Dimethylacetamide in Rooster Semen Cryopreservation.

BACKGROUND: Sperm cryopreservation of cockerels is a major challenge, and so far there is no adequate information to enable commercial use of frozen semen. OBJECTIVE: To test the toxicity of dimethylacetamide (DMA). MATERIALS AND METHODS: DMA was added at 3%, 6%, 9% and 12% to the freezing diluent, and maintained for equilibration with the semen sample for 1 min, 3 min, 5 min, 7 min and 9 min prior to freezing. Thawed semen was evaluated for kinetic characteristics by computer-assisted semen analysis (CASA) and for structural and functional properties by flow cytometry (plasma membrane rupture, mitochondrial functionality and plasma membrane functionality). RESULTS AND CONCLUSION: The addition of 6% DMA for 3-min equilibration resulted in the highest total and progressive motility, 42.0% and 36.9%, respectively. The point of intersection between a good protection and low plasma membrane rupture was obtained with the addition of 6% of DMA for 3-min equilibration with the rooster semen.

Pharmacological approaches to induce follicular growth and ovulation for fixed-time artificial insemination treatment regimens in ewes.

In Experiment I, during the non-breeding season, after intravaginal devices containing progesterone (P4) were withdrawn (n = 28), estrous rates were greater with treatment with 400 IU eCG (P < 0.05) than with FSH (10 and 15 mg) and no treatment. During the breeding season (n = 147), estrous and pregnancy rates after fixed-time artificial inseminations (FTAI) were similar among groups: 300 IU eCG; 10 mg FSH; and control (P > 0.05). In Experiment II (non-breeding season), ewes of one group were treated with 300 IU eCG (n = 8) and of two groups were treated with 10 mg FSH. In one FSH group, 250 µg estradiol benzoate (EB) were administered after 24 h (n = 9); in the other, 4 µg GnRH were administered after 36 h (n = 10). Serum P4 concentrations were greater in eCG-treated ewes (P < 0.05). Estrous rates were similar for the eCG- and FSH plus EB-treated ewes (P > 0.05). In Experiment III (breeding season), the treatments were: 300 IU eCG; 250 µg estradiol cypionate; 250 µg EB; or control (n = 22). Follicular growth was greater for eCG-treated ewes within 0-24 h and for control ewes within 48-72 h (P = 0.001). Although estrous and ovulation rates did not differ (P > 0.05), all eCG-treated ewes had ovulations. During the non-breeding season, FSH treatment promoted follicular growth but did not induce ovulations. For FTAI regimens, eCG was more effective than FSH plus GnRH and estradiol esters in inducing estrus and ovulation.