Efficacy of D-, L- and DL-Methionine for Growth of Chicks Fed Crystalline Amino Acid Diets R. S. K A T Z 1 ' 2 AND D . H . BAKER
Department of Animal Science, University of Illinois, Urbana, Illinois 61801 (Received for publication January 31, 1975)
POULTRY SCIENCE 54: 1667-1674, 1975
I
T has been established that the D-isomer of methionine will support the growth of many species when serving as a source of sulfur amino acids (Wretlind and Rose, 1950; Rose et ai, 1955; Stekol, 1935; Bauer and Berg, 1943). Evidence concerning the equivalence of the D- and L-isomers or the racemic mixture, however, has been somewhat inconsistent. The D-isomer has been shown to be nutritionally equivalent to the L-isomer by some (Leveille et ai, 1960; Fell et ai, 1959), inferior by others (Bruggemann et al., 1962; Smith, 1966) and even superior by still others (Gutteridge and Lewis, 1964; Tipton et ai, 1966). Explanations for these differences have usually been based on assumptions yet to be proven or on fragmentary evidence (Gordon and Sizer, 1965; Marrett and Sunde, 1965). The importance of learning the truth in this matter is essentially twofold. Firstly, when an animal consumes intact proteins, it is
receiving the natural or L-isomer. DLmethionine, however, is usually the form in which methionine is added to a diet deficient in sulfur-bearing amino acids. Thus, if the two isomers are not nutritionally equivalent, a given level of supplementation may be either inadequate to attain the desired response or more than adequate and thus uneconomical. Secondly, the use of a standard curve obtained with crystalline amino acids is often used in determining the availability of an amino acid in a particular food or feedstuff (Sasse and Baker, 1973). Again if the isomers are not equally utilized, an over- or underestimation of sulfur amino acid availability could occur. The studies reported herein were designed to investigate the relative biopotency of Dand L-methionine. The effects of the presence or absence of cystine and the level of supplementation were also studied. EXPERIMENTAL
1. Present address: The Quaker Oats Company, 617 West Main Street, Barrington, Illinois 60010. 2. Part of thesis submitted to the Graduate College of the University of Illinois in partial fulfillment of the requirements for the Ph.D. degree.
The composition of the basal diet used in all assays is presented in Table 1. Varying levels of D-, L- or DL-methionine were added to the basal diet which had been either left
1667
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ABSTRACT Four assays employing young male chicks were conducted to evaluate the relative efficacy of D-, L- and DL-methionine and to estimate the requirement for D- and L-methionine when serving as the sole source of sulfur amino acids or when added to a diet containing 0.27% L-cystine. Crystalline amino acid diets containing 14.9% protein equivalent and 4200 kcal. M.E./kg. were used in all assays. L-methionine supported faster and more efficient gains than D- or DL-methionine when fed at levels below the requirement. At levels of supplementation near the requirement, however, equal efficacy was attained. When serving as the sole source of sulfur amino acids, the requirement as estimated by least squares for optimal gain was 0.58% of the diet or 104 mg./day for L-methionine and 0.59% or 104 mg./day for D-methionine. In the presence of cystine, the requirements were estimated at 0.27% or 49 mg./day and 0.30% or 52 mg./day for L- and D-methionine respectively. The results indicate that at lower levels of supplementation, L-methionine is a better source of sulfur amino acids than D-methionine. On the other hand, L- and D-methionine appear to have equal efficacy when incorporated into diets that are only marginally deficient in sulfur-bearing amino acids.
