Resumen

VARGAS FERNANDEZ, T. L. et al. Effect of eCG post protocol J - Synch on pregnancy rate in Ecuadorian Amazon cows. Rev. vet. [online]. 2023, vol.34, n.2, pp.55-60. ISSN 1669-6840.  http://dx.doi.org/10.30972/vet.3427044.

27.

The objective of this study was to evaluate the effect of two doses of equine chorionic gonadotropin (eCG) in a J-Synch protocol, using 107 cows with calves at foot, Holstein, Brown Swiss, and their crosses, with a body condition (CC) of 2.5 (scale 1-5), and a silvopastoral system. The trial consisted of two treatments (T): T1 = 1 dose of eCG (n=52) and T2 = 2 doses of eCG (n=55). On day 0, an intravaginal device (BID) containing 0.5 g progesterone (P4) and 2 mg estradiol benzoate (BE) was administered. On day 6, the DIB was removed and 500 μg Cloprostenol (PGF2α) + 400 IU of eCG was administered. The base of the tail was painted, to determine estrus manifestation. Unpainted animals were inseminated at 60 h and painted animals at 72 h, + 100 µg of (GnRH). At T1 treatment, the size of the corpus luteum (CL) was measured on days 14 and 30 after insemination, and blood samples were taken. At T2 treatment, a second dose of 400 IU of eCG was administered on day 14, and CL size was measured, as well as on day 30, and blood samples were taken. The pregnancy diagnosis was made 40 days after the IATF, by ultrasonography. The highest pregnancy rate was observed in T2 (58.2%), and in cows in estrus (56.6%). No statistical differences were observed between treatments (p=0.7). Serum P4 concentrations were not different. Similarly, the diameter of the CL at days 14 and 30 post IATF did not differ (p>0.05). However, the size of the CL at days 14 and 30, is clearly related (p<0.001). In conclusion, a second dose of eCG on day 14 in the J - Synch protocol had no effect on pregnancy but a tendency to improve performance in Ecuadorian Amazonian cows.

Palabras clave : Time of IATF; presence of estrus; GnRH; dual purpose..

        · resumen en Español     · texto en Español     · Español ( pdf )