Castor Bean Meal as a Protein Source for Chickens Detoxification by hkksew3563rd


									Castor Bean Meal as a Protein Source for Chickens:
Detoxification and Determination of
Limiting Amino Acids '
                           Department of Nutrition, Rutgers University,
                           New Brunswick, New Jersey 08903

       ABSTRACT         A series of studies were carried out with commercially available
       castor bean meal (CBM), providing approximately 40% protein, to determine
       its usefulness as a protein source for growing chickens. It was found that hot
       water extraction was the best procedure, among several tried, for removal of
       most, if not all, of the growth-depressing components of CBM. Following hot
       water extraction, it was determined that lysine was the first, and tryptophan the
       second limiting amino acid. Supplementing CBM with both lysine and trypto

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       phan gave growth rates of chicks as good as those obtained with methionine-
       supplemented isolated soy protein and markedly improved the net protein util
       ization value (NPU), but the NPU value was still inferior to that obtained with
       methionine-supplemented     isolated soy protein. It is concluded that hot water-
       extracted CBM, properly supplemented with the limiting amino acids lysine and
       tryptophan is an acceptable protein source for chick diets.          J. Nutr. 101:
        1185-1192, 1971.

   The world demand for additional protein       effects 3 but when it was used as a protein
supplies has encouraged studies and exploi       supplement for dairy cattle at the same
tation of various inedible protein-rich by       level, butter made from the milk of these
products. One of these is castor bean meal       cows increased slightly in viscosity and the
(CBM) which contains about 40% crude             iodine value was reduced.4 When CBM was
protein (N X 6.25) but has found only lim        included at a level of 10% in rations for
ited use as a feedstuff or food because of       growing cattle, food intake was lower than
the presence of three potent toxicants:          for cattle fed cottonseed meal and their
ricin, castor allergen and ricinine (1).         growth response was correspondingly re
   The castor plant, Ricinus communi«, is       duced. It was concluded that incorporation
widely found as a perennial in tropical and      of 10% castor bean meal in cattle rations
subtropical regions and is cultivated for        was not economically sound.5
its oil as an annual in temperate zones.            Limited information is available from a
Production by Brazil and India accounts for      Japanese study with chickens reported by
over one-half of the world supply of castor      Okamoto et al.' These workers detoxified
beans (837,000 metric tons in 1969 )2 and,       CBM by washing it with water followed by
provided that reliable methods of detoxica-
                                                    Received for publication January 19, 1971.
tion and deallerginization are devised, the         1 Paper of the Journal Series, N. J. Agriculture Ex
defatted castor bean meal could become a         periment Station.
                                                    2 Oil Seeds and Industrial    Crops Research Branch,
potentially useful source of protein in these    USDA. Beltsville, Maryland.
                                                    3 Bris. E. J.. and J. W. Algee 1970 Castor bean by
 and other developing countries (2). Al          products for cattle rations. Feedstuffs, May 16. p. 26.
 though a great deal of information is avail        4 Popvic, M. P. 1967 Effect of castor oil meal on
                                                 feed utilization, yield and quality of meat and milk in
 able on the nature of the toxic factors pres    cattle. Acta Vet., Belgrade, 27: 253. Cited in Nutr.
ent in CBM (3), relatively little appears to     Abstr. Rev. 38: 643, 1968.
                                                    5 See footnote 3.
have been done to prepare an acceptable             * Okamoto, S., O. Koga, I. Goto, T. Aramaki, M.
                                                 Funatsu, T. Takahashi, C. Yamaguchi, S. Kusakawa
product for animal or human consumption.         and K. Murase 1965 Evaluation of castor seed resi
    CBM has been used at a level of 10% in       dues as cattle fodder. III. Detoxification and availabil
                                                 ity as a poultry feed. Nippan Kakin Gakkaishl 2: 1.
fattening rations for cattle without ill         Cited in Chem. Abstr. 65: 2914, 1966.

