Physiological responses of broiler embryos to in ovo implantation of temperature transponders

Previous techniques that have been used to monitor broiler embryonic temperature and metabolism during incubation either have been invasive to the embryo or have not directly determined internal egg temperature. Therefore, the current investigation was conducted to determine the earliest day of incubation on which temperature transponder implantation in the egg air cell could be performed with minimal invasiveness to broiler embryogenesis. Eggs from young broiler breeder hens (Ross 308; 27 wk of age) were weighed and set on 3 tray levels (approximately 120 eggs per tray level) of a single incubator. Randomly, on each tray level and on each day between d 10 and 14 of incubation, 4 embryonated eggs were assigned to an invasive control (IC) treatment (shell perforation only) and 4 other embryonated eggs were assigned to a transponder implantation (TI) treatment (shell perforation, followed by transponder implantation in the air cell). Four embryonated eggs per tray were also assigned to a noninvasive control treatment on d 10 of incubation. Percentage of embryo survivability through d 18 of incubation, and percentages of mean daily incubational egg weight loss between d 18 and each respective day of implantation were calculated. Furthermore, various internal organ and tissue parameters were examined on d 18 of incubation. Embryo survivability was reduced because of transponder implantation on d 10 and 11 of incubation; however, embryo survivability was not different between eggs in the noninvasive control and IC treatments and the eggs that received the TI treatment on d 12, 13, and 14 of incubation. In comparison with eggs in the IC treatment, those in the TI treatment had a higher percentage of embryo weight. Conversely, yolk sac moisture was significantly higher in IC-treated eggs than in TI-treated eggs. It was concluded that temperature transponders may be inserted into the air cells of broiler hatching eggs between d 12 and 14 of incubation without adversely affecting eggshell porosity or embryogenesis and without causing physiological stress to growing broiler embryos.