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Evaluating Cottonseed Meal Protein for Chick Growth by Enzymatic Release of Amino Acids
Evaluating Cottonseed Meal Protein for Chick Growth by Enzymatic Release of Amino Acids G. R. INGRAM, W. W. CRAVENS AND C. A. ELVEHJEM Departments of Poultry Husbandry and Biochemistry, University of Wisconsin, Madison (Received for publication March 8, 1950)
I
N A previous study by Ingram, Riesen, Cravens and Elvehjem (1949) it was found that a good measure of the biological value of the protein of soybean oil meal for chick growth could be obtained by subjecting the meal to enzymatic hydrolysis and then measuring the amounts of certain amino acids that were liberated in a given period of time. The soybean oil meal samples were first subjected to acid hydrolysis and the amino acid content determined microbiologically. After enzymatic hydrolysis similar determinations were carried out and the percentage of the amino acids liberated by the enzymes calculated. Good correlation was found between these values and the growth supported by the same soybean meal samples in chicks. The studies reported here were undertaken to determine if this in vitro technique would also accurately measure the relative biological value of different cottonseed meal samples. Since the work of Olcott and Fontaine (1941) showed the damaging effect of heat on cottonseed
Published with the approval of the Director of the Wisconsin Agricultural Experiment Station. Supported in part by a grant from Hiram Walker and Sons, Peoria, Illinois. We are indebted to Dr. Walter M. Scott and associates of the U.S.D.A. Southern Regional Research Laboratory, New Orleans, Louisiana, for the cottonseed meal samples and for the data contained in Table 3 regarding the samples. 590
meal protein, it was decided to further study the effect of heat and method of processing on the proteins of cottonseed meal. EXPERIMENTAL In the first series of tests, a sample of raw deglanded cottonseed meal prepared by the method of Boatner and Hall (1946) was used. Portions of this meal were subjected to the following treatments: 1. No treatment; 2. Autoclaved at 15 pounds for 15 minutes; 3. Autoclaved at 15 pounds for 4 hours. After autoclaving, the samples were dried at 140°F. for 24 hours and ground in a Wiley Mill. Portions of each sample were subjected to acid and enzymatic hydrolysis followed by microbiological amino acid determinations, according to the procedure described by Ingram et al. (1949). The organism Leuconostoc citrovorum was used in the assay for methionine and cystine (Steele, Sauberlich and Baumann, 1949). Alpha amino nitrogen determinations were made according to the method of Van Slyke (1915). In the chick feeding trials New Hampshire—Single Comb White Leghorn crossbred chicks were used. Two identical experiments were run with twelve chicks per lot in each experiment. There was no mortality. The method of selecting the chicks and calculating the percentage gain was the same as that reported pre-
591
COTTONSEED MEAL FOR CHICK GROWTH
viously (Ingram et al., 1949). The pre-test ration and control ration are also given in the paper mentioned. The basal test ration had the following composition, in percent: 57 ground yellow corn, 5 wheat bran, 5 wheat middlings, 5 alfalfa leaf meal, 2 granite grit, 2 limestone grit, 2 bone meal, 0.2 fish oil (400D-2,000A), 0.5 iodized salt, 222 mgs. MnS0 4 -H 2 0 per kg. of ration, and 2.75 mgs. riboflavin per kg. of ration. In addition the following vitamins were added at the level indicated per kg. of ration: choline chloride 1.5 gms., pyridoxin HC1 4,0 mgs., Capantothenate 20.0 mgs. and niacin 50 mgs. Twenty-one percent of the respective sample of cottonseed meal was added making the protein content of the ration approximately 20%.