J. NOTKITION,107: 1185-1192.                                                                       1185

extraction with ethanol, or further washing        The composition of the basal diet used
with dilute HC1. Although no detrimental        throughout these experiments is shown in
effects were found in laying hens fed CBM-      table 1. Except where otherwise stated, all
containing diets, retardation in growth of      experimental    diets that contained CBM
2- to 7-week-old chicks was observed even       provided it at 40% of the diet and were
when as little as 5 or 10% was incorporated     supplemented with 5% fish meal to provide
into their diet.                                essential amino acids found (by chemical
    Because of its toxicity, no proper bio      analysis, see table 2) to be limiting in CBM.
logical evaluation of CBM appears to have       These diets provided 19% crude protein.
been carried out to date. In the present        A similar diet, but one containing isolated
study, an attempt was made a) to detoxify       soy protein (18.8% of the diet to provide
commercial CBM, b) to determine its nu          17% protein), supplemented with 0.2%
tritive properties as a protein supplement      DL-methionine served as the positive con
in diets for growing chickens and c) to         trol diet in all experiments; it has long
improve its protein quality through judi        been recognized that isolated soy protein
cious supplementation     with the limiting     plus methionine supports excellent chick
amino acids.                                    growth and has a high net protein utiliza
                                                tion value (NPU) (4). The negative con
        EXPERIMENTAL    PROCEDURE               trol diet was identical to the other CBM-

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   Castor bean meal. The CBM under              containing diets except that untreated CBM
study was a commercially prepared de            (also supplemented with 5% fish meal)
fatted product.' It had been partially de       was used. Glucose was used to bring the
toxified by hydraulic pressing and crushing     diet to 100% after all other additions had
of the castor beans, followed by four to five   been made.
solvent extractions with heptane. The ex           The birds were housed in heated bat
tracted material was then steamed at            teries during experimental periods which
approximately     5.4 kg/cm1 for approxi        varied between 14 and 21 days. Feed was
mately 4 hours and finally dried and            supplied ad libitum and water and artificial
ground.                                         lights were provided continuously.
   Several treatments of this meal were            The feeding experiments fell into four
designed to improve its quality by removing     groups: a) an evaluation of the differently
substances present which are deleterious to     treated castor meal, b ) attempts to simulate
proper growth of monogastric         animals
(chickens).    CBM was extracted 4 or 8                              TABLEi
times with boiling water in a large coffee                   Composition of basal diet
percolator. Each extraction lasted 10 min
utes and 1000-ml quantities of distilled                      Ingredient                    Amount
water were used for each 200 g CBM. The
extracted CBM was dried at 105°.               Cornstarch                               28.0
                                                Corn dextrin                              5.0
   Other treatments such as autoclaving,        Corn oil                                  3.0
or extracting the meal with dilute HC1 (pH      Choline chloride (70% concentrate)         0.3
4) or with organic solvents (ethanol and        Mineral mix '                             4.9
acetone) did not enhance the growth-            Vitamin mix *                             0.2
promoting potential of CBM beyond that          Protein
                                                  (castor bean meal or isolated soy) variable
obtained from hot water extraction. The         Glucose monohydrate                  to 100.0
results of these treatments have, therefore,       ' In grams per 100kg diet: Ca3(PO<), 850; KHjPO4,
been omitted from the tables of results.        1050; NaCl, 8OO; CaCO3, 1900; Fe gluconate, 52;
   Feeding trials. Day-old male or female       MgS04, 250; MnSO4-H2O, 20; KI, 1; CuSO<, 1.28;
                                                ZnCOa, 10; NajMoCv2H2O, 1.
crossbred (New Hampshire male X Colum              'In milligrams per kilogram diet: thiamin-HCl, 25;
                                                riboflavin, 16; Ca pantothenate, 20; pyridoxine-HCl, 6;
bian female) chicks were used for the bio       biotin, 0.6; folie acid, 4; 2-methyl-l,4-naphthoquinone,
logical evaluation of CBM. The initial body     5; cobalamine, 0.02; ascorbic acid, 250; niacin, 150;
                                                vitamin A (100IU/mg),      100; vitamin Ds (250IU/mg),
weights of the birds used ranged between        2.4; DL-a-tocopheryl acetate (0.5 lU/mg),      20.
35 and 43 g, and 5 to 16 chicks were as
signed to each treatment group, usually            'We are grateful to Mr. D. Bolley of the Baker
                                                Castor Oil Company, Bayonne, New Jersey for provid
in duplicate lots of five or eight.             ing the castor bean meal used in these studies.
                             EVALUATION OF CASTOR BEAN PROTEIN                                          1187

