Letrozole (CGS 20267) is an oral non-steroidal type II aromatase inhibitor. It was approved by the FDA in 1997 as a form of treatment for women with breast cancer.
There are numerous studies of the effects of letrozole on chickens and quails. One of the greatest benefits is it's use as a contraceptive to stop egg laying in birds with reproductive disorders.
Results from research conducted by N Zandi et al., 2019 showed that egg production ceased 4 days after the start of treatment in female quails. It did not begin again 9 days after the treatment stopped. The serum concentrations of progesterone and testosterone increased 11–17- and 2.5–5.5-fold, respectively, and estrogen decreased 4–10-fold in letrozole groups as compared with the controls. Treatment with letrozole also resulted in regression of the oviduct and ovary and decreased liver relative weight.
A study on older roosters demonstrated that letrozole can improve fertility.
Treatment in prelay pullets resulted in physicochemical changes in the bone tissue and strengthened bone mechanical functions at structural and material levels.
Aromatase inhibitors work by inhibiting the action of the enzyme aromatase, which converts androgens into estrogens by a process called aromatization. Meaning, this drug lowers estrogen levels in the body which slows the growth of tumors that require estrogen to grow.
