Modeling incubation temperature: the effects of incubator design, embryonic development, and egg size

British United Turkeys Ltd., Tarvin, Chester, United Kingdom.

A simple model to describe the relationship between the temperature of the developing embryo, incubator temperature, embryo heat production, and thermal conductivity of the egg and surrounding air is presented. During early incubation, embryo temperature is slightly lower than incubator temperature because of evaporative cooling. However, from midincubation onwards, metabolic heat production from the embryo raises embryo temperature above incubator temperature. The extent of the rise in embryo temperature depends on thermal conductivity, which, in turn, is mainly influenced by the air speed over the egg. The importance of air speed and restrictions to air flow within artificial incubators is discussed. Exact determinations of optimum incubation temperatures from studies reported in the literature are difficult because only incubator temperatures are reported. Embryo temperatures can differ from incubator temperature because of differences in thermal conductivity between different incubation systems and differences between incubators in their ability to control temperatures uniformly. It is suggested that shell surface temperatures are monitored in experiments to investigate temperature effects to allow consistent comparisons between trials. Monitoring shell temperatures would also make it easier to translate optimum temperatures derived in small experimental incubators to the large commercial incubators used by the poultry industry. The relationship between egg temperature, the metabolism of the developing embryo and egg size is discussed.

This article has been cited by other articles:

				H. Yassin, A. G. J. Velthuis, M. Boerjan, J. van Riel, and R. B. M. Huirne Field Study on Broiler Eggs Hatchability Poult. Sci., November 1, 2008; 87(11): 2408 - 2417. [Abstract] [Full Text] [PDF]

				O. Elibol and J. Brake Effect of Egg Weight and Position Relative to Incubator Fan on Broiler Hatchability and Chick Quality Poult. Sci., September 1, 2008; 87(9): 1913 - 1918. [Abstract] [Full Text] [PDF]

				N. Leksrisompong, H. Romero-Sanchez, P. W. Plumstead, K. E. Brannan, and J. Brake Broiler Incubation. 1. Effect of Elevated Temperature During Late Incubation on Body Weight and Organs of Chicks Poult. Sci., December 1, 2007; 86(12): 2685 - 2691. [Abstract] [Full Text] [PDF]

				S. Yalcin, H. B. Molayoglu, M. Baka, O. Genin, and M. Pines Effect of Temperature During the Incubation Period on Tibial Growth Plate Chondrocyte Differentiation and the Incidence of Tibial Dyschondroplasia Poult. Sci., August 1, 2007; 86(8): 1772 - 1783. [Abstract] [Full Text] [PDF]

				R. M. Hulet Symposium: Managing the Embryo for Performance Managing Incubation: Where Are We and Why? Poult. Sci., May 1, 2007; 86(5): 1017 - 1019. [Abstract] [Full Text] [PDF]

				R. Hulet, G. Gladys, D. Hill, R. Meijerhof, and T. El-Shiekh Influence of Egg Shell Embryonic Incubation Temperature and Broiler Breeder Flock Age on Posthatch Growth Performance and Carcass Characteristics Poult. Sci., February 1, 2007; 86(2): 408 - 412. [Abstract] [Full Text] [PDF]

				O. Elibol and J. Brake Effect of Egg Turning Angle and Frequency During Incubation on Hatchability and Incidence of Unhatched Broiler Embryos with Head in the Small End of the Egg Poult. Sci., August 1, 2006; 85(8): 1433 - 1437. [Abstract] [Full Text] [PDF]