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Methionine Excess and Chick Growth1
Methionine Excess and Chick Growth1 PAUL GRIMINGER AND HANS FISHER
Departments of Animal Sciences and Nutrition, Rutgers-The State University, New Brunswick, New Jersey (Received for publication December 27, 1967)
I
floors in electrically heated batteries, and feed consumption and body weights were recorded weekly. Feed and water was available to the chicks at all times, except that the feed was removed 16 hours prior to the final weighing. In the second experiment, 12 groups of 10 females and 12 groups of 10 males of the same breed were given, under similar conditions as in the first experiment, graded levels of the calcium salt of 2-hydroxy-4methylthiobutyric acid (methionine hydroxy-analogue, MHA), containing 79.5% active material (free acid equivalent). In this, as in the following experiments, feed was available to the chicks up to the time of final weighing. In the third test we repeated the feeding of two critical levels of supplementation of DL-methionine and of MHA with female chicks, and in the final experiment DLmethionine was compared at the same levels with L-cystine, using male chicks. In both of these trials, conditions were the same as those decribed before, except that some groups consisted of 20 rather than 10 chicks.
EXPERIMENTAL
RESULTS AND DISCUSSION
In the first experiment, 12 groups of 10 female day-old chicks (Columbian $ X New Hampshire $ ) were fed a conventional starting ration, supplemented with graded levels of DL-methionine, for three weeks. The basal ration contained, by calculation, 22% protein, 0.39% methionine and 0.34% cystine. The chicks were grown on raised wire
Supplementation of the conventional starter ration with 1% or more of DL-methionine caused a growth depression (Table 1). This depression was noticeable at one week of age, becoming more severe as the experiment progressed. At one week of age, the chicks consuming the diet supplemented with 2.4% DL-methionine, the highest level fed, weighed 25% less than the average of the first five, non-depressed lots (0-0.8% DL-methionine supplementation). By two
1 Paper of the Journal Series. New Jersey Agricultural Experiment Station, New Brunswick.
1271
Downloaded from http://ps.oxfordjournals.org/ at Adams State University on April 8, 2015
T IS generally accepted that levels of methionine well beyond those required for growth or maintenance cause toxic effects distinct from those caused by an amino acid imbalance (Anonymous, 1965). In response to an inquiry, we recently searched the literature for information on the level of methionine that would, when added to a conventional starter feed, cause a growth depression in young chicks. We found that little information was available on this subject. The addition of 2.42% L-methionine to an otherwise adequately balanced purified diet had been shown to produce a severe growth depression in young chicks (Boorman and Fisher, 1966). Moderate growth depression was observed by Tamimie (1967) on supplementation of a conventional diet with 1.2% L-methionine. Essentially all other work on methionine toxicity reported in the literature was carried out with rats. Following is a report of several experiments, comparing the effect of graded levels of DL-methionine on chick growth with those of a methionine analogue and of Lcystine.
1272
P. GEIMINGEE AND H. FISHER
TABLE 1.—Body weights {gm.) and coefficients of
variation of three week old chicks receiving graded levels of DL-methionine, calcium methionine hydroxy analogue {MHA), and ^-cystine1 Supplement
DL-methionine
MHA
% of diet
Experiment l2
Experiment 2
2313 212 248 237 236 228 216 198 187 168 162 130
73 9 6 15 13 13 9 14 20 24 32 36
0 1.2 2.4
Experiment 32 255= u 214 IS 128' 41
278* 12
2472
269 264 267 270 272 266 268 255 250 259 243
254 242 245 258 244 252 245 221 240 263 232
10 6 8 17 11 10 7 9 10 8 16
9 11 6 10 9 12 9 10 18 9 8 11
239 18 2365 20
Experiment 4* L-cystine 0 1.2 2.4
2626 9 232 21 144 36
280 7 233 13
1 s 3
Ten chicks per lot, except when stated otherwise. Female chicks. Average weight (gm.) at three weeks of age, and the coefficient of variation. 4 Male chicks. 5 20 chicks per lot.
