Nutritional Value of High Lysine Corn for the Broiler Chick1

Nutritional Value of High Lysine Corn for the Broiler Chick1 M. S. C H I AND G. M. SPEERS Department of Animal Science, University of Minnesota, St. Paul, Minnesota 55101

POULTRY SCIENCE 52: 1148-1157, 1973

INTRODUCTION

T

HE opaque-2 mutant gene has been reported to change the amino acid pattern of corn protein resulting in a substantial increase in the lysine content (Mertz a al., 1964; Nelson et al., 1965). The higher lysine content of opaque-2 corn results from the reduction in the ratio of zein to glutelin. The nutritional superiority of opaque-2 corn compared to normal hybrid corn has been demonstrated with rats (Bressani et al., 1969; Mertz et al., 1965), with pigs (Beeson et al., 1966; Cromwell et al., 1969), and with humans (Bressani, 1966; Clark et al., 1967). Nutritional studies carried out with chicks indicated that opaque-2 corn produced faster and more efficient weight gains as compared with normal corn only after a deficiency of the first limiting amino acid was corrected by sup-

plementation with methionine (Cromwell et al., 1967). Opaque-2 corn has been shown to be superior in nutritional value for chicks compared to normal corn when lysine deficient protein sources such as sesame meal, cottonseed meal and corn gluten meal (Jarquin et al., 1970) and safflower meal (Fonseca et al., 1970) are used. Nutritional studies of sweet corn (Nordstrom and Meade, 1969) have shown that sweet corn contained greater concentrations of sulfur amino acids than normal or opaque-2 corn and produced greater growth of rats than normal corn. The purpose of this study was to evaluate the nutritional value of a commercial variety of high lysine corn derived by opaque-2 gene incorporation and a sweet corn variety for the broiler chick using corn-soybean meal type diets. MATERIALS AND METHODS

1

Published as Paper No. 8104, Scientific Journal Series of the Minnesota Agricultural Experiment Station.

Two experiments were conducted to evaluate the nutritional value of a com-

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(Received for publication September 29, 1972) ABSTRACT Two experiments were conducted using broiler chicks from one to 21 days (experiment 1) or to 28 days (experiment 2) of age to compare the nutritional value of high lysine, normal hybrid and sweet corn. Comparisons were made at varying dietary protein levels with the corns being substituted on an isonitrogenous basis within protein levels in corn-soybean meal diets. In experiment 1, only slight differences in performance of chicks fed high lysine or normal corn were observed at 14, 18 and 22% protein levels except that feed conversion at the 22% protein level was improved for chicks fed normal corn. For chicks fed sweet corn at the 22% protein level growth and feed conversion were significantly (P<.05) improved over that for chicks fed high lysine corn. At suboptimal protein levels performance was similar for chicks fed high lysine or sweet corn diets. Methionine supplementation gave a slight improvement in growth rate of chicks fed high lysine or normal corn diets at 18 and 22% protein levels, but depressed growth of chicks fed the normal corn diet at the 14% protein level. In experiment 2, at the optimal protein level (23%), chicks fed high lysine or normal corn performed similarly while at the suboptimal protein level (17%) growth rate of chicks fed normal corn was superior. Methionine supplementation significantly (P < .05) improved weight gain and feed conversion compared with the unsupplemented groups and the performance of chicks fed the methionine supplemented diets was similar between corns.

1149

H I G H L Y S I N E CORN TOR C H I C K S

TABLE 1.—Percent composition of basal diets used in experiment 1 Diets Ingredients 1-2 High lysine corn (LTXS 102, 1968) 49.00 Normal corn (TXS 102,1968) Sweet corn (N.K., 1968) 35.00 Soybean meal (48.5% protein) 10.75 Corn starch 0.25 Solka Floe 1.00 Corn oil

14

15

5.00 1.00

—

47.00 35.00 12.50 0.50 1.00

56.00 25.00 10.75 3.25 1.00

65.00 15.00 9.00 6.00 1.00

14.03 0.70

22.01 1.32

18.03 1.03

14.06 0.73

9-10

11-12

55.00

65.00

75.00

15.00 35.00 5.00 7.25 5.75 — 1.00 1.00

25.00 2.50 2.50 1.00

15.00

18.04 1.00

5-6

58.00

67.00

25.00 9.00 3.00 1.00

13

7-8

3-4

Constant Components 2.25 1.00 0.40 0.10

Protein content (%) Lysine content (%)

