Animal Reproduction (AR)
Animal Reproduction (AR)
Original Article

The sex ratio of in vitro produced bovine embryos is affected by the method of sperm preparation

M.G.T. Rheingantz, L.M.C. Pegoraro, O.A. Dellagostin, A.M. Pimentel, M.L. Bernardi, J.C. Deschamps

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With the in vitro production (IVP) of bovine embryos, a deviation in the expected sex ratio has been reported; the percentage of male embryos is > 50%. The objective of this study was to compare the effects of sperm preparation methods on the sex ratio of IVP bovine embryos. Cumulus oocyte complexes (COCs), recovered from abattoir-derived ovaries, were randomly allocated into two groups after in vitro maturation (IVM) and inseminated with sperm prepared with either a swim-up or Percoll gradient. From Days 1 to 8, presumptive zygotes were cultured in SOFaa medium with 5% fetal calf serum (FCS). Embryos (n = 2044) were sexed by PCR. Only the swim-up method resulted in > 50% male embryos (P < 0.05) on both Days 5 and 8 of culture (59.5 and 58.4%, respectively). Moreover, the swim-up method resulted in a greater percentage of male embryos than Percoll (P < 0.05) on every day analyzed (Day 2, 55.7 vs. 44.1%; Day 3, 53.8 vs. 42.6%; Day 5, 59.5 vs. 45.3%; and Day 8, 58.4 vs. 46.4%). In conclusion, the swim-up method altered the sex ratio of IVP bovine embryos by increasing the percentage of male embryos.


sex ratio, swim-up, Percoll, IVF, bovine
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