Report of the Veal Calf Vaccination Study with Rispoval IntraNasal (Zoetis)

Transcription

1 Report of the Veal Calf Vaccination Study with Rispoval IntraNasal (Zoetis) Date: February 18, 2014 H. A. Vahl, H. Bekman and J. van Riel Introduction: Substantial percentages of antibiotics applied in the white veal calf sector are used for controlling respiratory infections during the growth phase. There are several reasons why there is a need to significantly reduce this use of antibiotics. The veal calf sector itself is working to develop the necessary initiatives. One possibility that requires further investigation is the extent to which vaccination in young calves against respiratory viral pathogens can help in improving animal health and thereby reducing antibiotic use. This field trial aims to test the efficacy of Rispoval IntraNasal (Zoetis) in reducing the mean antibiotic treatment days / animal in white veal in the Netherlands. The trial was conducted under the responsibility of the Dutch Veal Board of the Product Board Livestock and Meat (PVV). An additional objective was to investigate the extent to which vaccination against respiratory conditions influences other performance measurements such as body weight gain. Methods and measurements Field test design: This study was a negatively controlled, blinded field trial including 40 white veal farms. The average capacity of number of calves per farm in this study was about 550 calves and varied from minimal 130 to maximal 1050 animals per site per batch. A cross over study design was executed. Each farm was enrolled for two sequential growing periods (Batch 1 and Batch 2) whereby the treatment allocation (of either a Control farm or a Vaccinated farm) was reversed between Batch 1 and Batch 2; e.g. a farm that was allocated to be a Vaccinated farm in the 1st Batch, was then enrolled as Control farm for the 2nd Batch. Simultaneously, another farm was allocated to be a Control farm in the 1st Batch. In this way seasonal and farm effects were accounted for. Animals on Vaccinated farms received a single dose of Rispoval IntraNasal (Rispoval IN) shortly after arrival (day 1-3, preferably within 36 hours ) and again around 3 months after arrival (~Day 84). Control farms were vaccinated with a placebo treatment (intranasally, 2 ml/animal with 0.9 % NaCl physiological saline solution). Animals, housing and management Report of the Veal Calf Vaccination Study with Rispoval IntraNasal Page 1

2 The test animals were veal calves (> 80% males, Holstein-Frisian originating from The Netherlands and Germany) as delivered to the farms. Age at arrival to the farm was between 2 and 3 weeks. In the Netherlands it is regulated that the minimum age for fattening of calves is 14 days and the maximum age is 35 days. Normally one animal batch for enrolment in the study arrived at the farm over a period of 3 to 5 days. The mean fattening period was 26.7 weeks and 27.5 weeks in the first and second batches respectively. For the first four to six weeks animals were housed separately with open fences (so called babyboxes) and group housed thereafter, in groups of 5-6 calves on most farms, in some instances in groups of up to 10 calves per group. The calves were milk-fed with commercial milk replacer from respective Integrators twice daily from the day of arrival throughout the growing period. From about 2 weeks after arrival a mixture of roughage and concentrate was fed. The composition of the mixture was mostly concentrate with maize silage and/or wheat straw. The daily quantity of the mixture was restricted in the start to semi-ad libitum during the finishing period. Regular health checks were performed at least twice daily by the farmer at every enrolled farm. Enrolment Criteria: Farms: The farms were selected from one of the four Dutch Veal integrations (Van Drie, Denkavit, former Alpuro and Pali-group). All participating farms were classed as white veal growers. Every participating farm fulfilled the following enrolment criteria: per site > 80 % male and all calves were intended for slaughter in Dutch slaughterhouses. All participating farms operated an all-animals-in all-animals-out principle. Animal intake was as much as possible completed within a maximum period of 5 days whenever possible. Animals: Only healthy animals were enrolled on the study and vaccinated. Vaccine and placebo: Vaccine: Rispoval IntraNasal (IN). This vaccine includes the following antigens: Bovine Respiratory Syncytial virus (BRSV; strain 375; modified live) and bovine parainfluenza type 3 virus (PI3V; strain RLB103; attenuated temperature-sensitive). Commercial batches were used (potency for BRSV between 5.0 and 7.2 log10 CCID50 / 2mL dose and for PI3V between 5.0 and 8.6 log10 CCID50 / 2mL dose). The commercial formulations used contained 25 doses per vial (RegNL 10424). The lyophilised pellet was dissolved in 50 ml sterile diluent (water for injection and sodium chloride, 18 mg per 2 ml) for intranasal administration. The Pellet was stored at +2 to +8 C, protected from frost, heat and direct sunlight, and the diluent < 25 C. Physiological Saline (0.9 % (w/v) sodium chloride ) stored at < 25 C was used as placebo. Report of the Veal Calf Vaccination Study with Rispoval IntraNasal Page 2