0.25 22.02 1.37

18.02 1.08

22.04 1.30

14.01 0.79

1 Trace mineral premix provides per kilogram of diet: 60.0 mg. manganese, 1.2 mg. iodine, 20.0 mg. iron, 2.0 mg. copper, 20.0 mg. zinc and 0.2 mg. cobalt (Delamix plus zinc; Limestone Products Corporation of America, Newton, New Jersey). 2 Vitamin premix VMCS B-665 plus procaine penicillin provides per kilogram of diet: 44101.U. vitamin A, 11001.U. vitamin D 3 , 5.5 I.U. vitamin E, 2.2 mg. vitamin K, 3.86 mg. riboflavin, 7.72 mg. pantothenic acid, 23.2 mg. niacin, 500 mg. choline chloride, 11.0 meg. vitamin Bi2, 0.55 mg. folic acid and 3.7 mg. procaine penicillin.

mercial variety of high lysine corn 2 in comparison to its normal corn 2 counterp a r t and a sweet corn variety 3 for broiler chicks. Proximate analyses of the corns were determined by a commercial laboratory and the amino acid composition of the corns was determined by ion exchange chromatography on an amino acid analyzer 4 following hydrolysis with 6N hydrochloric acid. In both experiments, day-old male broiler type chicks (VantressX Arbor Acres) 5 were weighed, wing-banded and allotted to the experiment units on the basis of weight range groups. T h e birds were placed on experiment at one day of 2

Trojan Seed Co., Olivia, Minnesota. Northrup King and Co., Minneapolis, Minnesota. 4 Beckman Model 120 Amino Acid Analyzer, Beckman Instruments Inc., Palo Alto, California. 6 Jack Frost, Inc., St. Cloud, Minnesota. 3

age and reared to either 21 (experiment 1) or 28 days (experiment 2) of age in electrically heated starter batteries with raised wire floors. The basal diets (Tables 1 and 2) were formulated so t h a t an equivalent a m o u n t of protein was contributed by each corn and a constant a m o u n t of soybean meal protein was added within each dietary protein level. Corn starch and Solka Floe 6 (a non-nutritive cellulose product) were used to make all diets isocaloric and also isonitrogenous within protein levels. In experiment 1, high lysine ( L T X S 102, 1968), normal ( T X S 102, 1968) and sweet corn (1968) were fed at 14, 18 and 2 2 % dietary protein levels. High lysine and normal corn diets were supplemented with DL-methionine a t each protein level to provide 0.85% total sulfur amino acids in the methionine supplemented diets. 6

Brown and Company, Boston, Massachusetts.

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Dicalcium phosphate Limestone Iodized salt Trace mineral premix1 Vitamin premix VMCS B-665 plus procaine penicillin2

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M. S. CHI AND G. M. SPEERS TABLE 2.—Percent composition of basal diets used in experiment 2 Diets Ingredients

High lysine corn (LTXS 102, 1969) Normal corn (TXS 102, 1969) Soybean meal (48.5% protein) Corn starch Solka Floe Corn oil Constant components 1 Protein content (%) Lysine content (%)

1-2

3-11

51.50

61.30

37.80 2.30 0.40 4.00 4.00

23.80 2.40 4.50 4.00 4.00

22.87 1.46

16.92 1.04

12-13

14-22

53.95 37.80

64.20 23.80

—

—

0.25 4.00 4.00

4.00 4.00 4.00

22.87 1.37

16.92 0.94

1 Constant components were identical with those used in experiment 1.

RESULTS

Chemical analyses. Proximate analyses of the corns (Table 3) revealed that high lysine corn had a slightly higher crude protein content than its normal corn

TABLE 3.—Analyses of high lysine and normal corn1 High lysine corn Component

Dry matter Crude protein Ether extract Crude fiber Ash Calcium Phosphorus 1 2

Normal corn

2

LTXS 102 (1968)

LTXS 102 (1969)

TXS 102 (1968)

TXS 102 (1969)

93.06 9.94 5.24

90.20 8.80 5.00 2.30 1.48 0.04 0.32

90.97 8.90 3.25 — — — —

87.50 8.40 2.90 2.00 1.26 0 05 0.30

— — — —

Means of triplicate analyses. Values expressed as percentage of the air dry corn.

