Browsing by Author "Bravo Mosquera, Sandra Elizabeth"

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Ajuste del tiempo de inseminación con semen sexado en vacas holstein en producción superovuladas
(2018) Argudo Garzón, Daniel Ernesto; Soria Parra, Carlos Alonso; Durán López, Juana Catalina; Bravo Mosquera, Sandra Elizabeth; Alvarado Molina, Juan Pedro; Alberio, Ricardo Horacio
The embryo production results after use of sex-sorted sperm to inseminate superovulated cows (SOV) have not been very encouraging so far, due to the low quantity of sperms used as well as their short half- life. In a previous study conducted in Brazil in Holstein cows, it was shown that using the protocol of SOV P36/Lh60 and inseminating with sexsorted sperm at 18 and 30h (interval of 12hs between the two inseminations) after application of the inductor of ovulation it was obtained a similar quantity of transferable structures than inseminating at the 12 and 24h with non-sorted sperm. The aim of this investigation was to adjust the moment of the artificial insemination (AI) in superovulated and inseminated cows with sex-sorted sperm to achieve better synchrony with ovulations and by this way to increase the quantity of transferable embryos obtained. For this, we evaluated 2 moments of AI in which the interval between both were of 6hs. We used 30 lactating Holstein cows treated with the protocol P36/LH60 and, at insemination, were divided at random in three groups: 1-group AI18/30 (control group; n=10), the AI were carried out at the 18 and 30h after application of the inductor of the ovulation (GnRH); 2- group AI18/24 (n=10) the AI inseminations were made at 18 and 24 h after GnRH and 3- group AI24/30(n=10) the AI were made at 24 and 30h. In all cases, each insemination was doing with 2.1 x 106 sex-sorted sperm. The results between groups were no different in the quantity of transferable embryos (1,9±0,6;4,1±1,5 and 1,3±0,4respectively; p>0,05) nor in the proportion of transferable from total structures (38,8%; 60,1% y 34,1% respectively). In conclusion, the low number of cows in each group and the high variability of responses do not permit to conclude on significant differences in the alternatives evaluated. However, the numerical results lead to propose new studies to increase the number of animals treated and so, reevaluate these results.
Efecto de la bST aplicada al inicio de un programa superovulatorio con FSHp y al momento de la inseminación artificial sobre la respuesta ovárica y la producción de embriones transferibles en vacas mestizas
(2017) Bravo Mosquera, Sandra Elizabeth; Perea Ganchou, Fernando Pedro
Application of bovine recombinant somatotropin (bST) at the beginning of a superovulation treatment (SOV) increased the number of antral follicles that emerged in a follicular wave, improved the SOV response and increased the rate of embryos recovered. A study was conducted with the objective of evaluate the quantity and quality of embryos obtained in response to the application of bST in two strategic moments of an ovarian super stimulation treatment. A total of 40 crossbred cows with a body condition between 2.75 and 3 on the scale of 1 to 5, clinically healthy and without apparent reproductive alterations were used. The cows were treated with an intravaginal progesterone device for 6 days (Day 0, beginning of the treatment) and with 4 daily decreasing doses of FSH-p from day 4, divided into two daily IM injections (50, 40, 30, 20 mg of FSH  2). The females were randomly assigned to one of the following treatments: GH0 (control group; n=10) without bST; GH1 (n=10) a dose of 500 mg bST at day 0; GH2 a dose of rbST at the time of the first insemination (IA) (day 8); GH3 two doses of 500 mg bST, at day 0 and 8 of the treatment. The embryos were recovered by a non-surgical method, 7 days after the first AI (day 15). Ultrasonography showed that the control group had a greater number of corpora lutea than the groups treated with rbST (13.9 ± 9.2 versus 8.0 ± 4.0, 7.1 ± 3.6 and 9.0 ± 4.4 for GH1, GH2 and GH3 respectively, P>0.05). The total number of structures recovered (oocytes and embryos), degenerate embryos and unfertilized oocytes did not differ between treatments, although in all cases the coefficient of variation was considerably lower in GH3 and GH2 than in the other groups. The percentage of transferable embryos was statistically similar between treatments, ranging from 74.1% in GH0 to 80.2% in GH1, with intermediate figures in the other experimental groups. It was concluded that the application of bST at the start of treatment with SOV and / or at the time of AI did not improve the superovulatory response nor the number of transferable embryos recovered.
Manejo reproductivo del hato
(2005) Bravo Mosquera, Sandra Elizabeth; Vidal Vidal, José Guillermo