Evaluation of Incubation Yield, Vaccine Response, and Performance of Broilers Submitted to In-Ovo Vaccination at Different Embryonic Ages

Effects of in ovo vaccination time on broiler performance parameters under field conditions

Hatchery performance is often evaluated based on descriptors such as hatchability, 7-d mortality, and cost. In addition to these descriptors, it is useful to include in this analysis aspects of chick quality through post-hatch performance. Realizing the bird's complete genetic potential necessitates meeting various criteria, with effective support for the chick's immune system being among the pivotal factors. To be effective, in ovo vaccination systems must deliver the vaccines to specific sites in the egg, a circumstance that directly depends on when the injection is made. We examined production data to evaluate the impact of in ovo vaccination time on performance parameters of male Ross308AP chicks. A comprehensive survey was conducted examining records from 3,722 broiler flocks produced and raised by the same company under standard nutrition and management conditions. The selected data specifically pertained to flocks that underwent slaughter between 41 and 45 d. In our analysis, 4 different linear models were built, one for each response variable: mean weight (MW), body weight gain (BWG), corrected feeding conversion rate (cFCR), and total mortality (TM). The linear models used in the analyses included as main predictor the timing of in ovo vaccination (440, 444, 448, 452, 456, 458, and 460 h of incubation), and as additional predictors: age of the breeding flock (26-35, 36-55 and 56-66 wks old), slaughter age, identity of the hatchery, and the season at which the data was collected. Our results showed that the timing of in ovo vaccination significantly affected BWG and cFCR, with procedures performed at 460 h of incubation showing the best outcomes. Breeding flock age affected all response variables, with older breeding flocks delivering increased MW, BWG and TM, and middle-aged flocks increased cFCR. Increasing slaughter age reduced BWG while MW, cFCR and TM were all increased. These data emphasize the benefits of performing in ovo vaccination as close as possible to 460 h of incubation to extract the best BWG and cFCR from Ross308AP male broiler.

Vaccines as alternatives to antibiotics for food producing animals. Part 2: new approaches and potential solutions

Vaccines and other alternative products are central to the future success of animal agriculture because they can help minimize the need for antibiotics by preventing and controlling infectious diseases in animal populations. To assess scientific advancements related to alternatives to antibiotics and provide actionable strategies to support their development, the United States Department of Agriculture, with support from the World Organisation for Animal Health, organized the second International Symposium on Alternatives to Antibiotics. It focused on six key areas: vaccines; microbial-derived products; non-nutritive phytochemicals; immune-related products; chemicals, enzymes, and innovative drugs; and regulatory pathways to enable the development and licensure of alternatives to antibiotics. This article, the second part in a two-part series, highlights new approaches and potential solutions for the development of vaccines as alternatives to antibiotics in food producing animals; opportunities, challenges and needs for the development of such vaccines are discussed in the first part of this series. As discussed in part 1 of this manuscript, many current vaccines fall short of ideal vaccines in one or more respects. Promising breakthroughs to overcome these limitations include new biotechnology techniques, new oral vaccine approaches, novel adjuvants, new delivery strategies based on bacterial spores, and live recombinant vectors; they also include new vaccination strategies in-ovo, and strategies that simultaneously protect against multiple pathogens. However, translating this research into commercial vaccines that effectively reduce the need for antibiotics will require close collaboration among stakeholders, for instance through public–private partnerships. Targeted research and development investments and concerted efforts by all affected are needed to realize the potential of vaccines to improve animal health, safeguard agricultural productivity, and reduce antibiotic consumption and resulting resistance risks.