Sweet corn (1968) 91.39 10.33 6.49

— — — —

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These 15 experimental diets were fed to 3 replicate groups of 10 chicks each. Feed and water were available to the birds ad libitum. In experiment 2, amino acid supplementations to high lysine corn (LTXS 102, 1969) and normal corn (TXS 102, 1969) diets containing 17 and 23% protein were studied. DL-methionine was supplemented to both corns at both protein levels. In additional treatments lysine, leucine and tryptophan were supplemented either alone or in combination to 17% protein diets of both normal and high lysine corn containing 0.85% total sulfur amino acids. An amino acid mixture consisting of DL-methionine, L-lysine, L-tryptophan, L-leucine, L-threonine and L-phenylalanine was also added to both corn diets containing 17% protein. All amino acid

supplementations were based on N.R.C. requirements (1966) adjusted for dietary energy. These 22 experimental diets were fed to 3 replicate groups of 5 chicks each. Feed and water were available to the chicks ad libitum. At the end of experiment 2, blood samples were taken for plasma free amino acid determination from six chicks with body weights close to the average for each treatment. The chicks were not fasted prior to obtaining samples. The blood samples were collected individually by cardiac puncture using heparinized syringes and after centrifugation equal aliquots of the plasma were pooled and deproteinized with picric acid by the method of Stein and Moore (1954). The protein free supernatants were frozen and kept in that state until analysis by ion exchange chromatography on an amino acid analyzer. Statistical analyses were performed using analysis of variance techniques and treatment means were compared using Duncan's new multiple-range test (Steel and Torrie, 1960).

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H I G H L Y S I N E C O R N FOR C H I C K S

TABLE 4.—A mino acid composition of high lysine, normal and sweet corn.1 Normal corn

High lysine corn Amino acids2

LTXS 102 (1969)

TXS 102 (1968)

TXS 102 (1969)

5.84 3.32 5.33 3.62 9.05 4.53 1.41 1.31 4.53 2.31 4.02 5.84 6.94 10.56 16.80 9.15 4.83

6.13 3.18 5.00 3.41 8.07 4.87 1.02 1.14 3.98 2.61 3.98 5.34 6.36 9.77 15.23 8.86 4.77

4.83 2.36 3.60 3.93 11.80 3.03 1.69 1.80 4.72 4.49 3.82 4.83 7.98 6.52 18.88 8.43 4.94

3.69 2.98 3.69 3.57 11.55 2.98 1.07 0.80 4.64 2.16 3.69 4.64 7.26 6.43 17.38 8.81 5.12

Sweet corn (1968) 5.00 3.00 4.62 4.04 12.31 3.59 1.80 2.41 4.84 3.20 4.02 5.91 8.15 7.07 19.03 9.51 5.11

1

Means of duplicate analyses. ' Expressed as percentage of protein.

counterpart and a slightly lower protein content than sweet corn. D r y matter, ether extract and ash contents of high lysine corn were slightly greater than those of normal corn b u t similar to those of sweet corn. Amino acid analyses (Table 4) indicated t h a t the lysine content of the high lysine corn was greater than normal corn with sweet corn being intermediate. The total sulfur amino acid contents of the proteins of L T X S 102 (1968), L T X S 102 (1969), T X S 102 (1968), T X S 102 (1969) and sweet corn (1968) were 2.72, 2.16, 3.49, 1.87 and 4 . 2 1 % , respectively. High lysine corn h a d higher percentages of lysine, arginine, histidine, threonine, tryptophan, valine, glycine and aspartic acid whereas normal corn had higher percentages of leucine, tyrosine, alanine and glutamic acid. Experiment 1. Table 5 presents the performance of chicks fed experimental diets. Small differences in weight gains of chicks fed high lysine or normal corn over all protein levels were observed. With 2 2 % dietary protein, weight gains of chicks fed

sweet corn were significantly ( P < . 0 5 ) greater than t h a t of chicks fed high lysine corn (Diets 13 vs. 1), b u t not significantly greater than t h a t of chicks fed normal corn (Diets 7 vs. 13). Weight gains and feed conversion a t the 14 and 1 8 % protein levels were similar for all corns. With 2 2 % dietary protein however, chicks fed normal or sweet corn exhibited significantly ( P < . 0 5 ) more efficient feed conversion compared with those fed high lysine corn. Increasing dietary protein for each corn variety significantly ( P < . 0 5 ) improved weight gain and feed efficiency (Diets 1 vs. 3 vs. 5; 7 vs. 9 vs. 1 1 ; 13 vs. 14 vs. 15). Addition of methionine to high lysine corn diets gave only a small, nonsignificant increase in weight gain at each protein level. With normal corn however, methionine supplementation significantly ( P < . 0 5 ) increased weight gain with 1 8 % dietary protein (Diets 10 vs. 9), and appeared to depress weight gain with 14% dietary protein (Diets 12 vs. 11). Supplementation of methionine to the

