Efectos de la vacunación de lechones frente a PCV2 en parámetros productivos y de calidad de canal en condiciones de campo

Abstract

At the end of the 90's an emergent disease apeared in animals of 10th to14th weeks of age. Formerly, the disease was called Postweaning Multisystemic Wasting Syndrome (PMWS) and subsequently was determined the responsibility of Porcine Circovirus Type 2 (PCV2). The condition results in an increase in production cost during finishing, not only due to the increase in mortality but also because higher cost in medication and increase of unmarketable animals. All these factors conduced to the apparition of vaccines against PCV2. The launching of vaccines resulted in a decrease in mortality during nursery and finishing and consequently an improve in productive performances. The objective of the study was to assess differences on performances, analysing different productive parameters, the protection against the virus analysing serological status and presence of viremia and the carcass quality on the basis of homogeneity in health and payment rate. The vaccine was substituted by a placebo in a batch of 250 animals. The piglets were sampled at different moments of life to get blood in order to perform an ELISA and a qPCR for serology and viremia detection, respectively. Animals were individually weighted and at slaughter every carcass was individually identified and weighted at different moments. Para conseguir estos objetivos se sustituyó la vacuna frente a PCV2 por un placebo en un lote de 250 animales. Se tomaron muestras de sangre en cinco momentos de la vida de los animales y se pesaron individualmente a lo largo de la transición y el cebo. Igualmente se registró el peso al sacrificio y a la canal de cada uno de ellos. Se utilizó una técnica ELISA para las serologías y una qPCR previamente descrita para determinar las viremias. Differences in several parameters were assessed, comparing vaccinated and no vaccinated animals. As regards productive performances, differences were found in mortality in nursery and finishing (1,6% lower. Other variation recorded was in unmarketable animals, reduced in vaccinated group, and previously recorded. The Average Daily Growth (ADG) improved in 16 g/day comparing all the animals tested, and up to 26 g/day removing record for animals heavier than 7 Kg at weaning. There also were differences in frequency distribution for weight at 101st day of life, because a reduction in the number of carcasses lighter than 75 Kg. (1.9% in vaccinated group vs. 5.2% in non-vaccinated group). The homogeneyty analysis showed 10% of Variation Coefficient. And regarding quality of carcasses there were significant differences in the proce payed by Kg; higher in 0,0015 ¿ for vaccinated animals. The return of investment was measured to be as high as 2,74. The q-PCR demonstrated that no vaccinated animals had viremia in the different sampling moments whilst 57.1% and a 65% of non-vaccinated animals in 15th and 19th weeks of life. There was no influence of PRRSv on the results. As conclusion, remove the vaccine in animals in a farm with a long-term vaccination program, resulted in viremia detection, differences in serologic response, lower quality in carcasses and improve in productive performances such as average daily gain, mortality, and homogeneity of weight at slaughter.