Pig Blastocyst Development In Vitro is Affected by Amino Acids

Pig embryos were removed 5 d after onset of estrus and cultured in modified Krebs-Ringer bicarbonate (mKRB) medium containing bovine serum albumin (BSA; 1 mg/ml). Media in Exp. 1 and 2, but not in Exp. 3, contained 10% heat-inactivated lamb serum (LS). In Exp. 1, embryos were cultured in 1) mKRB + LS or mKRB + LS supplemented with 2) glutamine (2 mM); 3) phenylalanine (.1 mM), methionine (.05 mM) and isoleucine (.2 mM); or 4) phenylalanine, methionine, isoleucine and glutamine. Embryos cultured in media with supplemental phenylalanine, methionine and isoleucine attained larger (P less than .05) volumes during culture and initiated hatching at an increased (P less than .05) frequency compared with embryos cultured without additional amino acids. In contrast, adding glutamine depressed (P less than .05) the maximum volumes observed during culture. In Exp. 2 mKRB + LS was compared with mKRB + LS plus phenylalanine (.1 mM), methionine (.05 mM) and isoleucine (.2 mM); methionine and isoleucine; phenylalanine and isoleucine, or phenylalanine and methionine. Embryos cultured in media supplemented with phenylalanine and methionine attained larger (P less than .05) volumes than embryos cultured in either media without added methionine. Fewer (P less than .05) embryos cultured without methionine initiated hatching (56%) compared with embryos provided methionine (89%). In Exp. 3, we evaluated the addition of glutamine (1 mM) with or without phenylalanine (.1 mM), methionine (.05 mM) and isoleucine (.2 mM) to serum-free mKRB. Adding glutamine alone, but not in combination, increased (P less than .05) blastocyst volumes on d 3 and maximum volume attained during culture compared with embryos cultured in mKRB alone.(ABSTRACT TRUNCATED AT 250 WORDS)