 28 and 56 of life from randomly selected calves of the WM, pWM and BM groups (each N = 8-9) and processed to obtain from each sample preferably two isolates of Escherichia (E.) coli and Enterococcus spp. respectively. Isolates were tested for their antimicrobial susceptibility to 25 antimicrobial agents by broth microdilution. Daily weight gain, milk and calf starter intake and health parameters did not differ significantly between the calves of the four feeding groups. The proportion of resistant E. coli isolates was significantly higher in calves fed WM and in calves fed pWM (most pronounced for cephalosporins) than in calves receiving BM. No differences in resistance were found for Enterococus spp. Thus, the concerns for selecting resistant faecal bacteria by feeding WM seem to be justified. Nonetheless, pasteurized WM of cows not treated with antimicrobials represents an acceptable feed for young calves.

Multiparous cows categorized by milk protein concentration and energy-corrected milk yield during early lactation--metabolism, productivity and effect of a short-term feed restriction

The objective of this experiment was to study milk productivity, metabolic adaptation and effect of a short-term feed restriction (FR) on key performance indicators during early lactation in cows classified according to energy-corrected milk (ECM) yield and milk protein concentration. Twenty-three multiparous Holstein-Friesian cows were categorized in four groups according to respective averaged values on Days 23-25 postpartum: high ECM yield and high protein concentration; low ECM yield and low protein concentration; high ECM yield and low protein concentration and low ECM yield and high protein concentration. Dry matter intake was reduced to 68.3% for three subsequent days. Our results showed that short-time FR in early lactation succeeded in enhancing energy deficit of cows in all groups. Milk fat, milk protein and lactose concentrations as well as milk fat yield were not influenced by FR. Several hepatic genes encoding for enzymes involved in catabolism of amino acids, β-oxidation, gluconeogenesis and ketogenesis as well as mRNA encoding for insulin receptor showed increased transcript abundances after FR, primarily in cows with high milk yield and low milk protein concentration.

[Red discolouration of the urine in a dairy cattle herd as a stock problem]

After feeding a new batch of rapeseed meal (2.5 kg/cow/day) in the total mixed ration (TMR) of dairy cows on a dairy farm in Bavaria, numerous puddles of reddish fluid were found on the floor of the cubicle housing system. These were caused by a red discolouration of the urine. Directly after urination, the urine was macroscopically yellow and bright; the discolouration developed throughout the consecutive hours. Feed intake was markedly decreased and milk yield was lowered by 10%. No disturbances of the general health and blood key parameters were evident. After feeding two other cows with rapeseed meal of this batch (three times daily 1 kg each), the phenomenon occurred in one animal on the third and fourth days. Further analyses revealed evidence that the discolouration was due to substances which were excreted via the kidney and led to reddish urine after delayed reaction with the oxygen in the air.

Rotfärbung des Harns als Bestandsproblem in einer Milchviehherde

In einem Milchviehbetrieb in Bayern wurden nach Einsatz einer neuen Charge von Rapsextraktionsschrot (2,5 kg/Tier/Tag; RES) in einer Gesamtmischration (TMR) zahlreiche rötliche Flüssigkeitslachen im Laufstall gefunden, die auf eine Rotfärbung des Harns zurückzuführen waren. Unmittelbar nach dem Harnabsatz war der Harn makroskopisch unauffällig; die rötliche Verfärbung entwickelte sich erst nach einigen Stunden. Die Kühe zeigten nach Einsatz des neuen RES eine deutlich reduzierte Futteraufnahme und eine um etwa 10% verminderte Milchleistung. Störungen des Allgemeinbefindens und Abweichungen labordiagnostischer Leitparameter traten nicht auf. Bei Fütterung des RES an zwei Versuchstiere wurde das Phänomen am dritten und vierten Tag bei einem Tier reproduziert. Offenbar befanden sich Substanzen in der RES-Charge, die renal ausgeschieden und mit einer Latenz von mehreren Stunden nach Zutritt von Luftsauerstoff zu einer rötlichen Verbindung oxidiert wurden.

