Effects of ammonia during different stages of culture on development of invitro produced bovine embryos

The effects of Various concentrations of ammonia in the media during in vit ro fertilization (IVF), culture (IVC), and throughout maturation (NM), IVF, and IVC were evaluated using a randomized complete block design. Ammonia w as added to the media at various concentrations during NF (experiment 1), d uring IVC (experiment 2), and throughout NM, NF, and IVC (experiment 3). In the first experiment, there was a significant (P < 0.05) increase in embry os developed to blastocyst, and to expanding and hatching blastocyst, in NF media containing moderate concentrations of ammonia compared with that in the IVF control media. In the second experiment, ammonia in the IVC media i ncreased (P < 0.05) the proportion of degenerate ova and decreased (P < 0.0 5) the proportion of ova that developed to blastocysts. In experiment 3, cl eavage rates tended (P = 0.06) to be greater for control groups than for tr eatment groups. The proportion of ova developing to morula was greater (P < 0.05) in media containing moderate concentrations of ammonia than that in the control groups. These results indicate that the effect of ammonia on de velopment of preimplantation bovine embryos depends on the concentration of ammonia and the stage of development when exposure to ammonia occurs. (C) 2000 Elsevier Science B.V. All rights reserved.