1668
R. S. KATZ AND D. H. BAKER TABLE 1.—Composition of basal diet
% to 100.00 19.74 15.00 5.37 3.00 1.00 0.20 0.20 + +
Amino acid mix L-arginine • HC1 L-histidine • HC1 •H 2 0 L-lysine • HC1 L-tyrosine L-tryptophan L-phenylalanine DL-methionine L-cystine L-threonine L-leucine L-isoleucine L-valine Glycine L-proline L-glutamic acid
g./19.74 g. 1.15 0.41 1.14 0.45 0.15 0.50 var var 0.65 1.00 0.60 0.69 0.60 0.40 12.00 19.74
'Velu etal. (1971).
devoid of or supplemented with L-cystine.3 All dietary additions were made at the expense of corn starch. On day 8 posthatching following an overnight fast, chicks originating from the cross of New Hampshire males and Columbian females were assigned to treatments. Information regarding selection and care of chicks prior to initiation of the assays and the assignment procedure has been outlined previously (Sasse and Baker, 1974a). The first assay consisted of 7 treatments in which methionine was provided either as the sole source of sulfur-bearing amino acids (diets 1-4) or as a supplement to a diet containing 0.30% L-cystine (diets 5-7). Diets 1-4 contained a basal level of 0.30% Lmethionine and were supplemented with 0.15% of either D-, L- or DL-methionine. Supplemental levels of methionine were such that growth of chicks would lie in the linear portion of the growth curve. Methionine additions to diets 5-7 were such that the total sulfur 3. Unless otherwise indicated, all amino acids were purchased from Ajinomoto U.S.A., Inc., New York, N.Y.
amino acid levels were at or near the requirement for optimal growth. In the second assay D-, L- or DL-methionine were again added in the presence of L-cystine. However, the level of total sulfur-bearing amino acids was such that growth would lie on the linear area of the growth curve. The results of the first assay had indicated less efficacy for the racemic mixture of methionine than for either the D- or L-isomer. This observation was disturbing and indeed difficult to explain. It was thought that the source of DL-methionine that had been used might possibly be less than 100% pure. Thus, two commercial sources of DL-methionine were used in the second assay. Assays 3 and 4 were conducted to estimate the requirement for L- and D-methionine in the absence (Assay 3) or presence (Assay 4) of L-cystine. The level of L-cystine used was slightly higher than the requirement estimated by Sasse (1973) in the presence of adequate sulfate. The estimate of the requirement was predicted by fitting a continuous broken line to the gain and gain/feed data for each series of diets by least squares analysis (Steel and Torrie, 1960).
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on June 19, 2015
Ingredient Corn starch Amino acid mix Corn oil Salt mixture' Cellulose NaHC03 Choline chloride Vitamins' a-tocopheryl acetate (20 mg../kg.) Ethoxyquin (125 mg • / k g . )
1669
EFFICACY OF D-, L- AND DL-METHIONINE
fed diets containing L-, D- or DL-methionine, although weight gain tended to be less for birds consuming the diet containing the racemic mixture. Efficiency of gain, however, was greater (P < 0.05) for birds receiving L-methionine than for those receiving either D- or DL-methionine. \
RESULTS
Assay 2. The results of assay 2 are presented in Table 3. Supplementation of the basal diet containing 0.20% L-cystine with Lmethionine resulted in faster (P < 0.05) and more efficient (P < 0.05) gains than that resulting from DL-methionine supplementation. Performance of chicks fed the two sources of DL-methionine was similar. Chicks fed D-methionine, however, gained slower and less efficiently (P < 0.01) than those fed DLmethionine.