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Arginine Histidine Glycine Isoleucine Leucine Lysine Cystine Methionine Phenylalanine Tyrosine Threonine Valine Alanine Aspartic acid Glutamic acid Proline Serine

LTXS 102 (1968)

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M. S. CHI AND G. M. SPEERS TABLE 5.—Performance of chicks fed high lysine, normal and sweet corn at three dietary protein lends. Experiment 1 Treatments

Corn1

Protein level

(%) HLC

22 18 14

NC

22

14 22 18 14

SC

1 2 3

Diet No.

21 day weight gain (gram)

Feed conversion (gram feed/gram gain)

+

1 2

390.2 de3 403.8 def

1.74i»* 1.62"

+

3 4

373.2" 383. I*1

1.83" 1.69"b

+

5 6

320.5 b 335.1b

2.09 d 2.00d

+

7 8

411.5
1.64" 1.63"

+

9 10

372.8= 404.6 def

1.79b° 1.76b0

+

11 12

329.7 b 301.3"

2.09 d 2.19 e

-

13 14 15

424.1' 389.8^ 328.6 b

1.61" 1.78b° 2.00*

HLC = high lysine com; NC = normal corn; SC = sweet corn. DL methionine was supplemented to basal diets to raise total dietary sulfur amino acids to 0.85%. Means not bearing the same superscripts within a column are significantly (P < .05) different.

high lysine corn diets significantly (P <.05) improved feed conversion at the 22 and 18% protein levels. With normal corn, methionine supplementation had no effect on feed conversion except at the 14% protein level where feed conversion was significantly (P<0.05) depressed in conjunction with the reduced weight gains. Experiment 2. In the second experiment (Table 6), chicks fed high lysine corn at the 23% protein level gained slightly faster than those fed normal corn (Diets 1 vs. 12), but this difference was not statistically significant. At the 17% protein level, weight gain of chicks fed normal corn was significantly (P<.05) greater than that of chicks fed high lysine corn (Diets 3 vs. 14). There was no significant difference in feed conversion between corns within either protein level in the absence of methionine supplementation.

The difference in weight gain of chicks due to protein levels was significant (P<.05) only with chicks fed high lysine corn diets, but significantly (P<.05) more efficient feed conversion was obtained with the higher protein level with both corn varieties (Diets 1 vs. 3; 12 vs. 14). When diets were supplemented with methionine, weight gain and feed conversion were significantly (P < .05) improved with both corns at both protein levels as compared with unsupplemented diets (Diets 1 vs. 2; 3 vs. 4; 12 vs. 13; 14 vs. 15). The addition of lysine to the methionine supplemented 17% protein diets gave no response in weight gain for chicks fed high lysine corn (Diets 5 vs. 4), but did give a slight response in weight gain for chicks fed normal corn (Diets 16 vs. 15). A slight increase in weight gain of chicks due to tryptophan addition to the methionine supplemented 17% protein diets was ob-

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18

Methionine supplementation 2

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HIGH LYSINE CORN FOR CHICKS

TABLE 6.—Performance of chicks fed high lysine (LTXS 102, 1969) and normal (TXS 102, 1969) corn with and without certain amino acid(s) at two protein levels. Experiment 2 Treatments Corn1

Protein level (%)

HLC

23

Amino acid addition2

Diet No.

Feed conversion (gram feed/gram gain)

1 2

527.1<*><* 586.8f

1 64cd3 1.32"

Met

3 4

432.8" 527.3 r f «

83" 56 bcd

Met + Lys Met + Try Met + Leu

5 6 7

526.5^ 541.3de 521.6<*»e

51"° 65"1 63^

8 9 10

536. H " 543.6^' 502.0 bod

57bocl Sgbcd

—

Met + Lys 4- Try Met + Lys + Leu Met + Try + Leu Amino acid mixture

d

63<**

11

521.7° <>

Met

12 13

M

504.8 570.9 et

65"« 46» b

Met

14 IS

480.9 b 526.4^

89' 62 b ° d

Met + Lys Met + Try Met + Leu

16 17 18

540.5 de 548.9ef 481.0 b

6ibcd 65=d 71
Met + Lys + Try Met + Lys + Leu Met + Try + Leu

19 20 21

517.5b=d<> 494.7 b ° 498.7 b °

59 b c d

Amino acid mixture

22

563.8 e!