chicks was also modified slightly. In addition to having each lot gaining at the same rate at the beginning of each experiment, the chicks were placed into the lots in such a way that each lot was of approximately the same weight. Cross-bred New Hampshire—Single Comb White Leghorn chicks were again used. The basal ration was the same as that used in the first series except 32% of each cottonseed meal sample was used with a corresponding decrease in the corn to balance the protein at 20%. RESULTS AND DISCUSSION
The results of the amino acid assays for samples 1, 2, and 3 are given in Table 1. The toxic effect of cottonseed meal was avoided in these samples, as demonstrated by Boatner, Altschul, Irving, Pollard and Schaefer (1948) by using a gland free meal. The differences noted in these samples can, therefore, be attributed to the treatment of the protein. The 15 minute autoclaving did not appreciably decrease the.amount of any of the four amino acids studied when determined after acid hydrolysis. There was a slight increase in the enzymatic release of lysine with possibly an increase in tryptophan, cystine and methionine. Four hours autoclaving destroyed approximately one-
In the second series of tests, five samples of cottonseed meal were obtained which had been subjected to various processing methods. Data on their preparation are given in Table 3. These samples were subjected to the same treatment and analyses as the samples in the first series. Due to the limited quantity of each sample, only six chicks were used in each lot for each experiment to determine the value of the cottonseed meal for chick growth. The method of selecting the
TABLE 1.—Liberation of amino acids f "om cottonseed meal samples Acid hydrolysis (yc of protein (ATX6.25)
Sample No.
Lysine Tryptophan Cystine Methionine Alpha amino N Amino acid total % of amino acid released
Enzymatic hydrolysis % of protein (#X6.25)
1
2
3
4.04 1.02f 1.94 1.33 70.5 8.33
3.90 0.95f 1.95 1.39 68.1 8.19
2.17 0.84f 1.34 1.40 67.6 5.75
f Determined by alkaline hydrolysis. % T,hese figures are percent of total alpha amino nitrogen.
1 1.26 0.36 0.93 0.38 18.2| 2.93 35.2
2
3
1.38 0.42 0.97 0.41 15.1\ 3.18 38.8
0.43 0.31 0.29 0.37 11.4t 1.03 17.9
592
G. R. INGRAM, W. W. CRAVENS AND C. A. ELVEHJEM
TABLE 2.—Effect of cottonseed meal samples on chick growth Experiment No. 1
Experiment No. 2
Lot No.
Ave. wt.
Ave. gam
%
gam
Gms. feed per gm. gain
Ave. wt.
Ave. gam
%
gain
Gms. feed per gm. gain
Ave. % gain for two tests
Control 1 2 3
207.3 181.6 189.7 144.9
105 91.7 90.5 40.9
103.0 100.4 99.7 39.3
2.77 2.96 2.80 5.38
206.2 161.5 194.3 125.6
107.6 71.8 98.9 29.6
109 80.1 103.7 30.8
2.29 3.07 2.36 5.21
106 90 102 35
half of the lysine, and some tryptophan and cystine. None of the methionine was destroyed. The enzymatic release of lysine, cystine and tryptophan was lowered while methionine did not seem to be affected to any great extent. Alpha amino nitrogen determinations showed a greater release from sample No. 1 than from sample No. 2. This may be due to a greater release of some of the nonessential amino acids, since on our diets, as shown in Table 2, the chick growth agrees with the amino acid determinations. The beneficial effect of heat on cottonseed protein is probably due to denaturation and rendering the protein more susceptible to attack by the enzymes of the digestive tract as has been demonstrated for casein by Hankes, Riesen, Henderson and Elvehjem (1948). The possibility also exists that this beneficial effect of heat is due to a destruction of some residual toxicity that remained in the cottonseed meal samples since Olcott and Fontaine (1941) showed that a comparable heat treatment actually damaged the protein. The results of the amino acid determi-
nations for samples No. 4 through 8 are given in Table 4. A comparison with Table 3 shows that in cottonseed meal the amount of heat or the time of heating is not directly correlated with the enzymatic release of amino acids from the cottonseed meal sample. Another factor, the toxic properties of cottonseed meal, must be considered. It was shown by Sewell (1943) and Sewell and Turney (1946) that the heating of cottonseed meal would render it less toxic. This would explain why more heat would be required for the proper preparation of certain samples than for others since the toxic properties of cottonseed vary considerably from one lot to another. The values for temperature and time ol cooking for the different samples shown in Table 3 refer to the treatment in the cooker prior to the pressing operation. Since in the screw press additional heat is applied to the meals at the time of pressing while very little heat is developed by the hydraulic process, the heat applied to samples No. 4 and No. 7 cannot be compared with that applied to samples No. 5, 6 and 8.
