According to some traditional manner for providing forced molting to chicken layers, fasting of birds for around 10-15 days was conducted to reduce the body weight to be 75% of original weight by giving only water. Approximately three weeks were needed to recover their original body weitht, then they started laying again. In this method, almost of the treated birds began to lay egg following the forced molting, showing improved egg shell color.

In these procedures, some of the egg shell quality was recovered after the forced molting, including the improvement of shell thickness, shell color and shell strength.

In addition to this new finding, some of endocrinological alteration of laying hens have been observed, such as the decline of plasma progesterone (P₄) concentration together with the forced molting, but plasma estradiol (E₂) level was not changed with the treatment. These results suggest a possibility of positive participation of plasma progesterone in the regulation of egg shell color of laying hens. This also reflects that positive correlation between ovarian steroid hormones and egg shell color in the hen.

The treatment of laying hens with T₄ resulted in the fading of egg shell color. This means that egg shell color could be regulated by some of endogenous steroid hormones originated from the organs other than the ovary. Based on the previous studies, thyroid hormone has been shown to partake in the control of progesterone level of layers, leading to the decrease of progesterone concentration of hens.

Collectively, the results of the present experiments probably suggest the possibility of controling egg shell color of hens by altering some of endocrinological correlation between thyroind hormones and steroid ones in dometic hens. Another possibility of changing shell color not by forced molting but also by controling of some feeding regimens which will be special to the layers.

The findings from this study is sure to be applicable for establishing artificial regulation of egg shell color without doing forced molting which has so far been commonly employed by poultry farmers all over the world. For doing this new techniques, it may be possible to use commercial feeding systems of poultry industry with some kind of modifications, which are also not so heavy for birds to be carried out.