Resynchronization of follicular wave using long-acting injectable progesterone or estradiol benzoate at 14 days post-timed AI in Bos taurus x Bos indicus beef heifers.

We compared pregnancy rates in beef heifers resynchronized 14 days after the first timed-artificial insemination (TAI) using a P intravaginal device associated with either long-acting injectable progesterone (iP) or estradiol benzoate (EB). Braford and Brangus heifers were submitted to a TAI (D0). On D14, all animals were given a P intravaginal device and were randomly divided into two groups, EB (1 mg; n = 339); or iP (75 mg; n = 338).

Decreasing the dose of equine chorionic gonadotropin does not affect ovarian or pregnancy responses of purebred taurine and crossbred beef heifers.

In this study there was evaluation of effects of different doses of equine chorionic gonadotropin (eCG: 200, 300, or 400 IU) administrated at progesterone (P4) plus estradiol-based timed AI (TAI). A total of 1080 heifers were included in the study. There was insertion of the intravaginal P4-device plus administration of 2 mg of estradiol benzoate IM.

Reduction in Percoll volume increases recovery rate of sex-sorted semen of bulls without affecting sperm quality and early embryonic development.

The aim of the present study was to evaluate the effects of Percoll volume on recovery rate, sperm quality, and embryo development kinetics in in vitro production of cattle embryos. Straws of conventional and sex-sorted semen were allocated to three different volumes of Percoll: 300 μL of each Percoll gradient (90%, 60%, and 30%), Control; 100 μL of each Percoll gradient, P100; and 200 μL of each Percoll gradient, P200. Sperm quality, fertilization rate, and embryo morpho-kinetic development using time lapse cinematography up to 48 h post-insemination were evaluated.