Chimera production in bovine and its sperm capacity
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In vitro produced bovine embryos were used to produce chimeras by combining the 8- cell stage embryos. Aggregated embryos were embedded in either 0, 1.0 and 1.2% agar and cultured in vitro. The aggregation rate of the embryos cultured without agar embedding was lower (P<.05) than with agar embedding (62%, 92% and 94% for 0, 1.0 and 1.2% agar, respectively). Five aggregated embryos were transferred non-surgically, resulting in the birth of 2 chimeric calves. Base on chromosome analysis, the chimera bull had apparently normal chromosomes (29 acrosentric pairsone large submetacentric X chromosome and one small submetacentric Y chromosome). Capacity of the Chimera (C) sperm were used for IVF to compare with sperm of the Japanese Black (JB), Limousin (L), Japanese Red (JR) and Holstein (H) bulls. Fertilization rates by using Chimera sperm were higher (P<.05) than JR and H sperm, but did not differ from JB and L sperm (81.8%, 80.0%, 6.9.4%, 44.2% and 18.2% for C, JB, L, JR and H, respectively). The blastocyst rates oocytes inseminated with C sperm were higher (P<.05) than with L, JR and H sperm,but not differ from JB sperm (38.1%, 39%, 25.0%, 23.3% and 17.8% for C, JB, L, JR and H sperm, respectively). These•findings suggested that chimera in bovine could be able to produce by aggregation method resulted in the normal calves. The sperm collected from chimeric bull could be used for producing bovine IVF embryos.