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Interaction of Dietary Nutrient Concentration and Supplemental Copper on Chick Performance and Tissue Copper Concentrations1
Interaction of Dietary Nutrient Concentration and Supplemental Copper on Chick Performance and Tissue Copper Concentrations 1 D. R. LEDOUX,2 R. D. MILES, 34 C. B. AMMERMAN,2 and R. H. HARMS3 Departments of Poultry Science and Animal Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida 32611 (Received for publication December 1, 1986)
1987 Poultry Science 66:1379-1384 INTRODUCTION
It is well established that dietary concentrations of Cu in excess of 250 mg/kg often result in reduced feed intake and growth of broilers (Jensen and Maurice, 1979; Robbins and Baker, 1980a,b; Christmas and Harms, 1984). This reduction in performance has traditionally been attributed to Cu toxicosis per se. However, Jensen and Maurice (1979) and Christmas and Harms (1979, 1984) were able to show that the growth-depressing effect of Cu could be alleviated with supplemental methionine (MET). Robbins and Baker (1980a) demonstrated that supplemental amino acids, minerals, and vitamins could overcome the growth depression observed when chicks were fed 500 mg/kg Cu in a purified diet. These results led Christmas and Harms (1984) to postulate that the growth de-
1 Florida Agricultural Experiment Stations Journal Series Number 7754. 2 Department of Animal Science. 3 Department of Poultry Science. "To whom correspondence should be addressed.
pression observed in chicks fed high levels of Cu may be the result of two separate factors: 1) a nutrient deficiency resulting from reduced feed intake, and 2) Cu toxicosis per se. This study was conducted to investigate the influence of high dietary Cu in combination with supplemental MET and selected nutrient supplementation (SN) on broiler performance and tissue Cu concentrations.
MATERIALS AND METHODS
Subjects were 576 1-day-old Cobb feathersexed female chicks used in a 3 x 2 x 2 factorial arrangement of treatments. The basal diet (Table 1) contained 12 mg Cu/kg (by analysis). Treatments included 0, 400, or 800 mg Cu/kg as copper sulfate (CuSCy5H20), Oor .4% MET, and 0 or 20% SN (Table 1) added to the basal diet. Six replicate pens of eight chicks were assigned to each of the 12 treatments. Chicks were housed in electrically-heated Petersime batteries. Chicks were allowed ad libitum access to feed and water and were maintained on a 24-h constant-light schedule.
1379
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ABSTRACT An experiment was conducted with 576 female Cobb feather-sexed chicks to study the influence of methionine (MET) and selected nutrient (SN) supplementation on the performance of chicks fed high Cu levels. Day-old chicks were allotted randomly to pens for the 22-day experiment. A 3 x 2 x 2 factorial arrangement of treatments was used which included Cu at 0, 400, and 800 mg/kg, MET at 0 and .4%, and SN at 0 and 20%. A significant (P<.001) Cu x MET x SN interaction was found for gain. Supplemental MET reversed the growth depression observed in birds fed 400 but not 800 mg/kg Cu. Additions of 400 and 800 mg/kg Cu to the basal diet depressed (P<.001) feed consumption by 8.6 and 19.4%, respectively. Hepatic Cu concentrations increased linearly (P<.001) with increasing dietary Cu and were not influenced (P>. 10) by supplemental MET or SN. Liver weights increased linearly (P<.001) with increasing dietary Cu and were higher (P<.05) for chicks on diets supplemented with SN, but lower (P<.05) for those with diets supplemented with MET. The interaction of MET x SN was significant (P<.001) for serum Cu; chicks supplemented with SN in conjunction with MET had the lowest (P<.05) serum Cu concentrations. Serum glutamicoxaloacetic transaminase (SGOT) activity was not influenced (P>. 10) by dietary Cu, but SN supplementation resulted in a 10% elevation (P<.001) in SGOT activity. Results indicated that the reduction in performance caused by high dietary Cu may not always be due to Cu per se, but may be due to nutrient deficiency as a result of reduced feed intake. (Key words: copper, methionine, nutrients, performance, chicks)
1380
LEDOUX ET AL. TABLE 1. Composition of basal diet1
Ingredients
Percent
Ground yellow corn Soybean meal, dehulled (48.5% crude protein) Corn oil Limestone, ground Dicalcium phosphate (18.5% P, 22% Ca) Salt, iodized Microingredients5 Filler, washed sand 3 ' 4
45.60 41.00 6.60
1.30 1.45 .40 .50 3.15
Total 1
100.00
As-fed basis.
