Utilizing in ovo telemetry to examine the effects of reduced incubation temperature on broiler embryo temperature and subsequent hatchability

Authors: LINDSEY, L - Mississippi State University; Collins Elliott, Katie; FATEMI, S - Mississippi State University; GERARD, P - Clemson University; PEEBLES, E - Mississippi State University

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2023
Publication Date: 2/3/2023
Citation: Lindsey, L.L., Collins Elliott, K.E., Fatemi, S.A., Gerard, P.D., Peebles, E.D. 2023. Utilizing in ovo telemetry to examine the effects of reduced incubation temperature on broiler embryo temperature and subsequent hatchability. Poultry Science. 102:102506. https://doi.org/10.1016/j.psj.2023.102506.
DOI: https://doi.org/10.1016/j.psj.2023.102506

Interpretive Summary: There is a concern that modern chickens raised for meat production (broiler chickens) may be overheating during incubation. Lowering incubation temperature mid-way through incubation may be beneficial for the broiler embryo. In order to detect the true temperature of the embryo itself, small transponders that can record temperature were inserted into the air cell of embryonated broiler eggs on day 12 of incubation. Eggs were divided into a standard incubation temperature of 37.5°C or a low incubation temperature 35.6°C. There were 60 eggs per each incubation temperature treatment with 2 incubators per each treatment. The temperature readings inside each egg were recorded 3 times daily and the temperatures within each incubator was continuously recorded by data loggers until the eggs hatched. Correlations were analyzed and found that the air temperature within the incubator and the air cell temperature within the eggs were positively correlated for the standard temperature treatment but not for the low incubation temperature treatment. The egg weight loss of the eggs (determined by weighing the eggs on day 13 and day 17 did not differ due to the incubation temperature treatment. There was another positive correlation between percent egg weight loss and the air cell temperature in the standard incubation temperature treatment but not for the low incubation temperature treatment. Percent hatch of fertile eggs containing live embryos at 12 DOI was 93.3% in the standard treatment and 100% in the low treatment. However, time of hatch occurred 14 to 19 h later and hatchling body weight was lower in the low treatment than in the standard treatment. These findings indicate that lowering incubation temperature to 35.6°C from day 12-day 21 of incubation may help improve hatch for commercial broilers but causes a delay in hatch time and reduced chick weights which may not be economically beneficial.

Technical Abstract: The current commercial broiler embryo experiences a rapid metabolism and growth rate and may produce more heat than those of the past. Consequently, it may be beneficial to lower standard incubation temperature for commercial broiler hatching eggs. The purpose of this experiment was to determine if lowering incubation temperature at 12 d of incubation (DOI) would affect embryo temperature (ET) in embryonated Ross 708 broiler hatching eggs. From 0 to 12 DOI, eggs were incubated under standard conditions (37.50°C dry bulb, 29.76°C wet bulb). At 12 DOI, temperature transponders were aseptically placed on the inner air cell membrane to measure air cell temperature (ACT) as an estimate of ET in 120 eggs. The eggs were then randomly assigned to 4 separate still-air incubators, each containing 30 eggs. Two replicate incubators were maintained at a standard (STRT; 37.5°C) or low (LTRT; 35.6°C) temperature treatment between 12 and 21 DOI. A significant positive correlation existed between incubator air temperature (IAT) and ACT across temperature treatment and in the STRT. However, IAT was not significantly correlated with ACT in the LTRT. A significantly higher ACT was observed in the STRT than in the LTRT for 88% of the readings taken between 12 and 21 DOI. Percent egg weight loss (PEWL) between 13 and 17 DOI did not significantly differ between temperature treatments. From 13 to 17 DOI, there was a significant positive correlation between PEWL and ACT in the STRT, however, no significant correlation occurred between PEWL and ACT in the LTRT. Percent hatch of fertile eggs containing live embryos at 12 DOI was 93.3% in the STRT and 100% in the LTRT. However, time of hatch occurred 14 to 19 h later and hatchling BW was lower in the LTRT than in the STRT. Although lowering IAT at 12 DOI may improve hatchability, an associated delay in hatch and a decrease in hatchling BW may not be commercially acceptable.