Introduction

Benefits of an oral application route of modified live vaccines include; route of infection that mimics natural onset of protective immunity, stress-free handling for humans and animals, absence of pathogen transfer via multi used needles and labour savings by contemporary vaccination of large sized pig groups. Enterisol® Ileitis is now available in 19 European countries and more than 3500 farms have started to vaccinate since the introduction in 2005. Recommendations on application, based on first user experiences with the lyophilized vaccine Enterisol® Ileitis and efficacy in Europe are presented in this paper.

Efficacy of Enterisol® Ileitis in Europe; “vaccinated pigs grow bigger and groups become more uniform”

The efficacy of Enterisol® Ileitis can be expressed by production traits like increased average daily weight gain, reduction of attrition, increased uniformity or reduction of clinical symptoms of the disease. Enterisol® Ileitis has shown in field studies in Belgium, Denmark, Germany, Greece and Switzerland to be very efficacious. Results show that the benefit is not only seen at the end of fattening but in case of an early infection already present in the nursery (see Figure 1a and 1b).

Figure 1a: Difference between Average Daily Weight Gain in groups of vaccinated and non-vaccinated animals

Figure 1b: Difference between Average Daily Weight Gain in groups of vaccinated and non-vaccinated animals

The vaccinated animals have a higher weight at the end of the nursery and are more uniform when they enter the grower units. Different trials across Europe showed an average daily weight gain improvement in vaccinated animals of 33 to 125 grams in the nursery and 18 to 74 grams in the finishing period. An additional benefit in subclinical infected finishing units is the significant reduction of lightweight animals. Combined results from Germany, Denmark, Switzerland and Belgium show that non-vaccinated groups have 7.3 % more lightweight animals (see Table 1).

Table 1: Distribution of lightweight and heavyweight carcasses at slaughter.
	Non-vaccinated groups	Vaccinated group
Lightweight pigs ( < 80 kg)	18.1 %	10.8 %
Heavyweight pigs ( > 110 kg)	6.7 %	8.9 %

Economy of Enterisol® Ileitis in Europe; “Vaccinated animals generate more profit”

Return of investment in relation to the costs of the vaccine and labour is the main driver in a production unit regarding the decision to start a vaccination against a disease. The return of investment is calculated from a beneficial gross margin divided by the costs for vaccination. The gross margin is the average carcase value minus the costs for feed, piglets and mortality within a group. Carcase value depends on the end weight, which is increased with a higher average daily weight gain and carcase composition. The latter is depending on the lean meat percentage and body conformation, which in return is linked to the exploitation of the growth potential of the pigs in the first half of the finishing period. As pigs are not able to compensate a loss of their growth potential during the finishing phase, diseases in the end of the flatdeck or early finishing phase will have a large impact on the end results. This is then expressed by a decrease of the uniformity within and between groups and a decrease in lean meat percentage.

An increased percentage of lightweight animals within a group will reduce the number of animals within the optimal grading grid, which will result in an overall lower average price per kg meat for the group.

The reduction of fattening days, mortality and an improved feed conversion ratio add up to the overall profit. The average gross margin benefit over the different trials in Europe is € 5 approximately, ranging between € 1.75 and € 3.20 in the nursery phase and € 3.14 and € 8.02 in the finishing barns. The return of investment varies from 2.5 : 1 up to 5 : 1.

Application of Enterisol® Ileitis

Being a live oral vaccine, Enterisol® Ileitis needs to arrive at the ileum enterocytes without loss of immunogenicity. Therefore, the application requires a seven day period free of any Lawsonia intracellularis-active antimicrobial substances, during at least three days before, at the day of vaccination and three days after vaccination. This includes all interfering antibiotics in the feed and water as well as in-feed growth-promoting substances. Disinfecting agents like chloride, chloride- derivates and quaternary-ammonium-compounds are also not allowed in the water at the time of vaccination.

Timing of Enterisol® Ileitis is essential. After vaccination the immune system needs three weeks to build up an adequate protection against a field challenge. Considering that seroconversion is normally seen at around three weeks after a field challenge, this implicates that vaccination needs to take place at least six weeks before seroconversion is detected in a herd.

In many herds in Europe, there are two forms of clinical Ileitis, one is the acute haemorrhagic form seen in older finisher and breeder pigs. Vaccination prior to this form of the disease is therefore relatively simple. The second form, the chronic adenomatosis, however is in many European herds more common and often seen in the grower stages from 6 to 16 weeks of age. This implies that the correct timing for Enterisol® Ileitis vaccination for prevention against this chronic from is around 3 weeks of age. A third subclinical form is the most common form, and has thus the highest impact on the production level of a farm, although often not recognised as such. The detection of a seroconversion in the herd implies that infection has taken place and vaccination with Enterisol® Ileitis should again be timed at least 6 weeks before the seroconversion is seen. In many cases this means vaccination of pigs of 3 weeks of age.

Conclusion

Feedback from field trials and field experiences confirm that oral vaccination against Ileitis has proven to be an efficacious, labour reducing and stress-free alternative to antibiotic treatments. Attention is necessary to ensure correct application of Enterisol® Ileitis. Correct diagnosis, timing of vaccination, and the minimum 7-day antibiotic-free window are the most important factors for the efficacy and economic benefit of Enterisol® Ileitis. The results from the trials show that ADWG is increased in vaccinated animals by 18 to 125 grams per day and 7.3 % less lightweight animals have been send to the slaughterhouse. Efficacy data show that the investment made for vaccination is easily returned and additional health benefits for the total herd will give the pigs the opportunity to exploit their full genetic potential. First time users replied that it takes little time and practice to vaccinate correctly and their expectations were fully met.

Further Information

Read more about: Enterisol® Ileitis

Source: Boehringer Ingelheim Animal Health - April 2006