Resumen

PEREZ G, Uri et al. Ultrasonographic evaluation in Brown Swiss cattle subjected to a heat synchronization protocol in the Peruvian highlands. Rev. investig. vet. Perú [online]. 2019, vol.30, n.1, pp.489-494. ISSN 1609-9117.  http://dx.doi.org/10.15381/rivep.v30i1.15688.

The follicular dynamics was evaluated by ultrasonography in Brown Swiss cattle subjected to a protocol of synchronization of estrus with progestogens in the Peruvian highlands. Three groups of Brown Swiss cattle of nine females each were evaluated. The groups were: lactating cows (<120 and >260 days in milk) and heifers. For synchronization, on day 0 a progesterone-based intravaginal device was applied, and 2 mg estradiol benzoate was injected, on day 8 the device was removed and 0.15 mg cloprostenol and 400 IU eCG were applied, and on day 10 1.05 mg GnRH was applied.Artificial insemination at fixed time was done 12 h after the application of GnRH. The ultrasound evaluation was done on days 8 and 10 to determine the growth rate and maximum diameter of the dominant follicle in the three groups. The follicular growth rate was 2.3 ± 1.5, 2.4 ± 1.8 and 2.3 ± 1.8 mm/day for the groups of lactating cows (<120 and >260 days in milk) and heifers, without significant difference between groups. The diameter of the dominant follicle was 14.5 ± 2.1 mm and 16.6 ± 3.1 mm in lactating cows (<120 and >260 days in milk, respectively) and 12.1 ± 2.0 mm in heifers, being significantly lower in heifers (p<0.05). The pregnancy rate was 44.4, 33.3 and 66.7% for lactating cows (<120 days, >260 days in milk) and heifers, respectively without significant difference between groups.

Palabras clave : follicle; pregnancy; anestrus; estradiol; ultrasonography.

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