weeks, this difference had risen to 40%, and by 3 weeks to 44%. As the level of methionine supplementation increased, the coefficient of variation of the body weights at each level also increased. Apparently there are marked individual differences in the chicks' ability to tolerate methionine overdoses, just as there are differences in the ability of chicks to withstand certain amino acid deficiencies (Griminger and Fisher, 1962). The calcium salt of MHA did not depress growth severely, nor was there a noticeable increase in the coefficient of variation with high levels of the compound. There was a mild growth depression at the highest levels of MHA fed to male chicks, but none with the slightly slower growing females. This general lack of depressive effect was confirmed in the third experiment, where doubling of the DL-methionine supplement to female chicks (from 1.2 to 2.4%) caused
Downloaded from http://ps.oxfordjournals.org/ at Adams State University on April 8, 2015
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.4
weight reductions of over 40%, while doubling the MHA supplement did not effect any significant change. In the last test, the doubling of DL-methionine reduced the threeweek weights of male chicks by 38%, while equal levels, by weight, of L-cystine reduced body weights by less than half that amount. The Ca-MHA used provides only 79.5% methionine-active material. On a molar basis, MHA has been considered either to equal methionine in promoting growth of young chicks (Calet and Melot, 1961), or to be somewhat inferior (Marrett and Sunde, 196S; Tipton et al., 1966). Thus, 2.4% MHA would have to be compared to slightly less than 2% DL-methionine. Even when compared in this manner, however, MHA caused a significantly smaller growth depression than methionine. According to Benevenga and Harper (1967), who studied methionine toxicity in the rat, it is not possible at this stage to conclude that one portion of the methionine molecule is more important than another in methionine toxicity. As far as our findings are concerned, cystine, which contains approximately 24% more sulfur than an equal amount of methionine, was found to be less toxic than methionine; thus, the sulfur content per se apparently does not play a decisive role in methionine toxicity. Since MHA is essentially non-toxic at the levels used, it is tempting to speculate on the role of excessive amino nitrogen. However, other amino acids at comparable levels do not have the same effect as methionine (Boorman and Fisher, 1966). This leaves the methyl group of methionine for consideration; this group, however, is also found in the non-toxic MHA. Perhaps the toxicity depends on the simultaneous presence of a methyl and an amino group, as in the intact methionine molecule. According to the in vitro studies of Gordon and Sizer (1965), MHA can be converted by chick liver to keto-methionine,
1273
EXCESS METHIONINE
SUMMARY The supplementation of a conventional starter ration with 1% or more of DL-methionine depressed growth in young chicks. Supplementation with the Ca-salt of methionine hydroxy analogue (MHA) up to
2
Feed intake and feed efficiency data will be provided on request.
2.4% had little effect on growth. L-cystine at 2.4% depressed growth, but much less so than similar quantities of DL-methionine. It is hypothesized that the lower toxicity of MHA may be related to quantitative limitations in the conversion of MHA to methionine. REFERENCES Anonymous, 1965. The toxic effect of methionine. Nutr. Revs. 23 : 202-204. Benevenga, N. J., and A. E. Harper, 1967. Alleviation of methionine and homocystine toxicity in the rat. J. Nutrition, 93: 44-52. Boorman, K. N., and H. Fisher, 1966. The arginine-lysine interaction in the chick. Brit. Poultry Sci. 7: 39-44. Calet, C , and M. Melot, 1961. Efficacite comparee pour la croissance du poussin de la methionine et du sel de calcium de l'acide hydroxymethylthiobutyrique (MHA). Ann Zootech. 10: 205213. Gordon, R. S., and I. W. Sizer, 1965. Conversion of methionine hydroxy analogue to methionine in the chick. Poultry Sci. 44:673-678. Griminger, P., and H. Fisher, 1962. Genetic differences in growth potential on amino acid deficient diets. Proc. Soc. Exp. Biol. Med. I l l : 754-756. Marrett, L. E., and M. L. Sunde, 1965. The effect of other D amino acids on the utilization of the isomers of methionine and its hydroxy analogue. Poultry Sci. 44: 957-964. Tamimie, H. S., 1967. Influence of niacin and t tryptophan on the growth depressive performance of chicks fed high levels of ^phenylalanine and L-methionine. Life Sci. 6: 587-594. Tipton, H. G, 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.