TABLE 3.—Description of cottonseed meal samples used in second series Sample No. Temperature °F. Time of Cooking, Min. % Free Gossypol Type of Press
118-230 36 0.108 Hydraulic
202-262 40 0.022
Screw press
110-200 15-20 0.009 Screw press
118-240 72 0.047 Hydraulic
222-278 100 0.030 Screw press
593
COTTONSEED M E A L FOR C H I C K G R O W T H
TABLE 4.—Liberation of amino acids from cottonseed meal samples Acid hydrolysis % of protein (7VX6.25)
Sample No. 4 Lysine Tryptophan Cystine Methionine Alpha amino N Amino acid total % of amino acid released
5
6
Enzymatic hydrolysis % of protein (iVX6.25) 7
3.43 3.22 3.15 0.93f 0.83f 0.81f 1.11 1.19 1.11 1.14 1.11 1.03 70.2 69.2 71.1 6.61 6.28 6.17
8
3.22 2.46 0.96f 0.51f 1.09 0.66 1.02 1.06 70.7 68.1 6.29 4.69
4
5
6
7
8
0.94 0.24 0.43 0.32 10.2% 1.93
1.20 0.37 0.47 0.50 13.6{ 2.54
1.51 0.37 0.55 0.50 14.2J 2.93
1.35 0.29 0.52 0.37 14.0J 2.53
0.65 0.24 0.30 0.38 6.8{ 1.57
29.1
40.5
47.7
40.7
33.3
t Determined after alkaline hydrolysis. | These figures are percent of total alpha amino nitrogen. A comparison of samples No. 5, 6 and 8 shows a decreasing liberation of the amino acids with an increase in heat. However, the gossypol content of the samples m a y also exert an influence. The poor results of sample N o . 8 m a y be attributed to over heating since there was an actual destruction of amino acids as shown in Table 4. The poor liberation of amino acids obtained with sample N o . 4, as compared with sample N o . 7, can probably be explained on the basis of its content of gossypol or other toxic substances. The chick growth supported by the different samples of this series is shown in Table 5. The growth of chicks agrees very closely with the amino acid assays on the enzymatic hydrolysate. TABLE 5.—Effect
Some indication as to the mode of action of the toxic substances of cottonseed meal is suggested by these studies. The action could be a general retardation of growth of both the chicks and the microorganisms used in the amino acid assays. If this were true, there would have been a definite lag in the growth curves obtained with the various microorganisms used for the amino acid determinations. Since for the assays, graded levels of the hydrolysate were used, any retardation of growth of the microorganisms would be more pronounced where the high levels of the hydrolysate were added, thus giving a lower reading in the upper limits of the growth curve. N o such lag was noted. I t appears, therefore, t h a t the presence
of cottonseed meal samples on chick growth Experiment No. 2*
Experiment No. 1 Lot No. Control 4 5 6 7
%
Ave. wt.
Ave. gain
gain
174 175 199 209 205 157
77.3 76.5 101.8 112.5 107.3 59.7
80.2 77.8 104.8 116.4 109.9 60.8
Gms. feed per gm. gain 95 42 67 45 83 38
* Vitamin supplement not added to the rations of this group.
Ave. wt.
Ave. gain
gain
%
Gms. feed per gm. gain
178 161 170. 182. 173 141
73. 57 67 78 69. 37.7
70 56 65 75. 67. 37
4.89 5.79 6.03 3.81 4.46 8.92
594
G. R. INGRAM, W. W. CRAVENS AND C. A. ELVEHJEM
of toxic materials in the cottonseed meal causes a retardation of the action of the proteolytic enzymes, thus reducing the liberation of amino acids. The agreement of the chick growth with the enzymatic release of the amino acid supports this contention. Since with our procedure the chicks were fed the experimental rations for only ten days, it is not known whether other factors might exert an influence in a longer feeding period. SUMMARY
A study has been made of the liberation of certain amino acids by acid and enzymatic hydrolysis of cottonseed meal. The enzymatic release of these amino acids from the protein has been correlated with the growth of chicks fed the corresponding samples. The results show that there is good correlation between the release of certain amino acids by the in vitro technique employed in these studies and the growth supported in chicks by the cottonseed meal. The toxic substances present in certain samples did not alter the results of this method of testing the biological value of the cottonseed meal.
