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Toxicity of Tannic Acid and its Metabolites for Chickens1
Toxicity of Tannic Acid and its Metabolites for Chickens1 G. V. N. RAYUDU, R. KADIRVEL, P. VOHEA AND F. H. KRATZER Department of Avian Sciences, University of California, Davis, California 95616 (Received for publication January 17, 1970)
T
In this study, an attempt has been made to assess the comparative toxicity of tannic acid and its metabolites when fed to chickens; and to overcome this growth depression by MHA, choline, arginine and ornithine. EXPERIMENTAL The composition of the stock basal diet used in this study is given in Table 1. Reagent grade gallic acid, pyrogallol and pyrocatechol were used and the dietary levels of the different phenolic compounds are indicated for each experiment in the tables. These were added to the basal diet without any adjustments in the composition. Dayold Arbor Acres broiler type chicks were wingbanded and distributed into different groups of approximately equal weight. Each group contained 10 chicks and each
1 Supported in part by U. S. Public Health Service—ES—00303. 2 Tannic acid -tac- Tannic acid powder, feed grade, lot number SHB 1763. Mol. wt. 1701. Mallinckrodt Chemical Works, St. Louis, Mo. This product is referred to as tannic acid in this report. 3 Tannic (digallic) Acid (Practical), Mol. wt. 322.22, Eastman Organic Chemicals, Distillation Products (Division of Eastman Kodak Company, Rochester 3, New York). This product is referred to as digallic acid in this report.
957
TABLE 1.—Composition of the basal diet
% Ground milo Ground corn Soybean meal (50% protein) Fish meal (66% protein) Brewer's dried yeast Dried whey products Alfalfa meal (20% protein) Dicalcium phosphate . 2H 2 0 Limestone, ground Salt (Iodized) Manganese sulfate Bifuran Zinc oxide Micro-mixture1
42.90 20.00 20.00 6.75 1.00 2.50 4.00 1.15 1.00 0.25 0.025 0.0125 0.005 0.1375
1 Micro-mixture (per kg. diet): vitamin A (stabilized) 4400 I.U.; vitamin D 3 , 1100 I.C.U.; alpha tocopheryl acetate, 5.S I.U.; menadione sodium bisulfite, 3.3 mg.; riboflavin, 4.4 mg.; niacin, 11 mg.; calcium pantothenate, 5.5 mg.; folacin, 0.55 mg.; vitamin B12, 0.0044 mg.; santoquin, 55 mg.
Downloaded from http://ps.oxfordjournals.org/ at Yale University on May 14, 2015
HE growth depressing properties of sorghum for chicks were attributed to tannins (Chang and Fuller, 1964). Chestnut, quercyl, wattle bark and quebracho tannins depressed growth when fed to chicks at a 1% level, and tannic acid2 was toxic even at a dietary level of 0.5% (Vohra et al., 1966). Grape seed tannin was growth depressing for rats at a 5% level in the diet (Joslyn and Glick, 1969). Fuller et al. (1967) partially alleviated the tannic acid3 -induced growth depression by supplementing the diet with methionine hydroxy analog (MHA), choline and arginine. However, Vohra et al. (1966), failed to confirm this result. Potter et al. (1968) identified gallic acid, pyrogallol, 4-0-methyl gallic acid and pyrocatechol as the metabolic end products of tannic acid in the chicken. Joslyn and Glick (1969) recorded a higher growth depressing effect for gallic acid than tannic acid in rats at 4 and 6 percent levels in the diet. For chicks no significant growth depression was observed with gallic at a dietary level of 1 percent (Vohra et al, 1966). Dollahite et al. (1962) observed pyrogallol to be more toxic than either tannic acid or gallic acid for rabbits.
958
G. V. N. RAYUDU, R. KADIRVEL, P. VOHRA AND F. H. KRATZER
TABLE 2.—Average gain in weight, feed/gain (F/G) and percentage mortality of chicks fed tannic acid and its metabolites at the indicated levels over an experimental period of 4 weeks Experiment 2
Experiment 1 Treatment
1 2 1 2 1 2 0.1 2 1 0.1
Weight Gain (gm-)
F/G
4S0.6 d 428.9 d l 385.9° 360.5 b 247.4° 244.3»
1.70 1.80 1.80 1.95 2.25 2.05
— — — — —
— — — — —
% Mortality
— — — — — 10 95
Weight Gain (mg.)
