Abstract:

In order to study the effect of letrozole on medullary bone osteogenesis and elucidate the mechanism of medullary bone osteogenesis in layer, 210 ISA pullets of 14week old were fed for one week before experiment, then 10 birds selected randomly from the total group were killed for collecting bone samples; the rest were averagely divided into two groups at random, control and the treated group. Animals of the treated group were fed with letrozole at 0.5 mg·d1·hen1, and the experiment lasted for 18 days. The results showed that letrozole could decrease the level of estrogen and the expression of estrogen receptor extremely significant （P<0.01）, increase the level of androgen significantly （P<0.05）, increase the bone cortex index significantly （P<0.05）and decrease the bone radiographic density of tibia significantly （P<0.05）. However, the periosteum and endosteum perimeter, cortical width and cortical area ratio of both the two groups were not significant （P>0.05）. It revealed that letrozole can inhibit the synthesization of estrogen, decrease the growth of bone and prevent the osteogenesis of medullary bone.

Key words: letrozole, estrogen, medullary bone, ISA hens