Use of in ovo transponder telemetry to determine the effects of a reduction in temperature initiated on day twelve of incubation on the subsequent body temperature and somatic characteristics of Ross 708 broiler chicks

Authors: Collins Elliott, Katie; LINDSEY, L - Mississippi State University; 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: 3/5/2025
Publication Date: 4/4/2025
Citation: Collins Elliott, K.E., Lindsey, L.L., Fatemi, S.A., Gerard, P.D., Peebles, E.D. 2025. Use of in ovo transponder telemetry to determine the effects of a reduction in temperature initiated on day twelve of incubation on the subsequent body temperature and somatic characteristics of Ross 708 broiler chicks. Poultry Science. 104(4):104991. https://doi.org/10.1016/j.psj.2025.104991.
DOI: https://doi.org/10.1016/j.psj.2025.104991

Interpretive Summary: The exact temperature applied during poultry incubation drives the development of the chicken embryo with lower temperatures delaying development and higher temperatures increasing or further driving development. The modern broiler (meat-type chicken) today develops and grows much quicker and bigger than the commercial broiler of 50+ years ago. Potentially lowering incubation temperature within an acceptable range that allows for development could be beneficial with concerns of overheating and the quick development of the modern broiler embryo. The current experiment tracked broilers following either a standard incubation temperature (37.5°C) or a lower incubation temperature of 35.6°C through growout to 21 days of age after hatching. The birds had a temperature transponder that allowed the measuring of temperatures within the egg before hatch located within the air cell of the egg. This specific transponder was collected at hatch from each chick specifically and then subcutaneously implanted into the neck of the chick at hatch. This transponder was then read to determine the chick body temperature. Litter temperatures were also read for replicate pens from each original incubation temperature treatment (standard or low temperatures). The growth of the birds was also charted by weighing the birds and measuring the body length of the birds at one, two, and three weeks of age. There was no relationship (correlation) found between the litter temperatures and the chick body temperatures. Additionally, there was no relationship found between the original embryo temperatures and the chick temperatures after hatching through to 3 weeks of age. The chick body temperatures of the low incubation temperature treatment were lower than the standard incubation temperature treatment chicks between 1 and 21 days of age. The low temperature treatment broilers also had reduced body weights and body lengths after the first week in comparison to the standard incubation treatment broilers. Thus, the extreme lowering of incubation temperature did affect the future broiler body temperature and reduced the growth rate of the broiler post-hatch up to 3 weeks of age.

Technical Abstract: The effects of a reduction in incubation temperature, made to accommodate higher levels of embryonic heat production, on the post hatch body temperature and somatic characteristics of Ross 708 broilers were determined. Incubation temperature treatments (TRT) were a standard (STRT, 37.5 'C) and a lower (LTRT, 35.6'C) TRT provided between 12 and 21 d of incubation (DOI). All eggs were incubated at 37.5 'C between 0 and 12 DOI. Temperature transponders implanted in the air cell of each egg at 12 DOI were extracted and inserted subcutaneously into the neck of the corresponding hatchling to record chick body temperature (CBT) through 21 d of grow out (DOG). After placement, multiple CBT and litter temperature (LT) readings were recorded daily between 1 and 21 DOG, and BW was determined at placement (0 DOG), and BW, body length (BL), and BW to length ratio (BWTLR) were determined on 7, 14, and 21 DOG. Thirteen daily mean CBT readings in the STRT were significantly higher than those in the LTRT between 1 and 21 DOG. Nevertheless, there was no significant correlation between LT and CBT, and when hatch time (HT) and BW were accounted for, embryo temperature (ET) and CBT were not significantly correlated. At 0 and 7 DOG, no significant differences in BW were observed between the STRT and LTRT within either sex; however, BW was greatest in males belonging to the STRT at 14 (x' = 483.1 g) and 21 (x' = 1,033.8 g) DOG. Across DOG and sex, BL was significantly longer in the STRT than in the LTRT, and at 14 and 21 DOG, BWTLR was greater in the STRT than in the LTRT. The LTRT subsequently lowered CBT and negatively affected chick BW, BL, and BWTLR. In conclusion, CBT is not directly associated with ET, but the reductions in CBT and various performance variables in Ross 708 broilers in response to the LTRT is a result of its adverse effects on chick HT and BW.