Laktationsinzidenzen von Produktionskrankheiten bei Fleckviehkühen in sechs bayerischen Milchviehbetrieben

Ziel: Erfassung der Laktationsinzidenzen (LI) von Produktionskrankheiten (PK) bei Deutsch-Fleckvieh-Milchkühen und Charakterisierung der betriebsspezifischen Varianz. Material und Methode: Auf sechs bayerischen Milchviehbetrieben (Herdendurchschnittsleistung 2008: 7834 ± 708 kg [Mittelwert ± SD]; Boxenlaufställe; Voll- oder aufgewertete Teilmischration auf Basis von Gras- und Maissilage) wurden insgesamt 116 pluripare und 58 primipare Kühe täglich standardisiert über 14 Tage post partum klinisch untersucht und gegebenenfalls standardisiert therapiert. Die Erfassung von Erkrankungen im weiteren Laktationsverlauf erfolgte durch regelmäßige Betriebsbesuche sowie die Kommunikation mit Betriebsleiter und Hoftierarzt. Ergebnisse: Die LI der erfassten PK (hypokalzämische Gebärparese, Retentio secundinarum, Ketose, Labmagenverlagerung, Metritis, Endometritis, Ovarialzysten, Mastitis) lagen bei Pluripara deutlich höher als bei Primipara: 33,3% bzw. 46,4% aller pluri- bzw. primiparen Tiere blieben klinisch gesund, 24,8 bzw. 30,4% der Kühe erkrankten in den ersten zwei Laktationswochen an einer PK und 41,9 bzw. 23,2% der Tiere litten an mehr als einer PK. Die LI der PK variierten vor allem bei den Pluripara erheblich zwischen den Betrieben: Retentio secundinarum 16,8 ± 13,2%, hypokalzämische Gebärparese 15,1 ± 7,0%, klinische Ketose 16,8 ± 12,4%, Metritis 3,8 ± 3,1%, Labmagenverlagerung 1,1% (Median 0,0%; 0,0/0,0), Endometritis 11,7 ± 7,0%. An mindestens einer Mastitis erkrankten 56,0 ± 7,4% der pluriparen Kühe; im Durchschnitt erkrankten diese 1,7-mal an Mastitis. Mindestens eine Follikel-Theka-Zyste wurde bei 28,4 ± 8,6% der Kühe diagnostiziert. In den ersten beiden Laktationswochen zeigten 18,5 ± 13,5% der primi- und pluriparen Kühe eine Lahmheit. Schlussfolgerung: Die LI der PK differierten nicht signifikant von publizierten Daten für Holstein-Friesian-Kühe mit Ausnahme der selteneren Labmagenverlagerung bei Fleckvieh-Kühen. Die Resultate deuten darauf hin, dass das Betriebsmanagement wesentlich größeren Einfluss auf die Inzidenz der PK hat als andere Faktoren wie z. B. die Rasse der Milchkühe.

[Lactational incidences of production diseases in German Fleckvieh cows of six Bavarian dairy farms]

OBJECTIVE

The aim of this study was to assess lactation incidences of production diseases in German Fleckvieh cows.

MATERIAL AND METHODS

Investigations were carried out on six dairy farms (mean milk yield of herds 2008: 7834 ± 708kg milk [mean ± SD]) in Bavaria. All farms kept the cows in free stall barns and fed them a total or partial mixed ration based on grass silage and corn silage. In total, 116 cows and 58 heifers were examined daily for 14 days post partum and treated - if necessary - according to standard protocols. The acquisition of data for diseases in the further lactation was carried out by regular visits to the farm as well as communication with the herd manager and the farm veterinarian.