REFERENCES Boatner, C. H., A. M. Altschul, G. W. Irving, Jr., E. F. Pollard and H. C. Schaefer, 1948. The nutritive value of cottonseed for chicks as affected by methods of processing and content of pigment glands. Poultry Sci. 27: 315-328. Boatner, C. H. and C. M. Hall, 1946. The pigment glands of cottonseed. I. Behavior of the glands toward organic solvents. Oil and Soap, 22: 123128. Hankes, L. V., W. H. Riesen, L. M. Henderson and C. A. Elvehjem, 1948. Liberation of amino acids from raw and heated casein by acid and enzyme hydrolysis. J. Biol. Chem. 176: 467-476. Ingram, G. R., W. H. Riesen, W. W. Cravens and C. A. Elvehjem, 1949. Evaluating soybean oil meal protein for chick growth by enzymatic release of amino acids. Poultry Sci. 28: 898-902. Olcott, H. S., and T. D. Fontaine, 1941. The effect of autoclaving on the nutritive value of the protein in cottonseed meal. J. Nutrition 22: 431-437. Sewell, W. E., 1943. The detoxification of cottonseed meal for hogs. Agri. Expt. Sta. Ala. Polytech. Inst. Bui. 259. Sewell, W. E. and D. M. Turney, 1946. further experiments with detoxification of cottonseed meal for hogs. Agri. Expt. Sta. Ala. Polytech. Inst. Progress Report, Series No. 25, July. Steele, B. F., H. E. Sauberlich, M. S. Reynolds and C. A. Baumann, 1949. Media for leuconostoc mesenteroides P-60 and leuconostoc citrovorum 8081. J. Biol. Chem. 177: 533-544. Van Slyke, D. D., 1915. Note on the micro-method for gasometric determination of aliphatic amino nitrogen. J. Biol. Chem. 23: 407-409.
I
N A previous study by Ingram, Riesen, Cravens and Elvehjem (1949) it was found that a good measure of the biological value of the protein of soybean oil meal for chick growth could be obtained by subjecting the meal to enzymatic hydrolysis and then measuring the amounts of certain amino acids that were liberated in a given period of time. The soybean oil meal samples were first subjected to acid hydrolysis and the amino acid content determined microbiologically. After enzymatic hydrolysis similar determinations were carried out and the percentage of the amino acids liberated by the enzymes calculated. Good correlation was found between these values and the growth supported by the same soybean meal samples in chicks. The studies reported here were undertaken to determine if this in vitro technique would also accurately measure the relative biological value of different cottonseed meal samples. Since the work of Olcott and Fontaine (1941) showed the damaging effect of heat on cottonseed
Published with the approval of the Director of the Wisconsin Agricultural Experiment Station. Supported in part by a grant from Hiram Walker and Sons, Peoria, Illinois. We are indebted to Dr. Walter M. Scott and associates of the U.S.D.A. Southern Regional Research Laboratory, New Orleans, Louisiana, for the cottonseed meal samples and for the data contained in Table 3 regarding the samples. 590
meal protein, it was decided to further study the effect of heat and method of processing on the proteins of cottonseed meal. EXPERIMENTAL In the first series of tests, a sample of raw deglanded cottonseed meal prepared by the method of Boatner and Hall (1946) was used. Portions of this meal were subjected to the following treatments: 1. No treatment; 2. Autoclaved at 15 pounds for 15 minutes; 3. Autoclaved at 15 pounds for 4 hours. After autoclaving, the samples were dried at 140°F. for 24 hours and ground in a Wiley Mill. Portions of each sample were subjected to acid and enzymatic hydrolysis followed by microbiological amino acid determinations, according to the procedure described by Ingram et al. (1949). The organism Leuconostoc citrovorum was used in the assay for methionine and cystine (Steele, Sauberlich and Baumann, 1949). Alpha amino nitrogen determinations were made according to the method of Van Slyke (1915). In the chick feeding trials New Hampshire—Single Comb White Leghorn crossbred chicks were used. Two identical experiments were run with twelve chicks per lot in each experiment. There was no mortality. The method of selecting the chicks and calculating the percentage gain was the same as that reported pre-