23 17

59bcd

1.56 b c d

1

HLC = high lysine corn; NC = normal corn. Amino acid addition was made to make the total dietary amino acid levels to the following levels in each diet: 0.85% DL-methionine (including cystine), 1.26% L-lysine, 0.23% L-tryptophan, 1.60% L-leucine. Amino acid mixture was composed of DL-methionine, L-lysine, L-tryptophan, L-leucine, L-threonine and L-phenylalanine to make the total dietary level to 0.85% (including cystine) 1.26%, 0.23%, 1.60%, 0.80% and 1.48% (including tyrosine), respectively. 3 Means not bearing the same superscripts within a column are significantly (P < .05) different. 2

served with both corns (Diets 6 vs. 4; 17 vs. 15). The addition of leucine to the methionine supplemented 17% protein diets showed no effect with high lysine corn (Diets 7 vs. 4), but resulted in a significant (P<.05) depression in weight gain of chicks fed normal corn (Diets 18 vs. 15). Feed conversion did not differ significantly due to the addition of these amino acids to the methionine supplemented 17% protein diets with either corn. The addition of leucine to the 17% pro-

tein normal corn diets supplemented with methionine plus lysine or methionine plus tryptophan again resulted in a significant (P<.05) growth depression as compared with similar diets without leucine supplementation (Diets 20 vs. 16; 21 vs. 17). The addition of leucine to the 17% protein high lysine corn diets however resulted in a slight increase in weight gain when combined with the addition of methionine plus lysine (Diets 9 vs. 5), but also depressed growth slightly when combined with the addition of methionine plus

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Met 17

NC

28 day weight gain (gram)

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M. S. C H I AND G. M. SPEERS

corn whereas plasma alanine, tyrosine, leucine and isoleucine were greater with chicks fed normal corn (Diets 3 vs. 14). Methionine addition to high lysine corn diets increased plasma methionine and cystine and reduced plasma lysine, threonine, isoleucine and leucine. Methionine addition to normal corn diets also showed a similar trend in the increase of plasma sulfur amino acids and in the reduction of plasma lysine and most other plasma amino acids. The addition of lysine to the methionine supplemented diets resulted in an increase in plasma lysine to nearly twice the level of the methionine only supplemented diets. Lysine supplementation reduced plasma methionine levels with both corn diets and also caused a decrease in plasma threonine with chicks fed high lysine corn.

TABLE 7.—Plasma amino acids of chicks as affected by corn variety and certain amino acid{s) addition in the 17% protein level. Experiment 2 Corn Amino acid addition1 Diet No.

Normal (TXS 102, 1969)

High lysine (LTXS 102, 1969) Met Lys 5

Met Try 6

Met Leu 7

a.a. mix 11

Amino acid Arginine3 4.71 — 3.04 Histidine 3.40 2.37 1.78 Glycine 3.92 3.62 3.71 Isoleucine 1.10 0.90 0.82 Leucine 2.26 1.64 1.48 Lysine 8.24 3.57 6.40 Methionine 0.26 1.90 1.28 Cystine 0.58 0.92 0.67 Phenylalanine 1.23 1.28 0.99 Tyrosine 1.56 2.24 1.58 Threonine 14.19 7.23 4.51 Valine 2.34 2.14 2.66 Alanine 7.34 7.03 8.06 Aspartic acid 0.90 0.52 1.79 Glutamic acid 5.38 2.61 4.31 Proline 7.64 5.90 5.78 Serine 10.07 8.36 8.59

2.17 3.64 1.08 1.88 4.65 1.62 0.74 1.24 2.29 8.33 2.00 6.16 0.62 4.23 5.76 9.36

—

3.53 2.15 3.19 0.83 1.92 3.33 1.78 1.07 1.46 1.47 5.13 2.07 7.94 1.12 6.59 6.24 8.16

5.35 1.70 3.79 0.78 2.16 6.22 2.79 0.84 1.46 2.09 15.68 2.06 7.55 1.91 4.34 7.03 9.71

—

Met

3

4

—

Met

14

15

Met Lys 16

Met Try 17

Met Leu 18

4.46 2.53 2.50 1.35 2.80 6.90 0.45 0.96 1.46 2.43 9.68 1.80 6.40 1.37 3.99 4.05 6.32

