Services and Supplies, York, England). The instrument
measures the ratio of red, green and blue light reflected
from the yolk when illuminated by a flashed white light and
automatically compares these values with known
percentages of the 1 to 15 colors of the Roche color fan
score which are pre-programmed into the colorimeter. The
yolk reflective color was expressed in level of 1 to 15.
Eggshell breaking strength of each egg was determined by
Egg Shell Force Gauge (model-II, Robotmation Co., LTD,
Japan). The eggs were placed horizontally in a cradle under
a sensor load and the load applied pressure to the eggs until
the shell fractured. The force needed to fracture the eggs
was automatically recorded in kg. Data from a replicate
were averaged to give one value per replicate.