591
COTTONSEED MEAL FOR CHICK GROWTH
viously (Ingram et al., 1949). The pre-test ration and control ration are also given in the paper mentioned. The basal test ration had the following composition, in percent: 57 ground yellow corn, 5 wheat bran, 5 wheat middlings, 5 alfalfa leaf meal, 2 granite grit, 2 limestone grit, 2 bone meal, 0.2 fish oil (400D-2,000A), 0.5 iodized salt, 222 mgs. MnS0 4 -H 2 0 per kg. of ration, and 2.75 mgs. riboflavin per kg. of ration. In addition the following vitamins were added at the level indicated per kg. of ration: choline chloride 1.5 gms., pyridoxin HC1 4,0 mgs., Capantothenate 20.0 mgs. and niacin 50 mgs. Twenty-one percent of the respective sample of cottonseed meal was added making the protein content of the ration approximately 20%.
chicks was also modified slightly. In addition to having each lot gaining at the same rate at the beginning of each experiment, the chicks were placed into the lots in such a way that each lot was of approximately the same weight. Cross-bred New Hampshire—Single Comb White Leghorn chicks were again used. The basal ration was the same as that used in the first series except 32% of each cottonseed meal sample was used with a corresponding decrease in the corn to balance the protein at 20%. RESULTS AND DISCUSSION
The results of the amino acid assays for samples 1, 2, and 3 are given in Table 1. The toxic effect of cottonseed meal was avoided in these samples, as demonstrated by Boatner, Altschul, Irving, Pollard and Schaefer (1948) by using a gland free meal. The differences noted in these samples can, therefore, be attributed to the treatment of the protein. The 15 minute autoclaving did not appreciably decrease the.amount of any of the four amino acids studied when determined after acid hydrolysis. There was a slight increase in the enzymatic release of lysine with possibly an increase in tryptophan, cystine and methionine. Four hours autoclaving destroyed approximately one-
In the second series of tests, five samples of cottonseed meal were obtained which had been subjected to various processing methods. Data on their preparation are given in Table 3. These samples were subjected to the same treatment and analyses as the samples in the first series. Due to the limited quantity of each sample, only six chicks were used in each lot for each experiment to determine the value of the cottonseed meal for chick growth. The method of selecting the
TABLE 1.—Liberation of amino acids f "om cottonseed meal samples Acid hydrolysis (yc of protein (ATX6.25)
Sample No.
Lysine Tryptophan Cystine Methionine Alpha amino N Amino acid total % of amino acid released
Enzymatic hydrolysis % of protein (#X6.25)
1
2
3
4.04 1.02f 1.94 1.33 70.5 8.33
3.90 0.95f 1.95 1.39 68.1 8.19
2.17 0.84f 1.34 1.40 67.6 5.75
f Determined by alkaline hydrolysis. % T,hese figures are percent of total alpha amino nitrogen.
1 1.26 0.36 0.93 0.38 18.2| 2.93 35.2
2
3
1.38 0.42 0.97 0.41 15.1\ 3.18 38.8
0.43 0.31 0.29 0.37 11.4t 1.03 17.9
592
G. R. INGRAM, W. W. CRAVENS AND C. A. ELVEHJEM
TABLE 2.—Effect of cottonseed meal samples on chick growth Experiment No. 1
Experiment No. 2
Lot No.
Ave. wt.
Ave. gam
%
gam
Gms. feed per gm. gain
Ave. wt.