F/G
507.3 d 2
1.84
— —
— —
355.2"
1.95
— — —
— — —
—
481.4°
1.93
—
— —h
440.6
— —
100 80
1.89
%
Mortality
— — — — — — — — — —
1
Statistically significant at 5% level from the control. '• Statistically significant at 1% level.
treatment was duplicated in an experiment lasting for 4 weeks. The birds were housed in an electrically heated cage battery and feed and water were made available ad libitum. Group weights of the birds were recorded except the final weight, which was taken individually. The feed consumption was recorded for each group and the feed efficiency was expressed as the feed/gain (F/G) ratio. The fat content of the livers was determined by drying homogenized samples under reduced pressure at 60°C. for 24 hours and extracting with petroleum ether in a Goldfish apparatus. The statistical analysis of the data was one by Duncan's multiple range test (Duncan, 19S5). RESULTS AND DISCUSSION The average weight gain, feed/gain ratio and percent mortality of chicks fed tannic acid, galic acid, pyrogallol and pyrocatechol are listed in Table 2. Mortality was 100% with pyrocatechol and 95% with pyrogallol at the 2% level in the diet. In both the groups, the mortality occurred within the first 10 days. Tannic acid and gallic acid were significantly growth depressing (P = 0.01) at a level of 2%. Mortality was 80% when the chicks were fed pyrocatechol at the 1% level and death occurred mostly during
the 3rd and 4th week of the experiment. At this level, pyrogallol caused a mortality of 10% only. Pyrogallol and pyrocatechol depressed growth even at the 0.1% level in the diet and this was statistically significant (P = 0.01). Vohra et al. (1966) mistakenly reported no mortality in chicks fed diets containing 1% pyrocatechol. The material used by them was gum catechu and not pyrocatechol. Tannic acid and pyrogallol were growth depressing at a dietary level of 1% (P — 0.01). There was also a decrease in gain in body weight caused by 1% gallic acid in the diets but the results were significant only at a probability of 5%. Tannic acid and digallic acid were equally growth depressing at the 1% level, but digallic acid caused less depression of growth at the 0.5% level (Table 3). A significant depression in growth of chicks was observed when the basal diet was supplemented with a mixture of 0.09% DL-methionine, 0.2% choline and 1% arginine. This supplement partially alleviated the growth depression induced by both tannic acid or digallic acid. The improvement in growth was of approximately equal magnitude when the supplements were added to either tannic acid or digallic acid at the 0.5% level. At the 1% level, however, the supple-
Downloaded from http://ps.oxfordjournals.org/ at Yale University on May 14, 2015
Basal diet +Gallic acid +Gallic acid +Tannic acid +Tannic acid +Pyrogallol +Pyrogallol +Pyrogallol +Pyrocatechol +Pyrocatechol +Pyrocatechol
Dietary Level (%)
959
TANNIC ACID TOXICITY
TABLE 3.—Effect of methionine, choline and arginine supplementation on the growth and F/G of chicks fed two types of tannins in diets over 4 weeks. Superscripts indicate statistical significance at P<0.01 Experiment 2 Treatment
Basal diet + 0 . 5 % Tannic acid + 0 . 5 % Digallic acid + 1% Tannic acid + 1% Digallic acid +SuppIement I +Supplement 0.5% Tannic acid +Supplement 0.5% Digallic acid +Supplement 1% Tannic acid +Supplement 1% Digallic acid
Gain in Weight F / G (gm-) 507.3£ 398.7b 427.7° 355.2" 363.3* 475.8d.« 463.5d.e 480.6= 412.4d.° 452.0d
1.84 1.87 1.83 1.95 1.97 1.76 1.77 1.77 1.84 1.79
1 The supplement contained 0.09% DL-methionine, 0.2% choline and 1% arginine.
TABLE 4.—Effect of methionine, arginine, ornithine, ornithine and choline on growth depression of chicks induced by a level of 1% tannic acid in the diet over an experimental period of 4 weeks. Different superscripts denote statistical significance at P<0.05 % Level of supplement in the diet Methionine Choline Arginine
— 0.2 0.2 0.2 0.2 — — —
—. — — — 0.2 — 0.2 0.2
— — 1.0
1.0 1.0 1.0 1.0
—
Weight gain of chicks (gm.)
fhjJL
Tannic Control acid, 1%
— — — 0.75.