NEWS AND NOTES (Continued from page 1257) Bologna of Italy, renowned publishers of leading agricultural books and journals. Involving upwards of 90,000 words this multilingual Dictionary will occupy some 400 pages with a type measurement per page 8 X 5 inches. The work opens with a 10,000 word four-lan-
guage vocabulary of 1,680 terms and is followed by Glossaries, Alphabetical Lists, and Lists of Group Terms, again in all four languages. A novel system of coding enables users to turn from one language to another quite easily for cross translation. The Dictionary is expected to be published in
(Continued on page 1302)
Downloaded from http://ps.oxfordjournals.org/ at Adams State University on April 8, 2015
and the keto acid transaminated to methionine. The lower toxicity of MHA might well be due to rate limitations in the in vivo conversion of MHA to methionine, thus resulting in less available methionine at a given time when it is fed in this form. Clearly, MHA has to be converted to take part in protein synthesis. Were there no quantitative limitations to this conversion, one might expect a similar degree of toxicity for methionine and MHA, unless the animals were reacting to the specific taste of methionine by lower feed intake. This has not been reported to be the case. Differences in feed intake2 essentially paralleled differences in body weights. Efficiency of feed conversion, calculated as gm. of gain per gm. of feed, was affected by high doses of DL-methionine, but not by high doses of MHA or cystine. Since in the calculation of feed efficiency the amount of feed utilized for maintenance purposes is disregarded, chicks with a significantly slower rate of growth naturally have poorer feed conversion.
Departments of Animal Sciences and Nutrition, Rutgers-The State University, New Brunswick, New Jersey (Received for publication December 27, 1967)
I
floors in electrically heated batteries, and feed consumption and body weights were recorded weekly. Feed and water was available to the chicks at all times, except that the feed was removed 16 hours prior to the final weighing. In the second experiment, 12 groups of 10 females and 12 groups of 10 males of the same breed were given, under similar conditions as in the first experiment, graded levels of the calcium salt of 2-hydroxy-4methylthiobutyric acid (methionine hydroxy-analogue, MHA), containing 79.5% active material (free acid equivalent). In this, as in the following experiments, feed was available to the chicks up to the time of final weighing. In the third test we repeated the feeding of two critical levels of supplementation of DL-methionine and of MHA with female chicks, and in the final experiment DLmethionine was compared at the same levels with L-cystine, using male chicks. In both of these trials, conditions were the same as those decribed before, except that some groups consisted of 20 rather than 10 chicks.
EXPERIMENTAL
RESULTS AND DISCUSSION
In the first experiment, 12 groups of 10 female day-old chicks (Columbian $ X New Hampshire $ ) were fed a conventional starting ration, supplemented with graded levels of DL-methionine, for three weeks. The basal ration contained, by calculation, 22% protein, 0.39% methionine and 0.34% cystine. The chicks were grown on raised wire
Supplementation of the conventional starter ration with 1% or more of DL-methionine caused a growth depression (Table 1). This depression was noticeable at one week of age, becoming more severe as the experiment progressed. At one week of age, the chicks consuming the diet supplemented with 2.4% DL-methionine, the highest level fed, weighed 25% less than the average of the first five, non-depressed lots (0-0.8% DL-methionine supplementation). By two
