2. Universidad Cardenal Herrera-CEU

The sensitivity of different methods for the isolation and identification of Campylobacter, Listeria and Salmonella was compared, and their application in food safety control in a poultry slaughterhouse was evaluated. The VIDAS, SimPlate, Reveal and VIP systems were used, together with traditional microbiological methods. The study was carried out in a slaughterhouse and in the poultry carving room. One hundred and twenty samples (40 per microorganism) obtained from carcasses, viscera, different chicken parts, water and the environment were evaluated. For Campylobacter, the VIDAS system performed better than plate confirmation. The traditional method yielded results similar to those obtained with the SimPlate method. For Listeria, the plate count method proved less sensitive than the VIDAS, VIP and Reveal systems, which yielded similar results. For Salmonella, the VIDAS system displayed a detection rate comparable to that of traditional methods, while the Reveal system detected twice as many positive samples (16 in total). The Reveal method performed significantly better than either the plate count method or the VIDAS system. The alternative methods used here could be successfully applied in food safety control in poultry slaughterhouses, providing similar or better results and taking less time to perform. The VIDAS system, in general, and the Reveal system in the case of Listeria and Salmonella, appear to be effective alternatives to traditional methods.

The incidence of Listeria monocytogenes in refrigerated and frozen chicken parts was investigated, using the Mini-Vidas™ system (bioMérieux). Two hundred and eigthy chicken parts were tested: 40 skin samples from the breast and leg, 120 samples from refrigerated wings, breasts and legs and 120 samples from frozen wings, breasts and legs (40 of each). The 219 samples tested positive (78.21%). The parts with the highest incidence were frozen breasts (100%) and wings (95%). In frozen legs, the values were lower (60%). In refrigerated parts, the incidence was higher in breasts (85%) and in wings (80%). In legs samples, similarly to the frozen ones, the incidence was lower (50%). In the skin of the breasts and legs, the incidence was 77.50%. Statistical evaluation demonstrated that there are no differences between frozen breasts and wings but there are differences between similar refrigerated parts. The refrigerated and frozen legs are the only parts that are statistically equal. The percentages that were detected show the importance of requiring the absence of Listeria spp. in chickens.

The study was carried out under field conditions in a commercial farm, and 1,440 as-hatched Ross-308 broilers were included. Broilers were randomly distributed into 24 experimental 4-m2 pens (60 broilers/pen). Pens were randomized to the 3 treatment groups: a) tylvalosin 10 mg/kg of live BW during 2 d, b) positive control (tylosin during 2 d), and c) negative control (no treatment). The drugs were provided in the water supply. Mortality, individual BW, and feed intake were assessed. Clostridium presence was assessed in fecal and cecal samples, coccidian oocyst counts were assessed in fecal samples, and bacterial diversity was assessed in ileal content. Live BW at 42 d old was significantly better in the tylvalosin group than in tylosin and no-treatment groups, with tylvalosin-treated broilers reaching 80 to 100 g higher final live weight. Average daily gain results mirrored BW findings. The improvement of feed conversion rate with tylvalosin amounted to 0.13 and to 0.10 versus tylosin and no-treatment, respectively, with mortality being similar in all groups. Significantly reduced sulfite-reducing Clostridium and Clostridium perfringens counts in tylvalosin and tylosin groups versus the no-treatment group were observed in cecum content samples. In conclusion, according to the present study results, tylvalosin, at doses substantially lower than registered for poultry in Europe, has proven effective in controlling the colonization of the cecum by Clostridium ssp. in broilers, improving some productive performances.