475. l d:
0.75 0.75
— 0.75
— —. — —. —. — —
392.la 431.2 bb ' c d. 433.2 -°' 411. O*-d 449.6°' 402.3a'b 379.4" 385.5"
postulated methylation as the detoxification mechanism of gallic acid because of detection of 4-0-methyl gallic acid but not methylpyrogallol in the urine of animals. Gallic acid, 4-0-methylgallic acid, pyrogallol and pyrocatechol were found to be the metabolites of tannic acid in the chicken (Potter et al., 1968; Kadirvel et al., 1969). From the present study and that of Vohra et al. (1966) it is clear that gallic acid is less toxic than tannic acid. It appears that pyrogallol and pyrocatechol, the two metabolites of tannic acid, are more important in deciding the intensity of toxic action of tannic acid since none of them are excreted as a methylated product; and both of them are toxic even at a level of 0.1% in the diet. Gallic acid, another metabolite of tannic acid may not be that important because it is less toxic perhaps due to detoxification by methylation. It was observed that digallic acid is less toxic at a 0.5% level than tannic acid and the improvement in weight gain by the addition of methionine, choline and arginine was better with respect to digallic acid than tannic acid. It could be explained if digallic acid were metabolized more to gallic acid and less to pyrogallol and pyrocatechol. Tannic acid could yield relatively more pyrogallol and pyrocatechol and/or less gallic acid. The liver fat was increased in the group of chicks fed a 1% dietary level of gallic
Downloaded from http://ps.oxfordjournals.org/ at Yale University on May 14, 2015
mentation was less effective with tannic acid than with digallic acid. The growth depression caused by addition of the supplement to the basal diet probably indicates that the basal diet was high in one or more of the components of the supplement. An addition of a mixture of methionine (0.2%), choline (0.2%), arginine (1%), and ornithine (0.75%) was as beneficial as the following supplements: methionine; methionine plus arginine (Table 4). The growth depressing properties of 1% tannic acid for chicks were not alleviated by taurocholic acid or cholesterol at a level of 0.01% in the diet (unpublished data). The growth depression caused by tannic acid at a 2% level could not be corrected, even partially, by the addition of methionine and other supplements (unpublished data). This clearly shows that methyl donors along with arginine and ornithine were useful only when the dietary level of tannic acid was 1 % or less. It has been established in rats and rabbits that gallic acid, a hydrolytic product of tannic acid, is decarboxylated to form pyrogallol (Booth et al., 1959). They also
960
G. V. N. RAYUDU, R. KADIRVEL, P. VOHRA AND F. H. KRATZER TABLE S.—Effect of tannic acid and its metabolites on the fat content of liver Treatment
% Fat (Dry weight) Liver 9.81+0.92"1 16.96 + 2.08 b 23.16±1.53 d 9.53±1.65»
Experiment 2 Basal diet + 0 . 5 % Tannic acid -t-0.5% Tannic acid and supplements
9.28±0.70» 10.44±0.72» 11.72 + 0.64"
1
P = 0.01.
