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Keeping a good shell quality is important to maximize broiler performance from breeders since quality and hatchability go together.
A thin shell favors water vapor loss during incubation, leading to higher late embryonic mortality and dehydrated chicks. Also, thin shells crack more easily during collection and transport, leading to contamination and moisture loss, resulting in fewer hatches and higher chick losses.
The main factors that influence the quality of the shell are:
Genetics
Diet
Environment
Housing
Broiler breeders age
Knowing the eggshell quality of a flock allows to improve their management practices by making changes to enhance the shells of poor quality together with hatchability and quality of the chick.
Among the available shell quality measures, egg-specific gravity is the simplest and most widely used method. Specific gravity is used to measure the shell’s thickness and, indirectly, the percentage of shell deposited on the egg.
There are two methods to determine the egg-specific gravity:
The Archimedes method, which includes the individual weighing of the eggs and their subsequent age into water, applying the following formula:
Dry weight/( Dry weight – Wet weight)
The salt bath method, which uses several containers of saltwater with different concentrations of saline.
To perform the salt bath method, the eggs are placed in the solution with the lowest salt concentration, and those that do not float are removed and transferred to the next solution with a higher concentration of salt.
This procedure is repeated until the egg floats. The specific gravity of the solution in which the egg floats corresponds to the egg’s specific gravity.
This method allows rapid measurement of large quantities of eggs with minimal effect on them. The best time to perform this measurement is in the hatchery once the eggs have reached the same temperature as the saline solution.
SPECIFIC GRAVITY AND HATCHING
A study was conducted to determine the relationship between hatchability and specific gravity in modern broiler breeder lines. In that study, 1,944 eggs were used to evaluate their color and the specific gravity. Each egg was marked to follow up throughout the entire incubation process.
The eggs came from five different broiler breeder flocks between 33 to 45 weeks in the middle of egg production.
The saline solutions were in the egg storage room of a commercial hatchery. The meas...