1 Paper of the Journal Series. New Jersey Agricultural Experiment Station, New Brunswick.
1271
Downloaded from http://ps.oxfordjournals.org/ at Adams State University on April 8, 2015
T IS generally accepted that levels of methionine well beyond those required for growth or maintenance cause toxic effects distinct from those caused by an amino acid imbalance (Anonymous, 1965). In response to an inquiry, we recently searched the literature for information on the level of methionine that would, when added to a conventional starter feed, cause a growth depression in young chicks. We found that little information was available on this subject. The addition of 2.42% L-methionine to an otherwise adequately balanced purified diet had been shown to produce a severe growth depression in young chicks (Boorman and Fisher, 1966). Moderate growth depression was observed by Tamimie (1967) on supplementation of a conventional diet with 1.2% L-methionine. Essentially all other work on methionine toxicity reported in the literature was carried out with rats. Following is a report of several experiments, comparing the effect of graded levels of DL-methionine on chick growth with those of a methionine analogue and of Lcystine.
1272
P. GEIMINGEE AND H. FISHER
TABLE 1.—Body weights {gm.) and coefficients of
variation of three week old chicks receiving graded levels of DL-methionine, calcium methionine hydroxy analogue {MHA), and ^-cystine1 Supplement
DL-methionine
MHA
% of diet
Experiment l2
Experiment 2
2313 212 248 237 236 228 216 198 187 168 162 130
73 9 6 15 13 13 9 14 20 24 32 36
0 1.2 2.4
Experiment 32 255= u 214 IS 128' 41
278* 12
2472
269 264 267 270 272 266 268 255 250 259 243
254 242 245 258 244 252 245 221 240 263 232
10 6 8 17 11 10 7 9 10 8 16
9 11 6 10 9 12 9 10 18 9 8 11
239 18 2365 20
Experiment 4* L-cystine 0 1.2 2.4
2626 9 232 21 144 36
280 7 233 13
1 s 3
Ten chicks per lot, except when stated otherwise. Female chicks. Average weight (gm.) at three weeks of age, and the coefficient of variation. 4 Male chicks. 5 20 chicks per lot.
weeks, this difference had risen to 40%, and by 3 weeks to 44%. As the level of methionine supplementation increased, the coefficient of variation of the body weights at each level also increased. Apparently there are marked individual differences in the chicks' ability to tolerate methionine overdoses, just as there are differences in the ability of chicks to withstand certain amino acid deficiencies (Griminger and Fisher, 1962). The calcium salt of MHA did not depress growth severely, nor was there a noticeable increase in the coefficient of variation with high levels of the compound. There was a mild growth depression at the highest levels of MHA fed to male chicks, but none with the slightly slower growing females. This general lack of depressive effect was confirmed in the third experiment, where doubling of the DL-methionine supplement to female chicks (from 1.2 to 2.4%) caused
Downloaded from http://ps.oxfordjournals.org/ at Adams State University on April 8, 2015
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.4
weight reductions of over 40%, while doubling the MHA supplement did not effect any significant change. In the last test, the doubling of DL-methionine reduced the threeweek weights of male chicks by 38%, while equal levels, by weight, of L-cystine reduced body weights by less than half that amount. The Ca-MHA used provides only 79.5% methionine-active material. On a molar basis, MHA has been considered either to equal methionine in promoting growth of young chicks (Calet and Melot, 1961), or to be somewhat inferior (Marrett and Sunde, 196S; Tipton et al., 1966). Thus, 2.4% MHA would have to be compared to slightly less than 2% DL-methionine. Even when compared in this manner, however, MHA caused a significantly smaller growth depression than methionine. According to Benevenga and Harper (1967), who studied methionine toxicity in the rat, it is not possible at this stage to conclude that one portion of the methionine molecule is more important than another in methionine toxicity. As far as our findings are concerned, cystine, which contains approximately 24% more sulfur than an equal amount of methionine, was found to be less toxic than methionine; thus, the sulfur content per se apparently does not play a decisive role in methionine toxicity. Since MHA is essentially non-toxic at the levels used, it is tempting to speculate on the role of excessive amino nitrogen. However, other amino acids at comparable levels do not have the same effect as methionine (Boorman and Fisher, 1966). This leaves the methyl group of methionine for consideration; this group, however, is also found in the non-toxic MHA. Perhaps the toxicity depends on the simultaneous presence of a methyl and an amino group, as in the intact methionine molecule. According to the in vitro studies of Gordon and Sizer (1965), MHA can be converted by chick liver to keto-methionine,
1273
EXCESS METHIONINE
SUMMARY The supplementation of a conventional starter ration with 1% or more of DL-methionine depressed growth in young chicks. Supplementation with the Ca-salt of methionine hydroxy analogue (MHA) up to
2
Feed intake and feed efficiency data will be provided on request.
