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Table 2 The modified Baker and NRC patterns of changes in amino acid compositions in ideal proteins for 0- to 56-d-old chicks (% of lysine in diet)

From: Dietary requirements of synthesizable amino acids by animals: a paradigm shift in protein nutrition

Amino acid

Baker’s modified models (1997) for chicks[38]1

NRC (1994)[37] (0- to 21-d-old chicks)5

 

0 to 21 d2

21 to 42 d3

42 to 56 d4

Lysine

100

100

100

100

Methionine

36

37

37

42

Cystine

36

38

38

33

Threonine

67

70

70

67

Valine

77

80

80

75

Arginine

105

108

108

104

Tryptophan

16

17

17

17

Isoleucine

67

69

69

67

Leucine

109

109

109

100

Histidine

35

35

35

29

Phe + Tyr

105

105

105

112

  1. 1These ratios are based on true digestible levels of amino acids in diet (as-fed basis; 90% dry matter). Adapted from Baker [38]. Except for glycine, all amino acids are L-isomers.
  2. 2Patterns of amino acid composition in the ideal protein are the same for male and female chickens. The amounts of digestible lysine in diet (as-fed basis; 90% dry matter) are 1.12% and 1.02% for male and female chickens, respectively.
  3. 3Patterns of amino acid composition in the ideal protein are the same for male and female chickens. The amounts of digestible lysine in diet (as-fed basis; 90% dry matter) are 0.89% and 0.84% for male and female chickens, respectively.
  4. 4Patterns of amino acid composition in the ideal protein are the same for male and female chickens. The amounts of digestible lysine in diet (as-fed basis; 90% dry matter) are 0.76% and 0.73% for male and female chickens, respectively.
  5. 5These ratios are based on total amino acids in a typical corn- and soybean meal-based diet. The amount of digestible lysine in diet (as-fed basis; 90% dry matter) is 1.2% for 0- to 21-d-old chicks.