382 Lewis: Synthetic Amino-

References continued 15. Tsen, C. C., & Hlynka, I., Cereal Chem., 1962, 39, 309 16. Narayanan, K. M., & Hlynka, I., Cereal Chem., 1962, 39, 351 17. Fisher, N., Ritchie, M. L., & Coppock, J. B. M., Chemy Znd.

18. Dahle, L. K., & Sullivan, B., Cereal Chem., 1963, 40, 372 19. Bloksma, A. J., J. Sci. Fd Agric., 1963, 14, 529 20. Morrison, W. R., J. Sci. Fd Agric., 1963, 14, 245 21. Morrison, W. R., Chemy Znd., 1963, p. 1196 22. Irvine, G. N., & Anderson, J. A., Cereal Chem., 1953,30,247 23. Cookson, M. A., & Coppock, J. B. M., J. Sci. Fd Agric., 1956,

(Lond.), 1958, p. 720

7, 72

.Acids in Poultry Diets

24. Rank Ltd., J., & Hay, J. G. , B.P. No. 646,311; ‘Blanchard Batter Process’, Blanchard, G . H., & Coppock, J. B. M., Rep. 22 and 23, of the Brit. Baking Ind. Res. Ass.; also Bakers’ Rev., 1965, p. 2171

25. Fisher, E. A., & Jones, C. R., Cereal Chem., 1936, 13,496 26. Balls, A. K., & Hale, W. S . , Cereal Chem., 1940, 17,243 27. Bure, J., Zndustrie aliment. agric., 1964, 71, 175, 275 28. Irvine, G. N., & Anderson, J. A., Cereal Chem., 1953, 30, 255 29. Owren, P. A., Tidsskr. norske Laegeforen, 1964, p. 985 30. Owren, P. A., Hellem, A. J., & Odegaard, A., Lancet, 1964,

i i , p. 975

SYNTHETIC AMINO-ACIDS IN POULTRY DIETS* By D. LEWIS

(The University of Nottinghani)

An approach is outlined to the formulation of poultry feeds in relation to the economic advantages of meeting amino-acid requirements either by natural feedingstuffs or by synthetic amino-acids.

The protein component in the diet serves to meet the needs of the animal in terms of essential amino-acids and the materials to synthesise those amino-acids that are individually dispensable. The adequacy of a protein as a source of amino- acids is still frequently assessed in terms of protein quality as a single figure to represent a compromise for several nutrients. In this respect fish meal and other animal proteins are considered to be of good quality, soya-bean meal is thought to be reasonably good, whereas most other plant proteins are regarded to be of poor quality. When this concept is analysed, it is apparent that ‘good quality’ means in the first instance a high methionine content and secondly a high lysine content, the two amino-acids most limiting in the cereal fraction that constitutes the bulk of animal food. The situation is, however, changing since both methionine and lysine are becoming available as synthetic materials and can be included in diets as the pure amino-acids.

A series of hypothetical formulations can be presented to demonstrate the significance of these developments. Chick rations are shown in Table I containing a 5% supplement to cover an inclusion of vitamins, minerals and drugs. The cereal component is calculated to be a mixture of equal parts of maize, milo and wheat. An appropriate proportion of a protein-rich material is included to bring the protein content to 200/, and its name is given at the top of a column. The amino-acid contents of such mixtures have been calculated and expressed as a percentage of standard requirements for the growing chick.‘ The particular merit of fish meal is thus clear and also of soya-bean meal especially in terms of lysine.

* Read at meeting of the Agricultural Group, 23 November, 1965

The other protein sources are particularly deficient in lysine and methionine but, now that supplementation with these amino-acids in synthetic form is feasible, the protein sources need not necessarily be regarded as being of poor quality.

It has become inevitable in the formulation of poultry and pig diets that the suitability and level of inclusion of protein sources be determined by an assessment of the separate supply of individual essential amino-acids.

It is no longer necessary to demonstrate that free dietary amino-acids can meet the needs of the animal as effectively as those found within protein. The case for the inclusion of

TABLE I Proportions of chick requirements supplied by various diets

containing 20 % protein, the main protein source being indicated Soya- Cotton Ground Maize

Fish bean Sesame seed nut gluten meal meal meal meal meal meal

Methionine

Cystine Lysine Tryptophan Isoleucine Threonine Phenylalanine

Tyrosine Histidine Leucine Valine Arginine Glycine

107

119 100 114 130

1 20

190 149 1 24 117 135

J.