RESULTS

Pluriparous cows suffered more frequently from production diseases (milk fever, retained placenta, clinical ketosis, abomasal displacement, metritis, endometritis, ovarian cysts, mastitis) than primiparous heifers: 33.3% and 46.4% of pluriparous and primiparous cows, respectively, remained clinically healthy, while 24.8% and 30.4%, respectively, suffered from one production disease during the first 2 weeks of lactation; more than one production disease was diagnosed in 41.9% and 23.2% of pluriparous and primiparous cows, respectively. The lactation incidences of production diseases varied considerably among pluriparous cows of the six farms: retained placenta 16.8 ± 13.2%, milk fever 15.1 ± 7.0%, clinical ketosis 16.8 ± 12.4%, metritis 3.8 ± 3.1%, abomasal displacement 1.1% (median 0.0; 0.0/0.0%), endometritis 11.7 ± 7.0%. Mastitis affected 56.0 ± 7.4% of the pluriparous cows, which experienced 1.7 mastitis episodes on average. At least one follicular cyst was diagnosed among 28.4 ± 8.6% of the cows. Lameness affected 18.5 ± 13.5% of pluriparous cows and heifers during the first 2 weeks of lactation.

CONCLUSION

The lactation incidences of production diseases did not significantly differ from reference values reported for Holstein Friesian cows except the lower incidence of LDA among German Fleckvieh cows. The results indicate that the farm management affected lactation incidences of production diseases to a greater degree than additional factors, such as the breed of the cows.

Effects of continuous milking during the dry period or once daily milking in the first 4 weeks of lactation on metabolism and productivity of dairy cows

The objective was to compare the effects of 3 management systems in high-yielding dairy cows on metabolic profiles and milk production. Thirty-six multiparous Brown Swiss cows were randomly assigned to 1 of 3 treatment groups (n=12 cows/group): the control (C) group, in which cows were dried off 56 d before calving and milked twice daily throughout next lactation (305 d); the once daily milking (ODM) group, in which cows were dried off 56 d before calving and milked once daily for the first 4 wk of lactation and twice daily for the remaining lactation; and the continuous milking (CM) group, in which cows were milked twice daily until calving and also during the subsequent lactation. Serum glucose concentrations decreased between wk 1 and 4 exclusively in C cows. Serum concentrations of NEFA and BHBA in the first 4 wk of lactation were highest in C cows compared with ODM and CM cows. Decreased backfat thickness during early lactation and reduction of body condition score were markedly more pronounced in C cows compared with ODM and CM cows. Mean lactational milk yield of C cows [11,310+/-601 kg of energy-corrected milk (ECM)/305 d] was approximately 16% higher compared with ODM cows (9,531+/-477 kg of ECM/305 d) and CM cows (9,447+/-310 kg of ECM/305 d). The lactation curve of CM cows compared with C cows was characterized by a similar time of peak yield (wk 3), a reduced peak yield, and no obvious differences in persistency. Mean percentage of milk protein was significantly higher for CM cows (3.91%) compared with C cows (3.52%). In contrast, once daily milking was accompanied by a reduced and significantly delayed peak yield (wk 8) compared with the control treatment, whereas persistency was better and milk protein (3.79%) was higher in ODM cows than in C cows. In conclusion, continuous milking and once daily milking, targeting the interval before or after calving, respectively, substantially reduced the metabolic challenge of fresh cows and improved milk protein percentage. Continuous milking and once daily milking increased milk protein percentage markedly; furthermore, once daily milking during the first 4 wk of lactation improved the lactation curve.

A novel isotonic-balanced electrolyte solution with 1% glucose for perioperative fluid management in children- an animal experimental preauthorization study

BACKGROUND

The recommendations for perioperative maintenance fluid in children have been adapted from hypotonic to isotonic electrolyte solutions with lower glucose concentrations (1-2.5% instead of 5%) to avoid hyponatremia or hyperglycemia.

OBJECTIVE

The objective of this prospective animal study was to determine the margin of safety of a novel isotonic-balanced electrolyte solution with 1% glucose (BS-G1) in comparison with normal saline with 1% glucose (NS-G1) in the case of accidental hyperhydration with a focus on acid-base electrolyte balance, glucose concentration, osmolality and intracranial pressure in piglets.

