Circovirus porcino 2 y Mycoplasma hyopneumoniaeestudios de seguridad y eficacia vacunal, y adaptacióde futuras reproductoras

Resumo

The main objective of this Doctoral thesis was the study of the efficacy and safety of porcine circovirus 2 (PCV-2) and Mycoplasma hyopneumoniae (Mhyo) vaccines, as well as the correct acclimation to Mhyo of gilts, by demonstrating their influence on the productive performance and welfare parameters of pigs. To achieve this general objective, the study was divided into different specific objectives distributed into 3 Chapters. The objective of Chapter 1 was to analyze the effect of mother-derived antibodies (AOM) levels of PCV-2 on the efficacy of the vaccine in piglets vaccinated at three weeks of age with a commercial vaccine against this disease. For that purpose, a group of piglets with different levels of AOM were vaccinated and compared with the non-vaccinated group. The results showed that the use of the vaccine was able to decrease the PCV-2 viremia, improve the average daily gain and reduce mortality in vaccinated piglets compared to non-vaccinated piglets, regardless of the level of maternal antibodies present at the time of vaccination. The results of the study showed that AOM against PCV-2 transferred through colostrum intake has a protective effect against this viral infection. The vaccine used was effective when applied at three weeks of age and was not affected by the level of AOM. In order to control Enzootic Pneumonia, the goal to be pursued must be to vaccinate piglets with minimal lung colonization of Mhyo. In this regard, the main objective of Chapter 2 was to evaluate the use of nebulization technology (Neb) for effective exposure of gilts to Mhyo bacteria under field conditions. Phase I consisted of comparing the exposure to the bacteria either intratracheally (IT) or by Neb. Tracheobronchial swabs (TBS) were taken after challenge to assess infection success. No statistically significant differences were observed in terms of proportion of positive TBS samples or in the bacterial load between the batches exposed by IT or by Neb at any point of the sampling. Then, in phase II of the study, three other different batches of gilts were exposed to Mhyo by Neb. All TBS samples were positive. The information generated in this research consolidates the use of nebulization as a reliable method of exposure to Mhyo in field conditions and useful for acclimation of gilts to Mhyo strategies before entering the breeding herd. Vaccines are used to control diseases generated by these pathogens and they have to be products as safe as possible for pig industry. In Chapter 3 the objective of the study was to compare the safety of different vaccination protocols used against PCV-2 and Mhyo, studying two acute phase proteins, haptoglobin (Hp) and C-reactive protein (CRP), and changes in rectal temperature (TR). In addition, the possible influence of the vaccination day and breed were analyzed. In one experiment, commercial crossbred piglets were vaccinated on the day of weaning with two different protocols. In another experiment, commercial crossbred and Iberian piglets were vaccinated 7 days after weaning also with two different protocols in each farm. Blood and TR samples were taken before and after vaccination. Vaccines that produced greater increases in TR also produced greater increases in PFA. No influence was found on the day of vaccination or breed. The serum concentrations of the PFA differed depending on the vaccine used, which can be useful, together with the TR, to choose the vaccine or protocol that produces a minor phase response.