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Table 5 Free amino acid contents in serum of laying hens fed dietary citrulline at 42 weeks old

From: Dietary L-citrulline supplementation modulates nitric oxide synthesis and anti-oxidant status of laying hens during summer season

Amino acids, ng/μL Control 0.25% L-Cit 0.50% L-Cit 1.00% L-Cit P-value
Essential amino acids
 Phenylalanine 21.02 ± 1.05 21.84 ± 0.96 21.79 ± 0.85 22.24 ± 0.75 0.824
 Threonine 28.96 ± 2.07 35.04 ± 4.06 30.15 ± 5.44 36.73 ± 3.54 0.456
 Valine 19.43 ± 0.73 23.36 ± 2.32 23.23 ± 2.14 24.53 ± 1.79 0.255
 Methionine 15.38 ± 1.14 15.69 ± 0.77 15.57 ± 0.80 16.19 ± 1.01 0.942
 Tryptophan 5.42 ± 0.30b 4.90 ± 0.26b 5.28 ± 0.53b 7.67 ± 0.88a 0.008
 Lysine 42.15 ± 3.90 45.88 ± 3.29 43.27 ± 1.27 46.97 ± 3.43 0.681
 Histidine 17.64 ± 1.09c 19.36 ± 0.96bc 22.53 ± 0.80a 20.78 ± 1.20ab 0.016
 Isoleucine 11.43 ± 0.61 13.34 ± 1.22 13.45 ± 0.93 13.84 ± 0.68 0.302
 Leucine 24.70 ± 1.04 27.61 ± 2.16 27.23 ± 1.50 26.20 ± 1.61 0.727
Non-essential amino acids
 Taurine 24.31 ± 0.73a 18.20 ± 0.78b 17.57 ± 1.26b 19.41 ± 2.08b 0.006
 Aspartate 13.42 ± 1.48 16.19 ± 2.03 15.58 ± 1.44 16.53 ± 1.01 0.491
 Serine 59.65 ± 4.72 63.90 ± 2.80 66.91 ± 4.00 66.53 ± 3.51 0.524
 Glutamate 30.12 ± 2.51 29.11 ± 1.13 28.34 ± 0.91 26.91 ± 0.95 0.505
 Glycine 42.74 ± 2.50 39.78 ± 2.39 44.44 ± 3.09 40.04 ± 2.07 0.518
 Alanine 39.72 ± 2.50 42.18 ± 3.20 37.42 ± 1.62 40.14 ± 2.34 0.609
 Cysteine 5.48 ± 0.80 4.46 ± 0.67 5.61 ± 0.99 5.09 ± 0.78 0.755
 Tyrosine 25.87 ± 1.42 27.86 ± 2.22 27.19 ± 1.62 25.91 ± 0.85 0.771
 β-Alanine 4.90 ± 0.51 4.51 ± 0.14 4.34 ± 0.46 5.65 ± 0.35 0.111
 GABA 0.24 ± 0.02b 0.26 ± 0.02b 0.28 ± 0.03b 0.57 ± 0.06a 0.004
 3-Methylhistidine 2.07 ± 0.15 1.72 ± 0.07 2.09 ± 0.13 1.54 ± 0.26 0.073
 Cystathionine 1.05 ± 0.08ab 0.85 ± 0.04b 1.15 ± 0.08a 1.08 ± 0.07a 0.032
 P-Serine 7.20 ± 0.59 6.53 ± 0.78 5.53 ± 0.3 5.88 ± 0.55 0.217
 Sarcosine 2.06 ± 0.16 2.31 ± 0.08 2.24 ± 0.17 2.03 ± 0.20 0.556
 Carnitine 2.46 ± 0.26 2.08 ± 0.19 2.20 ± 0.13 1.94 ± 0.11 0.241
  1. Data were presented as mean ± SEM. Means with different superscripts within the same row differ significantly, P < 0.05 (n = 8); GABA means γ-aminobutyric acid