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

ABSTRACT

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.

KEYWORDS:

• Amino acids
• amniotic fluid
• yolk
• embryo development

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was financially supported by the Project of Innovative Research Groups of the Natural Science Foundation of Hubei Province (No. 2019CFA015)