acid or tannic acid (Table 5). Pyrogallol did not increase the liver fat. This was in agreement with the studies of Booth et al. (1961) for rats fed gallic acid and pyrogallol. Chang and Fuller (1964) also observed an increase in liver fat in birds fed a tannic acid diet. An addition of methionine and/ or choline along with tannic acid or gallic acid decreased the liver fat (Chang and Fuller, 1964; Booth et al, 1961). In the present study no increase in liver fat was observed in chickens on a 0.5% tannic acid diet. SUMMARY
Pyrocatechol and pyrogallol, the metabolites of tannic acid were growth depressing for chicks even at a dietary level of 0.1% and about 100% mortality was observed when the dietary level of these compounds reached 2%. Tannic acid was less growth depressing than the above compounds and caused no mortality at 2% dietary level. Digallic acid was even less toxic than tannic acid at a level of 0.5% but not at the 1% level. Gallic acid was the least toxic metabolite of tannic acid. A mixture of ar-
REFERENCES Booth, A. N., M. S. Masri, D. J. Robbins, O. H. Emerson, F. T. Jones and F. DeEds, 1959. The metabolic fate of gallic acid and related compounds. J. Biol. Chem. 234: 3014-3016. Booth, A. N., D. J. Robbins and F. DeEds, 1961. Effect of dietary gallic acid and pyrogallol on choline requirement of rats. J. Nutrition, 75: 104-106. Chang, S. I., and H. L. Fuller, 1964. Effect of tannin content of grain sorghums on their feeding value for growing chicks. Poultry Sci. 43: 3036. Dollahite, J. W., R. F. Pigeon and B. J. Camp, 1962. The toxicity of gallic acid, pyrogallol, tannin acid and Quercus havardi in the rabbit. Am. J. Vet. Res. 23 : 1264-1267. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Fuller, H. L., S. I. Chang and D. K. Potter, 1967. Detoxication of dietary tannic acid by chicks. J. Nutrition, 9 1 : 477-481. Joslyn, M. A., and Z. Glick, 1969. Comparative effects of gallotannic acid and related phenolics on the growth of rats. J. Nutrition, 98: 119126. Kadirvel, R., G. V. N. Rayudu and P. Vohra, 1969. Excretion of metabolites of tannic acid by chickens with and withouc ceca. Poultry Sci. 48: 1511-1513. Potter, D. K., and H. L. Fuller, 1968. Metabolic fate of dietary tannins in chicks. J. Nutrition, 96: 187-191. Vohra, P., F. H. Kratzer and M. A. Joslyn, 1966. The growth depressing and toxic effects of tannins to chicks. Poultry Sci. 45: 135-142.
Downloaded from http://ps.oxfordjournals.org/ at Yale University on May 14, 2015
Experiment 1 Basal diet + Gallic acid 1% +Tannic acid 1% +Pyrogallol 1%
ginine, ornithine and methyl donors like methionine and choline partially alleviated the growth depression induced by tannic acid but were more effective against digallic acid-induced growth depression. The fat content of livers of chicks receiving 1% gallic acid or tannic acid was increased but was not influenced by 1% pyrogallol or 0.5% tannic acid.
T
In this study, an attempt has been made to assess the comparative toxicity of tannic acid and its metabolites when fed to chickens; and to overcome this growth depression by MHA, choline, arginine and ornithine. EXPERIMENTAL The composition of the stock basal diet used in this study is given in Table 1. Reagent grade gallic acid, pyrogallol and pyrocatechol were used and the dietary levels of the different phenolic compounds are indicated for each experiment in the tables. These were added to the basal diet without any adjustments in the composition. Dayold Arbor Acres broiler type chicks were wingbanded and distributed into different groups of approximately equal weight. Each group contained 10 chicks and each
1 Supported in part by U. S. Public Health Service—ES—00303. 2 Tannic acid -tac- Tannic acid powder, feed grade, lot number SHB 1763. Mol. wt. 1701. Mallinckrodt Chemical Works, St. Louis, Mo. This product is referred to as tannic acid in this report. 3 Tannic (digallic) Acid (Practical), Mol. wt. 322.22, Eastman Organic Chemicals, Distillation Products (Division of Eastman Kodak Company, Rochester 3, New York). This product is referred to as digallic acid in this report.
957
TABLE 1.—Composition of the basal diet
% Ground milo Ground corn Soybean meal (50% protein) Fish meal (66% protein) Brewer's dried yeast Dried whey products Alfalfa meal (20% protein) Dicalcium phosphate . 2H 2 0 Limestone, ground Salt (Iodized) Manganese sulfate Bifuran Zinc oxide Micro-mixture1
42.90 20.00 20.00 6.75 1.00 2.50 4.00 1.15 1.00 0.25 0.025 0.0125 0.005 0.1375
1 Micro-mixture (per kg. diet): vitamin A (stabilized) 4400 I.U.; vitamin D 3 , 1100 I.C.U.; alpha tocopheryl acetate, 5.S I.U.; menadione sodium bisulfite, 3.3 mg.; riboflavin, 4.4 mg.; niacin, 11 mg.; calcium pantothenate, 5.5 mg.; folacin, 0.55 mg.; vitamin B12, 0.0044 mg.; santoquin, 55 mg.
