Table 5 Plasma free amino acid concentrations of growing pigs fed low-protein diets

 Lysine

193.75

186.80

192.99

184.23

193.29

13.59

0.761

 Methionine

38.27^a

39.85^a

40.79^a

22.73^b

34.30^a

3.21

0.038

 Threonine

134.37^ab

112.11^b

156.53^a

169.01^a

120.61^b

9.10

0.050

 Tryptophan

53.89

55.99

54.04

58.42

50.14

4.88

0.662

 Isoleucine

143.83

130.90

164.25

157.92

148.31

13.91

0.295

 Valine

167.45

130.89

135.64

170.67

151.29

15.77

0.193

 Arginine

187.40^a

138.29^b

147.71^ab

138.25^b

129.40^b

14.20

< 0.001

 Histidine

92.25^ab

74.46^b

69.74^b

111.68^a

73.87^b

8.01

0.048

 Phenylalanine

93.44

88.92

90.69

84.81

93.02

5.51

0.526

 Total EAA

1104

958

1052

1097

994

65

0.440

 Aspartic acid

74.46

69.13

72.64

75.41

73.52

4.51

0.214

 Glutamine

318.44

328.10

310.45

324.92

322.20

14.39

0.588

 Glutamate

146.15^ab

154.90^ab

195.08^a

132.51^b

175.78^ab

18.20

0.045

 Alanine

194.03^a

107.76^b

126.14^b

108.56^b

129.69^b

10.46

0.018

 Cystine

66.28^a

46.84^b

51.31^b

57.93^ab

51.15^b

4.52

0.044

 Glycine

473.45^a

439.48^a

427.28^a

309.02^b

417.49^a

22.91

0.008

 Proline

142.50

126.59

134.49

121.52

133.99

10.77

0.523

 Serine

86.62

78.29

89.62

82.62

92.62

6.76

0.146

 Tyrosine

173.33

166.77

166.65

173.13

165.69

12.65

0.291

 Taurine

74.76^abc

78.56^ab

85.96^a

79.96^ab

62.28^c

5.27

0.021

 Asparagine

168.53^ab

178.60^a

165.93^ab

115.43^c

125.53^bc

15.73

0.008

 Citrulline

71.52^a

55.35^b

73.03^a

78.15^a

78.25^a

2.78

< 0.001

 Ornithine

134.00

129.12

141.52

135.64

144.87

7.09

0.553

 Total NEAA

2176^a

2010^abc

2101^ab

1854^c

2030^abc

81

0.027

 Total AA, μmol/L

3280

2969

3150

2952

3024

135

0.674