Ammonia concentration in bovine follicular fluid and its effect during in vitro maturation on subsequent embryo development

Ammonia concentration in bovine follicular fluid (bFF) at different develop mental stages and the effects on oocyte maturation in vitro were investigat ed in this study. In Experiment 1, 80 bFF samples were collected from folli cles in four size categories (< 1 mm, 2-4 mm, 5-8 mm, and > 10 mm) to deter mine ammonia concentration. Ammonia concentration was greater (P < 0.001) i n the bFF from smaller follicles compared with bFF from larger follicles, a nd ammonia concentration decreased (P < 0.05) as follicle size increased. A mmonia concentrations in bFF were 366 +/- 61 mu M, 247 +/- 24 mu M, 134 +/- 21 mu M, and 33 +/- 19 mu M in < 1 mm, 2-4 mm, 5-8 mm, and > 10 mm follicl es, respectively. In Experiment 2, abattoir oocytes (n = 2885) were matured in vitro in media containing ammonia at the concentrations of 0 mu M (Cont rol), 29 mu M (A1), 88 mu M (A2), 132 mu M (A3), 176 mu M (A4) and 356 mu M (A5), followed by in vitro fertilization and culture. There was no differe nce (P > 0.05) in cleavage rates and morula or blastocyst development betwe en treatments, indicating that in vitro exposure of bovine oocytes to ammon ia does not adversely influence subsequent embryonic development, (C) 2000 Elsevier Science B.V. All rights reserved.