Search

In the present study, there was an evaluation of in vitro embryo production (IVEP) in Bos indicus donor cows with small or large antral follicle counts (AFCs) when there was synchronization of follicular dynamics among cows before ovum pick-up (OPU). Donor cows classified as having small or large AFC were submitted to OPU/IVEP program (Experiment-I) or had follicular-stage synchronization imposed before OPU/IVEP (Experiment-II). In Experiment-I, the cows with a large AFC had a greater (P < 0.01) mean of embryos developing to the blastocyst stage compared to those with a small AFC. In Experiment-II, percentage of viable oocytes/OPU were not affected (P = 0.33) by synchronization of follicular dynamics, but the AFC had an effect (P < 0.0001). There was an interaction (P = 0.01) indicating the larger AFC, with or without imposing of a synchronization treatment regimen, resulted in the most desirable outcome. The number of embryos was affected (P < 0.001) by follicular-stage synchronization and AFC, with there being an interaction (P = 0.002) with the most desirable results for the large AFC-synchronized group. Number of pregnancies was greater (P ≤ 0.02) for recipient females with embryos from synchronized donors and with a large AFC. There was an interaction (P = 0.03) with there being a greater pregnancy percentage for cows with synchronized follicular stages and the large AFC. Bos indicus donor with a large AFC when associated with the synchronization of stage of follicular dynamics pre-OPU results in improvement of the efficacy of IVEP., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The objective of this study was to evaluate the effects of two different egg yolk extenders incubated with or without Sperm Talp on the motility and plasma membrane integrity of cryopreserved bovine epididymal spermatozoa after freezing. Twenty-five testicles with epididymides from mature bulls were collected at the abattoir. Epididymal sperm recovery was performed by retrograde flushing using a skim milk-extender (Botu-Semen™). After recovery, sperm were incubated either without or with Sperm Talp and then submitted to centrifugation. For the freezing process, half of the testes were processed with Tris egg yolk extender, and half were processed with Botu-Bov™ egg yolk extender. Samples incubated in Sperm Talp exhibited better results than epididymal spermatozoa that were incubated without Sperm Talp (p<0.05). Both Botu-Bov™ and Tris could be utilised to freeze sperm from the bovine epididymides if the sperm were previously incubated with Sperm Talp. The extenders examined in this work did not differ in their effect on plasma membrane integrity after freezing., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The objective of the present study was to characterize ovarian follicular dynamics and hormone concentrations during follicular deviation in the first wave after ovulation in Nelore (Bos indicus) heifers. Ultrasonographic exams were performed and blood samples were collected every 12h from the day of estrus until 120-144 h after ovulation in seven females. Deviation was defined as the point at which the growth rate of the dominant follicle became greater than the growth rate of the largest subordinate follicle. Deviation occurred approximately 65 h after ovulation. Growth rate of the dominant follicle increased (P<0.05) after deviation, while growth rate of the subordinate follicle decreased (P<0.05). Diameter of the dominant follicle did not differ from the subordinate follicle at deviation (approximately 5.4mm). The dominant follicle (7.6mm) was larger (P<0.05) than the subordinate follicle (5.3mm) 96 h after ovulation or 24h after deviation. Plasma FSH concentrations did not change significantly during the post-ovulatory period. The first significant increase in mean plasma progesterone concentration occurred on the day of follicular deviation. In conclusion, the interval from ovulation to follicular deviation (2.7 days) was similar to that previously reported in B. taurus females, but follicles were smaller. Diameters of the dominant follicle and subordinate follicle did not differ before deviation and deviation was characterized by an increase in dominant follicle and decrease in subordinate follicle growth rate. Variations in FSH concentrations within 12-h intervals were not involved in follicular deviation in Nelore heifers.