                     TABLE 2                                     Protein and amino acid supplementation
     Amino acid composition of castor bean                   studies c) were carried out after we were
                meal protein '
                                                             satisfied that little further improvement
        Amino                                                could be achieved from washing or extract
                                                  g          ing CBM. Chemical analysis of CBM (table
                                                             2) suggested deficiencies in the essential
                                                             amino acids lysine, tryptophan and methio
                                                             nine. Experiments were designed to ascer
                                                             tain the effect of supplementing water-
                                                             extracted CBM (four times) with good
                                                             quality proteins including fish meal, iso
                                                             lated soy protein and egg albumin, and
                                                             later by supplementing the extracted CBM
                                                             diet directly with amino acids to establish
                                                              the order in which they were limiting for
                                                             chick growth.
                                                                  For the protein evaluation studies d), the
                                                              carcass nitrogen retention method of Ben

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                                                              der (5) as modified for use with the chick
      acidGlutamic                                            by Summers and Fisher (4) was carried
                                                              out to determine NPU for extracted, sup
   1Unextracted, 42.5% protein (N x 6.25); this analy         plemented and unsupplemented CBM. The
sis was typical of several carried out at different times.
Unextracted meal differed from water-extracted meal procedure, with minor modifications (the
by 0.2% protein (Nx 6.25); there was no discernible experimental feeding period was 10 and 12
difference in amino acid composition between the two
types of meal.                                                days, instead of the 14 days originally
                                                              described), was the same as previously
the growth-depressing properties of CBM in described (4).
soy protein-containing           (control) diets, c)
                                                                          RESULTS AND DISCUSSION
evaluation of protein and amino acid sup
plementation of detoxified (hot water-ex                          a) Treatment of CBM —Experiment 1.
tracted) CBM, and d) net protein utilization In experiment 1 (table 3) untreated CBM,
studies of extracted CBM with or without although supplemented with 5% fish meal,
amino acid supplementation.                                   did not support satisfactory chick growth,
    The extraction treatments a) have al suggesting that the original commercial
                                                              processing had not removed all toxicity.
ready been listed (under castor bean meal).                       Three methods for detoxification of CBM
The studies under b ) were as follows : Since were tested and compared to a positive con
CBM is high in fiber, lignin, and ash it trol diet containing                                    methionine-supple-
was also considered of interest to increase mented isolated soy protein. Extraction of
the caloric density of a diet containing CBM four times with percolating boiling
water-extracted CBM by adding more fat water gave promising results, and growth
(3% ) to see if that measure would enhance of chicks with this material was far supe
CBM utilization.                                               rior to that obtained with untreated CBM.
    CBM has an ash content of about 8% The average food intake for birds fed the
compared with only 2.5% in isolated soy extracted CBM diet was 263 g compared
protein. It was of interest to study whether to an average of 268 g for birds fed the
 the amount or the composition of CBM ash methionine-supplemented                                   isolated soy pro
might be harmful.              CBM was therefore tein diet. However, the feed efficiency
 ashed and added to the control diet contain                   ratio was much lower on the water-
ing isolated soy protein + methionine. extracted CBM diet than for the isolated
 Also, the fiber level of the isolated soy pro soy protein diet (0.39 vs. 0.50). The con
 tein control diet was increased by adding siderable difference in body weight between
 pure cellulose to match (quantitatively, but the chicks fed the control and the extracted
 not qualitatively) that of a CBM-containing                   CBM diets was not significant due to the
diet.                                                          large variation in weight within the group
1188                     LAUFEY VILHJALMSDOTTIR                 AND HANS FISHER