3.69 2.33 2.59 1.09 2.45 3.64 2.26 0.83 1.44 3.00 5.56 1.74 7.22 1.12 4.30 5.67 7.08

5.00 — 2.47 1.97 2.79 3.69 1.04 2.71 2.99 5.00 3.37 6.14 2.07 1.81 1.01 1.04 1.59 1.12 2.56 1.12 6.13 15.94 1.89 1.92 6.48 7.96 0.86 0.96 4.25 4.50 3.37 5.01 9.66 8.73

a.a. mix 22

2

— 9.68 2.53 2.28 3.03 2.82 1.45 1.20 2.78 2.76 5.08 2.60 0.29 2.25 0.68 0.95 1.35 1.57 1.99 2.83 10.27 9.08 2.19 1.89 8.44 8.21 0.79 0.80 4.73 4.56 7.72 5.83 10.00 8.94

1 Amino acid addition was made to make the total dietary amino acid levels to the following levels in each diet: 0.85% DL-methionine (including cystine), 1.26% L-lysine, 0.23% L-tryptophan, 1.60% L-leucine. Amino acid mixture was composed of DL-methionine, L-lysine, L-tryptophan, L-leucine, L-threonine and L-phenylalanine to make the total dietary level to 0.85% (including cystine) 1.26%, 0.23%, 1.60%, 0.80% and 1.48% (including tyrosine), respectively. 2 Expressed as /xmole/100 ml. plasma. 3 Arginine level could not be determined on 4 samples.

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tryptophan (Diets 10 vs. 6). Feed conversion was not significantly influenced by the addition of any of these three amino acid combinations. With 17% protein, the addition of a mixture of six amino acids was no more effective than methionine addition alone for improving growth rate and feed conversion of chicks fed high lysine corn (Diets 11 vs. 4). In contrast, weight gain of chicks fed the normal corn diet supplemented with the six amino acid mixture was increased to the level of those fed the 23% protein diet supplemented with methionine (Diets 22 vs. 13). Levels of plasma amino acids for selected dietary treatments from experiment 2 are presented in Table 7. Plasma lysine, threonine, histidine and valine were greater with chicks fed high lysine

HIGH LYSINE CORN FOR CHICKS

DISCUSSION

The greater gains and more efficient feed conversion of chicks fed sweet corn compared to chicks fed high lysine or normal corn and the improvement of these criteria by methionine supplementation to high lysine or normal corn diets suggest that methionine was the most limiting amino acid in both the high lysine and normal corn diets. This was expected in view of the work of Cromwell et al. (1967) and the fact that methionine has long been recognized as the first limiting amino acid for the chick in a corn-soybean meal type diet (Rosenberg and Baldini, 1957; Featherston and Stephenson, 1960). It is also known that the methionine requirement of chicks is decreased as the dietary protein level is lowered in an isocaloric diet (Rosenberg and Baldini, 1957). In the present study, methionine supplementation to the 14% protein diet containing normal corn was apparently excessive, resulting in growth depression. Methionine toxicity had previously been reported

by Blaylock and Richardson (1950), Richardson et al. (1953) and Griminger and Fisher (1968). The improved performance of chicks fed high lysine corn compared with those fed normal corn in the 14% protein diet supplemented with methionine in experiment 1 was apparently due first to the growth depression of chicks fed normal corn. Secondly, the addition of methionine to the high lysine corn diet slightly improved chick performance since lysine was probably the second limiting amino acid in the 14% protein diet in comparison with the N.R.C. requirements (1966), It is also possible that the higher glycine content of high lysine corn might be partially responsible for the superior performance if there was a methionine toxicity effect in that treatment, since glycine has been shown to alleviate the toxic effect of excess methionine (Roth and Allison, 1949). There were different trends in the response of chicks fed high lysine and normal corn between experiments 1 and 2. These may be due to the different amino acid patterns of the corns produced in different years. Corns used in experiment 1 were produced in 1968 and corns used in experiment 2 in 1969. High lysine corn produced in 1968 contained less sulfur amino acids and aromatic amino acids than normal corn produced in the same year whereas the levels of these amino acids were approximately equal in the normal and high lysine corn produced in 1969. The lysine content of the supplementary protein source used in the basal diet is also important in an evaluation of the protein quality of opaque-2 or high lysine corn. It has been reported that lysine was the limiting amino acid whether the corn was opaque-2 or normal corn when cottonseed meal or sesame meal (Jarquin et al.,

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The results indicate that the protein quality of the commercial variety of high lysine corn tested in this present study was about the same as that of its normal corn counterpart for weight gain and feed conversion of growing chicks fed an equal amount of corn protein in corn-soybean meal diets. These results agree with those previously reported by Cromwell et al. (1967, 1968) where only slight differences in growth rate and feed conversion resulted from the isonitrogenous substitution of opaque-2 corn for normal corn in corn-soybean meal diets. Drews et al. (1969) reported that chicks fed opaque-2 corn gained significantly faster and more efficiently than those fed normal corn when corns were compared on an equal weight basis. The opaque-2 corn diets used in that study contained more protein than the normal corn diets.