In the presence of 0.30% L-cystine and at levels of sulfur amino acids at or near the requirement, growth was similar for chicks
TABLE 2.—Performance of chicks fed two levels of L-, D- or DL- methionine, in combination with L-methionine or L-cystine (Assay l)1-2 Diet no. 1 2 3 4 5 6 7
L-met
r>met
DL-met
L-cys
Gain
Gain/feed
%
% —
% — — —
% — — — —
g. 38a 73b 79c 68b 92d 92d 87d
0.42a 0.62b 0.65c 0.62b 0.72d 0.74e 0.71d
2.7
0.01
0.30 0.30 0.45 0.30
—
0.15
— —
0.15
— —
0.30
0.30
0.30
—
0.30 0.30 0.30
— —
Pooled SE
'Average of triplicate groups of 7 male chicks for the period 8-14 days posthatching; avg. initial weight was 85 g. 2 Values within a column not followed by a similar small letter are significantly different (P < 0.05). TABLE 3.—Performance of chicks fed L-, DL- or D-methionine in the presence of 0.20% L-cystine (Assay 2)U2 L-met
DL-met
D-met
%
%
0.20
% —
— —
0.20 0.20' 0.20
Gain
Gain/feed
53a 46b 45b 37c
0.57a 0.55a,b 0.54b 0.50c
Pooled SE 2.6 0.01 'Average of triplicate groups of 7 male chicks for the period 8-13 days posthatching; avg. initial weight was 82 g. 2 Values within a column not followed by a similar superscript are significantly different (P < 0.05). 3 Ajinomoto U.S.A., Inc. 4 Nutritional Biochemicals Corporation.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on June 19, 2015
Assay 1. Supplementation of the basal diet containing 0.30% L-methionine with either D-, L- or DL-methionine resulted in faster and more efficient gains (P < 0.01) for chicks fed these diets than for those fed the unsupplemented diet (Table 2). Performance of chicks fed the diet in which L-methionine supplied the sole source of sulfur amino acids was superior to that of chicks consuming diets containing D- or DL-methionine (P < 0.05). Moreover, chicks fed the D-isomer gained somewhat faster but not more efficiently than those fed an equivalent level of the racemic mixture.
1670
R. S. KATZ AND D. H. BAKER
TABLE 4.—Determination of the requirement for L- or D-methionine when acting as the sole source of sulfur amino acids (Assay 3)] Dietary methionine level
Gain
%
D
L
D
g73 96 99 114 115 117 110
g. 65 83 103 104 118 112 110
0.52 0.61 0.63 0.69 0.70 0.71 0.67
0.50 0.57 0.65 0.69 0.70 0.68 0.67
4.4
Pooled SE
.01
'Average of duplicate groups of 8 male chicks for the period 8-17 days posthatching; avg. initial weight was 69 g.
20 I 10 -
CTl 00
>-
100 90 L-i somer
< o
80 z
, L- AND DL-METHIONINE
TABLE 5.—Determination of the requirement for L- or D-methionine in the presence of 0.27% L-cystine (Assay 4)' Dietary methionine level
Gain/feed
Gain
%
D
L
D
g28 69 112 115 118 118 121
g18 49 90 119 118 124 121
0.34 0.53 0.66 0.69 0.69 0.72 0.63
0.27 0.49 0.62 0.68 0.71 0.71 0.71
.02 2.5 Pooled SE 'Average of duplicate groups of 8 male chicks for the period 8-17 days posthatching; avg. initial weight was 69.0 g.
160 140 ' 120 " w 100>< CT>
80 -
amino acids on the utilization of the isomers of methionine and its hydroxy analogue. Poultry Sci. 44: 957-964. Nasset, E. S., and J. T. Anderson, 1951. Nitrogen balance index in the adult rat as affected by diets low in L- and DL-methionine. J. Nutr. 44: 237-247. Rose, W. C , J. Coon, H. B. Lockhart and G. F. Lambert, 1955. The amino acid requirements of man, XI. The threonine and methionine requirements. J.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on June 19, 2015
addition of a feedstuff which contains the L-isomer only might result in greater growth at an equal level of methionine contribution. This would result in an overestimation of the availability of methionine in the test ingredient. As pointed out by Sasse and Baker (1973), it is likewise important to use both methionine and cystine in constructing the standard availability curve, since neither Dnor L-methionine is as effective a source of cystine as cystine itself. Hence, a mixture of L-methionine and L-cystine should be used to construct the standard curve for sulfur amino acid availability assays.
