National Engineering Laboratory for Animal Breeding and MOA Key Laboratory of Animal Genetics and Breeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
Beijing Engineering Research Center of Layer, Beijing, 101206, China.
Poult Sci. 2018 Jun 1;97(6):1948-1953. doi: 10.3382/ps/pey044.
The dynamic change in brown eggshell color as hens age has been observed, but much uncertainty still exists. We aimed to analyze the depth of eggshell color and quantity of protoporphyrin ΙΧ throughout the laying period to explore the reasons for color variation. In this study, 120 Rhode Island Red hens were used, and two eggs were collected from each individual at 26, 34, 42, 50, 60, and 70 wk of age. The eggshell color (L*, a*, b*), egg weight, eggshell dry weight, and protoporphyrin ΙΧ quantity in eggshell were measured for individual eggs. Our results showed that the intensity of brown eggshell color weaken as hens aged from 26 to 60 wk of age (L* gradually increased from 61.43 to 68.07), while eggshell lightness recovered slightly at 70 wk (L* = 64.77). The correlation analysis indicated that the content of protoporphyrin ΙΧ deposited in the eggshell was an important factor for lightness fading with the ageing process (the average r was 0.66, P < 0.01), while the egg weight had little impact on the eggshell color (the average r was 0.07, P > 0.05). The shade of the eggshell color (L* and a*) at the early laying period (26 or 34 wk) had a low correlation with the other age points (42, 50, 60, and 70 wk). However, high correlations between the shell color at 42 wk of age and subsequent ages (50, 60, and 70 wk) were found, suggesting that the intensity of eggshell color is more stable after egg-laying peaks (such as 42 wk of age). In conclusion, the intensity of brown eggshell color varies greatly among the whole laying cycle and breeders can choose the proper age for eggshell color measurements to ensure the degree of shell color in the late laying period.
褐壳鸡蛋蛋壳颜色随母鸡年龄的动态变化已经被观察到，但仍存在许多不确定性。我们旨在分析蛋壳颜色深度和原卟啉 ΙΧ 的量在整个产蛋期的变化，以探讨颜色变化的原因。本研究使用 120 只 Rhode Island Red 母鸡，在 26、34、42、50、60 和 70 周龄时从每个个体收集两个鸡蛋。测量个体鸡蛋的蛋壳颜色（L*、a*、b*）、蛋重、蛋壳干重和蛋壳中原卟啉 ΙΧ 的量。结果表明，褐壳鸡蛋颜色的强度从 26 周龄到 60 周龄逐渐减弱（L* 逐渐从 61.43 增加到 68.07），而在 70 周龄时蛋壳颜色略有恢复（L* = 64.77）。相关分析表明，蛋壳中原卟啉 ΙΧ 的含量是随老化过程蛋壳褪色的重要因素（平均 r 值为 0.66，P < 0.01），而蛋重对蛋壳颜色影响较小（平均 r 值为 0.07，P > 0.05）。早期产蛋期（26 或 34 周龄）蛋壳颜色的色调（L和 a）与其他年龄点（42、50、60 和 70 周龄）相关性较低。然而，在 42 周龄时壳色与随后的年龄（50、60 和 70 周龄）之间存在高度相关性，表明产蛋高峰期（如 42 周龄）后蛋壳颜色的强度更为稳定。总之，褐壳鸡蛋蛋壳颜色在整个产蛋周期内变化很大，饲养者可以选择适当的年龄进行蛋壳颜色测量，以确保后期产蛋期蛋壳颜色的程度。