1155

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M. S. CHI AND G. M. SPEERS

The amino acid composition of the diet may influence the free amino acid concentration in plasma (Denton and Elvehjem, 1954) and plasma free amino acid patterns and the changes in plasma amino acid concentrations in response to amino acid supplementation have been used for prediction of dietary amino acid adequacy and availability (Smith and Scott, 1965). The plasma amino acid data of the

meal, mixtures of soybean and cottonseed, and mixtures of soybean and peanut meals as sources of protein for baby chicks. Poultry Sci. 29: 656660. Bressani, R., 1966. Protein quality of opaque-2 maize in children. Proc. High Lysine Corn Conf., Corn Ind. Res. Fnd., 1001 Conn. Ave., Washington, D. C. Bressani, R., L. G. Elias and R. A. Gomez-Brenes, 1969. Protein quality of opaque-2 corn evaluation in rats. J. Nutrition, 97: 173-180. Clark, H. E., P. E. Allen, S. M. Meyers, S. E. Tuck-

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1970), or safSower meal (Fonseca et al., present study are consistent with the 1970) was used as the supplementary pro- dietary amino acid pattern. Methionine tein source. When such lysine deficient addition to both corn diets resulted in a protein sources are used as a protein sup- large increase in plasma methionine and a plement, opaque-2 corn has been shown decrease of most other amino acids, parnutritionally superior to normal corn for ticularly lysine, in plasma compared with chicks. Since soybean meal protein is a unsupplemented diets. This suggests that good source of lysine, the higher lysine plasma amino acids are utilized rapidly content of high lysine corn does not bene- for protein synthesis when the dietary fit growing chicks fed a corn-soybean meal amino acid balance was improved by the diet unless lysine becomes limiting by use correction of methionine deficiency as of the low protein diets along with supple- suggested by Almquist (1954). mentation of other deficient amino acid(s). ACKNOWLEDGMENTS An antagonism between leucine and isoThe authors wish to thank the Trojan leucine and valine has been reported Seed Co., Olivia, Minnesota and Northrup (Harper et al., 1955; D'Mello and Lewis, King and Co., Minneapolis, Minnesota 1970) in which excess leucine in the diet for providing the corn used in these increases the need for isoleucine and valine studies. We also wish to thank Dr. J. W. and causes the growth retardation unless Nordstrom for the amino acid analysis of isoleucine or valine is adequately supple- the corn samples. Appreciation is exmented. The addition of leucine to the tended to Merck and Company, Rahway, 17% protein diets in experiment 2 caused New Jersey; Hoffmann-LaRoche Inc., a growth depression which was more Nutley, New Jersey; Commercial Solsevere with normal corn. These results vents Corporation, Terre Haute, Indiana support the findings of the leucine-isoleu- and Distillation Products Corporation, cine or leucine-valine antagonism. It is Rochester, New York, for providing also of interest to note that when leucine vitamins. was supplemented in combination with methionine plus lysine to the high lysine REFERENCES corn diet, weight gain was slightly im- Almquist, H. J., 1954. Utilization of amino acids by proved rather than depressed (Diets 9 vs. chicks. Arch. Biochem. Biophys. 52: 197-202. 5) although the dietary isoleucine and Beeson, W. M., R. A. Pickett, E. T. Mertz, G. L. Cromwell and O. E. Nelson, 1966. Nutritional valine content of high lysine and normal value of high lysine corn. Proc. Distillers Feed corn diet was similar. This result cannot Res. Conf., Cincinnati, Ohio. be explained at the present time. Blaylock, L. G., and L. R. Richardson, 1950. Peanut

