Tags: Incubation | Whitepaper
August 27 2012,
Broody hens provide optimum conditions for embryos developing in the eggs they are sitting on. The brood patch provides heat from one direction only, and the eggs at the side of the patch are cooler than those in the middle of the nest. However, because the broody hen regularly turns and moves the eggs in the nest, uniform egg temperature is achieved.
In commercial incubation, we try to mimic the natural conditions in the nest. From the point of view of uniform egg temperature turning of eggs seems to be of less importance in modern incubators. Are there other reasons for turning eggs?
As summarized by Deeming (2002), egg turning is essential to normal development for several reasons.
Recently Elibol and Brake (2004) confirmed the finding of New (1957), that the most critical period for turning broiler hatching eggs is during the first week of incubation. Elibol and Brake observed differential effects due to an absence of turning between 0 to 2 days (primarily increased early mortality) versus 3 to 8 days (primarily increased late mortality).
The effect of not turning during the first half of incubation is only seen during the second half of incubation, but by then it is too late to take corrective actions. Turning failures during the second half of incubation will generally have less dramatic effects, although the growth rate of the embryo can be affected, depending on the moment and duration of the turning failure.
The angle through which the eggs are turned is important. Hatch of fertiles was significantly better in eggs turned over an angle of 45˚ either side of the short axis of the egg, as compared to turning of 30˚ and 15˚. Hatched chicks from eggs turned 45˚ weighed more and had less dry matter in the residual yolk. (Cutchin et al, 2007)
Deeming D.C. (2002). The role of egg turning during incubation. In: Practical aspects of commercial incubation in poultry. Ed. Deeming D.C. Ratite conference books. Pp 27 - 31.
Elibol and Brake (2004). Identification of critical periods for turning broiler hatching eggs during incubation British Poultry Science Oct; 45(5): 631 - 637.
Cutchin H.R. et al (2007). Embryonic development when eggs are turned different angles during incubation, International Poultry Scientific Forum - January 2007, Atlanta, Georgia.