2
3 Selected nutrients added per kilogram of diet: folic acid, 1.21 mg; pyridoxine hydrochloride, 6.6 mg; biotin, .22 mg; lysine, 150 g; potassium magnesium sulfate, 1 g; salt, 20% increase; phosphorus, 20% increase; calcium, 20% increase; microingredients, 20% increase. 4
Selected nutrients and dietary additions substituted for equivalent weights of washed sand.
On Day 22, chicks were weighed individually and feed consumption was determined per pen. Three chicks from each pen were randomly selected, killed by cervical dislocation, and their livers excised, blotted dry, weighed, then frozen in heat-sealed polyethylene bags for subsequent mineral analysis. Blood was collected by anterior cardiac puncture from two chicks per pen selected randomly from the remaining five chicks for determination of serum Cu and serum glutamic-oxaloacetic transaminase (SGOT) activity. Feed and tissue Cu were determined by flame atomic absorption spectrophotometry on a Perkin-Elmer Model 5000 spectrophotometer with an AS-50 Autosampler (Anonymous, 1982). The SGOT activity was estimated using Fisher GOT Kits (Fisher Scientific Company, Fair Lawn, NJ). Data were analyzed by analysis of variance procedures by the general linear models procedure of the Statistical Analysis System Institute, Inc. (1982). RESULTS
Mean body weight gain, feed consumption, and feed conversion of chicks fed each diet for 22 days are presented in Table 2. There was a significant (P<.001) Cu x MET x SN interaction for gain. This resulted from differences in response to supplemental MET and SN at each dietary Cu level. With no added Cu, there were no differences (P<.10) in gain due to supple-
mental MET or SN. At 400 mg/kg added Cu, chicks fed MET gained 10% more (P<.001) than those not receiving MET, resulting in a restoration in growth equal to that observed in control birds. For chicks fed 800 mg Cu/kg diet, there was an interaction (P< .001) between MET and SN, with chicks fed MET in the presence or absence of SN having higher gains, while chicks fed SN in the absence of MET gained less (345 g) than those not fed SN (380 g). Additions of 400 and 800 mg Cu/kg to the basal diet depressed (P<.001) feed consumption by 8.6 and 19.4%, respectively (Table 2). Within dietary Cu concentrations there were no differences (P>.10) in intake, indicating that SN and MET failed to affect intake. The interaction for Cu x MET was significant (P<.05) for feed efficiency (Table 2). In the absence of MET, birds fed 400 and 800 mg Cu/kg were less efficient than control birds (no added Cu). However, in the presence of MET, birds fed 400 mg Cu/kg were as efficient as control birds, while those fed 800 mg Cu/kg were less efficient. Liver Cu concentrations and liver weights (g/100 g body weight) as influenced by dietary treatments are shown in Table 3. Liver Cu concentrations were not influenced (P>.10) by MET or SN supplementation. However, increasing dietary Cu concentration resulted in a linear increase (P<.001) in liver Cu. Liver weights increased linearly (P<.001) with increasing di-
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Supplied per kilogram of diet: vitamin A palmitate, 6,600 IU; vitamin D 3 , 2,000 ICU; menadione dimethylpyrimidinol bisulfite, 2.2 mg; riboflavin, 4.4 mg; pantothenic acid, 13.2 mg; niacin, 39.6 mg; choline chloride, 500 mg; vitamin B 1 2 , .022 mg; ethoxyquin, 125 mg; manganese, 60 mg; iron, 50 mg; copper, 6 mg; iodine, 1.1 mg; zinc, 35 mg.
