Sêmen criopreservado com extrato de casca de Noz Peçã pode alterar a produção in vitro de embriões bovinos?

Abstract

In Vitro Embryo Production (IVEP) is an important biotechnology applied to bovine reproduction, promoting greater genetic gain in cattle herds. In vitro fertilization (IVF) relies heavily on semen quality, which may be compromised by cryopreservation due to increased oxidative stress and cellular damage to spermatozoa. In this context, natural antioxidants have been investigated as a strategy to preserve sperm functionality and improve embryonic development. Therefore, the present study aimed to evaluate the effects of adding different concentrations of a natural pecan nutshell extract with antioxidant potential (NP) to bovine semen used for IVF. A completely randomized experimental design was adopted in a 4 × 2 factorial arrangement, consisting of four concentrations of natural extract added to cryopreserved semen (0%, 0.5%, 0.75%, and 1.0%) and two embryo culture media (basal and commercial). Eight oocyte collections were performed from slaughterhouse-derived ovaries, totaling 2,191 cumulus–oocyte complexes (COCs), classified as Grade I (17.7%), Grade II (27.0%), and Grade III (55.3%). In each collection, COCs were allocated into two experimental groups (M1 and M2) and subjected to in vitro maturation (IVM), fertilization, and embryo culture procedures. COCs from M1 were used to assess fertilization 16 hours after IVF through pronuclear formation analysis, whereas COCs from M2 remained in embryo culture until 168 hours post-IVF for evaluation of embryonic development. The pronuclear formation rate ranged from 85.1% to 87.7%, with no significant effect of either NP concentration or culture medium (p > 0.05). However, a significant reduction in cleavage rate and blastocyst production was observed as NP concentration increased. Cleavage rates were 80.6%, 76.6%, 70.0%, and 56.9% for the control, 0.5%, 0.75%, and 1.0% NP groups, respectively (p < 0.0001). Likewise, blastocyst production decreased from 44.8% in the control group to 30.7%, 25.6%, and 14.5% in the groups supplemented with 0.5%, 0.75%, and 1.0% NP, respectively (p < 0.0001). No differences were detected between embryo culture media (p > 0.05), with average cleavage rates of 69.0% and 73.0% and embryo production rates of 27.3% and 30.5% for the basal and commercial media, respectively. In conclusion, supplementation of bovine semen with NP did not affect the initial events of fertilization. However, increasing NP concentrations, particularly at 1.0%, significantly impaired embryonic development, resulting in reduced cleavage rates and lower blastocyst production.