Developmental changes of free amino acids in amniotic, allantoic fluids and yolk of broiler embryo.

1. A study was conducted to evaluate the developmental changes of protein and free amino acid concentrations in amniotic, allantoic fluids and yolk during the incubation period of broiler eggs.2. A total of 120 Cobb 500 fertile eggs were individually weighed and then placed in an incubator. On incubation day: 8, 11, 13, 14, 16, and/or 18, amniotic, allantoic fluids and yolk were collected from 20 eggs for analysis of protein content and free α-amino acid concentration in allantoic and amniotic fluids and yolk.3. The total protein concentration in amniotic fluid increased from d 11 of incubation, and reached a peak at d 16 (69.85 g/l; P < 0.01), then declined at d 18 (P < 0.05). The total protein concentration in allantoic fluid increased with age of the embryo (P < 0.01). Crude protein concentration in yolk decreased (P < 0.05) from d 0 to 8, then increased gradually from d 8, and reached a peak at d 16 (P < 0.05). The concentration of most free amino acids in amniotic and allantoic fluids and yolk was related to embryo weight. Amniotic fluid amino acids gradually increased from d 13 to 18, with arginine being the most abundant at d 11 and 14. Glutamate was the most predominant amniotic fluid amino acid at d 16 and 18. From d 13 to 18, the concentrations of most α-amino acids in allantoic fluid increased, and reached a peak at d 18 (aspartate, 373 μmol/l; asparagine, 519 μmol/l; glutamine, 1230 μmol/l; threonine, 537 μmol/l; citrulline, 112 μmol/l; arginine, 2747 μmol/l; alanine, 276 μmol/l; tyrosine, 330 μmol/l; tryptophan, 212 μmol/l; valine, 140 μmol/l; phenylalanine, 102 μmol/l; isoleucine, 92.39 μmol/l; lysine, 1088 μmol/l; P < 0.05). Glutamine was the second most abundant amino acid in allantoic fluid at d 13 and 18. Glutamate was the most abundant α-amino acids at d 8, and 13 in the yolk.4. These results demonstrated that the concentration of free α-amino acids in chicken embryo fluid was related to embryo weight. Arginine, glutamine and glutamate were abundant free α-amino acids in chicken embryo fluid, to support the higher rates of tissue protein synthesis and growth for the embryo.