                                                 TABLE 3
               Body weight and food intake of day-old female chicks fed castor bean
                                meal-containing diets for 3 weeks

           Dietary treatment iNo.        chickensBody             wt0Food                     utilizationg
                                               feedExperiment                                  gain/g
            » 0.2%
       untreatedCBM,                                       5b138
       xCBM,extracted 4                                    ±19«145
       xCBM,extracted 8                                  ±12«67±
              cooked666106170±103>94±        5C2681792632931520.500.330.390.370.21Experiment
           + 0.2%
      DL-methionineCBM,                                 6«112±
      untreatedCBM,                                     8b107±13b155
           + CBM extract910510162±                         ± 8-2732142182570.450.350.320.45
      1Castoi bean meal (CBM), where used, was provided at 40% of the diet and was supplemented
    with 5% fish meal to provide 19% protein (16 + 3 (Nx 6.25)).
      'Isolated soy protein, 18.8% (17% protein (Nx 6.25)). Assay Protein C-l, Skidmore Enterprises,

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    Cincinnati, Ohio.
      3Mean ±  SE;means within an experiment not followed by the same letter are significantly different.

fed the extracted CBM. Apparently some                     b) Attempt to simulate CBM growth de
chicks were more sensitive to the growth                pression in isolated soy diets—Experiment
depressant(s) in water-extracted CBM than               3. Table 4 gives the results of an experi
others; it also suggested that the extracted            ment in which CBM ash and cellulose (fi
material was not entirely satisfactory                  ber) were tested as possible contributing
despite a significant (P<0.01)       improve            factors to the low biological value of CBM.
ment in body weight and increased food                     Two diets were prepared: one a CBM-
intake when compared with the results of                containing diet with increased caloric den
the group fed untreated CBM.                            sity (more fat) to attempt to counteract
   The eight hot water extractions of CBM               the high level of fiber in CBM; the other
(table 3) were no more effective than the               diet corresponded to the positive control
four as seen from the similar growth re                 but 16% glucose was replaced by 2.7%
sponse.                                                 CBM ash and 13.3% cellulose. No im
   The third method of detoxification evalu             provement in growth or food utilization
ated in experiment 1 involved boiling CBM               was observed by increasing the level of fat
in water without extraction. This led to                from 3 to 6% ; by the end of the second
even poorer growth and food consumption                 week the values for both body weight and
than observed with the negative control                 food intake were actually lower for the
group (P<0.01),        and suggested some               high fat group than for the low fat group.
change or release of a growth-depressing                The addition of the fiber and CBM ash did
substance in the CBM.                                   not impair growth or feed utilization of
   Experiment 2. The effect of boiling                  the positive control diet (isolated soy pro
CBM in water without extraction was tested              tein + methionine).
again; this time boiling neither increased                 c) Protein and amino acid supplementa
growth depression nor improved the growth               tion of extracted castor bean meal—Ex
rate.                                                   periment 4. In this experiment water-
   The other objective of this study was to             extracted (four times) CBM was supple
ascertain whether the material removed                  mented with three relatively good quality
from CBM by hot water extraction, when                  proteins, fish meal, isolated soy protein
added to the positive control diet, would               and egg albumin, and also with the amino
depress growth; the average weights (table              acids lysine plus methionine, plus trypto-
3) of the chicks were slightly, but non-                phan (table 5). The growth response was
significantly, lower than for the birds on              greatest in the chicks fed the diet supple
the positive control diet.                              mented with the three amino acids. Fish
                            EVALUATION OF CASTOR BEAN PROTEIN                                            1189

