Water vapor conductance: a technique using eggshell fragments and relations with other parameters of eggshell

ABSTRACT The objective of this study was to evaluate a technique for quantifying eggshell conductance using shell fragments from hatched eggs. Additional objectives were to calculate the correlation between eggshell conductance, porosity, and thickness and correlate these parameters with incubation data. The study design was fully randomized in a 3 × 3 factorial scheme (three egg regions - large end, equator, and narrow end - and three ages of broiler breeders – 29, 35, and 59 weeks). A total of 216 eggs were used, with 24 repetitions for each treatment. Neither conductance nor shell thickness showed any interaction with egg region. Breeder age influenced eggshell conductance, such that it was greatest in eggshells from 59-week breeders (0.323 mg day−1 torr−1), while for 29-week and 35-week breeders, the conductance values found were 0.285 and 0.270 mg day−1 torr−1, respectively. The eggshell thickness was similar in eggs from 29 and 35-week breeders and these were greater than the thickness of eggshells from 59-week breeders. Correlations between mean eggshell conductance and chick body weight and yolk free chick body weight were found significant. There were no correlations between mean eggshell thickness and any of the data evaluated. There were positive correlations between mean eggshell porosity and egg weight loss up to the time of transfer, chick weight, and yolk free body weight. The technique of using eggshell fragments can be used for measuring eggshell conductance. Eggshell porosity is the characteristic that best correlates with incubation parameters.摘要 本研究旨在评估一种利用孵出卵的蛋壳碎片量化蛋壳导水性（eggshell conductance）的实验技术。次要研究目标为：计算蛋壳导水性、蛋壳孔隙率（porosity）与蛋壳厚度（eggshell thickness）三者间的相关性，并将上述参数与孵化数据进行关联分析。本研究采用3×3因子设计的完全随机实验方案，设置3个蛋采集区域（钝端、赤道区、锐端）以及3个肉鸡种鸡（broiler breeders）周龄组别（29、35与59周龄）。实验共使用216枚卵，每个处理组设置24次生物学重复。 蛋壳导水性与蛋壳厚度均未表现出与蛋采集区域的交互效应。种鸡周龄对蛋壳导水性存在显著影响：59周龄种鸡所产蛋壳的导水性最高，为0.323 mg·d⁻¹·torr⁻¹；29周龄与35周龄种鸡所产蛋壳的导水性分别为0.285与0.270 mg·d⁻¹·torr⁻¹。29周龄与35周龄种鸡所产卵的蛋壳厚度无显著差异，且二者均高于59周龄种鸡所产卵的蛋壳厚度。 研究发现，平均蛋壳导水性与雏鸡体重、去卵黄雏鸡体重（yolk free chick body weight）之间存在显著相关性。平均蛋壳厚度与所有评估指标均未呈现显著相关性。平均蛋壳孔隙率与直至移盘时的卵重损失、雏鸡体重及去卵黄体重呈正相关。 本研究所采用的蛋壳碎片法可用于蛋壳导水性的测定。蛋壳孔隙率是与孵化参数相关性最优的特征。