Ciência Animal Brasileira (Dec 2011)
USO DA rbST NO DIA DO ESTRO EM RECEPTORAS DE EMBRIÃO BOVINO CRIOPRESERVADO
Abstract
The aim of this study was to evaluate the effects of the administration of 250 and 500 mg of rbST to bovine recipients of frozen embryos on estrus day on pregnancy rate and on serum progesterone concentration. In experiment I, 44 recipients were allotted into two treatments: T1(n = 22, control) and T2(n = 22), in which animals received 250 mg rbST subcutaneously. In experiment II, 71 recipients were allotted in: T1(n = 31, control) and T2(n = 40), in which animals received 500 mg rbST. Pregnancy diagnosis occurred 30 days after estrus. Pregnancy rates did not differ between treatments in both experiments: 40.9%(T1) vs 50.0%(T2) and 48.4%(T1) vs 52.5%(T2) in experiments I and II, respectively. Likewise, the average progesterone concentration (ng/mL plasma) obtained from blood collection samples on the embryo transfer day did not show differences between the treatments: 5.29 ± 0.62(T1) vs. 5.77 ± 0.48(T2) and 4.94 ± 0.54(T1) vs. 4.77 ± 0.51(T2) in experiments I and II, respectively. These results demonstrate that the administration of 250 or 500 mg rbST on estrus day does not increase pregnancy rate nor the serum progesterone concentration of frozen bovine embryo recipients.