1673
1674
R. S. KATZ AND D. H. BAKER
1972. L-methionine and L-cystine requirements of the growing rat. J. Anim. Sci. 35: 782-788. Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., New York. Stekol.J. A., 1935. Metabolismof L-and DL-methionine in adult dogs maintained on diets of various protein content. J. Biol. Chem. 109: 147-157. Tipton, H. C , B. C. Dilworth and E. J. Day, 1966. A comparison of D-, L-, DL-methionine and methionine hydroxy analogue calcium in chick diets. Poultry Sci. 45: 381-387. Wretlind, K. A. J., and W. C. Rose, 1950. Methionine requirement for growth and utilization of its optical isomers. J. Biol. Chem. 187: 697-703. Velu, J. G., D. H. Baker and H. M. Scott, 1971. Protein and energy utilization by chicks fed graded levels of a balanced mixture of crystalline amino acids. J. Nutr. 101: 1249-1256.
Cadmium and the Laying Hen: Apparent Absorption, Tissue Distribution and Virtual Absence of Transfer into Eggs1 J. L. SELL
Animal Science Department, North Dakota State University, Fargo, North Dakota 58102 (Received for publication February 3, 1975)
ABSTRACT After being given a single oral dose of 40 (xCi. of 109CdCl2, laying hens were fed a practical type ration to which 0 or 60 p.p.m. cadmium (Cd, as CdCI2) was added. On the basis of ,09Cd in excrement, apparent absorption of the isotope averaged less than 10% of the dose for both diets. Less than 4% of the dose was retained in total body tissue 23 days after dosing. Dietary Cd level did not significantly influence excretion of 109Cd by hens, but hens fed 60 p.p.m. Cd retained a significantly higher proportion of l09Cd dose in liver, kidneys and whole body than did control hens. 109Cd was only detected in blood 48 hours after dosing and more than 75% of radioactivity in the blood occurred in plasma. Hens fed 60 p.p.m. Cd consumed less feed and produced less eggs than control hens. l09Cd was found infrequently at very low levels in yolks of eggs produced by hens fed 60 p.p.m. Cd. No radioactivity was detected in any egg whites, or in yolks of eggs produced by control hens. POULTRY SCIENCE 54: 1674-1678, 1975
C
ADMIUM, an element of considerable
1973). Exposure of animals and man to rela-
economic significance in a variety of
tively high levels of cadmium (Cd) in food,
industries, has received attention recently as
water or air has been observed to cause
a constituent of the environment which may
deleterious effects
be hazardous to man (Flick et al., 1971;
1971;ParizekandZahor, 1956;Supplee, 1961;
Friberg et al., 1971; and Page and Bingham,
Powell et al., 1964; Fox et al., 1971; Flick
(Fitzhugh and Meiller,
et al., 1971; Cousins et al., 1973; Chernoff, 1. Published with the approval of the Director of the North Dakota Agricultural Experiment Station as Journal article No. 575.
