MGA and growth promotants administered to beef feedlot heifers have no effect on subsequent oocyte quality or in vitro embryo production

摘要

Beef feedlot heifers have the potential to serve as viable donors of oocytes post-slaughterfor in vitro embryo production. Oocyte quality is a critical factor affecting the success ofin vitro embryo production and can be influenced by factors such as age and reproductivestatus, ovarian follicle size, and nutritional status of the donor female. In a conventionalfeedlot setting, heifers are typically administered steroid-based growth promotantsand fed melengestrol acetate (MGA) for suppression of estrus, which increasescirculating concentrations of reproductive steroids, particularly estradiol. The effects ofthese management practices on oocyte quality and numbers are unknown. The purposeof this study was to compare oocytes harvested from traditionally managed beef feedlotheifers implanted with growth promotants and fed MGA with oocytes from heifersgiven neither MGA nor growth promotants, and to evaluate potential effects of thesefeedlot management practices on early embryo development.