METHODS

Ten piglets (bodyweight 11.8 +/- 1.8 kg) were randomly assigned to receive either 100 ml.kg(-1) of BS-G1 or NS-G1 within one hour. Before, during and after fluid administration, electrolytes, lactate, hemoglobin, hematocrit, glucose, osmolality and acid-base parameters were measured.

RESULTS

Unlike BS-G1, administration of NS-G1 produced mild hyperchloremic acidosis (base excess BS-G1 vs NS-G1, baseline 1.9 +/- 1.7 vs 2.9 +/- 0.9 mmol.l(-1), study end 0.2 +/- 1.7 vs -2.7 +/- 0.5 mmol.l(-1), P < 0.05, chloride BS-G1 vs NS-G1 baseline 102.4 +/- 3.4 vs 102.0 +/- 0.7 mmol.l(-1), study end 103.4 +/- 1.8 vs 109.0 +/- 1.4 mmol.l(-1)P < 0.05). The addition of 1% glucose led to moderate hyperglycemia (P < 0.05) with a concomitant increase in serum osmolality in both groups (P < 0.05).

CONCLUSION

Both solutions showed a wide margin of safety in the case of accidental hyperhydration with less acid-base electrolyte changes when using BS-G1. This novel solution could therefore enhance patient's safety within the scope of perioperative volume management.

Rumen-protected conjugated linoleic acid supplementation to dairy cows in late pregnancy and early lactation: effects on milk composition, milk yield, blood metabolites and gene expression in liver

Background

Conjugated linoleic acid (CLA) is a collective term for isomers of octadecadienoic acid with conjugated double-bond system. Thus, it was the objective to investigate whether milk composition and metabolic key parameters are affected by adding CLA to the diet of dairy cows in the first four weeks of lactation.

Methods

A study was carried out with five primiparous cows fed a CLA supplemented diet compared to five primiparous cows without CLA supplementation. CLA supplemented cows received 7.5 g CLA/day (i.e. 50% cis(c)9,trans(t)11- and 50% t10,c12-CLA) starting two weeks before expected calving and 20 g CLA/day (i.e. 50% c9,t11- and 50% t10,c12-CLA) throughout day 1 to 28 of lactation.

Results

The CLA supplement was insufficiently accepted by the animals: only 61.5% of the intended amount was ingested. Fed CLA were detectable in milk fat, whereas contents of c9,t11-CLA and t10,c12-CLA in milk fat were higher for CLA supplemented cows compared to the control group. On average over the entire treatment period, there was a decrease of saturated fatty acids (FA) in milk fat of CLA supplemented cows, combined with a higher content of monounsaturated and trans FA.

Our study revealed no significant effects of c9,t11- and t10,c12-CLA supplementation either on milk yield and composition or on metabolic key parameters in blood. Furthermore the experiment did not indicate significant effects of c9,t11- and t10,c12-CLA-supplementation on gene expression of peroxisome proliferator-activated receptor-alpha (PPARα), PPARγ, sterol regulatory element-binding protein-1 and tumor necrosis factor-alpha in liver tissue.

Conclusions

Feeding c9,t11- and t10,c12-CLA during the first weeks after calving did not affect metabolic key parameters of blood serum or milk composition of fresh cows. Milk fatty acid composition was changed by feeding c9,t11- and t10,c12-CLA resulting in higher contents of these isomers in milk fat. High contents of long chain FA in milk fat indicate that CLA supplementation during the first four weeks of lactation did not affect massive peripheral lipomobilization.