Ave. gam
%
gain
Gms. feed per gm. gain
Ave. % gain for two tests
Control 1 2 3
207.3 181.6 189.7 144.9
105 91.7 90.5 40.9
103.0 100.4 99.7 39.3
2.77 2.96 2.80 5.38
206.2 161.5 194.3 125.6
107.6 71.8 98.9 29.6
109 80.1 103.7 30.8
2.29 3.07 2.36 5.21
106 90 102 35
half of the lysine, and some tryptophan and cystine. None of the methionine was destroyed. The enzymatic release of lysine, cystine and tryptophan was lowered while methionine did not seem to be affected to any great extent. Alpha amino nitrogen determinations showed a greater release from sample No. 1 than from sample No. 2. This may be due to a greater release of some of the nonessential amino acids, since on our diets, as shown in Table 2, the chick growth agrees with the amino acid determinations. The beneficial effect of heat on cottonseed protein is probably due to denaturation and rendering the protein more susceptible to attack by the enzymes of the digestive tract as has been demonstrated for casein by Hankes, Riesen, Henderson and Elvehjem (1948). The possibility also exists that this beneficial effect of heat is due to a destruction of some residual toxicity that remained in the cottonseed meal samples since Olcott and Fontaine (1941) showed that a comparable heat treatment actually damaged the protein. The results of the amino acid determi-
nations for samples No. 4 through 8 are given in Table 4. A comparison with Table 3 shows that in cottonseed meal the amount of heat or the time of heating is not directly correlated with the enzymatic release of amino acids from the cottonseed meal sample. Another factor, the toxic properties of cottonseed meal, must be considered. It was shown by Sewell (1943) and Sewell and Turney (1946) that the heating of cottonseed meal would render it less toxic. This would explain why more heat would be required for the proper preparation of certain samples than for others since the toxic properties of cottonseed vary considerably from one lot to another. The values for temperature and time ol cooking for the different samples shown in Table 3 refer to the treatment in the cooker prior to the pressing operation. Since in the screw press additional heat is applied to the meals at the time of pressing while very little heat is developed by the hydraulic process, the heat applied to samples No. 4 and No. 7 cannot be compared with that applied to samples No. 5, 6 and 8.
TABLE 3.—Description of cottonseed meal samples used in second series Sample No. Temperature °F. Time of Cooking, Min. % Free Gossypol Type of Press
118-230 36 0.108 Hydraulic
202-262 40 0.022
Screw press
110-200 15-20 0.009 Screw press
118-240 72 0.047 Hydraulic
222-278 100 0.030 Screw press
593
COTTONSEED M E A L FOR C H I C K G R O W T H
TABLE 4.—Liberation of amino acids from cottonseed meal samples Acid hydrolysis % of protein (7VX6.25)
Sample No. 4 Lysine Tryptophan Cystine Methionine Alpha amino N Amino acid total % of amino acid released
5
6
Enzymatic hydrolysis % of protein (iVX6.25) 7
3.43 3.22 3.15 0.93f 0.83f 0.81f 1.11 1.19 1.11 1.14 1.11 1.03 70.2 69.2 71.1 6.61 6.28 6.17
8
3.22 2.46 0.96f 0.51f 1.09 0.66 1.02 1.06 70.7 68.1 6.29 4.69
4
5
6
7
8
0.94 0.24 0.43 0.32 10.2% 1.93
1.20 0.37 0.47 0.50 13.6{ 2.54
1.51 0.37 0.55 0.50 14.2J 2.93
1.35 0.29 0.52 0.37 14.0J 2.53
0.65 0.24 0.30 0.38 6.8{ 1.57
29.1
40.5
47.7
40.7
33.3
t Determined after alkaline hydrolysis. | These figures are percent of total alpha amino nitrogen. A comparison of samples No. 5, 6 and 8 shows a decreasing liberation of the amino acids with an increase in heat. However, the gossypol content of the samples m a y also exert an influence. The poor results of sample N o . 8 m a y be attributed to over heating since there was an actual destruction of amino acids as shown in Table 4. The poor liberation of amino acids obtained with sample N o . 4, as compared with sample N o . 7, can probably be explained on the basis of its content of gossypol or other toxic substances. The chick growth supported by the different samples of this series is shown in Table 5. The growth of chicks agrees very closely with the amino acid assays on the enzymatic hydrolysate. TABLE 5.—Effect
Some indication as to the mode of action of the toxic substances of cottonseed meal is suggested by these studies. The action could be a general retardation of growth of both the chicks and the microorganisms used in the amino acid assays. If this were true, there would have been a definite lag in the growth curves obtained with the various microorganisms used for the amino acid determinations. Since for the assays, graded levels of the hydrolysate were used, any retardation of growth of the microorganisms would be more pronounced where the high levels of the hydrolysate were added, thus giving a lower reading in the upper limits of the growth curve. N o such lag was noted. I t appears, therefore, t h a t the presence
of cottonseed meal samples on chick growth Experiment No. 2*
Experiment No. 1 Lot No. Control 4 5 6 7
%
Ave. wt.
