EFFECT OF GLYCINE AND ALANINE SUPPLEMENTATION ON DEVELOPMENT OF CATTLE EMBRYOS CULTURED IN CRLAA MEDIUM WITH OR WITHOUT CUMULUS CELLS

The effect of alanine (1 mM) and glycine (10 mM) supplementation on bo vine embryo development in vitro was investigated. Presumptive bovine zygotes, produced by in vitro maturation and insemination of oocytes, were cultured for 144 h in CR1aa medium in the absence (Experiments 1 and 2) or presence of cumulus cells (Experiment 3). In Experiment I, t he proportion of morulae and blastocysts of cleaved embryos in glycine -supplemented medium was not different from that of the control medium (34% in both media); however, the cell numbers of morulae and blastoc ysts were significantly higher in the glycine-enriched medium (69.5 vs . 53.3, P = 0.016). In Experiment 2, addition of alanine did not impro ve the formation of morulae and blastocysts (13% vs. 21% in control me dium), and the mean cell numbers in morulae and blastocysts were lower than those in the control group (34.3 vs. 68.7, P = 0.007). In the pr esence of cumulus cells, the combined supplementation of glycine and a lanine increased the proportion of morulae and blastocysts over that i n the control medium (31% vs. 14%, P = 0.003).