Chicken – Oinks and Bots

For many years, elevated CO2 levels at the end of the incubation period have been considered detrimental to developing avian embryos. This myth is extremely far from the truth. Under natural conditions, the level of CO2 measured in the micro-environment under your hen reaches a maximum of 0.4%, or 4000 ppm or more. This is ten times higher than typical outdoor CO2 levels. Sitting on the eggs, the brooding hen closes them off from freshly circulating air and this creates a protected environment where embryos can develop in the best conditions. Three Key Parameters For Healthy Chick Development Chick embryo development in hatcheries depends on the control of the following three key parameters; TemperatureCarbon DioxideHumidity Levels Temperature best for your chick eggs This is the most important parameter of the environment for your eggs - its slight increase or decrease can significantly affect the development of embryos, ease of hatching and postnatal indicators. You will want your hen to ideally incubate her eggs at 37.5 degrees Celsius. A range of 35 to 40.5 Celsius is however acceptable. CO2 levels best for your chick eggs The gas levels can affect the development of the cardiovascular system of the embryo and hence its respiration. 4000 ppm is ideal for CO2 levels and is actually 10 times higher than what you would find in a typical environment. This is to help facilitate chick growth through diffusion. Humidity best for your chick eggs This determines the rate at which the eggs lose moisture and, as a result, lose weight. Many studies have found that significant changes, both physical and physiological, occur from about the 18th day of the incubation period with the chick. The most important change occurs when the inner hatch begins, when the inner membrane of the eggshell is perforated to allow access to the air chamber. This is followed by external pecking, which continues until the chick is completely hatched from the egg. The whole process is a transition from a liquid to a dry medium. Basically, the levels of O2 and CO2 in the air chamber of the egg change as the embryo begins to carry out convective gas exchange, inflating the lungs - in other words, breathing. Previous studies have shown that O2 levels drop to about 14.2% and CO2 levels rise to about 5.6%. Some may consider these levels to be excessively high and therefore harmful to the embryo - as they would be to humans - but this is not the case for birds that have an extra tidal volume over a period of time. Indeed, within about 24 hours from the beginning of internal hatching, the embryo uses both the vascular and pulmonary systems for respiration, which increases the absorption of O2 and, therefore, increases the tidal volume. Different CO2 Levels For Chick Development Scientific evidence combined with practical observations in commercial hatcheries confirms that a controlled increase in CO2 concentration, even above 1% (10,000 ppm), between the hatching and hatching phases, actually results in a narrower hatch window and does not adversely affect quality and health. CO2 Levels During Hatching Increased CO2 levels were thought to cause stress during elimination and to be a stimulant. Research shows that changing CO2 levels are actually a positive incentive - a persistent myth finally debunked. The right CO2 level at the right time helps the embryo switch from chorioallantoic respiration to pulmonary respiration, just as it does in nature. The benefits were also confirmed by hatch rates: for eggs exposed to 0.80% CO2, hatchability increased by 0.50%. One-Stage Incubation Principles During incubation, embryos take up oxygen (O2) and release carbon dioxide (CO2). In single-stage incubation, a ventilation mode based on carbon dioxide control can be used instead of ventilation at a predetermined constant. This improves chick quality and post-hatch performance. Carbon Dioxide: A Byproduct Of Incubation Most scientists agree that CO2 is simply a by-product of incubation, toxic at certain stages of embryonic development but with adequate ventilation, your eggs will be perfectly safe. The sensitivity of embryos to the harmful effects of CO2 varies with the incubation period. In multi-stage incubation, some eggs inevitably go through a phase of increased sensitivity to CO2. Therefore, the only way to keep CO2 levels low during all incubation stages is through good ventilation. With the advent of single-stage incubation and research into the subsequent optimization of this process, the understanding of the functioning of CO2 has significantly improved. The notion that this is just a potentially dangerous by-product of incubation, the level of which needs to be kept under strict control, is no longer relevant. CO2 is now understood to be an important part of the incubation process. Turning To Nature As with all matters related to Embryo-Response Incubation technology, nature itself holds the most valuable information. The best way to understand gas exchange is to imagine the mechanism of partial pressure as it would be during gas exchange in the natural environment of embryonic development. Due to the large amount of air and constantly moving air currents, it is impossible to recreate the natural conditions of the nest in industrial incubators. However, the regulation of the partial pressure of gases and liquids in the incubator provides optimal conditions for the development of the embryo. Effect of CO2 Levels On Chick Embryo Development Numerous studies have shown that CO2 levels at different stages of embryo incubation have a direct impact on chick quality and postnatal performance. The graph below shows how changes in CO2 levels during embryonic development affect the growth curve at the production site. By maintaining the correct CO2 level during incubation, you can optimize postnatal performance and achieve the correct chick weight. The optimal growth rate depends on the customer's requirements. Output Window The CO2 level affects not only the rate of embryo growth, but also the hatch window. The need to continuously ventilate, heat and cool multi-stage incubators leads to a significant increase in the temperature range. The result is a fairly wide hatch window in multistage incubators. It is possible to significantly reduce the hatch window by monitoring the CO2 level at various stages of the hatch process. This idea is also borrowed from the natural incubation process. You can mimic the care of the parent bird in its natural environment. By using the same stimuli as in the real nest, optimal conditions for hatching can be achieved. There is lots to consider when raising chickens and I've written a whole article on it that you can ready here!