47 ROLE OF INSULIN-LIKE GROWTH FACTOR-I ON THE FUNCTIONAL PARAMETERS AND FERTILITY OF OVINE FROZEN–THAWED SEMEN

The objective of the present experiment was to evaluate the effects of insulin-like growth factor-I (IGF-I) on the viability and fertility of ovine frozen/thawed semen. For evaluating the semen parameters, 5 rams were used. Before cryopreservation, semen samples from each ejaculate were divided into 4 aliquots and extended with Tris+ alone or supplemented with 1 of 3 different concentrations of IGF-I (50, 100 and 250 ng mL–1). Semen was evaluated immediately after thawing (T0), after 1 (T1) and 2 (T2) post-incubation at 37°C. The percentage of morphologically normal spermatozoa and live cells (fluorescence analysis-calcein and ethidium), acrosome integrity (NAR) and motility were analysed and hypoosmotic swelling tests (HOST) were performed to evaluate in vitro sperm survival. This experiment was replicated 5 times. In addition, AI was performed using 121 ewes to compare the optimal concentration of IGF-I versus Tris+ alone on fertility. Data for sperm parameters were analysed by 1-way ANOVA and the differences among groups were examined by Duncan's multiple range test. Pregnancy rates were analysed by the chi-square test of independence. After 1 and 2 h post-incubation, a decrease was observed in all groups in the percentage of motility, NAR and HOST when compared to the semen at T0. The motility rate was higher (P < 0.05) in the IGF-I 100 and IGF-I 250 groups when compared to the IGF-I 50 and Tris+ alone groups (76.2 and 75% vs 66.2 and 64.4%, respectively) at T0, after 1 h (67 and 63.6% vs 57.4 and 56.2%) and 2 h post-incubation (58.2 and 55.4% vs 48 and 47.2%). Furthermore, viability was higher (P < 0.05) in the IGF-I 100 and IGF-I 250 groups than in the IGF-I 50 and Tris+ alone 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 HOST among groups. No significant differences (P > 0.05) in fertility were observed between IGF-I 100 and Tris+ groups. In conclusion, the supplementation of Tris extender with IGF-I (100 and 250 ng mL–1) appears to be a successful way to preserve functional parameters of ovine sperm during cryopreservation.

129 EFFECT OF INSULIN-LIKE GROWTH FACTOR 1 AND FOLLICLE-STIMULATING HORMONE IN A DYNAMIC MEDIUM ON VIABILITY AND FOLLICULAR DEVELOPMENT OF CAPRINE EARLY PREANTRAL FOLLICLES

The goal of this study was to investigate the effect of a dynamic medium supplemented with insulin-like growth factor 1 (IGF-1), FSH, or both on the viability, activation and secondary follicle rates and on the follicle and oocyte diameters of caprine preantral follicles submitted to a long-term (16 days of culture) in vitro culture system. Fragments from goat ovaries (n = 16) obtained from slaughterhouse were cultured in α-MEM containing or not containing IGF-1 (50 ng mL–1), FSH (50 ng mL–1), or both as a dynamic medium that was added in the first (Day 0 to 8) and second (Day 8 to 16) halves of culture, resulting in 6 treatments: α-MEM alone, IGF-1/IGF-1, FSH/FSH, IGF-1/FSH, FSH/IGF-1 and IGF-1 + FSH/IGF-1 + FSH. Noncultured (fresh control) and cultured fragments were processed for morphological and viability analyses. Follicles within ovarian fragments were mechanically isolated and early-stage follicles were classified as normal or abnormal and primordial, primary, or secondary. The viability of isolated follicles was determined by trypan blue dye and follicles were classified as live or dead. For this experiment, 6240 preantral follicles were analysed. Data for statistical analyses were transformed and submitted to ANOVA using the GLM procedure of SAS, followed by the Duncan test for comparison of means. At Day 8 of culture, more (P < 0.05) follicles in the treatments containing IGF-1 alone or associated with FSH were normal and viable than in the treatments cultured with FSH or α-MEM alone. At Day 16 of culture, the highest (P < 0.05) percentage of viability was observed in the IGF-1/IGF-1 (68%), IGF-1/FSH (68%) and IGF-1 + FSH/IGF-1 + FSH (72%) treatments. However, more (P < 0.05) normal follicles were observed on Day 16 in the IGF-1 + FSH/IGF-1 + FSH treatment (76%) than in all other treatments, except for the IGF-1/FSH treatment (72%). The percentage of follicular activation (primordial to primary) increased (P < 0.05) in all treatments from Day 0 to 8 (mean, 5 to 49%, respectively). The rate of follicular activation increased (P < 0.05) from Day 8 to 16 in all groups, except for the FSH/FSH and IGF-1 + FSH/IGF-1 + FSH treatments. Nevertheless, at Day 16, the IGF-1 + FSH/IGF-1 + FSH treatment had the highest (P < 0.05) percentage of secondary follicles (28%) when compared with the other groups (range, 6 to 17%). Furthermore, the IGF-1 + FSH/IGF-1 + FSH treatment had the largest (P < 0.05) mean follicular and oocyte diameters after 16 days of culture. In summary, follicular morphology and viability were maintained, follicle activation was promoted and secondary follicle formation was stimulated with the association of IGF-1 and FSH. Therefore, our results demonstrate the importance of IGF-1 associated with FSH during the entire long-term culture period on early folliculogenesis in goats.