1973; and Doyle et al., 1974). In addition, Schroeder (1965), Carroll (1966) and Piscator and Lind (1972) have presented circumstantial
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on June 19, 2015
Biol. Chem. 215: 101-110. Sasse, C. E., 1973. Effect of dietary inorganic sulfate on performance and sulfur amino acid nutrition of the chick. PhD. thesis, University of Illinois, Urbana. Sasse, C. E., and D. H. Baker, 1973. Availability of sulfur amino acids in corn and corn gluten meal for growing chicks. J. Anim. Sci. 37: 1351-1355. Sasse, C. E., andD. H. Baker, 1974a. Factors affecting sulfate-sulfur utilization by the young chick. Poultry Sci. 53: 652-662. Sasse,C.E.,andD. H.Baker, 1974b. Sulfur utilization by the chick with emphasis on the effect of inorganic sulfate on the cystine-methionine interrelationship. J. Nutr. 104: 244-251. Smith, R. E., 1966. The utilization of L-methionine, DL-methionine and methionine hydroxy analogue by the growing chick. Poultry Sci. 45: 571-577. Sowers, J. E., W. L. Stockland and R. J. Meade,
Department of Animal Science, University of Illinois, Urbana, Illinois 61801 (Received for publication January 31, 1975)
POULTRY SCIENCE 54: 1667-1674, 1975
I
T has been established that the D-isomer of methionine will support the growth of many species when serving as a source of sulfur amino acids (Wretlind and Rose, 1950; Rose et ai, 1955; Stekol, 1935; Bauer and Berg, 1943). Evidence concerning the equivalence of the D- and L-isomers or the racemic mixture, however, has been somewhat inconsistent. The D-isomer has been shown to be nutritionally equivalent to the L-isomer by some (Leveille et ai, 1960; Fell et ai, 1959), inferior by others (Bruggemann et al., 1962; Smith, 1966) and even superior by still others (Gutteridge and Lewis, 1964; Tipton et ai, 1966). Explanations for these differences have usually been based on assumptions yet to be proven or on fragmentary evidence (Gordon and Sizer, 1965; Marrett and Sunde, 1965). The importance of learning the truth in this matter is essentially twofold. Firstly, when an animal consumes intact proteins, it is
receiving the natural or L-isomer. DLmethionine, however, is usually the form in which methionine is added to a diet deficient in sulfur-bearing amino acids. Thus, if the two isomers are not nutritionally equivalent, a given level of supplementation may be either inadequate to attain the desired response or more than adequate and thus uneconomical. Secondly, the use of a standard curve obtained with crystalline amino acids is often used in determining the availability of an amino acid in a particular food or feedstuff (Sasse and Baker, 1973). Again if the isomers are not equally utilized, an over- or underestimation of sulfur amino acid availability could occur. The studies reported herein were designed to investigate the relative biopotency of Dand L-methionine. The effects of the presence or absence of cystine and the level of supplementation were also studied. EXPERIMENTAL
1. Present address: The Quaker Oats Company, 617 West Main Street, Barrington, Illinois 60010. 2. Part of thesis submitted to the Graduate College of the University of Illinois in partial fulfillment of the requirements for the Ph.D. degree.
The composition of the basal diet used in all assays is presented in Table 1. Varying levels of D-, L- or DL-methionine were added to the basal diet which had been either left
1667
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on June 19, 2015
ABSTRACT Four assays employing young male chicks were conducted to evaluate the relative efficacy of D-, L- and DL-methionine and to estimate the requirement for D- and L-methionine when serving as the sole source of sulfur amino acids or when added to a diet containing 0.27% L-cystine. Crystalline amino acid diets containing 14.9% protein equivalent and 4200 kcal. M.E./kg. were used in all assays. L-methionine supported faster and more efficient gains than D- or DL-methionine when fed at levels below the requirement. At levels of supplementation near the requirement, however, equal efficacy was attained. When serving as the sole source of sulfur amino acids, the requirement as estimated by least squares for optimal gain was 0.58% of the diet or 104 mg./day for L-methionine and 0.59% or 104 mg./day for D-methionine. In the presence of cystine, the requirements were estimated at 0.27% or 49 mg./day and 0.30% or 52 mg./day for L- and D-methionine respectively. The results indicate that at lower levels of supplementation, L-methionine is a better source of sulfur amino acids than D-methionine. On the other hand, L- and D-methionine appear to have equal efficacy when incorporated into diets that are only marginally deficient in sulfur-bearing amino acids.
