Meeting embryonic requirements of broilers throughout incubation: a review

Abstract

During incubation of chicken embryos, environmental conditions, such as temperature, relative humidity, and CO2 concentration, must be controlled to meet embryonic requirements that change during the different phases of embryonic development. In the current review, the effects of embryo temperature, egg weight loss, and CO2 concentration on hatchability, hatchling quality, and subsequent performance are discussed from an embryonic point of view. In addition, new insights related to the incubation process are described. Several studies have shown that a constant eggshell temperature (EST) of 37.5 to 38.0°C throughout incubation results in the highest hatchability, hatchling quality, and subsequent performance. Egg weight loss must be between 6.5 and 14.0% of the initial egg weight, to obtain an adequate air cell size before the embryo internally pips. An increased CO2 concentration during the developmental phase of incubation (first 10 days) can accelerate embryonic development and hatchability, but the physiological mechanisms of this acceleration are not completely understood. Effects of ar increased CO2 concentration during late incubation also need further investigation. The preincubation warming profile, thermal manipulation, and in ovo feeding are new insights related to the incubation process and show that the optimal situation for the embryo during incubation highly depends on the conditions of the eggs before (storage duration) and during incubation (environmental conditions) and on the conditions of the chickens after hatching (environmental temperature)

Comparison of Three Temperatures for the Hatching Phase in the Artificial Incubation of Red-legged Partridge (Alectoris rufa) Eggs

“…incubation temperature is reduced during the hatching phase because the heating needs of the embryos are lower at this late stage of incubation (Decuypere & Michels, 1992;Molenaar et al, 2010). However, optimal incubation temperature during the hatching period of A. rufa has not been precisely established by scientific studies yet.…”

Higher levels of CO2during late incubation alter the hatch time of chicken embryos

“…Furthermore, it 52 is questionable how it affects hatchability and chick quality. Despite the tolerance of embryos for high 53 ambient levels of CO2 increasing with embryonic age (Molenaar et al, 2010), higher ambient CO2 54 levels could still exert stress on the embryo and represent a hazard for respiration gas transport, acid-55 base balance and overall physiological status of the newly hatched chicks. However, the effect of altered…”

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

“…Relative humidity should be maintained within the recommended range, as deviations affect hatchling quality (Molenaar et al, 2010). When the RH is above the optimal range during incubation, hatchling weight increases because excessive water is incorporated in the embryonic tissues, resulting in worse performance during the starter rearing phase (Bruzual et al, 2000).…”