Define candling of eggs. Why is it done? How will you differentiate between fertile and infertile eggs?

Candling of eggs is a process used in poultry farming to examine the internal contents of eggs by passing them over a bright light source. The term "candling" originates from the historical practice of using candles for illumination, although modern methods often utilize LED lights or specialized candling equipment.

Candling is performed for several reasons:

1. Assessment of Egg Viability: Candling allows producers to determine the viability of eggs by inspecting the contents for signs of fertility, development, and quality. It helps identify eggs that are fertile, infertile, or contain early-stage embryos.

2. Detection of Defects: Candling enables the detection of external and internal defects in eggs, such as cracks, blood spots, meat spots, or abnormalities in the yolk or albumen. This helps ensure the production of high-quality eggs for consumption or incubation.

3. Management of Incubation: In hatcheries, candling is used to monitor the development of embryos during incubation, assess hatchability rates, and identify eggs that are suitable for continued incubation or should be removed from the hatchery.

To differentiate between fertile and infertile eggs during candling, several characteristics are considered:

1. Development: Fertile eggs may show signs of embryonic development, such as visible blood vessels, a dark spot (the embryo), and a network of veins when candled after a few days of incubation. In contrast, infertile eggs will appear clear or translucent, with no visible signs of development.

2. Size and Shape: Fertile eggs may exhibit slightly different characteristics in size and shape compared to infertile eggs, although this can vary depending on factors such as breed and age of the bird.

3. Uniformity: Fertile eggs tend to have a more uniform appearance and consistency in the contents, with a well-defined air cell and evenly distributed albumen. In contrast, infertile eggs may show irregularities in shape, size, or contents.

By carefully examining the internal contents of eggs through candling, poultry producers can make informed decisions regarding incubation, egg quality, and management practices, ultimately ensuring the production of healthy chicks and high-quality eggs.