TechFocus_EGGS 0325 - Late-Stage Incubation Temps, Optimisi…

Figure 1. Temperature Effects on Hatch Performance and Chick Quality

Data from a single unpublished internal trial, for reference only.

absolute minimum required for complete hatching.

Internal trial data demonstrates the advantages of maintaining lower eggshell temperatures (EST) during the hatch phase (Figure 1). At 98.5 °F (36.9 °C) EST, we observed a slight increase in Hatch of Fertile (+0.21 %) compared to 100 °F control, and a reduction in both B grade (-2.27 %) and C grade (-0.92 %) chicks. The contrast becomes even more pronounced when comparing 98.5 to 101.5 °F EST, with a 0.66 % improvement in HOF, 9.7 % fewer B grade chicks, and 1.19 % fewer C grade chicks at the lower temperature. These findings suggest that maintaining EST from 98.5 to 100 °F (36.9 to 37.8 °C) provides optimal results. Our data aligns with findings from Sözcu et al. (2022), that reported even moderate temperature increases to 100.8 °F (38.2 °C) during late incubation resulted in reduced hatchability, increased late-term embryonic mortality, and poorer chick quality. Likewise, Maatjens et al. (2016) found that an eggshell temperature of about 98.5 to 99.5 °F (36.9 to 37.5 °C) during the last week of incubation led to superior chick quality metrics and enhanced first-week performance relative to higher temperatures. It’s important to note that these eggshell temperatures represent averages measured in controlled trial conditions. In commercial incubators, temperature variation and hot spots are inevitable. Given this natural variation, our findings suggest that targeting the 98.5 to 100 °F (36.9 to 37.8 °C) range, rather than 100 to 101.5 °F (37.8 to 38.6 °C), provides better insurance against quality issues. Targeting the slightly lower range acknowledges the reality of temperature variations while optimising both hatchability and chick quality. Tell-Tale Signs of Overheating in the Hatcher 1. Urates Inside the Egg When chicks are exposed to higher-than-optimal

Image 1: Urates inside the egg

temperatures, their metabolism accelerates, and they may excrete excess uric acid before fully using yolk nutrients. The excess uric acid appears as urates within the shell after hatching. 2. Early Hatching, Weak and Lethargic Chicks When embryos are exposed to excessively high temperatures, their metabolic processes accelerate, causing them to develop and hatch earlier than expected. Early-hatched chicks from overheated eggs typically appear weak, lethargic, and less alert compared to chicks incubated at optimal temperatures. 3. Red Hocks and Beaks When hatcher temperatures are too high, embryos increase blood flow to their extremities (like hocks and beaks) to dissipate heat. This causes visible redness. Additionally, overheating can make chicks more active inside the shell as they attempt to reposition or cool themselves, rubbing against the shell at contact points. These physical and physiological responses are indications of heat stress and warrant better temperature management in the hatcher. 4. Dead Pipped Chicks Pipping is an energy-intensive process. If the environment is too hot, chicks can become exhausted, dehydrate quickly, and fail to progress from external pipping to complete hatch. High temperatures shorten the time when