                                                TABLE 4
           Body weight and food intake of chickens fed castor bean meal or isolated soy
                                    protein diets for 14 days
                Dietary treatment i                Body
                                             wtgExperiment                               utilizationg
              + 0.2%
        ±4''CBM, DL-methionine                    118
        «CBM, untreated                                5
                                                    79 ±
        bCBM,extracted 4 x                              5
                                                    97 ±
               extracted 4 x +3% corn ou4
            + 0.2%
                   fiber5 + 2.7% CBM ash            121±4'Food
     1Castor bean meal (CBM), where used, was provided at 40% of the diet and was supplemented
   with 5% fish meal to provide 19% protein (16 + 3 (Nx6.25)).
     * Isolated soy protein, 18.8% (17% protein (Nx6.25)).
     3Mean ±   SEfor duplicate groups of eight female, day-old chicks; means followed by the same letter
   are not significantly different.
     4 In addition to 3% com oil in the basal diet.
     9In addition to 3% fiber normally added to the ISP diet.

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                                           TABLE 5
   Body weight and food intake of chicks fed castor bean meal-containing    diets supplemented
                  s nini
             •with I quantities of other proteins or with amino acids for 16 days

        iISP Dietary treatment                      wt0                 intakeg/bird201 utilizationg
                                      Experiment 4
           ' + 0.2% DL-methionine      152± 7»«
        CBM* + 5% fish meal            120± 9"                          210                  0.38
        CBM + 3.7% ISP                  68± 6"                          123                  0.22
        CBM + 3.7% egg albumin »Body   76± 4«=Food                    110Feed              0.32
        CBM+ 0.8% L-lysine-HCl
          + 0.2% L-methionine
          + 0.2% L-tryptophan          155±10»                         251                  0.45
      1The three protein supplements were added to provide 3% additional protein (N x 6.25).
      •Isolated protein, 18.8% (17% protein (Nx6.25)).
      3Mean + SEfor duplicate groups of five female, day-old chicks; means followed by the same letter
    are not significantly different.
      «40%Water-extracted (4 times) castor bean meal (17% protein (N x 6.25) before addition of
      »Spray-dried, Henningsen Foods, White Plains, N. Y.

meal supplementation     (5% ) was signifi- with additional essential amino acids (be-
cantly inferior (P < 0.001) to the amino yond lysine, tryptophan and methionine)
acid supplementation.    However, fish meal would further improve the biological value
was superior to either isolated soy protein   of water-extracted CBM. (There was a
or egg albumin. The amino acid supple- difference of 0.2% protein (N X 6.25) be-
mentation of CBM produced body weights         tween extracted and unextracted CBM; the
in close agreement with those observed on amino acid composition given in table 2 is
the positive control diet (155 vs. 152 g).     representative of both extracted and un-
The feed utilization for the birds fed the extracted meal. )
amino acid-supplemented, water-extracted          The results (table 6) showed that lysine
CBM diet, although better than for the was the first limiting amino acid in water-
group which received the fish meal-supple-    extracted CBM. Half of the chicks died
mented diet, was not as good as that of within 2 weeks on the CBM diet supple-
birds fed the positive control diet (isolated  mented only with methionine and trypto-
soy protein + methionine).                    phan. Tryptophan was the second limiting
   Experiment   5. This experiment was amino acid. All 10 birds fed the extracted
undertaken to ascertain the order of the CBM-containing diet, supplemented with
limiting amino acids in water-extracted        lysine and methionine, survived the 3-week
CBM and also to test if supplementation        experimental period, but their final body
1190                     LAUFEY VILHJALMSDOTTIR            AND HANS FISHER

                                                 TABLE 6
            Body weight and food intake of chicks fed castor bean meal supplemented
                                 with amino acids for 17 days
        Dietary                    amino
        proteinISP'CBM acid
                    supplementExperiment0.2%               wt95125            intakeg/bird18521821217122680Feed
                                                                                            gain/ g
               DL-methionine0.8%                              ±
               L-tryptophan0.8%                            6«129±
                     0.15%                                 8*108±
                     0.2%                                  6b135±10»50±

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                     0.2% L-tryptophanBody                        2*Food
      'Isolated soy protein, 18.8% (17% protein (Nx6.25)).
      *Mean ±   SEfor duplicate groups of five female, day-old chicks; means followed by the same letter
    are not significantly different.
      338% Water-extracted (four times) castor bean meal (16% protein (Nx6.25)).
      *Five out of ten died.