1668
R. S. KATZ AND D. H. BAKER TABLE 1.—Composition of basal diet
% to 100.00 19.74 15.00 5.37 3.00 1.00 0.20 0.20 + +
Amino acid mix L-arginine • HC1 L-histidine • HC1 •H 2 0 L-lysine • HC1 L-tyrosine L-tryptophan L-phenylalanine DL-methionine L-cystine L-threonine L-leucine L-isoleucine L-valine Glycine L-proline L-glutamic acid
g./19.74 g. 1.15 0.41 1.14 0.45 0.15 0.50 var var 0.65 1.00 0.60 0.69 0.60 0.40 12.00 19.74
'Velu etal. (1971).
devoid of or supplemented with L-cystine.3 All dietary additions were made at the expense of corn starch. On day 8 posthatching following an overnight fast, chicks originating from the cross of New Hampshire males and Columbian females were assigned to treatments. Information regarding selection and care of chicks prior to initiation of the assays and the assignment procedure has been outlined previously (Sasse and Baker, 1974a). The first assay consisted of 7 treatments in which methionine was provided either as the sole source of sulfur-bearing amino acids (diets 1-4) or as a supplement to a diet containing 0.30% L-cystine (diets 5-7). Diets 1-4 contained a basal level of 0.30% Lmethionine and were supplemented with 0.15% of either D-, L- or DL-methionine. Supplemental levels of methionine were such that growth of chicks would lie in the linear portion of the growth curve. Methionine additions to diets 5-7 were such that the total sulfur 3. Unless otherwise indicated, all amino acids were purchased from Ajinomoto U.S.A., Inc., New York, N.Y.
amino acid levels were at or near the requirement for optimal growth. In the second assay D-, L- or DL-methionine were again added in the presence of L-cystine. However, the level of total sulfur-bearing amino acids was such that growth would lie on the linear area of the growth curve. The results of the first assay had indicated less efficacy for the racemic mixture of methionine than for either the D- or L-isomer. This observation was disturbing and indeed difficult to explain. It was thought that the source of DL-methionine that had been used might possibly be less than 100% pure. Thus, two commercial sources of DL-methionine were used in the second assay. Assays 3 and 4 were conducted to estimate the requirement for L- and D-methionine in the absence (Assay 3) or presence (Assay 4) of L-cystine. The level of L-cystine used was slightly higher than the requirement estimated by Sasse (1973) in the presence of adequate sulfate. The estimate of the requirement was predicted by fitting a continuous broken line to the gain and gain/feed data for each series of diets by least squares analysis (Steel and Torrie, 1960).
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on June 19, 2015
Ingredient Corn starch Amino acid mix Corn oil Salt mixture' Cellulose NaHC03 Choline chloride Vitamins' a-tocopheryl acetate (20 mg../kg.) Ethoxyquin (125 mg • / k g . )
1669
EFFICACY OF D-, L- AND DL-METHIONINE
fed diets containing L-, D- or DL-methionine, although weight gain tended to be less for birds consuming the diet containing the racemic mixture. Efficiency of gain, however, was greater (P < 0.05) for birds receiving L-methionine than for those receiving either D- or DL-methionine. \
RESULTS
Assay 2. The results of assay 2 are presented in Table 3. Supplementation of the basal diet containing 0.20% L-cystine with Lmethionine resulted in faster (P < 0.05) and more efficient (P < 0.05) gains than that resulting from DL-methionine supplementation. Performance of chicks fed the two sources of DL-methionine was similar. Chicks fed D-methionine, however, gained slower and less efficiently (P < 0.01) than those fed DLmethionine.
