The objective of this study was to determine the intrafollicular concentrations of
free amino acids in pigs and to examine the effect of amino acids in a chemically
defined maturation medium on oocyte maturation, in vitro fertilization (IVF), and
embryo development in vitro. Pooled follicular fluid aspirated separately from small
(<3mm in diameter), medium (3-8mm), and large follicles (>8mm) in three pairs of ovaries
was analyzed for amino acid concentration. In addition, oocyte maturation, fertilization,
and embryo development were examined after in vitro maturation (IVM) of oocytes in
a defined maturation medium supplemented individually with glutamate (GLU), glutamine
(GLN), glycine (GLY), aspartate (ASP), asparagine (ASN), arginine (ARG), alanine (ALA),
leucine (LEU), lysine (LYS), proline (PRO), and valine (VAL). Irrespective of follicle
size, GLY, GLU, ALA, GLN, and PRO were the most abundant amino acids in pig follicular
fluid (pFF). Sperm penetration was not altered by amino acid treatment during IVM,
but monospermic fertilization was increased (P<0.05) by GLN, ASP, and VAL. All amino
acids except ASP and ASN stimulated (P<0.05) male pronuclear formation after IVF.
ARG and ALA treatment during IVM improved (P<0.05) blastocyst formation. In conclusion,
GLY, GLU, ALA, GLN, and PRO were the most abundant amino acids in pFF and amino acids
in a defined medium improved porcine monospermic fertilization, male pronuclear formation,
and preimplantation development.