Incubation and Fertility Research Group - {WPSA Working Group 6(Reproduction)} - 2001 Meeting - St Edmund's Hall, Oxford, UK - 17th-18thSeptember - Increasing Chicken Eggs Hatchability by Matching IncubatorHumidity to Eggshell Conductance - Abstracts

摘要

To achieve maximal hatchability and chick quality, each egg should loose an optimal amount of its mass during incubation as water vapour. Each eggshell has his own porosity because of a fixed conductance for water vapour. According to French and Tullett (1991), eggshell conductance between eggs is highly variable. When incubating all eggs at the same incubator humidity, the eggs with mean eggshell conductance will loose their optimal mass. However, a lot of eggs will loose more or less mass than this optimum because incubator humidity does not match with their conductance for optimal mass loss, resulting in a decreased hatchability. To address these questions experimentally, three experiments with each 1,800 Hybro~(R) eggs (Euribrid, Aarschot, Belgium) were carried out. Before incubation started, all eggs were weighed. During the first four days all eggs were incubated in three incubators (PasReform~(R), Zeddam, The Netherlands) at the same conditions of 37.8 deg C and 55 percent relative humidity. On the fourth day of incubation, all eggs were weighed again and the percentage loss of mass was calculated as an indicator of eggshell conductance. Afterwards all eggs were divided in three groups according to eggshell conductance (Iow, mean and high). 200 eggs of each eggshell conductance group were taken together and those three groups of 600 eggs, each composed of the three conductance groups were incubated in three incubators with different humidity (45 percent, 55 percent and 70 percent) but the same temperature (37.8 deg C). On the 18th day of incubation, all eggs were weighed again to calculate there mass loss during incubation and transferred to the hatching baskets. From day 18 onwards, the relative humidity and the temperature was the same for all eggs (37.8 deg C and 55 percent RH). After hatching, the non-hatched eggs were collected and examined for fertility. The results show a different mass loss during incubation in the groups of eggs, depending on their eggshell conductance and the incubator-humidity. For the eggs with high and medium eggshell-porosity, the groups of eggs with an approximate optimal loss of mass had an elevated hatchability in contrast with the groups of eggs with the Iow eggshell conductance, indicating that other factors than water loss may have become critical for maximal hatchability. As a conclusion, matching the incubator humidity to eggshell conductance may increase hatchability in eggs with a mean to high eggshell conductance, but this is not possible in eggs which Iow-conductance eggshells. In the latter eggs, it can be hypothesised that the O_2/CO_2-exchange is the limiting factor rather than the water balance of the growing embryo.