What is egg translucency?
Egg translucency, also known as eggshell mottling, is an abnormality in eggs caused by the disorganization of the eggshell’s structural layers during formation. A study showed that translucent shells are missing a layer with low organic content, which leads to more pores and higher water content. When the air around the egg doesn’t evaporate the water quickly, it seeps into the shell, creating translucent spots. It’s suspected that these translucent areas may also be linked to small cracks in the shell. These spots can be seen when the eggs are candled.
Possible Causes of Egg Translucency
Several factors can contribute to egg translucency, including the hen’s diet, breed, health, and environmental conditions:
- Nutrition: Studies show that supplementing the diet of 48-week-old Lohmann hens with 25-hydroxyvitamin D and essential oils decreased translucency (Zhao et al., 2021). Similarly, adding mono-dicalcium phosphate to their diet also helped reduce this issue (Shi et al., 2023).
- Environmental Factors: Translucency tends to increase in the summer due to high heat and humidity (Shi et al., 2023).
- Breed: Some breeds, like Hy-Line Brown and Taihang, show lower translucency than others, such as Rhode Island Red and Jingfen-1 (Zhang et al., 2021).
While translucency has been extensively studied in table eggs, its impact on hatchability has received less attention. However, some studies reveal interesting findings:
Effect of egg translucency on shell quality and hatchability
A study on Ross 708 eggs found that low-translucency eggs had a higher hatchability rate (78.1%) compared to high-translucency eggs (71.2%). The latter also lost more water during incubation, despite having thicker shells (Orellana et al., 2023).
In another study, highly translucent eggs experienced greater weight loss (10.95%) and lower hatchability (81.48%) compared to medium-translucency eggs (9.92% weight loss and 89.42% hatchability; Neto et al., 2024).
The relationship between translucency and shell strength is complex and can vary according to the breed used and the sample size. Wang et al. (2017) found that translucent eggs had stronger shells. However, other studies show that translucent eggs are more prone to microcracks, which can allow bacteria like E. coli and Salmonella to penetrate the shell. This increases the risk of contamination and decreases hatchability.
Conclusion
Egg translucency negatively impacts both table and hatching eggs by increasing the risk of contamination and lowering hatchability. More research is needed to find effective ways to reduce translucency and improve the quality of table and hatching eggs.
References
Bain et al., 2006. link
Chousalkar et al., 2010. link
Neto et al., 2024. link
Orellana et al., 2023. link
Ren et al., 2023. link
Shi et al., 2023. link
van den Brand et al., 2023. link
Wang et al., 2017. link
Zhang et al., 2021.link
Zhao et al., 2021. link
Thania joined PIP as the PIP Extension technician in 2021.
