Comparação das taxas de prenhez entre receptoras com corpos lúteos cavitários ou compactos após protocolo de sincronização com cloprostenol ou transferência de embriões em tempo fixo Comparison the pregnancy rates between bovine recipients with cavitary or compact corpus luteum after cloprostenol or fixed time embryo transfer

The aim of this work was to evaluate pregnancy rates in bovine embryo recipients with compact and cavitary corpus luteum. Two hundred and three crossbred heifers were divided in two groups. In the first group (G-PGF, n=103), the animals received 500 mg de Cloprostenol IM (Sincrocio, Ouro fino, Brasil) after CL identification by ultrasonography. After that, heifers were detected for heat the next 72 hours. The animals from second group (G-P4, n=100) received an intravaginal progesterone device (CIDR, Pfizer, Brasil) and 2 mg estradiol benzoate (Estrogin, Farmavet, Brasil) IM, in random stages from estrus cycle. On the 8th day the devices were removed and the animals received 500 mg of Cloprostenol IM. After 24h all animals received 1 mg BE, IM. The CL was identified and evaluated at 10 and 17 days after the beginning of the treatment in G-PGF and G-P4, respectively. All the heifers with CL received IVP embryos. The pregnancy diagnosis was made by transrectal ultrasonography after 23 days. The results were analyzed by Chi-square. There were no significant difference in number of heifers ready to embryo transfer in G-PGF and G-P4, respectively 72.8% (75/103) e 79% (79/100); (P>0.05)Twenty one percent (16/ 75) had cavitary CL in G-PGF and 22.7% (18/79) in G-P4 (P>0.05). Among all embryo recipients with a cavitary or compact CL there was no difference on pregnancy rates (41.1% 14/34 and 38.3% 46/120, respectively, P>0.05), regardless of protocol treatment.