In the presence of 0.30% L-cystine and at levels of sulfur amino acids at or near the requirement, growth was similar for chicks
TABLE 2.—Performance of chicks fed two levels of L-, D- or DL- methionine, in combination with L-methionine or L-cystine (Assay l)1-2 Diet no. 1 2 3 4 5 6 7
L-met
r>met
DL-met
L-cys
Gain
Gain/feed
%
% —
% — — —
% — — — —
g. 38a 73b 79c 68b 92d 92d 87d
0.42a 0.62b 0.65c 0.62b 0.72d 0.74e 0.71d
2.7
0.01
0.30 0.30 0.45 0.30
—
0.15
— —
0.15
— —
0.30
0.30
0.30
—
0.30 0.30 0.30
— —
Pooled SE
'Average of triplicate groups of 7 male chicks for the period 8-14 days posthatching; avg. initial weight was 85 g. 2 Values within a column not followed by a similar small letter are significantly different (P < 0.05). TABLE 3.—Performance of chicks fed L-, DL- or D-methionine in the presence of 0.20% L-cystine (Assay 2)U2 L-met
DL-met
D-met
%
%
0.20
% —
— —
0.20 0.20' 0.20
Gain
Gain/feed
53a 46b 45b 37c
0.57a 0.55a,b 0.54b 0.50c
Pooled SE 2.6 0.01 'Average of triplicate groups of 7 male chicks for the period 8-13 days posthatching; avg. initial weight was 82 g. 2 Values within a column not followed by a similar superscript are significantly different (P < 0.05). 3 Ajinomoto U.S.A., Inc. 4 Nutritional Biochemicals Corporation.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on June 19, 2015
Assay 1. Supplementation of the basal diet containing 0.30% L-methionine with either D-, L- or DL-methionine resulted in faster and more efficient gains (P < 0.01) for chicks fed these diets than for those fed the unsupplemented diet (Table 2). Performance of chicks fed the diet in which L-methionine supplied the sole source of sulfur amino acids was superior to that of chicks consuming diets containing D- or DL-methionine (P < 0.05). Moreover, chicks fed the D-isomer gained somewhat faster but not more efficiently than those fed an equivalent level of the racemic mixture.
1670
R. S. KATZ AND D. H. BAKER
TABLE 4.—Determination of the requirement for L- or D-methionine when acting as the sole source of sulfur amino acids (Assay 3)] Dietary methionine level
Gain
%
D
L
D
g73 96 99 114 115 117 110
g. 65 83 103 104 118 112 110
0.52 0.61 0.63 0.69 0.70 0.71 0.67
0.50 0.57 0.65 0.69 0.70 0.68 0.67
4.4
Pooled SE
.01
'Average of duplicate groups of 8 male chicks for the period 8-17 days posthatching; avg. initial weight was 69 g.
20 I 10 -
CTl 00
>-
100 90 L-i somer
< o
80 z
, L- AND DL-METHIONINE
TABLE 5.—Determination of the requirement for L- or D-methionine in the presence of 0.27% L-cystine (Assay 4)' Dietary methionine level
Gain/feed
Gain
%
D
L
D
g28 69 112 115 118 118 121
g18 49 90 119 118 124 121
0.34 0.53 0.66 0.69 0.69 0.72 0.63
0.27 0.49 0.62 0.68 0.71 0.71 0.71
.02 2.5 Pooled SE 'Average of duplicate groups of 8 male chicks for the period 8-17 days posthatching; avg. initial weight was 69.0 g.
160 140 ' 120 " w 100>< CT>
80 -
amino acids on the utilization of the isomers of methionine and its hydroxy analogue. Poultry Sci. 44: 957-964. Nasset, E. S., and J. T. Anderson, 1951. Nitrogen balance index in the adult rat as affected by diets low in L- and DL-methionine. J. Nutr. 44: 237-247. Rose, W. C , J. Coon, H. B. Lockhart and G. F. Lambert, 1955. The amino acid requirements of man, XI. The threonine and methionine requirements. J.
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on June 19, 2015
addition of a feedstuff which contains the L-isomer only might result in greater growth at an equal level of methionine contribution. This would result in an overestimation of the availability of methionine in the test ingredient. As pointed out by Sasse and Baker (1973), it is likewise important to use both methionine and cystine in constructing the standard availability curve, since neither Dnor L-methionine is as effective a source of cystine as cystine itself. Hence, a mixture of L-methionine and L-cystine should be used to construct the standard curve for sulfur amino acid availability assays.
