1. Investigación

Infectious Bronchitis Virus (IBV) is one of the most important viral diseases which causes important economic losses in poultry industry. This study aimed to assess the seroprevalence, prevalence, and variants of IBV in broilers, layers, and broiler breeders farms of Gallus gallus species in Eastern Spain. Thus, 29, 16, and 14 flocks of broilers, layers and broiler breeders, respectively were analyzed. To assess seroprevalence, sera samples were analyzed by ELISA. Tracheal swabs and tissue samples were tested by PCR to know the prevalence and detect specific variants. An IBV seroprevalence of 100% was detected in the 3 productive orientations. According to PCR results, a prevalence of 38% in broilers, 44% in layers and 43% in broiler breeders was obtained. The variant-specific RT-PCR analysis showed that 4/91, Massachusetts, QX, Italy- 02 and D274 strains were present in commercial flocks in eastern Spain, being 4/91 the most prevalent in all the productive orientations. In layers 100% of QX prevalence, 14% of Italy 02 and 14% of D274 was detected. Regarding broilers, a prevalence of 18% of Massachusetts strain was also detected. In contrast, in broiler breeders farms only 4/91 strain was found. In conclusion, our findings showed the presence of IBV in eastern Spain and the changing situation of the IBV variants prevalence, being different according to the productive orientation. The continuous emergence of new variants emphasizes the importance of continuous IBV monitoring in order to optimize vaccination strategies.

Mycoplasma species are worldwide recognized poultry pathogens, with Mycoplasma synoviae being the second most important species from the clinical point of view that causes considerable economic losses in the poultry industry. The aim of this study was to assess the seroprevalence, prevalence, and phylogenetic variants of M. synoviae present in layers and broiler breeders’ farms of Gallus gallus species located in eastern Spain. Thus, 19 and 23 flocks of layers and broiler breeders, respectively, were analyzed at 3 different ages. To assess seroprevalence, sera samples were analyzed by ELISA. Tracheal swabs were tested by PCR to assess the prevalence. A M. synoviae seroprevalence of 95 and 74% was detected in layers and broiler breeders, respectively. Regarding age-wise analysis, the positive rates obtained seemed to be higher as the age of sampling increased. As per PCR results, a prevalence of 95% in layers and 35% in broiler breeders was obtained. The genetic analysis showed that the strains present in broilers breeders were vaccine strains (MS H strain). In contrast, 6 different field strains were detected in layer hens. In conclusion, this study carried out in eastern Spain showed a higher seroprevalence and prevalence of M. synoviae field strains in layer flocks regarding broiler breeders, highlighting the usefulness of monitoring flocks to control this poultry pathogen. Moreover, our findings suggest M. synoviae vaccination in broiler breeders could be an effective prevention strategy.

New measures applied to reduce antimicrobial resistances (AMR) at field level in broiler production are focused on improving animals’ welfare and resilience. However, it is necessary to have better knowledge of AMR epidemiology. Thus, the aim of this study was to evaluate AMR and multidrug resistance (MDR) dynamics during the rearing of broilers under commercial (33 kg/m2 density and max. 20 ppm ammonia) and improved (17 kg/m2 density and max. 10 ppm ammonia) farm conditions. Day-old chicks were housed in two poultry houses (commercial vs. improved), and no antimicrobial agents were administered at any point. Animals were sampled at arrival day, mid-period and at slaughter day. High AMR rates were observed throughout rearing. No statistical differences were observed between groups. Moreover, both groups presented high MDR at slaughter day. These results could be explained by vertical or horizontal resistance acquisition. In conclusion, AMR and MDR are present throughout rearing. Moreover, although a lower level of MDR was observed at mid-period in animals reared under less intensive conditions, no differences were found at the end. In order to reduce the presence of AMR bacteria in poultry, further studies are needed to better understand AMR acquisition and prevalence in differing broiler growing conditions.