0 400 800
Feed conversion, g feed/g gain3
± 7.3 ± 10.0 ± 8.0
1.58 ± 1.69 ± 1.87 ±
.01 .05 .08
5
4
3
Each value represents the mean ± standard error of six pens, eight chicks per pen.
Significant interaction of copper X methionine (P<.05).
Significant effect of copper (P-C001).
± ± ±
+ ± ±
8.10 1.20 .73
7.6 8.1 7.9
1.54 ± .02 1.54 ± .02 1.67 ± .02
37.9 37.5 30.7
543 537 405
.4% MET
0 Added nutrients
39.7 ± .54 36.3 ± .66 32.0 ± 2.20
552 474 380
OMET
'Significant interaction of copper X methionine X selected nutrients (P<.001).
Each value represents the mean ± standard error of 48 chicks.
0 400 800
Daily feed consumption, g3
1
0 400 800
(mg/kg)
Added Cu
Body weight gain, g1
Production parameter
TABLE 2. Body weight gain, feed consumption, and feed conversion of broiler chicks fed 0, 400, o 0 and .4% added methionine (MET) and 0 and 20% added selected nut
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LEDOUX ET AL.
1382
etary Cu and were higher (P<.05) for chicks supplemented with SN, but lower (P<.05) for those supplemented with MET. Table 4 contains a summary of the influence of dietary treatments on serum Cu and SGOT activity. There was a significant (P<.001) MET X SN interaction for serum Cu. Chicks fed diets supplemented with both MET and SN had lower serum Cu concentrations than those fed no supplement or those fed either MET or SN alone. The SGOT activity, used in this study as an indicator of Cu toxicosis per se, was not influenced (P>. 10) by dietary Cu or MET. Selected nutrient supplementation, however, caused a 10% elevation (P<.001) in SGOT activity for those receiving excess Cu.
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Addition of MET to the basal diet (zero added Cu) resulted in no improvement in gain, indicating that the basal diet was not deficient in sulfuramino acids (SAA). Depressions in intake and gain with increasing dietary Cu observed in this study are congruent with those found in previous reports (Christmas and Harms, 1979, 1984; Jensen and Maurice, 1979; Robbins and Baker, 1980a,b). The ability of MET to alleviate the growth depressing effect of Cu has also been reported previously (Jensen and Maurice, 1979; Christmas and Harms, 1979, 1984). In the present study MET completely restored growth and feed efficiency in chicks fed 400 mg/kg Cu and improved growth by 14.2% for those fed 800 mg/kg Cu. The failure of SN and success of MET in reversing the growth depression in chicks fed 400 mg/kg Cu may indicate that SAA become the first-limiting factor in corn-soybean diets containing high Cu concentrations. Evidence of this is provided by the way chicks fed 800 mg/kg Cu responded to MET and SN supplementation. Supplemental MET improved gains by 6.2%, and addition of SN in the presence of added MET produced a further improvement in gain of 8.2%. These results confirm findings of Robbins and Baker (1980a,b) who reported that chicks fed high dietary levels of Cu (>250 mg/kg) have an increased SAA requirement. Using a semi-purified diet, Robbins and Baker also demonstrated that cysteine was more effective than cystine or MET in reversing growth depression in chicks fed high dietary Cu levels. The increase in hepatic Cu concentrations observed in this study is consistent with that ob-
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COPPER AND NUTRIENT INTERACTION
1383
TABLE 4. Serum Cu and glutamic oxaloacetic transaminase (SGOT) concentrations of broiler chicks fed 0, 400 or 800 ppm Cu in combination with 0 and .4% added methionine (MET) and 0 and 20% added selected nutrients 0 Added nutrients Parameter
A d d e d Cu
OMET
.4% MET
20% A d d e d n u t r i e n t s OMET
.4% M E T
(mg/kg) Serum copper, g / 1 0 0 m L
SGOT, IU/L 1 ' 3 - 4
,,!