weight was below that of the positive con              valine, phenylalanine, arginine and histi-
trol (108 vs. 132 g) and that of the group             dine (44.9 vs. 45.8% ).
receiving lysine as well as tryptophan.                   Experiment 7. The results of experi
    Methionine appeared not to be limiting             ment 5 had suggested that methionine was
in extracted CBM. The chicks receiving                 not limiting in extracted CBM diets which
the CBM diet supplemented only with ly                 supplied 17% protein (N X 6.25). The last
sine and tryptophan grew as well as those              experiment (table 7) was carried out to
receiving methionine in addition to lysine             evaluate again the importance of methio
and tryptophan (133 vs. 132 g).                        nine supplementation with dietary protein
    No further improvement in growth was               reduced to 13%, the level ordinarily used
obtained by adding other essential amino               in chick NPU studies (4). Although the
acids (calculated to be borderline from the            growth rate for the chicks given the methi-
chemical analysis, table 2) to the extracted           onine-supplemented diet was slightly (but
CBM.                                                   nonsignificantly) higher than for those on
    d) NPU studies -with castor bean meal—           the diet from which methionine          was
Experiment 6. The NPU value for unsup-                 omitted, the NPU value for the latter group
plemented, water-extracted CBM was 25%                 was considerably better than for the for
(table 7). This low value was not unex                 mer. In this experiment (with a lower
pected since we had earlier shown that                 dietary protein content), the body weights
extracted CBM was deficient in both lysine             of the chicks receiving CBM were signifi
and tryptophan.        Supplementation    with         cantly lower than for the control birds
these amino acids (plus methionine)                    (P<0.05).
greatly improved the NPU value of ex
tracted CBM although its utilization was                             GENERAL COMMENTS
still inferior to that of isolated soy protein            The results of these studies indicate that
plus methionine (44.9 vs. 53.1%). The                  presently available commercial CBM can
NPU value was not improved by further                  be further processed so as to provide a
supplementation      of CBM with serine,               much improved source of protein for grow-
                             EVALUATION OF CASTOR BEAN PROTEIN                                         1191

                                               TABLE 7
 Net protein utilization   studies with chicks fed castor bean meal supplemented          with amino acids
    Dietary           Dietary amino                                                     Feed
    protein          acid supplement                  Body wt        Food intake    utilization     NPU
                                                            9          g/bird      g gain/g feed
                                              Experiment 6 »
    ISP 2     0.2% DL-methionine                     140 ±4»•        169           0.44         53.1
    CBM«     0.8% L-lysine-HCl
                 + 0.2% L-methionine
                 + 0.2% L-tryptophan                  145±3«           214           0.37         44.9
    CBM       0.8% L-lysine-HCl
                 + 0.2% L-methionine
                 + 0.2% L-tryptophan
                 + 0.3% L-serine
                 + 0.2% L-arginine-HCl
                 + 0.1% L-phenylalanine
                 + 0.15% L-valine
                    0.05%                             140±4«67±2b46±1
              diet)0.2%                       *Experiment

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  1Triplicate groups of five male, 7-day-old chicks were fed the experimental diets for 10 days; mean starting
weight was 66 g.
  2Isolated soy protein, 18.8% (17% protein (Nx6.25)).
             SE; means within an experiment not followed by the same letter are significantly different.
  3Mean •+•
         Water-extracted (four times) castor bean meal (17% protein (Nx6.25)).
  9Triplicate groups of 5 male, 7-day-old chicks were fed the experimental diets for 12 days; mean starting
weight was 67 g.
  «Isolatedsoy protein, 16% (13% protein (Nx6.25)).
  730% Water extracted (four times) castor bean meal (13% protein (N x 6.25)).

