Resumo

CALLEJAS, S. et al. Comparación de dos protocolos para sincronizar ovulación e implementar inseminación artificial en vaquillonas. Rev. vet. [online]. 2014, vol.25, n.2, pp.100-104. ISSN 1669-6840.

Two experiments were performed in Bos taurus heifers (EI, n = 16; EII: 173, body condition score: 3-3.5, scales 1-5, age: 20-24 months). The objective was to compare two protocols for synchronization of ovulation (PSO): progesterone intravaginal devices (PID) combined with estradiol cypionate (ECP) administered at PID removal or estradiol benzoate (EB) 24 h later. On day 0, heifers received a PID (1 g of progesterone) plus 2 mg BE; PID was removed on day 8, 0.150 mg of D-cloprostenol were administered and heifers were distributed into two PSO: injection of 1 mg of ECP at that time or 1 mg of EB 24 h later. In EI, ultrasonography examinations (days 0, 8 and 9 and from this last time every 12 h until day 11) were performed and blood samples were collected to determine plasma progesterone (P4, on days: 8, 9, 10, 11 and 21); percentage of heifers with corpus luteum (days 0 and 8), the diameters of the dominant (DF, day 8) and ovulatory follicle, were determined. In EII, FTAI (day 10) was performed and pregnancy rate (day 35) was determined. Statistical analysis was performed by SAS. The diameters of DF (13.1±2.4 mm) and ovulatory follicle (15.4±2.2 mm) and PID removal-ovulation interval (65.3±5.3 h) did not differ between PSO (p>0.05). There was an effect of day on the level of P4 (p<0.05), but not of the PSO or PSO by day interaction (p>0.05), P4 level on day 8 (4.6±4.4 ng/ml) decreased to <1 ng/ml after PID removal. Pregnancy rate was similar between PSO (60.7%; p>0.05). In conclusion in Bos taurus heifers, both PSO produce similar ovarian changes, variation in P4 levels and pregnancy rates.

Palavras-chave : heifer; synchronization of ovulation; artificial insemination; protocols comparison.

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