Quantification of the heat exchange of chicken eggs

Abstract

In the incubation process of domestic avian eggs, the development of the embryo is mainly influenced by the physical microenvironment around the egg. Only small spatiotemporal deviations in the optimal incubator air temperature are allowed to optimize hatchability and hatchling quality. The temperature of the embryo depends on 3 factors: (1) the air temperature, (2) the exchange of heat between the egg and its microenvironment and (3) the time-variable heat production of the embryo. Theoretical estimates on the heat exchange between an egg and its physical microenvironment are approximated using equations that assume an approximate spherical shape for eggs. The objective of this research was to determine the heat transfer between the eggshell and its microenvironment and then compare this value to various theoretical estimates. By using experimental data, the overall and the convective heat transfer coefficients were determined as a function of heat production, air humidity, air speed, and air temperature. Heat transfer was not affected by air humidity but solely by air temperature, embryonic heat generation, and air speed and flow around eggs. Also, heat transfer in forced-air incubators occurs mainly by convective heat loss, which is dependent on the speed of airflow. A vertical airflow is more efficient than a horizontal airflow in transferring heat from the egg. We showed that describing an egg as a sphere underestimated convective heat transfer by 33% and was, therefore, too simplistic to accurately assess actual heat transfer from real eggs.

Design of Stocking Density of Broilers for Closed House in Wet Tropical Climates

“…Total heat released from the whole body of bird has to be taken into consideration in designing closed house system in wet tropical climates. Heat transfer coefficient of convection (h) of birds was calculated from equation developed by Yahav et al (2004) and Van Brecht et al (2005) as follow: ) and m= bird weight (kg).…”

Infrared Thermography - Applications in Poultry Biological Research

“…Sensible heat loss from fertile eggs can be calculated according to van Brecht et al (2005) and Shinder et al (2007), on the assumption that heat exchange occurs via the whole eggshell surface. The eggshell surface area is determined from the length and breadth of the egg, which, for the purpose of the following model were measured with calipers (Mitutoyo-Ser.…”

“…No 51015023; precision, 0.02 mm; Mitutoyo Corporation, Kanagawa, Japan). The egg was assigned a characteristic dimension, i.e., the diameter of a sphere with the same surface area (van Brecht et al, 2005).…”

Influence of a Commercial Hatchery Thermal Environmental on the Heat Loss of Fertile Broiler Eggs

“…The incubation temperature is the most important physical factor affecting hatchability (Decuypere & Michels, 1992;van Brecht et al, 2005). Wilson (1991) determined that the optimal incubation temperature for chicken eggs is between 37 and 38º C.…”