Downloaded from http://ps.oxfordjournals.org/ at Yale University on May 14, 2015
HE growth depressing properties of sorghum for chicks were attributed to tannins (Chang and Fuller, 1964). Chestnut, quercyl, wattle bark and quebracho tannins depressed growth when fed to chicks at a 1% level, and tannic acid2 was toxic even at a dietary level of 0.5% (Vohra et al., 1966). Grape seed tannin was growth depressing for rats at a 5% level in the diet (Joslyn and Glick, 1969). Fuller et al. (1967) partially alleviated the tannic acid3 -induced growth depression by supplementing the diet with methionine hydroxy analog (MHA), choline and arginine. However, Vohra et al. (1966), failed to confirm this result. Potter et al. (1968) identified gallic acid, pyrogallol, 4-0-methyl gallic acid and pyrocatechol as the metabolic end products of tannic acid in the chicken. Joslyn and Glick (1969) recorded a higher growth depressing effect for gallic acid than tannic acid in rats at 4 and 6 percent levels in the diet. For chicks no significant growth depression was observed with gallic at a dietary level of 1 percent (Vohra et al, 1966). Dollahite et al. (1962) observed pyrogallol to be more toxic than either tannic acid or gallic acid for rabbits.
958
G. V. N. RAYUDU, R. KADIRVEL, P. VOHRA AND F. H. KRATZER
TABLE 2.—Average gain in weight, feed/gain (F/G) and percentage mortality of chicks fed tannic acid and its metabolites at the indicated levels over an experimental period of 4 weeks Experiment 2
Experiment 1 Treatment
1 2 1 2 1 2 0.1 2 1 0.1
Weight Gain (gm-)
F/G
4S0.6 d 428.9 d l 385.9° 360.5 b 247.4° 244.3»
1.70 1.80 1.80 1.95 2.25 2.05
— — — — —
— — — — —
% Mortality
— — — — — 10 95
Weight Gain (mg.)
F/G
507.3 d 2
1.84
— —
— —
355.2"
1.95
— — —
— — —
—
481.4°
1.93
—
— —h
440.6
— —
100 80
1.89
%
Mortality
— — — — — — — — — —
1
Statistically significant at 5% level from the control. '• Statistically significant at 1% level.
treatment was duplicated in an experiment lasting for 4 weeks. The birds were housed in an electrically heated cage battery and feed and water were made available ad libitum. Group weights of the birds were recorded except the final weight, which was taken individually. The feed consumption was recorded for each group and the feed efficiency was expressed as the feed/gain (F/G) ratio. The fat content of the livers was determined by drying homogenized samples under reduced pressure at 60°C. for 24 hours and extracting with petroleum ether in a Goldfish apparatus. The statistical analysis of the data was one by Duncan's multiple range test (Duncan, 19S5). RESULTS AND DISCUSSION The average weight gain, feed/gain ratio and percent mortality of chicks fed tannic acid, galic acid, pyrogallol and pyrocatechol are listed in Table 2. Mortality was 100% with pyrocatechol and 95% with pyrogallol at the 2% level in the diet. In both the groups, the mortality occurred within the first 10 days. Tannic acid and gallic acid were significantly growth depressing (P = 0.01) at a level of 2%. Mortality was 80% when the chicks were fed pyrocatechol at the 1% level and death occurred mostly during
the 3rd and 4th week of the experiment. At this level, pyrogallol caused a mortality of 10% only. Pyrogallol and pyrocatechol depressed growth even at the 0.1% level in the diet and this was statistically significant (P = 0.01). Vohra et al. (1966) mistakenly reported no mortality in chicks fed diets containing 1% pyrocatechol. The material used by them was gum catechu and not pyrocatechol. Tannic acid and pyrogallol were growth depressing at a dietary level of 1% (P — 0.01). There was also a decrease in gain in body weight caused by 1% gallic acid in the diets but the results were significant only at a probability of 5%. Tannic acid and digallic acid were equally growth depressing at the 1% level, but digallic acid caused less depression of growth at the 0.5% level (Table 3). A significant depression in growth of chicks was observed when the basal diet was supplemented with a mixture of 0.09% DL-methionine, 0.2% choline and 1% arginine. This supplement partially alleviated the growth depression induced by both tannic acid or digallic acid. The improvement in growth was of approximately equal magnitude when the supplements were added to either tannic acid or digallic acid at the 0.5% level. At the 1% level, however, the supple-