3 Randomisation and Blinding: This trial was blinded, and participating farmers and veterinary practitioners were not aware of the allocation of farm to treatment. None of the veterinarians who made disease assessments and/or treatment decisions on any participating farm, made treatment decisions, or involved farmers knew the treatment allocations or were present during test article administration. The treatment allocation plan was only available to the statistician and the vaccination team. The random treatment allocation plan was produced by the statistician. The vaccinating veterinarian selected the treatments of the farms and batches via a lottery list received from the statistician. All farms and growing batches were identified by a unique number. Method of vaccination Vaccine: Vaccinations were performed by a vaccination team. This team comprised the vaccinating veterinarian, assisted by one or two paraveterinarians. Only healthy animals (no signs of respiratory disease or other signs of clinical illness) were vaccinated. Day 0 is the day of arrival. Animals were vaccinated as soon as possible after their arrival on the farm (but preferably within 36 hours). Vaccine was used within 2 hours after reconstitution. On approximately day 1 and approximately day 84 a 2 ml dose was administered intranasally to each animal using the provided intranasal applicators recommended for vaccination. Approximately animals were vaccinated with a single applicator. For vaccine administration the animals were restrained with their noses facing upwards and vaccine was administered during inhalation if possible. An automated dosing gun was used for administration. Any delayed vaccination was recorded. If, in generally healthy batches,, individual calves were not suitable for vaccination, the number of these animals was registered, and those calves were not vaccinated. Placebo Treatment: 2 ml sterile saline solution (REGNL 01247) was administered intranasally on approximately day 1 and on approximately day 84 using an identical type of intranasal applicator to that used for the vaccinated calves. Approximately 25 animals were dosed with a single applicator. Procedure for veterinarians and antibiotic treatment: Report of the Veal Calf Vaccination Study with Rispoval IntraNasal Page 3

4 A record was kept of any animal with signs of respiratory disease or with any other signs requiring veterinary attention and the veterinarian was notified. Any treatments given, dose and duration of treatment and diagnosis or suspect diagnosis were recorded (by the vet or farmer) on local site records according to site practice. In case of respiratory disease antibiotic treatments were administered as much as possible on an individual animal basis up to a disease incidence level of 10% within 5 days. Also if during a 24 hour period the increase of diseased animals in the herd was 4 %, blanket treatment was permitted. Statistical methods & data analysis: The statistical analysis were two-sided, using a 5% significance level (P 0.05 ). The farm-period combination was the experimental unit. Individual cold carcass weight, group body weight gain, group number of daily antibiotic dosages (for four different time periods), mortality rate and rate of poor growers were analysed with a mixed model with the fixed effect of treatment and period and random effects: block farm within block, period by block and period by farm within block (which is the residual term). Cold carcass weight and body weight gain (= calculated) are considered as normal distributed. The number of daily antibiotic dosages was log transformed prior to analysis. Least squares means and standard errors (both cold carcass weight and calculated group body weight gain on the original scale; the other on the transformed scale) were calculated for each treatment. The statistical analysis was performed using the Genstat program. For each growing period from every farm enrolled (= one experimental unit) the following data were collected or calculated: a. Days of fattening period (days) b. Mean cold carcass weight per animal c. mean live body weight at slaughter per animal (= slaughter weight / 0.63) d. Mean input body weight (kg) e. Mean (estimated) body weight gain (kg/day) f. Mortality rates (%) (difference between number of animals at arrival versus at slaughter) g. Rate of poor growers (%) h. Mean number of daily antibiotic dosages for the following periods: h days h days h days h days i. Mean number of daily individual antibiotic dosages (all treatments) j. Mean number of daily individual antibiotic dosages for respiratory disease k. Mean number of daily individual corticosteroid dosages l. Mean number of daily individual NSAID s dosages m. Mean number of daily individual bromohexine dosages Report of the Veal Calf Vaccination Study with Rispoval IntraNasal Page 4