83

95 96

119 1 20

121

140 138 114 1 1 1 116

102 87

52 65 124 114 122 111 116 108

150 122

140 144 146 142 120 110 115 145 130 94

68

56 90

101 101

141

160 136 103 136 95

99

39 82

114 112

126

142 205 114 68 81

Sci. Fd Agric., 1966, Vol. 17, August

Lewis: Synthetic Amino-Acids in Poultry Diets 383

synthetic amino-acids in animal diets must be based upon economic factors. The only question is whether the needs of the animal are more effectively met by the addition of amino- acids or the inclusion of more protein in the diet. The information that is needed includes a clear statement of the needs of the animal, the extent to which the various protein sources contribute to the supply of particular amino-acids, and the relative costs of the proteins and synthetic amino-acids.

There are, however, two variables that slightly confuse the issue. The first is the question of amino-acid availability. Uncertainty in this respect makes it difficult to decide exactly how much of a particular amino-acid is made available from the different protein sources that can be used. The other issue is that of the sequence of amino-acid limitation within the diet. I t is possible to consider that the first fraction of protein serves to supply a whole range of amino-acids, but that the final inclusion serves only to ensure adequacy of the most limiting amino-acid. The pattern of development of such a concept of partial nutritional worth is reasonably obvious.

These principles can be considered in more detail using the specific examples of the growing chick and the laying hen. A selection of the information available on appropriate allowances of amino-acids for the growing chick are given in Table I1 together with a set of arbitrarily selected values. The ease with which these allowances are met can be shown by considering a series of hypothetical formulations at differ- ent protein levels (Table 111). The cereal component was again taken to be a mixture of equal parts of maize, wheat and milo and after an allocation of 5 O 6 for a minor supplement an

TABLE I1 Amino-acid allowances for growing chick

(% of diet) ARC NRC Dean & Selected

(1963Y (1960)3 Scott' values

Arginine Lysine Histidine Methionine t cystine Tryptophan Glycine Phenylalanine -t- tyrosine Leucine Isoleucine Threonine Valine

- 1.0 0.35 0.7 0.15 1.0 1.2 1.5 0.5 0.55 0.8

1.2 1.1 1.0 1.2 0.3 0.3 0.8 0.9 0.2 0.22 1.0 1.6 1.4 1.3 1.4 1.2 0.6 0.8 0.6 0.65 0.8 0.8

1.0 1.2 0.35 0.9 0.2 1 .0 1.3 1.2 0.8 0.65 0.8

appropriate proportion of a protein concentrate of 1 part of white fish meal to 4 parts of soya-bean meal was included to bring the protein level to the stated value. The amino-acid pattern of such hypothetical diets has been calculated and expressed in the form of content of the diet and also as a percentage of the arbitrarily selected amino-acid allowances. It is obvious that the 17%-protein diet is deficient in most of the amino-acids but grossly so in terms of lysine and methio- nine. Even the 220/,-protein diet does not meet the needs for sulphur-containing amino-acids and the case for supple- mentation with the synthetic material is readily obvious. In the intermediate case (19.5% protein) the allowances for allamino-acidsother than lysine and methionine have been met and the question is readily put in economic terms--whether the addition of a protein concentrate or the two synthetic amino-acids constitute the most economically attractive procedure to bridge the gap.

An exactly parallel situation can be considered i n the case of the laying hen. Although it may not be possible to be quite as precise in defining appropriate amino-acid allowances, a series of published values is given in Table IV and also a set of arbitrarily selected figures. The amino-acid composition of hypothetical diets calculated in the same way as for the growing chick is represented in Table V. It would appear in this case that lysine is the first limiting amino-acid. There is a much smaller marginal area within which only one or two amino-acids are limiting.

There are several ways in which to calculate the relative merits in terms of cost of free amino-acids and intact proteins to meet a particular amino-acid allowance. A simple impression can be gained by recording the cost as free amino- acid of that which a particular protein supplies. The inform-

TABLE 1V Amino-acid allowances for laying hen

(% of diet) NRC

(1960)2

Lysine 0.50 His t idine - Methionine + cystine 0.55 Tryptophan 0.15 Phenylalanine + tyrosine - Leucine 1.20 Isoleucine 0.50 Threonine 0.40 Valine -

Fisher4

0.55 0.20 0.44 0.13 0.79 0.75 0.50 0.40 0.59

Selected Combs5 values

0.60 0.55 0.21 0.20 0.49 0.55 0.13 0.13 0.87 0.85 0.83 0.80 0.55 0.50 0,44 0.40 0.65 0.60

