ABSTRACT
Proper control of infectious bronchitis, pursued through strict biosecurity and mass vaccination, is essential in intensive broiler production. Despite effective and routinely adopted, hatchery spray vaccination has been hypothesized to affect body temperature and wellbeing of day-old chicks. Recently, gel administration has been proposed as an alternative and proved feasible in experimental settings. In this study, IBV spray and gel vaccination were compared in field conditions. One hundred birds from the same hatch were vaccinated, half by spray and half by gel, with 793B and Mass vaccines. After vaccination, rectal temperature was measured and vaccine intake assessed. The two groups were raised for 35 days in separate pens, and swabs and blood samples were collected at multiple time points for lineage-specific molecular analyses and serology, respectively. Temperature was significantly lower in spray vaccinated chicks 10 minutes and an hour after administration. A similar trend in 793B titres was observed in both groups, while Mass-based vaccine was detected later but persisted longer in gel vaccinated chicks. No differences were observed in mean antibody titres. Compared to spray, gel administration appears equally effective and less impactful on body temperature, thus supporting its application for IBV vaccmatlon.