Downloaded from http://ps.oxfordjournals.org/ at Yale University on May 14, 2015
Basal diet +Gallic acid +Gallic acid +Tannic acid +Tannic acid +Pyrogallol +Pyrogallol +Pyrogallol +Pyrocatechol +Pyrocatechol +Pyrocatechol
Dietary Level (%)
959
TANNIC ACID TOXICITY
TABLE 3.—Effect of methionine, choline and arginine supplementation on the growth and F/G of chicks fed two types of tannins in diets over 4 weeks. Superscripts indicate statistical significance at P<0.01 Experiment 2 Treatment
Basal diet + 0 . 5 % Tannic acid + 0 . 5 % Digallic acid + 1% Tannic acid + 1% Digallic acid +SuppIement I +Supplement 0.5% Tannic acid +Supplement 0.5% Digallic acid +Supplement 1% Tannic acid +Supplement 1% Digallic acid
Gain in Weight F / G (gm-) 507.3£ 398.7b 427.7° 355.2" 363.3* 475.8d.« 463.5d.e 480.6= 412.4d.° 452.0d
1.84 1.87 1.83 1.95 1.97 1.76 1.77 1.77 1.84 1.79
1 The supplement contained 0.09% DL-methionine, 0.2% choline and 1% arginine.
TABLE 4.—Effect of methionine, arginine, ornithine, ornithine and choline on growth depression of chicks induced by a level of 1% tannic acid in the diet over an experimental period of 4 weeks. Different superscripts denote statistical significance at P<0.05 % Level of supplement in the diet Methionine Choline Arginine
— 0.2 0.2 0.2 0.2 — — —
—. — — — 0.2 — 0.2 0.2
— — 1.0
1.0 1.0 1.0 1.0
—
Weight gain of chicks (gm.)
fhjJL
Tannic Control acid, 1%
— — — 0.75.
475. l d:
0.75 0.75
— 0.75
— —. — —. —. — —
392.la 431.2 bb ' c d. 433.2 -°' 411. O*-d 449.6°' 402.3a'b 379.4" 385.5"
postulated methylation as the detoxification mechanism of gallic acid because of detection of 4-0-methyl gallic acid but not methylpyrogallol in the urine of animals. Gallic acid, 4-0-methylgallic acid, pyrogallol and pyrocatechol were found to be the metabolites of tannic acid in the chicken (Potter et al., 1968; Kadirvel et al., 1969). From the present study and that of Vohra et al. (1966) it is clear that gallic acid is less toxic than tannic acid. It appears that pyrogallol and pyrocatechol, the two metabolites of tannic acid, are more important in deciding the intensity of toxic action of tannic acid since none of them are excreted as a methylated product; and both of them are toxic even at a level of 0.1% in the diet. Gallic acid, another metabolite of tannic acid may not be that important because it is less toxic perhaps due to detoxification by methylation. It was observed that digallic acid is less toxic at a 0.5% level than tannic acid and the improvement in weight gain by the addition of methionine, choline and arginine was better with respect to digallic acid than tannic acid. It could be explained if digallic acid were metabolized more to gallic acid and less to pyrogallol and pyrocatechol. Tannic acid could yield relatively more pyrogallol and pyrocatechol and/or less gallic acid. The liver fat was increased in the group of chicks fed a 1% dietary level of gallic
Downloaded from http://ps.oxfordjournals.org/ at Yale University on May 14, 2015
mentation was less effective with tannic acid than with digallic acid. The growth depression caused by addition of the supplement to the basal diet probably indicates that the basal diet was high in one or more of the components of the supplement. An addition of a mixture of methionine (0.2%), choline (0.2%), arginine (1%), and ornithine (0.75%) was as beneficial as the following supplements: methionine; methionine plus arginine (Table 4). The growth depressing properties of 1% tannic acid for chicks were not alleviated by taurocholic acid or cholesterol at a level of 0.01% in the diet (unpublished data). The growth depression caused by tannic acid at a 2% level could not be corrected, even partially, by the addition of methionine and other supplements (unpublished data). This clearly shows that methyl donors along with arginine and ornithine were useful only when the dietary level of tannic acid was 1 % or less. It has been established in rats and rabbits that gallic acid, a hydrolytic product of tannic acid, is decarboxylated to form pyrogallol (Booth et al., 1959). They also
960
G. V. N. RAYUDU, R. KADIRVEL, P. VOHRA AND F. H. KRATZER TABLE S.—Effect of tannic acid and its metabolites on the fat content of liver Treatment
% Fat (Dry weight) Liver 9.81+0.92"1 16.96 + 2.08 b 23.16±1.53 d 9.53±1.65»
Experiment 2 Basal diet + 0 . 5 % Tannic acid -t-0.5% Tannic acid and supplements
9.28±0.70» 10.44±0.72» 11.72 + 0.64"
1
P = 0.01.
