Statistical Analysis
Statistical analysis was performed using the mixed
model and t-test procedure of SAS (SAS, 1998). A completely
randomized, repeated measure design was used
to analyze the production and exterior egg quality data
for the 10 experimental periods of the whole production
trial. Compound symmetry with heterogeneous variance
across periods, which allows for unequal variance
across periods, proved to be the most accurate method
available for the data. Differences between means were
determined using the least squares differences test.
Plumage condition and physiological response parameter
were analyzed using the t-tests procedure. Mortality
data were analyzed using PROC FREQ (SAS, 1998).
Unless otherwise stated, the level of significance was
assessed at P < 0.05.