HIGH LYSINE CORN FOR CHICKS

and increases lysine content of maize endosperm. Science, 145: 279-280. Mertz, E. T., O. A. Veron, L. S. Bates and O. E. Nelson, 1965. Growth of rats fed on opaque-2 maize. Science, 148: 1741-1742. National Academy of Sciences—National Research Council, 1966. Nutrient requirements of domestic animals. 1. Nutrient requirements of poultry. Publication 1345. NAS-NRC, Washington, D.C. Nelson, O. E., E. T. Mertz and L. S. Bates, 1965. Second mutant gene affecting the amino acid pattern of maize endosperm proteins. Science, 150: 1469-1470. Nordstrom, J. W., and R. J. Meade, 1969. Effect of gene mutations on the nutritive value of corn (Zea mays). Proceedings of the 8th International Congress on Nutrition, Prague, Czechoslovakia. Excerpta Medica International Congress Series No. 213: 732-735. Richardson, L. R., L. G. Blaylock and C. M. Lyman, 1953. Influence of dietary amino acid supplements on the free amino acids in the blood plasma of chicks. J. Nutrition, 51: 515-522. Rosenberg, H. R., and J. J. Baldini, 1957. Effect of dietary protein level on the methionine-energy relationship in broiler diets. Poultry Sci. 36: 247252. Roth, J. S., and J. B. Allison, 1949. The effect of feeding excess glycine; L-arginine and DLmethionine to rats on a casein diet. Proc. Soc. Exp. Biol. Med. 70: 327-330. Smith, R. E., and H. M. Scott, 1965. Use of free amino acid concentrations in blood plasma in evaluating amino acid adequacy of intact proteins for chick growth. 1. Free amino acid patterns of blood plasma of chicks fed unheated and heated fish meal proteins. J. Nutrition 86: 37-44. Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics 1st ed. McGrawHill Book Company, Inc., New York. Stein, W. H , and S. Moore, 1954. The free amino acids of human blood plasma. J Biol. Chem. 211:915-926.

AUGUST 19-23. ANNUAL MEETING, AGRICULTURAL INSTITUTE OF CANADA, UNIVERSITY OF VICTORIA, VICTORIA, BRITISH COLUMBIA AUGUST 20-29. 13th INTERNATIONAL CONGRESS OF GENETICS, UNIVERSITY OF CALIFORNIA, BERKELEY.

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ett and Y. Yamamura, 1967. Nitrogen balance of adults consuming opaque-2 maize protein. American J. Clin. Nutr. 20: 825-833. Cromwell, G. L., R. A. Pickett, T. R. Cline and W. M. Beeson, 1969. Nitrogen balance and growth studies of pigs fed opaque-2 and normal corn. J. Animal Sci. 28: 478-483. Cromwell, G. L., J. C. Rogler, W. R. Featherston and T. R. Cline, 1968. A comparison of the nutritive value of opaque-2, floury-2 and normal corn for the chick. Poultry Sci. 47: 840-847. Cromwell, G. L., J. C. Rogler, W. R. Featherston and R. A. Pickett, 1967. Nutritional value of opaque-2 corn for the chick. Poultry Sci. 46: 705712. Denton, A. E., and C. A. Elvehjem, 1954. Availability of amino acids in vivo. J. Biol. Chem. 206: 449-454. Drews, J. E., N. W. Moody, V. W. Hays, V. C. Speer and R. C. Ewan, 1969. Nutritional value of opaque-2 corn for young chicks and pigs. J. Nutrition, 97:537-541. D'Mello, J. P. F., and D. Lewis, 1970. Amino acid interactions in chick nutrition. 2. Interrelationships between leucine, isoleucine and valine. Brit. Poultry Sci. 11: 313-323. Featherston, W. R., and E. L. Stephenson, 1960. Dietary interrelations between methionine, glycine, choline, protein level and energy content of the chick diet. Poultry Sci. 39: 1023-1029. Fonseca, J. B., J. C. Rogler, W. R. Featherston and T. R. Cline, 1970. Further studies on the nutritive value of opaque-2 corn for the chick. Poultry Sci. 49: 1518-1523. Griminger, P., and H. Fisher, 1968. Methionine excess and chick growth. Poultry Sci. 47:1271-1273. Harper, A. E., D. A. Benton and C. A. Elvehjem, 1955. L-leucine, an isoleucine antagonist in the rat. Arch. Biochem. Biophys. 57: 1-12. Jarquin, R., C. Albertazzi and R. Bressani, 1970. Value of opaque-2 corn protein for chicks. J. Agr. Food Chem. 18: 268-272. Mertz, E. T., L. S. Bates and O. E. Nelson, 1964. Mutant gene that changes protein composition

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