TABLE 111

Amino-acids supplied in growing chick diets (values expressed both as a % of the diet and as % of the arbitrarily selected allowance)

% Diet % Allowance

17% 19.5% 22 % 17% 19.5% 22% Allowance Protein Protein Protein Protein Protein Protein

Arginine Lvsine -, Histidine Methionine I cysline Tryptophan Glycine phenylalanine 1 tyrosine Leu c i n e Isoleucine Threonine Valinc

1.0 1.2 0.35 0.9 0.2 1 .o 1 . 3 1 . 2 0.8 0.65 0.8

0.95 0.80 0,38 0.63 0.18 1.00 1.32 1.49 0.73 0.64 0.80

1.19 1.06 0.44 0.71 0.20 1.29 1.56 1.68 0.85 0.78 0,97

1.45 i .33 0.50 0.79 0.22 1.56 1.79 1.87 0.99 0.92 1.12

95 ..

66 109 70 90

100 102 124 91 98

100

119 88

126 79

100 129 120 140 106 120 121

145 111 143 88

110 156 138 156 1 24 142 140

J . Sci. Fd Agric., 1966, Vol. 17, August

3 84 Lewis: Synthetic Amino-Acids in Poultry Diets

TABLE V Amino-acids supplied in diets for laying hens

(values expressed both as % of the diet and as % of the arbitrarily selected allowance) % Diet % Allowance

10.5% 12.5% 14.5% 10.5% 12.5% 14.5% Allowance Protein Protein Protein Protein Protein Protein

Lysine 0.55 0.28 0.46 0.63 51 83 114 Histidine 0.20 0.25 0.29 0.35 125 145 175 Methionine + cystine 0.55 0.47 0.53 0.59 88 96 107 Tryptophan 0.13 0.11 0.125 0.14 85 96 109 Phenylalanine + tyrosine 0.85 0.88 1 -01 1.14 103 119 134 Leucine 0.80 1.15 1.26 1.38 143 158 172 Isoleucine 0.50 0.44 0.52 0.61 88 104 122 Threonine 0.40 0.38 0.47 0.56 95 118 140 Valine 0.60 0.53 0.63 0.73 89 105 122

TABLE VI Partial amino-acid values

(Pounds sterling) White Soya-bean

Partial values fish meal meal (65 % protein) (50 % protein)

Total cost/ton 75 45

Available lysine 42 21

Available S-amino-acids* 20 12 Total lysine + S-amino-acids* 89 47 Available lysine + S-amino-acids* 62 33

Total lysine content 60 30

Total S-amino-acids* 29 17

Total tryptophan 254 240 * i.e., rnethionine t cystine

ation in Table VI refers to both methionine and lysine in white fish meal and soya-bean meal. It shows clearly a cost advantage of supplying a single limiting amino-acid in syn- thetic form. The merit of adding both amino-acids together is only apparent if the protein concentrate is calculated only to supply that part of its total amino-acid content that can be regarded as available.

These observations are presented to exemplify an approach. Many of the figures that have been quoted are arbitrarily selected and, if certain alternative values are used, a somewhat different result can be obtained. Amongst the variables that have to be accommodated are: the relative cost of

protein concentrates and synthetic amino-acids; the amino- acid allowances that are chosen and their uniformity with different strains, systems of management or nutrient densities ; the effects of amino-acid imbalance especially in regard to arginine and glycine allowances ; the importance of the non- essential amino-acid component; amino-acid availability in proteins and the effects of rapid absorption of free amino- acid on efficiency of utilisation.

There would seem, however, to be a case to encourage the greater use of synthetic amino-acids in poultry diets and also probably the diets of other farm animals except ruminants. Should increasing production lead to a substantial drop in costs, the time may not be too far distant when the use of synthetic methionine and lysine increases very greatly. It is even of interest to speculate as to how soon the laboratory will become a more effective site for the production of amino- nitrogen than the farm.

References 1. Dean, W. F., & Scott, H. M.Povlt. Sci., 1965,+, 803 2. Agricultural Research Council, 1963, ‘The nutrient requirements

3. ‘Nutrient requirements of poultry’, 1960, Misc. Pub. 827,

4. Fisher, H., Proc. Cornell Nutr. Conf., 1958, pp. 5-10 5. Combs, G. F. in ‘Nutrition of Pigs and Poultry’ (Eds 3. T.

of farm livestock. No. 1, Poultry’

National Research Council (Washington, D.C.)

Morgan and D. Lewis), 1961 (London: Butterworths)

J. Sci. Fd Agric., 1966, Vol. 17, August