The effect of Letrozole on frozen-thawed sperm quality and fertility of broiler breeder roosters

Document Type : Research Paper


1 M.Sc. student, Department of Animal Science, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran

2 Professor, Department of Animal Science, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran

3 Associate Professor, Department of Animal Science, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran

4 Ph.D. Condidate, Department of Animal Science, University College of Agriculture & Natural Resources, University of Tehran, Karaj, Iran


This study was carried out to evaluate the effect of the oral administration of Letrozole on blood testosterone level and frozen-thawed sperm quality and fertility of broiler breeder roosters. Twenty 50-week-old Ross 308 roosters were randomly divided into four groups (five roosters per each), individually housed in pens and received 0 (Control), 0.5 (L0.5), 1 (L1) or 1.5 (L1.5) mg Letrozole/bird/day. Semen and blood collections were done weekly for seven and six weeks, respectively. Sperm quality parameters including total and forward motility, viability and plasma membrane functionality were assessed prior freezing and these parameters along with abnormality were evaluated using post-thawed semen samples. The last three weeks were frozen and artificially inseminated to evaluate sperm penetration and fertility rate. According to the results, total and forward motility and viability of fresh and frozen-thawed sperm were significantly higher in Letrozole treated groups compared to control group. Plasma membrane functionality of fresh and frozen-thawed sperm as well as penetration and fertility rates were significantly improved in both L0.5 and L1 groups compared to control group. However, blood testosterone level was significantly higher in L1.5 than control group. In spite of observing negative effects in 1.5 level, both 0.5 mg of Letrozole/bird/day could improve sperm freezability of roosters, however, further research are needed to ascertain this results.


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