Effect of insulin-like growth factor-I on some quality traits and fertility of cryopreserved ovine semen

• Published in: Theriogenology 2012-09, Vol.78 (4), p.907-913
• Main Authors: Padilha, R.T, Magalhães-Padilha, D.M, Cavalcante, M.M, Almeida, A.P, Haag, K.T, Gastal, M.O, Nunes, J.F, Rodrigues, A.P.R, Figueiredo, J.R, Oliveira, M.A.L
• Format: Article
• Language: English
• Subjects: acrosome; Acrosome - drug effects; Acrosome - physiology; Animals; Artificial insemination; Cell Survival - drug effects; cryopreservation; Cryopreservation - veterinary; Drug Evaluation, Preclinical; ewes; Female; Fertility - drug effects; Fertility - physiology; fluorescence; Frozen-thawed sperm; humans; IGF-I; insemination; Insemination, Artificial - veterinary; insulin-like effect; insulin-like growth factor I; Insulin-Like Growth Factor I - pharmacology; Male; Osmotic Pressure - drug effects; Osmotic Pressure - physiology; plasma membrane; Pregnancy; pregnancy diagnosis; Pregnancy Rate; Ram semen; rams; semen; Semen - cytology; Semen - drug effects; Semen - physiology; Semen Analysis - veterinary; Semen cryopreservation; Semen Preservation - adverse effects; Semen Preservation - methods; Semen Preservation - veterinary; Sheep - physiology; sperm motility; thawing; ultrasonography; viability
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2012.04.005

The objective was to evaluate the effects of insulin-like growth factor-I (IGF-I) on the quality and fertility of frozen/thawed ovine semen. Five rams (five ejaculates/ram) were used for evaluation of semen parameters. Before cryopreservation, ejaculates were divided into four aliquots and extended with Tris alone or supplemented with human IGF-I (50, 100, or 250 ng/mL). Semen was evaluated immediately after thawing (T0), after 1 h (T1) and 2 h (T2) post-incubation at 37 °C. The percentage of live cells (fluorescence analysis-calcein and ethidium), acrosome integrity (NAR) and motility were analyzed, and hypo-osmotic swelling tests (HOST) were used to evaluate membrane resistance. In addition, AI was performed using 121 ewes to compare the optimal concentration of IGF-I vs. Tris alone on pregnancy rates after laparoscopic insemination. Pregnancy diagnosis was performed by transrectal ultrasonography. After 1 and 2 h post-incubation, in every group, percentage motile sperm, NAR and HOST decreased compared to semen at T0. Motility was higher (P < 0.05) in the IGF-I 100 and IGF-I 250 groups when compared to the IGF-I 50 and Tris groups (76.2 and 74.4% vs. 66.2 and 64.4 percent, respectively) at T0, after 1 h (67 and 63.6% vs. 56.2 and 54.7%) and 2 h post-incubation (58.2 and 55.8% vs. 48 and 47.2%). Furthermore, viability was higher (P < 0.05) in the insulin-like growth factor-I (IGF-I) 100 and IGF-I 250 groups than in the IGF-I 50 and Tris groups (88.7 and 88.3% vs. 76.6 and 77.6%, respectively) at T0. There was no difference (P > 0.05) in NAR or hypo-osmotic swelling tests (HOST) among groups. There were no differences (P > 0.05) in fertility between the IGF-I 100 and Tris groups. In conclusion, IGF-I improved subjective sperm motility and structural integrity of the plasma membrane without a significant effect on 45-day pregnancy rates after laparoscopic insemination of ewes with frozen-thawed semen.