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Table 4 Plasma free amino acid concentrations of growing barrows pigs (25 to 42 kg body weight) fed different levels of threonine (70%, 85%, 100%, 115%, and 130% of the ideal threonine:lysine ratio of 0.65) in an individual precision-feeding (IPF) system or a group phase-feeding (GPF) system

From: Pigs receiving daily tailored diets using precision-feeding techniques have different threonine requirements than pigs fed in conventional phase-feeding systems

Parameters IPF GPF   P-valueb
70 85 100 115 130 70 85 100 115 130 MSEa Thr FS Thr × FS
Number of observations 10 8 11 10 10 11 10 11 11 11     
Essential amino acids, μmol/L
 Arginine 215.26 210.37 222.60 212.17 208.10 216.69 226.5 217.58 195.36 210.64 18.40 0.87 0.98 0.92
 Histidine 54.23 41.64 39.29 44.31 30.26 58.55 45.08 33.79 35.65 35.50 4.05 < 0.001e 0.92 0.18
 Isoleucine 89.37 78.62 93.25 82.33 88.10 84.62 85.85 82.43 83.39 83.93 5.35 0.67 0.43 0.37
 Leucine 148.46 159.01 169.55 166.34 155.39 154.52 153.0 153.95 156.69 157.46 7.62 0.27 0.18 0.25
 Lysine 136.93 80.90 75.53 59.26 76.68 125.19 70.60 64.79 62.92 64.32 11.86 < 0.001d 0.17 0.89
 Methionine 58.56 51.48 47.48 48.34 51.24 46.68 46.42 44.62 51.22 40.38 4.71 0.44 0.04 0.37
 Phenylalanine 64.69 70.51 61.73 58.04 61.18 58.25 59.41 59.03 63.69 62.14 3.66 0.69 0.19 0.12
 Threonine 50.61 93.59 133.52 245.22 256.03 42.70 93.98 157.41 235.81 258.58 19.75 < 0.001c 0.87 0.89
 Tryptophan 46.20 41.19 43.72 39.76 39.57 44.84 41.96 40.98 41.36 42.52 2.76 0.21 0.87 0.72
 Valine 242.59 238.27 261.83 249.92 239.29 250.49 226.3 239.95 247.28 253.52 10.37 0.34 0.63 0.30
Non-essential amino acids, μmol/L
 Alanine 437.05 468.17 390.13 446.80 490.21 423.24 413.6 404.66 451.39 419.79 28.47 0.15 0.14 0.37
 Asparagine 39.87 40.07 42.51 42.70 41.25 40.86 40.77 42.00 40.47 41.52 3.75 0.94 0.93 0.98
 Aspartic acid 11.57 13.91 13.14 15.50 14.86 12.77 13.22 14.47 12.80 13.77 1.30 0.37 0.59 0.37
 Cysteine 193.73 189.57 204.18 200.91 211.29 195.79 200.8 207.32 195.66 201.82 7.36 0.17 0.93 0.54
 Glutamate 163.27 217.79 207.69 235.01 238.14 207.22 200.5 214.63 203.51 225.17 20.14 0.12 0.85 0.26
 Glutamine 452.58 483.11 490.92 491.77 485.81 438.95 478.8 500.46 533.40 477.22 31.74 0.06 0.74 0.76
 Glycine 967.1 1116.3 990.8 1028.5 1108.8 939.9 914.6 1037.9 1060.6 1112.0 16.78 0.07c 0.40 0.18
 Homocysteine 19.72 20.42 22.07 22.29 25.53 18.15 20.44 24.24 22.15 21.70 2.24 0.08c 0.58 0.58
 Proline 185.7 194.93 183.91 206.57 197.87 186.82 180.70 188.69 198.42 187.42 10.56 0.09c 0.22 0.60
 Serine 93.00 103.71 99.89 111.67 108.68 86.12 93.51 98.25 98.64 108.81 4.97 < 0.001c 0.02 0.44
 Tyrosine 67.24 64.18 55.65 63.62 59.75 66.12 62.22 59.40 59.41 55.32 3.79 0.03c 0.45 0.74
  1. aMSE, maximum standard error
  2. bThr, level of threonine; FS, feeding system; L × Thr, interaction between level of threonine and feeding system; clinear effect for Thr; dquadratic effect for Thr; ecubic effect for Thr