2.4% had little effect on growth. L-cystine at 2.4% depressed growth, but much less so than similar quantities of DL-methionine. It is hypothesized that the lower toxicity of MHA may be related to quantitative limitations in the conversion of MHA to methionine. REFERENCES Anonymous, 1965. The toxic effect of methionine. Nutr. Revs. 23 : 202-204. Benevenga, N. J., and A. E. Harper, 1967. Alleviation of methionine and homocystine toxicity in the rat. J. Nutrition, 93: 44-52. Boorman, K. N., and H. Fisher, 1966. The arginine-lysine interaction in the chick. Brit. Poultry Sci. 7: 39-44. Calet, C , and M. Melot, 1961. Efficacite comparee pour la croissance du poussin de la methionine et du sel de calcium de l'acide hydroxymethylthiobutyrique (MHA). Ann Zootech. 10: 205213. Gordon, R. S., and I. W. Sizer, 1965. Conversion of methionine hydroxy analogue to methionine in the chick. Poultry Sci. 44:673-678. Griminger, P., and H. Fisher, 1962. Genetic differences in growth potential on amino acid deficient diets. Proc. Soc. Exp. Biol. Med. I l l : 754-756. Marrett, L. E., and M. L. Sunde, 1965. The effect of other D amino acids on the utilization of the isomers of methionine and its hydroxy analogue. Poultry Sci. 44: 957-964. Tamimie, H. S., 1967. Influence of niacin and t tryptophan on the growth depressive performance of chicks fed high levels of ^phenylalanine and L-methionine. Life Sci. 6: 587-594. Tipton, H. G, 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.
NEWS AND NOTES (Continued from page 1257) Bologna of Italy, renowned publishers of leading agricultural books and journals. Involving upwards of 90,000 words this multilingual Dictionary will occupy some 400 pages with a type measurement per page 8 X 5 inches. The work opens with a 10,000 word four-lan-
guage vocabulary of 1,680 terms and is followed by Glossaries, Alphabetical Lists, and Lists of Group Terms, again in all four languages. A novel system of coding enables users to turn from one language to another quite easily for cross translation. The Dictionary is expected to be published in
(Continued on page 1302)
Downloaded from http://ps.oxfordjournals.org/ at Adams State University on April 8, 2015
and the keto acid transaminated to methionine. The lower toxicity of MHA might well be due to rate limitations in the in vivo conversion of MHA to methionine, thus resulting in less available methionine at a given time when it is fed in this form. Clearly, MHA has to be converted to take part in protein synthesis. Were there no quantitative limitations to this conversion, one might expect a similar degree of toxicity for methionine and MHA, unless the animals were reacting to the specific taste of methionine by lower feed intake. This has not been reported to be the case. Differences in feed intake2 essentially paralleled differences in body weights. Efficiency of feed conversion, calculated as gm. of gain per gm. of feed, was affected by high doses of DL-methionine, but not by high doses of MHA or cystine. Since in the calculation of feed efficiency the amount of feed utilized for maintenance purposes is disregarded, chicks with a significantly slower rate of growth naturally have poorer feed conversion.