Consequently, it is important to incubate eggs at a temperature that optimizes hatchability, currently defined as being between 37 and 38☌ (most often between 37.5 to 37.8☌) -.Īs incubation (and therefore embryo development) progresses and nutrients ( e.g., lipids) are incorporated into the embryo and metabolized, the egg loses water through evaporation. It has been hypothesized that, if embryonic growth deviates from optimum, both post-hatch growth and organ function will be impaired. It has been shown that, early in incubation, the metabolic rate rises in response to higher incubation temperatures whereas, prior to pipping, both chicken and duck embryos show decreased metabolic rates as the internal egg temperature exceeds 40.0☌. Įxposure to low temperatures early in incubation not only appears to affect embryonic heat production (by influencing embryonic metabolic rates), but is also reported to influence embryonic and post-hatch development. Raising temperature initially accelerates embryonic growth and utilization of nutrients and energy from yolk and albumen, but as incubation progresses, exposure to constant high temperatures decreases embryonic growth. Temperature may, however, have a divergent, or biphasic, effect during the course of incubation. Therefore, temperature influences the metabolic rate of yolk and albumen mobilization and consumption and, subsequently, embryonic development throughout incubation. Together with further studies, these patterns may prove helpful in the diagnosis of equipment malfunctions relating to temperature or relative humidity.Ĭhicken embryos are poikilothermic, relying on an external source (hen or incubator) to provide the heat necessary for development and maintenance of normal metabolic functions. This paper describes changes in embryonic metabolism and behaviour, as well as in mortality and malformation rates, in response to manipulations in environmental temperature and relative humidity. Overall, manipulations in environmental (incubator) temperature during incubation produced more drastic changes in embryo development than humidity-related manipulations, especially where mortality and malformation rates were concerned. Malformation rates were higher for embryos subjected to high incubation temperatures and were most prominently related to the abdominal wall, head, skull and limbs. Changes in relative humidity have produced less radical effects on mortality. Mortality rates for both temperature-related treatments were higher during the first four days of incubation. HR and VMM were considered to be strong indicators of embryonic stress, as all treatments applied resulted in elevated heart rate and decreased embryo movement. ER tended to grow more slowly and remain lower than the established normal, especially in embryos challenged with temperature treatments. The most significant changes in the evolution of AR and YR throughout incubation involved delay and reduction in the amplitude of the expected drop in albumen and yolk levels, reflecting lower nutrient consumption by the embryo. Of all the parameters monitored throughout embryonic development the ones shown to be most affected were: albumen-weight to egg-weight ratio (AR) yolk-weight to egg-weight ratio (YR) embryo-weight to egg-weight ratio (ER) heart rate (HR) voluntary movements per minute (VMM) mortality rates malformation prevalence and type. This study was aimed at establishing patterns of metabolic and behavioural response, as well as mortality and the development of malformations, all of which can potentially be used in monitoring incubating operations and diagnosing problems with faulty equipment. This study aimed at characterizing embryonic metabolic and behavioural response to a harsh incubation environment generated by manipulations (elevations and drops) in these two key factors. Temperature and relative humidity (RH) are very important factors affecting embryo development, hatchability, and posthatch performance.
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