5 Data collection: The data from this study were collected from the participating integrators. To help ensure that results from all four integrators were calculated in a comparable way, each data set was checked for validity using by LEI. The calculations concerning the use of antibiotic and other medicines is based on the methods as mentioned in the publication of LEI (2012, Trends in veterinary antibiotic use in the Netherlands , LEI ). In summary the number of daily dosages per animal was determined by calculating the total number of kilograms of animal (at the respective time of treatment) that can be treated with each active ingredient: the treatable weight. This was then divided by the total weight of the number of veal calves on the farm. Table 1 shows in more detail how the below mentioned data were defined and which calculations are done. Table 1 Definitions used for the calculations Description Date of start Date of slaughter Cold carcass weight (kg) Starter body weight (kg) Days of fattening period mortality (% / herd) Live body weight of slaughtered animals body weight gain ( g / day) % poor-do-ers in the herd Quantity of used antibiotics live body weight during the treatment (kg) antibiotic daily dosages total individual treated antibiotic daily dosages Definition mentioned as one starting day (if more than 1 day started then a weighted average) mentioned as one slaughtering day (if more than 1 day slaughtered then a weighted average) The cold carcass weight was determined after a slaughtering process regulated by Dutch Veal Board-standards. The calves were slaughtered in The Netherlands. The mean live body weight of the calves at arrival. This can be weighted or estimated, based on age and condition. If more than one day arrival then a weighted average is calculated. total days of fattening period between start and final of the fattening period (approximately 196 days) percentage of died animals per herd based of total animals at start minus total number of animals at slaughtering The cold carcass weight divided by 0.63 (kg/animal) Mean kg of growth ( = live weight of slaughtered calf minus the group mean body weight at arrival) of the slaughtered animal divided by total fattening days (grams/day/herd) number of slaughtered calves with a body weight at slaughter 85 % of mean carcass weight of the herd divided by the total number of slaughtered calves of the herd Quantity of delivered antibiotics per herd minus retour antibiotics per herd (grams per herd) mean body weight of herd based on current date of fattening during treatment (kg) the number of daily dosages per fattening animal was determined by calculating the total number of kilograms of animal that can be treated with each active ingredient: the treatable weight. This was than divided by the total weight of the number of veal calves on the farm, based on the estimated body weight at the current date of treatment. the number of total individual treated daily dosages per fattening animal was determined by calculating the total number of kilograms of animal that can be treated Report of the Veal Calf Vaccination Study with Rispoval IntraNasal Page 5

6 total individual treated antibiotic daily dosages for respiratory diseases Corticosteroids daily dosages NSAID s daily dosages Bromohexine daily dosages with the total quantity of antibacterial active ingredient used as individual treatment: the treatable weight. This was than divided by the total weight of the number of veal calves on the farm, based on the estimated body weight at the current date of treatment. the number of total individual treated daily dosages per fattening animal for respiratory diseases was determined by calculating the total number of kilograms of animal that can be treated with the total quantity of antibacterial active ingredient used as individual treatment for respiratory disease: the treatable weight. This was than divided by the total weight of the number of veal calves on the farm, based on the estimated body weight at the current date of treatment. the number of daily dosages per fattening animal was determined by calculating the total number of kilograms of animal that can be treated with each active ingredient: the treatable weight. This was than divided by the total weight of the number of veal calves on the farm, based on the estimated body weight at the current date of treatment. the number of daily dosages per fattening animal was determined by calculating the total number of kilograms of animal that can be treated with each active ingredient: the treatable weight. This was than divided by the total weight of the number of veal calves on the farm, based on the estimated body weight at the current date of treatment. the number of daily dosages per fattening animal was determined by calculating the total number of kilograms of animal that can be treated with each active ingredient: the treatable weight. This was then divided by the total weight of the number of veal calves on the farm, based on the estimated body weight at the current date of treatment. Blinding: To check the blindness of this field trial we sent farmers a questionnaire after the vaccinations in the second batch in which they were asked if they had an idea to which batches the placebo and real vaccination were administered. Results The field trial progressed according to the protocol. The first batch started in February 2011 and the last batch was slaughtered in the spring of From the 80 vaccinated batches twelve batches were excluded by the statistician because of too many females (n = 4); too late first vaccination (n = 3); wrong type of calves (n = 3) and wrong collection of data (n = 2). In Table 2 the results of antibiotic treatment, other medicines and some performance parameters are summarised. Report of the Veal Calf Vaccination Study with Rispoval IntraNasal Page 6

