The document discusses factors that affect embryo temperature during incubation. It finds that machine temperature does not equal embryo temperature, as embryo temperature depends on a balance between heat production and heat loss. Heat production is influenced by developmental stage, physical traits, biological traits like breed and egg size, and environmental factors like oxygen levels. Heat loss depends on evaporation, which is affected by humidity and air temperature, and heat transfer, which depends on temperature differences, air properties, and velocity. Maintaining a constant eggshell temperature close to 37.8°C is important for optimal embryo development.

1. Incubation research: latest findings & ideas [email_address]

2. Incubation through the embryos point of view Sander Lourens (researcher poultry health & welfare) Bas Kemp (professor at Wageningen University) Henry van den Brand (Lecturer at Wageningen University) Marcel Heetkamp (Technician at Wageningen University) Ron Meijerhof (Hybro B.V., now at HatchBrood B.V.)

4. Machine temperature ≠ embryo temperature

5. Machine temperature ≠ embryo temperature

6. Machine temperature ≠ embryo temperature

7. Machine temperature ≠ embryo temperature

8. Machine temperature ≠ embryo temperature

10. Machine temperature ≠ embryo temperature

11. Machine temperature ≠ embryo temperature

15. 0 5 10 15 20 25 30 0 25 50 75 100 Relative humidity (%) Heat loss (mW) Heat loss by evaporation Average egg (10% at 37.8 o C x 55% RH) 8% 12%

18. Heat loss: heat transfer Van Brecht et al., 2005

19. Heat loss: heat transfer Calculated for eggs incubated at the same MT

21. Physical factors: egg storage Hague et al., 1996

22. Physical factors: egg turning Pearson et al., 1996

23. Biological factors: egg size

24. Biological factors: egg size Lourens et al., 2006

25. Biological factors: egg size Lourens et al., 2006

26. Biological factors: breed Metabolic heat production (mW per egg) d R308* R508* Layer* Traditional** 17 151 160 133 130 18 156 149 130 137 19 164 161 127 124 20 252 239 131 169 *Janke, Tzschenktke and Boerjan (2004) ** Romijn and Lokhorst (1960)

29. Climate Respiration Chamber (CRC)

31. Control Room

34. CL BW YFB RY HW LW HT (cm) (g) (g) (g) (g) (g) (d) EST 37.8°C 19.7 41.5 a 37.4 a 4.0 0.40 a 1.65 a 20.5 a 38.9°C 19.8 39.8 b 35.8 b 4.0 0.33 b 1.53 b 19.8 b O2 17% 19.0 c 40.6 35.3 b 5.3 a 0.36 1.49 20.2 21% 19.9 b 40.6 36.9 a 3.7 b 0.35 1.63 20.2 25% 20.4 a 40.7 37.7 a 3.0 c 0.38 1.65 20.2 EST NS * * NS ** * ** O2 ** NS * ** NS NS NS ESTxO2 NS NS NS NS NS NS NS

35. Hatch window???

37. O 2 heat CO 2 H 2 O + + YFB RY

38. Energy utilization, efficiency of energy transfer between egg and hatchling (E YFB ). After Lourens et al. (unpublished). 152 a 138 b 119 c 148 a 131 b HP at d18 (mW.egg -1 ) 52.4 54.9 52.5 50.8 b 55.7 a E YFB (%) 326 a 313 b 286 c 311 305 Utilized (kJ) 31 c 43 b 68 a 46 48 RY (kJ) 171 a 172 a 150 b 158 b 170 a YFB (kJ) 281 281 282 282 280 Yolk (kJ) 76 75 73 76 73 Albumen (kJ) 25% 21% 17% 38.9 o C 37.8 o C O 2 EST

39. Table 4. Factors affecting HP through energy utilization and efficiency of energy transfer between egg and hatchling (E YFB ) Factors affecting HP through energy utilization and efficiency of energy transfer between egg and hatchling (E YFB ). After Lourens et al. (unpublished) Yes No Eggshell temperature No Yes Oxygen No Yes Breed No Yes Egg weight E YFB Energy utilization

40. Environmental factors O 2 heat CO 2 H 2 O + + Concentration Air pressure Altitude Eggshell conductance Oxygen availability to the embryo (red blood cells)

44. Eggshell temperature is the key!!! To know EST, you have to measure it Keep EST close to 37.8 o C constantly Take home message: