This study investigated the use of previously superovulated ovaries as a source of oocytes, assessing the competence of them for in vitro embryo production. Two superovulatory treatments were performed: equine Chorionic Gonadotrophin (eCG) plus porcine Follicle-Stimulating Hormone (pFSH) in a single dose or the conventional protocol of six decreasing doses of pFSH. Thirty donor ewes of the endangered Ojalada breed were given either the simplified (group S; n 015) or the decreasing-dose (group D; n 015) treatments three times at intervals of ]50 days. Ovaries were recovered on day 7 after the oestrus following the third treatment, just after embryo flushing, and the oocytes were collected to assess in vitro maturation, fertilisation and development to the blastocyst stage. The two superovulatory treatments did not differ in the mean number of oocytes selected for maturation (7.191.2 and 8.591.5 per ewe in the D and S groups, respectively). The oocytes recovered from ewes in Group D (87.5%) had a significantly (p B0.05) higher maturation rate than did those recovered from ewes in group S (75%), but no differences were found in fertilisation rate (94% and 94.6% in the D and S groups, respectively); both groups did not differ in their blastocyst rates and the total number of cells in in vitro-produced blastocysts. In the two experimental groups, 1.7 (D) and 1.8 (S) in vitro-produced blastocysts were generated per ewe, which indicate that it is feasible to combine in vivo and in vitro techniques to maximise embryo production in endangered sheep breeds.
The effect of melatonin implants on semen quality in fresh and frozen/thawed semen, Scrotal circumference and plasma testosterone levels has been studied During two consecutive years in the Patagonia region of Argentina (43ºS). Sixteen Dohne Merino rams (experiment 1) and 12 Dohne Merino and Merino rams (experiment 2) were used from September to December 2011 and 2012, respectively. Half of the rams were treated with melatonin implants (M groups), the remaining rams being the non-treated, control group (C groups). Differences between groups (P<0.01) for scrotal circumference were observed from 30 days after melatonin implantations up to the end of experiment 1, M rams presenting a higher scrotal circumference than animals in the C group. In the second experiment, similar differences between groups (P<0.01) were observed from day 45 to day 75. No differences between groups were detected for any of seminal parameters under study (volume, sperm concentration, mass motility and percentage of live sperm) and plasma testosterone levels. Semen quality of frozen/thawed semen was similar between treated and non-treated rams (rectilinear progressive individual motility, percentage of live spermatozoa, and membrane permeability test). No significant differences for the parameter derived (mitochondrial functionality) and the chlortetracycline (acrosomal state) tests were observed. In conclusion, the use of melatonin implants during the seasonal anoestrous at 43ºS provokes a significant increment of the scrotal circumference of rams without changing seminal quality parameters of fresh and frozen/ thawed semen.
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