7 Table 2 Effects of vaccination with Rispoval IntraNasal on the daily dosages of antibiotic, other medicines and some performance parameters Antibiotic (1) : Total (Day 0 (2) to day ± 190) Control Rispoval IntraNasal p-value Batch 1 Batch 2 p-value Day 0 to day Day 14 to day Day 14 to day Total (individual) (3) Total (individual, respiratory disease) (3) Other medicines: (total period) Corticosteroids NSAIDs Bromohexine Performances parameters: Growth (relative % ) n.s (4) sign. (4) Mortality ( relative %) n.s sign. Poor do-ers (relative n.s n.s %) (1) : By using log transformation before analyses of daily antibiotic dosages the antibiotic dosages for the different periods cannot be added and subtracted (2) : Day 0 = day of arrival of calves on site (3) : Total Individual antibiotics are all antibiotics applied non orally, whereas total (individual for respiratory disease are a list of antibiotics used at that time for respiratory diseases (4) : sign. and n.s. means significant, respectively not significant The mean number of daily antibiotic doses was reduced in batches vaccinated with Rispoval IN when compared to the controls. This reduction was statistically significant in the period from day 14 to 84 (14.6 versus 10.4) and in the period from day 14 to day 190 (18.0 versus 14.7 days). Across the total period the mean number of daily antibiotic dosages per animal and fattening period was numerically lower in the vaccinates when compared to the controls (34.5 and 32.3, respectively), but this difference was not statistically significant. Vaccination with Rispoval IN did not lead to a statistically significant reduction in the use of bromohexine or NSAIDs over the total fattening period. Vaccination had no effect on performances parameters such as(growth, mortality and % of poor doers. In the second batch significantly lower antibiotics were used, both in the total period and in the different subperiods. Moreover in the second batch there was also a trend of reduction of individual antibiotics used for respiratory diseases. In the second batch the body weight gain was higher than in the first batch, probably because of the longer fattening period (190 versus 183 days). Report of the Veal Calf Vaccination Study with Rispoval IntraNasal Page 7

8 Discussion The vaccine used in this field trial had a significant reducing effect on the use of antibiotics after day 14. In the period from days the reduction in daily antibiotic dosages was about 4 days (- 29 %) in the period between 14 and 190 days about 3 days (- 18 %). According to the information of Zoetis the onset of immunity cannot be expected before day 5 for BRSV and day10 for Pi3V.However over the full fattening period (day 0 to day 190) the reducing effect on the use of antibiotics is not significant. A possible explanation might be that in this first period from arrival till day 14 the protective effect of the vaccination is still too low or even adverse due to additional stress for the veal calf caused by the vaccine. The reduction in use of antibiotics in the second batch was possibly the effect of changing attitudes by veterinarians and farmers to be more restrictive in the use of antibiotics and is in line with the decline of the average use of antibiotics in the veal sector nationwide. We have to underline that in this report the number of daily antibiotic dosages was log transformed prior to analysis. This means that our calculated daily dosages are not comparable with the method of the current measurement of daily dosages in practice. Concerning blindness valid questionnaires which could be used were returned from 26 of the 40 farms. Nine farmers correctly identified the batches to which the placebo and vaccination was administered. Of these nine correct responses, three mentioned that their suggestion was based on signs and vaccination reaction from the animals. Four farmers mentioned that their opinion was based on positive impressions. In our opinion therefore this questionnaire showed that the blinding of the trial was successful. Acknowledgment: We like to thank the members of the vaccination team for their precise working attitude during the vaccinations. Besides we thank the guiding group of the Product Board for their advises during this vaccination field test. Also we thank LEI for checking the data concerning the provided medicines. We thank Zoetis for providing the vaccine. Report of the Veal Calf Vaccination Study with Rispoval IntraNasal Page 8