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Riveros J.L.,University of Chile | Riveros J.L.,University of Santiago de Chile | Schuler G.,Justus Liebig University | Bonacic C.,University of Santiago de Chile | And 3 more authors.
Animal Reproduction Science | Year: 2010

The objective of the present study was to describe ovarian activity in 11 adult non-mated guanacos, evaluated every second day for 40 days by transrectal ultrasonography and by plasma estradiol-17β and progesterone concentrations. An inverse relationship (r = -0.29, P < 0.001) was observed between the diameter of the largest ovarian follicle and the total number of follicles indicating that follicular growth in guanacos occurs in waves. The mean duration of follicular wave was 15.1 ± 4.2 days with a range from 9 to 26. The follicular growth phase was 7.0 ± 2.4 days, the static phase 3.0 ± 1.2 days, the regression phase 5.2 ± 2.1 days and the inter-wave interval was 12.6 ± 5.6 days. The maximum follicular diameter in each follicular wave was 10.2 ± 2.1 mm with a range from 7.2 to 16.1 mm. Inter-wave intervals of longer duration were associated with a larger maximum follicle diameter (P < 0.001). Follicular activity alternated between ovaries in 93% of the waves with 48% of dominant follicles occurring in the left and 52% in the right ovary without differences (P > 0.05). Plasma estradiol-17β concentrations showed a wave-like pattern, varying from 20.0 to 92.1 pmol/L. Plasma progesterone concentrations remained below 1 nmol/L without any ultrasonic evidence of ovulation during the study. These results in guanacos suggest a follicular wave pattern more similar to the llama (Lama glama) than previously described in other South American and Old World camelid species. © 2009.

Breininger E.,Institute Investigacion y Tecnologia en Reproduccion Animal | Descalzo A.,Instituto Nacional de Tecnologia Agropecuaria | Rossetti L.,Instituto Nacional de Tecnologia Agropecuaria | Abramovich D.,CONICET | Beconi M.T.,Institute Investigacion y Tecnologia en Reproduccion Animal
Andrologia | Year: 2011

Boar spermatozoa are sensitive to oxidative damage produced during cryopreservation. Our aim was to evaluate the participation of different antioxidants in the improvement of cryopreserved boar sperm functionality. Spermatozoa frozen with 200μgml -1α-tocopherol, 0.5mm 17β-oestradiol or seminal plasma were used to evaluate sperm parameters and capacitation-like changes. The 17β-oestradiol and α-tocopherol concentrations were assessed by RIA and HPLC respectively. Motility was improved but lipid peroxidation and capacitation-like changes were diminished (P<0.05) in antioxidant samples. A significant increase in 17β-oestradiol concentration was detected in 17β-oestradiol or seminal plasma samples. Alpha-tocopherol content increased in α-tocopherol, 17β-oestradiol or seminal plasma samples, obtaining the lowest level in the α-tocopherol ones. The 17β-oestradiol or seminal plasma components may be acting in the regeneration of the α-tocopherol antioxidant capacity. The α-tocopherol concentration may be conditioning the cryopreserved boar sperm functionality. The addition of antioxidants could be useful to reduce oxidative stress, thus improving the functionality of cryopreserved boar spermatozoa. © 2011 Blackwell Verlag GmbH.

Carretero M.I.,Institute Investigacion y Tecnologia en Reproduccion Animal | Miragaya M.,Institute Investigacion y Tecnologia en Reproduccion Animal | Chaves M.G.,Institute Investigacion y Tecnologia en Reproduccion Animal | Gambarotta M.,University of Buenos Aires | Aguero A.,Institute Investigacion y Tecnologia en Reproduccion Animal
Small Ruminant Research | Year: 2010

Llamas are monotocous and the length of their gestation period varies between 342 and 350 days. Thus the average number of offspring any female can produce throughout her reproductive life is very limited to spread a desired genome. The multiple ovulation and embryo transfer (MOET) technique allows an alternative to this limitation and reduces the generation interval. The objective of this study was to evaluate embryo recovery in superstimulated llamas which had previously been hormone-treated to inhibit follicular growth. A total of 50 female llamas were monitored daily via rectal palpation and ultrasound and divided according to their ovarian follicular growth into four phases. The females in each phase were then randomly divided into two groups: A (n = 20) received a single dose of 1 mg of estradiol benzoate (EB) on the first day of the treatment + 100 mg of progesterone (P4) i.m. for 5 days with 5 animals per phase and B (n = 20) received 1 mg EB at onset + 150 mg P4 i.m. for a period of 5 days with 5 animals per phase. Group C (n = 10) or control did not receive any prior hormonal treatment and the females were in follicular phase I. All groups were monitored daily and, in the presence of ovarian follicles smaller than the dominant size at the end of treatment, all were superstimulated with 1000 IU eCG. For plasma progesterone concentration recording, daily blood samples were collected from days -1 to 5 in the treated females in Group A and B. No significant differences were observed regarding the inhibition of follicle growth and in the plasma progesterone concentrations between Group A and B. The ovarian response to superstimulation was 56.2%, 71.4% and 90%, with the average number of dominant follicles produced per female being 4.4 ± 0.9; 4.8 ± 0.7 and 4.6 ± 0.6 in Groups A, B and C, respectively. The embryo recovery rate was 77.7%; 90% and 66.7% and the average number of embryos recovered per female was 2.9 ± 0.9; 2.6 ± 0.9 and 2.4 ± 0.8 for Groups A, B and C, respectively. In Groups A and B, the static follicular phase (III) seemed to be ideal for initiating the assisted reproductive technique of MOET. Although prior administration of P4 + EB seems to have no effect on the number of females that responded to the superstimulation treatments, the number of embryos recovered showed a tendency to be higher when ovarian follicle growth inhibition was performed beforehand. © 2009 Elsevier B.V. All rights reserved.

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