Ave. gain
gain
174 175 199 209 205 157
77.3 76.5 101.8 112.5 107.3 59.7
80.2 77.8 104.8 116.4 109.9 60.8
Gms. feed per gm. gain 95 42 67 45 83 38
* Vitamin supplement not added to the rations of this group.
Ave. wt.
Ave. gain
gain
%
Gms. feed per gm. gain
178 161 170. 182. 173 141
73. 57 67 78 69. 37.7
70 56 65 75. 67. 37
4.89 5.79 6.03 3.81 4.46 8.92
594
G. R. INGRAM, W. W. CRAVENS AND C. A. ELVEHJEM
of toxic materials in the cottonseed meal causes a retardation of the action of the proteolytic enzymes, thus reducing the liberation of amino acids. The agreement of the chick growth with the enzymatic release of the amino acid supports this contention. Since with our procedure the chicks were fed the experimental rations for only ten days, it is not known whether other factors might exert an influence in a longer feeding period. SUMMARY
A study has been made of the liberation of certain amino acids by acid and enzymatic hydrolysis of cottonseed meal. The enzymatic release of these amino acids from the protein has been correlated with the growth of chicks fed the corresponding samples. The results show that there is good correlation between the release of certain amino acids by the in vitro technique employed in these studies and the growth supported in chicks by the cottonseed meal. The toxic substances present in certain samples did not alter the results of this method of testing the biological value of the cottonseed meal.
REFERENCES Boatner, C. H., A. M. Altschul, G. W. Irving, Jr., E. F. Pollard and H. C. Schaefer, 1948. The nutritive value of cottonseed for chicks as affected by methods of processing and content of pigment glands. Poultry Sci. 27: 315-328. Boatner, C. H. and C. M. Hall, 1946. The pigment glands of cottonseed. I. Behavior of the glands toward organic solvents. Oil and Soap, 22: 123128. Hankes, L. V., W. H. Riesen, L. M. Henderson and C. A. Elvehjem, 1948. Liberation of amino acids from raw and heated casein by acid and enzyme hydrolysis. J. Biol. Chem. 176: 467-476. Ingram, G. R., W. H. Riesen, W. W. Cravens and C. A. Elvehjem, 1949. Evaluating soybean oil meal protein for chick growth by enzymatic release of amino acids. Poultry Sci. 28: 898-902. Olcott, H. S., and T. D. Fontaine, 1941. The effect of autoclaving on the nutritive value of the protein in cottonseed meal. J. Nutrition 22: 431-437. Sewell, W. E., 1943. The detoxification of cottonseed meal for hogs. Agri. Expt. Sta. Ala. Polytech. Inst. Bui. 259. Sewell, W. E. and D. M. Turney, 1946. further experiments with detoxification of cottonseed meal for hogs. Agri. Expt. Sta. Ala. Polytech. Inst. Progress Report, Series No. 25, July. Steele, B. F., H. E. Sauberlich, M. S. Reynolds and C. A. Baumann, 1949. Media for leuconostoc mesenteroides P-60 and leuconostoc citrovorum 8081. J. Biol. Chem. 177: 533-544. Van Slyke, D. D., 1915. Note on the micro-method for gasometric determination of aliphatic amino nitrogen. J. Biol. Chem. 23: 407-409.