A live attenuatedTyphimurium vaccine dose and diluent have minimal effects on the caecal microbiota of layer chickens.

Abstract

Among thereduction strategies in poultry production, one option is to use avaccine. The aim of vaccinating layer flocks is to reduce the shedding of wild-typein the poultry environment, thereby reducing the contamination of poultry products (eggs and meat). Nutritive diluent and a higher dose of vaccine may enhance its colonization potential in the gut of chickens. In this study, a commercially available live attenuated vaccine (VaxsafeST) was reconstituted in different media and delivered orally to day-old chicks at three different doses (10, 10, and 10CFU/chick). Gut colonization of the vaccine strain and the effects of vaccination on gut microbiota were assessed in commercial-layer chickens. The vaccine diluent and dosage minimally affected microbiota alpha diversity. Microbiota beta diversity was significantly different (P < 0.05) based on the vaccine diluent and dose, which indicated that the vaccinated and unvaccinated chickens had different gut microbial communities. Differences were noted in the abundance of several genera, including, and. The abundance ofwas significantly lower in chickens that received vaccine reconstituted in Marek's and water diluents, whileabundance was significantly lower in the water group. The highest vaccine dose (10CFU/chick) did not significantly alter (> 0.05) the abundance of microbial genera. Chicken age affected the microbiota composition more significantly than the vaccine dose and diluent. The abundance of, andwas significantly higher on day 14 compared with day 7 post-vaccination. TheTyphimurium vaccine load in the caeca was not significantly affected by diluent and vaccine dose; however, it was significantly lower (< 0.0001) on day 14 compared with day 7 post-vaccination. Overall, the. Typhimurium vaccine minimally affected the gut microbiota structure of layer chicks, whereas changes in microbiota were more significant with chicken age.