ing chickens (and presumably other mono-                protein or egg white was not as effective
gastric animals as well).                               as when the right amount of the limiting
   Of the several treatments applied to                 amino acids was added.
CBM, hot water extraction was the most                     Lysine was found to be the first limiting
successful. It appears to remove most, if               amino acid in CBM and tryptophan the
not all, of the toxic factors present in CBM.           second. According to the chemical analy
   The pattern and concentration of the                 sis (table 2) CBM provides only 60% of
essential amino acids in CBM (table 2)                  the National      Research  Council-recom
suggested that the major reason for the                 mended methionine requirement (6). The
low biological value of CBM, as found by                feeding studies, however, indicated that
feeding tests with chicks, was a deficiency             CBM provided adequate sulfur amino acids,
of lysine, tryptophan and the sulfur amino              thus confirming the findings of Scott and
acids. When water-extracted         CBM was             co-workers (7) who reported the NRC
supplemented with lysine, methionine and                figure as too high.
tryptophan,     it promoted equally good                   An interesting observation was noted
growth in chicks as obtained with isolated              relative to the variation in body weight
soy protein + methionine ( a good standard              among chicks. When water-extracted CBM
for chickens).      No further improvement              was supplemented with fish meal, chick
was observed with additional supplementa                weight varied greatly within each group;
tion (table 6) of amino acids that appeared             however, when it was supplemented with
of borderline adequacy, based upon the                  the limiting amino acids only, variation
chemical analysis. Supplementation with                 dropped markedly (coefficients of varia
small amounts of fish meal, isolated soy                tion 25 vs. 15% ). This phenomenon

might be related to individual differences                     LITERATURE CITED
in amino acid requirements for growth on        1. Jaffe, W. G. 1969 Hemagglutinins.             In:
an amino acid-deficient diet. Such differ          Toxic Constituents of Plant Foodstuffs, ed.,
ences have been shown previously in our            I. E. Liener. Academic Press, New York, p. 69.
                                                2. Bolley, D. S., and R. L. Holmes         1958 In
laboratories on diets limiting in either           edible oilseed meals. In: Processed Plant
arginine or lysine for the breed of chickens       Protein Foodstuffs, ed., A. M. Altschul. Aca
used in the present studies (8).                   demic Press, New York, p. 829.
    Despite the very marked improvement         3. Jenkins, F. P. 1963 Allergenic and toxic
                                                   components of castor bean meal: Review of
in NPU achieved with amino acid supple             literature and studies of the inactivation of
mentation of extracted CBM, this value             these components. J. Sci. Food Agr. 14: 773.
is still low in comparison to the value ob      4. Summer, J. D., and H. Fisher           1961 Net
tained for methionine-supplemented        iso      protein values for the growing chicken as
                                                   determined by carcass analysis: exploration
lated soy protein. The difference is possibly      of the method. J. Nutr. 75: 435.
due to the high level of fiber (including       5. Bender, A. E., and D. S. Miller 1952 A
lignin) in CBM (38% ), in contrast to near         new method of estimating net protein value.
zero fiber provided by isolated soy protein.       Biochem. J. 53; vii.
The CBM-containing diets supplied about         6. National Research Council, Committee on
                                                   Animal Nutrition         and Subcommittee      on
 15% fiber, and this relatively high level         Poultry Nutrition       1966 Nutrient Require

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caused an approximately 20% increase               ments of Poultry, pub. 1345, National Aca
in food intake above that observed on the          demy of Sciences-National      Research Council,
 isolated soy protein diet. The increased          Washington, D.C.
                                                7. Klain, G. J., H. M. Scott and B. C. Johnson
protein intake associated with the greater          1960 The amino acid requirement           of the
food intake might well explain part of the         growing chick fed a crystalline amino acid
lower NPU value of CBM, since NPU                  diet. Poultry Sci. 39: 39.
values are inversely proportional to protein    8. Griminger, P., and H. Fisher       1962 Genetic
intake (5). If part or all of the fiber were       differences in growth potential on amino
                                                    acid-deficient diets. Proc. Soc. Exp. Biol. Med.
removed from castor bean meal it would              Ill: 754.
further increase its potential as a source         8 According to commercial sources, removal of con
 of protein for monogastric animals.8           siderable portions of the castor bean hulls is feasible.

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