RESUMO
The effect of estradiol-17beta (E(2)) supplementation on superovulation with (PMSG) or (FSH) was investigated in Swamp buffalo. Sixty-eight buffalo were treated in seven groups. Group 1 served as control and was superovulated by standard PMSG or FSH treatment used in routine bovine embryo transfer protocols. Group 2 was superovulated by standard PMSG regimen plus two injections of E(2) at a 48 h interval beginning one day before the onset of gonadotropin treatment (short-term supplementation) for a total dosage of 2.5 mg E(2); Groups 3 and 4 received the same regimen as Group 2, but in doses of 5.0 and 7.5 mg E(2), respectively. Group 5 received the standard FSH regimen (40% LH). Group 6 received short-term E(2) (7.5 mg) supplementation of FSH-p. Group 7 was superovulated by standard FSH regimen (40% LH) plus three injections of E(2) at 48-72 h intervals beginning five days before the onset of gonadotropin treatment (long-term supplementation) for a total dosage of 7.5 mg E(2). The number of corpora lutea (CL) and follicles >/= 8 mm in diameter were recorded by palpation per rectum and after slaughter. The mean numbers of CL and follicles were 0.99, 5.8, 8.0, 10.6, 4.0, 3.9, 8.1 and 0.25, 6.8, 6.2, 6.2, 1.6, 0.0, 4.1 for Groups 1, 2, 3, 4, 5, 6, 7, respectively. In Group 7, the rates of nonsurgical and postmortem embryo recovery were 46 and 90.4%, respectively and 54.4% of the collected ova were fertilized. These results indicate the possibility of producing viable embryos in buffalo by using E(2) supplementation for the gonadotropin treatment.