Cholesterol synthesis in the lactating cow: Induced expression of candidate genes

Despite the extensive knowledge for other species, cholesterol metabolism in ruminants is nowadays still not clear. Huge differences in milk cholesterol concentration are observed between breeds, managing strategies, individuals and moment of the lactating cycle, but the genetic actors working in the process of cholesterol secretion into milk have not been identified. As ruminant diet contains no cholesterol, understanding the mechanisms and regulation of synthesis, transport and secretion into milk is crucial when trying to reduce the amount of this metabolite in dairy products. The present work aims to study the expression of candidate genes for these processes in the liver of Bos taurus during the lactating cycle. Liver biopsies were obtained from 16 adult brown Swiss cows at different time points (2 weeks pre-partum and 0, 2, 4 and 8 weeks post-partum). After RNA extraction and reverse transcription, gene expression of candidate genes was studied using quantitative RT-PCR. Key enzymes of the cholesterol synthesis (3-hydroxy-methyglutaryl-coenzyme-A (HMG-CoA) synthase, HMG-CoA reductase and farnesyldiphosphat-farnesyltransferase (FDFT)) and gene expression feed-back regulators involved in lipid metabolism (sterol regulatory element binding proteins (SREBP1and 2) SREBP-cleavage activating protein (Scap) were selected as candidate genes. HMG-CoA-reductase and FDFT showed a huge expression increase until week 2 post-partum (p<0.01), most probably in response to the new requirements in the mammary gland. As well, and as a possible explanation for such modifications, an increase in the expression of the regulators SREBP1 and Scap was observed (p<0.01 and p<0.05 respectively). Most important, the whole synthesis machinery showed a coordinated regulation, as highly significant positive correlations were found between the expression levels of the above mentioned enzymes (p<0.01). The increase of milk and blood cholesterol levels in B. taurus after parturition might be the result of a coordinated induction in the expression of key liver enzymes and their regulating factors.

Verabreichung von Antibiotika in Geflügelbeständen

Aus Gründen der Praktikabilität kann auf eine orale Medikation von Antibiotika zur Behandlung bakterieller Erkrankungen in Geflügelbeständen nicht verzichtet werden. Die Verabreichung von Antibiotika über das Futter oder das Trinkwasser ist jedoch mit vielen Problemen behaftet, wie Unterdosierung und Kontamination der Stalleinrichtungen, die eine Selektion von Antibiotikaresistenzen begünstigen. Auch die eingeschränkte Verfügbarkeit zugelassener Arzneimittel für verschiedene Spezies des Wirtschaftsgeflügels erschwert die Therapie bakterieller Erkrankungen in der Geflügelpraxis. Dieser Beitrag soll einen Überblick über die Probleme im Praxisalltag und mögliche Lösungsansätze geben.

Clinical efficacy of intravenous hypertonic saline solution or hypertonic bicarbonate solution in the treatment of inappetent calves with neonatal diarrhea

Background: The clinical efficacy of IV administered hypertonic saline solution and hypertonic bicarbonate solution (HBS) in the treatment of inappetent diarrheic calves has not been compared yet.

Hypothesis: HBS is more advantageous than hypertonic saline in the treatment of calves with severe metabolic acidosis.

Animals: Twenty‐eight dehydrated, inappetent calves with neonatal diarrhea.

Methods: In 2 consecutive clinical studies, calves were initially treated with saline (5.85%; 5 mL/kg body weight [BW] over 4 minutes; study I: N = 16) or bicarbonate solution (8.4%; 10 mL/kg BW over 8 minutes; study II: N = 12), respectively, followed by oral administration of 3 L isotonic electrolyte solution 5 minutes after injection. Clinical and laboratory variables were monitored for 72 hours.

Results: Treatment failed in 6 calves of study I and in 1 calf of study II as indicated by a deterioration of the general condition. All treatment failures had more severe metabolic acidosis compared with successfully treated calves before treatment. In the latter, rehydration was completed within 18 hours after injection; metabolic acidosis was corrected within 24 hours (study I) and 6 hours (study II) after injection.

Conclusions and Clinical Importance: Diarrheic calves with slight metabolic acidosis (base excess [BE] >−10 mM) can be treated successfully with hypertonic saline. HBS is appropriate in calves without respiratory problems with more severe metabolic acidosis (BE up to −20 mM). Intensive care of the calves is required to ensure a sufficient oral fluid intake after the initial IV treatment.