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 P4 intravaginal device associated with either long-acting injectable progesterone (iP4) or estradiol benzoate (EB). Braford and Brangus heifers were submitted to a TAI (D0). On D14, all animals were given a P4 intravaginal device and were randomly divided into two groups, EB (1 mg; n = 339); or iP4 (75 mg; n = 338). On D22, P4 devices were removed, and non-pregnant (NP) heifers were identified by assessing morphological luteolysis with Doppler ultrasonography. The NP heifers had the dominant follicle diameter measured and were submitted to a second TAI on D24. Dominant follicle diameter (mm) on D22 in NP heifers did not differ (P > 0.05) between EB (9.77 ± 0.25) and iP4 (9.92 ± 0.22) groups. No difference was observed between EB and iP4 groups for pregnancy rate on D22 (56.3% vs. 60.1%, respectively), and D40 post-first TAI (49.6% vs. 53.3%, respectively). The rate of potential pregnancy losses from D22 to D40 did not differ between EB (12%, 23/191) and iP4 (11.3%, 23/203) groups. The resynchronization pregnancy rate in the EB group (45.9%, 68/148) was greater (P<0.05) than the iP4 group (31.8%, 43/135). In conclusion, treatment with either 1 mg EB or 75 mg iP4 in combination with P4 device at 14 days after TAI are equally safe for the ongoing pregnancy. The EB treatment can improve the reproductive efficiency, as it resulted in greater resynchronization pregnancy rates than iP4 treatment in beef heifers resynchronized 14 days after TAI.

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. On D7, 12.5 mg of dinoprost tromethamine IM was administered and on D9, the P4 insert was removed and 0.5 mg of estradiol cypionate IM was administered. Heifers were categorized according to Reproductive Tract Status (RTS; 1-5) and were assigned to one of three treatments: 200 IU (n = 387), 300 IU (n = 357), or 400 IU (n = 336) of eCG. Estrous occurrence was evaluated at TAI 48 h later (D11). A subset of heifers (n = 213) had the largest follicle (LF) evaluated on D9 and on D11, and the formation of a new CL evaluated on D18.There was no effect of eCG treatment on LF on D11 (P = 0.79), occurrence of estrus (P = 0.92), and pregnancy at 30 days after AI (P/AI; 52.2%, 49.8%, and 51.5% for 200 IU, 300 IU, and 400 IU, respectively; P = 0.46). Regardless of the treatment, there was a greater P/AI when heifers had a functional CL, at initiation of the estrous synchronization treatment regimen. It, therefore, is efficacious to reduce the dose of eCG to 300 or 200 IU in purebred taurine and crossbred beef heifers without negative effects on ovarian, estrous or pregnancy responses.

Effect of γ-oryzanol on testicular degeneration induced by scrotal insulation in rams.

The present study assessed the effects of daily supplementation with 33 mg/metabolic weight (MW) of γ-oryzanol on testicular degeneration induced by scrotal insulation in rams. Eight animals were divided into two groups: Control (subjected to scrotal insulation without treatment) and Gamma (subjected to scrotal insulation and γ-oryzanol treatment). The rams were subjected to scrotal insulation by covering the scrotum with a thermal bag for 72 h. Animals in the Gamma group received 33 mg/MW oral γ-oryzanol once-daily, beginning 7 days before insulation and continuing during insulation and for 20 days afterward, for a total treatment period of 30 days. Samples of semen and blood were collected during the experiment to perform biochemical evaluations of oxidative stress, seminal kinetics and morphology, and plasma testosterone concentrations. Ultrasound examinations of the testicular parenchyma and clinical evaluations of its consistency and the scrotal perimeter were also performed at weekly intervals. Testicular tissue was collected for biochemical analyses of oxidative stress parameters at the end of the experiment by orchiectomy. The results showed that testicular degeneration was induced by scrotal insulation, as was demonstrated by the reduced scrotal perimeter and increased in testicular flaccidity immediately after insulation. Moreover, a delayed increase in the number of hyperechoic points in the parenchyma and a delayed reduction in sperm motility were observed at 10 weeks after insulation by ultrasonography. Treatment with γ-oryzanol reduced levels of reactive oxygen species (ROS) levels in the testes, and increased the total antioxidant potential (assessed based on the ferric reducing ability (FRAP)) in week 10 and levels of lipid peroxidation (TBARS). It also increased the number of intact spermatozoa in week 3, but increased the total number of sperm defects from week 5 onwards. Although γ-oryzanol protected the semen and testes by reducing the levels of the parameters of oxidative stress evaluated herein, the other parameters studied were not improved by the treatment. In addition, supplementation with γ-oryzanol led to more morphological abnormalities in the sperm. This study presented new information on the oral administration of γ-oryzanol to rams with testicular degeneration, and described potential therapies for this pathology, which currently has no established treatment and has important impacts on reproductive health.

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. For conventionally processed semen, sperm motility, vigor, and recovery rate were greater in the P100 and P200 treatment groups compared to the Control (P < 0.05), whereas reactive oxygen species (ROS) concentrations, lipid peroxidation, and superoxide dismutase enzyme activity were not influenced by treatments. For sex-sorted semen, treatment with P100 increased sperm curvilinear velocity, average path velocity, and amplitude of lateral head displacement (P < 0.05). Recovery rate was greater in the P100 group than Control and P200 groups (P < 0.05), formation of ROS was less in the P100 than Control and P200 groups, and superoxide dismutase enzyme activity was less in the P100 than Control group. Fertilization and cleavage rates, time of first cleavage, and cell number were similar between the P100 and Control groups (P > 0.05). The inclusion of Percoll volumes of 100 µL resulted in an increased sperm recovery rate without damage to sperm quality or affecting early embryonic development.