1673
1674
R. S. KATZ AND D. H. BAKER
1972. L-methionine and L-cystine requirements of the growing rat. J. Anim. Sci. 35: 782-788. Steel, R. G. D., and J. H. Torrie, 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., New York. Stekol.J. A., 1935. Metabolismof L-and DL-methionine in adult dogs maintained on diets of various protein content. J. Biol. Chem. 109: 147-157. Tipton, H. C , B. C. Dilworth and E. J. Day, 1966. A comparison of D-, L-, DL-methionine and methionine hydroxy analogue calcium in chick diets. Poultry Sci. 45: 381-387. Wretlind, K. A. J., and W. C. Rose, 1950. Methionine requirement for growth and utilization of its optical isomers. J. Biol. Chem. 187: 697-703. Velu, J. G., D. H. Baker and H. M. Scott, 1971. Protein and energy utilization by chicks fed graded levels of a balanced mixture of crystalline amino acids. J. Nutr. 101: 1249-1256.
Cadmium and the Laying Hen: Apparent Absorption, Tissue Distribution and Virtual Absence of Transfer into Eggs1 J. L. SELL
Animal Science Department, North Dakota State University, Fargo, North Dakota 58102 (Received for publication February 3, 1975)
ABSTRACT After being given a single oral dose of 40 (xCi. of 109CdCl2, laying hens were fed a practical type ration to which 0 or 60 p.p.m. cadmium (Cd, as CdCI2) was added. On the basis of ,09Cd in excrement, apparent absorption of the isotope averaged less than 10% of the dose for both diets. Less than 4% of the dose was retained in total body tissue 23 days after dosing. Dietary Cd level did not significantly influence excretion of 109Cd by hens, but hens fed 60 p.p.m. Cd retained a significantly higher proportion of l09Cd dose in liver, kidneys and whole body than did control hens. 109Cd was only detected in blood 48 hours after dosing and more than 75% of radioactivity in the blood occurred in plasma. Hens fed 60 p.p.m. Cd consumed less feed and produced less eggs than control hens. l09Cd was found infrequently at very low levels in yolks of eggs produced by hens fed 60 p.p.m. Cd. No radioactivity was detected in any egg whites, or in yolks of eggs produced by control hens. POULTRY SCIENCE 54: 1674-1678, 1975
C
ADMIUM, an element of considerable
1973). Exposure of animals and man to rela-
economic significance in a variety of
tively high levels of cadmium (Cd) in food,
industries, has received attention recently as
water or air has been observed to cause
a constituent of the environment which may
deleterious effects
be hazardous to man (Flick et al., 1971;
1971;ParizekandZahor, 1956;Supplee, 1961;
Friberg et al., 1971; and Page and Bingham,
Powell et al., 1964; Fox et al., 1971; Flick
(Fitzhugh and Meiller,
et al., 1971; Cousins et al., 1973; Chernoff, 1. Published with the approval of the Director of the North Dakota Agricultural Experiment Station as Journal article No. 575.
1973; and Doyle et al., 1974). In addition, Schroeder (1965), Carroll (1966) and Piscator and Lind (1972) have presented circumstantial
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Biol. Chem. 215: 101-110. Sasse, C. E., 1973. Effect of dietary inorganic sulfate on performance and sulfur amino acid nutrition of the chick. PhD. thesis, University of Illinois, Urbana. Sasse, C. E., and D. H. Baker, 1973. Availability of sulfur amino acids in corn and corn gluten meal for growing chicks. J. Anim. Sci. 37: 1351-1355. Sasse, C. E., andD. H. Baker, 1974a. Factors affecting sulfate-sulfur utilization by the young chick. Poultry Sci. 53: 652-662. Sasse,C.E.,andD. H.Baker, 1974b. Sulfur utilization by the chick with emphasis on the effect of inorganic sulfate on the cystine-methionine interrelationship. J. Nutr. 104: 244-251. Smith, R. E., 1966. The utilization of L-methionine, DL-methionine and methionine hydroxy analogue by the growing chick. Poultry Sci. 45: 571-577. Sowers, J. E., W. L. Stockland and R. J. Meade,