acid or tannic acid (Table 5). Pyrogallol did not increase the liver fat. This was in agreement with the studies of Booth et al. (1961) for rats fed gallic acid and pyrogallol. Chang and Fuller (1964) also observed an increase in liver fat in birds fed a tannic acid diet. An addition of methionine and/ or choline along with tannic acid or gallic acid decreased the liver fat (Chang and Fuller, 1964; Booth et al, 1961). In the present study no increase in liver fat was observed in chickens on a 0.5% tannic acid diet. SUMMARY
Pyrocatechol and pyrogallol, the metabolites of tannic acid were growth depressing for chicks even at a dietary level of 0.1% and about 100% mortality was observed when the dietary level of these compounds reached 2%. Tannic acid was less growth depressing than the above compounds and caused no mortality at 2% dietary level. Digallic acid was even less toxic than tannic acid at a level of 0.5% but not at the 1% level. Gallic acid was the least toxic metabolite of tannic acid. A mixture of ar-
REFERENCES Booth, A. N., M. S. Masri, D. J. Robbins, O. H. Emerson, F. T. Jones and F. DeEds, 1959. The metabolic fate of gallic acid and related compounds. J. Biol. Chem. 234: 3014-3016. Booth, A. N., D. J. Robbins and F. DeEds, 1961. Effect of dietary gallic acid and pyrogallol on choline requirement of rats. J. Nutrition, 75: 104-106. Chang, S. I., and H. L. Fuller, 1964. Effect of tannin content of grain sorghums on their feeding value for growing chicks. Poultry Sci. 43: 3036. Dollahite, J. W., R. F. Pigeon and B. J. Camp, 1962. The toxicity of gallic acid, pyrogallol, tannin acid and Quercus havardi in the rabbit. Am. J. Vet. Res. 23 : 1264-1267. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics, 11: 1-42. Fuller, H. L., S. I. Chang and D. K. Potter, 1967. Detoxication of dietary tannic acid by chicks. J. Nutrition, 9 1 : 477-481. Joslyn, M. A., and Z. Glick, 1969. Comparative effects of gallotannic acid and related phenolics on the growth of rats. J. Nutrition, 98: 119126. Kadirvel, R., G. V. N. Rayudu and P. Vohra, 1969. Excretion of metabolites of tannic acid by chickens with and withouc ceca. Poultry Sci. 48: 1511-1513. Potter, D. K., and H. L. Fuller, 1968. Metabolic fate of dietary tannins in chicks. J. Nutrition, 96: 187-191. Vohra, P., F. H. Kratzer and M. A. Joslyn, 1966. The growth depressing and toxic effects of tannins to chicks. Poultry Sci. 45: 135-142.
Downloaded from http://ps.oxfordjournals.org/ at Yale University on May 14, 2015
Experiment 1 Basal diet + Gallic acid 1% +Tannic acid 1% +Pyrogallol 1%
ginine, ornithine and methyl donors like methionine and choline partially alleviated the growth depression induced by tannic acid but were more effective against digallic acid-induced growth depression. The fat content of livers of chicks receiving 1% gallic acid or tannic acid was increased but was not influenced by 1% pyrogallol or 0.5% tannic acid.