0 400 800 0 400 800
38.7 ± 4.4 38.1 ± 3.2 4 4 . 3 ± 3.7 139 119 117
±7.9 ± 7.7 ±4.9
32.8 ± 3.0 37.9 ± 2.8 38.9 ± 2.9 123 117 113
Each value represents the mean ± standard error of 12 chicks.
2
Significant interaction of methionine X selected nutrients (P<.001).
3
Significant effect of selected nutrients (P<.001).
138 135 127
±6.3 ±5.7 ± 7.4
18.1 ± 1.3 2 0 . 7 ± 1.5 2 5 . 6 ± 2.1 135 138 137
±6.2 ±5.9 ± 8.3
4
One IU represents the oxidation of one micromole of nicotinamide adenine dinucleotide reduced per minute at 30 C.
served in previous research (Jensen and Maurice, 1979; Robbins and Baker, 1980a,b; Nam etal., 1984). The influence of MET supplementation on hepatic Cu concentration remains disputed. Jensen and Maurice (1979) found that .4% MET significantly reduced hepatic Cu concentrations in birds fed 500 and 750 mg/kg Cu. In studies by Robbins and Baker (1980a,b), supplemental MET reduced hepatic Cu concentrations at 250 but not at 500 mg Cu/kg. Recently Nam etal. (1984) reported that additional MET failed to reduce hepatic Cu in birds fed 500 and 1,000 mg Cu/kg even when MET was added at 2% of the diet. Results of the present study confirm findings of Robbins and Baker (1980a,b) and Nam et al. (1984) and may indicate that MET does not reduce absorption of Cu in chicks as has been suggested by Jensen and Maurice (1979). Other workers (Pearce et al., 1983; Stevenson et al., 1983) indicated that high dietary concentrations of Cu fed to laying hens resulted in decreased liver weights. This reduction in liver weight was attributed to reduced feed intake, since force-fed birds showed an increase in liver weights. In this study liver weights indicated that in broiler chicks, unlike laying hens, increasing dietary Cu resulted in an increase in liver weights. These results, however, should be interpreted with caution as previous reports have demonstrated that small chicks have a higher liver weight when expressed as a percentage of body weight than large chicks of equal
age regardless of dietary treatments imposed (Leeson and Summers, 1980; Plavnik and Hurwitz, 1982; Southerner al., 1984; Brown et al., 1985). Therefore, it appears that, as with the layers, observed differences were the result of reduced feed intake. The significantly lower serum Cu concentrations observed in chicks fed MET in conjunction with SN may, in part, be the result of an interrelationship between MET and sulfate (included as a component of SN). Martin (1972) reported that dietary sulfate was utilized by chicks to synthesize taurine and that in the presence of MET there was increased synthesis. Taurine as an essential component of bile salts may well play a role in enhancing biliary excretion of Cu, resulting in lower serum Cu levels. In an attempt to determine if Cu toxicosis per se was occurring, activity of the serum enzyme glutamic-oxaloacetic transaminase (GOT) was determined. A marked rise in GOT activity is indicative of organ damage and would provide evidence of Cu toxicosis per se. Failure of dietary Cu to affect SGOT activity, indicated that Cu toxicosis per se was not occurring, and although SN supplementation resulted in increased SGOT activity, levels were well within normal ranges reported in the literature (Dalvi and McGowan, 1984; Madhusudhan et al., 1986). It is concluded that the reduction in performance observed in this study was primarily due to a copper-mediated reduction in feed intake and not to copper toxicosis per se.
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1
± 7.6 ±5.3 ±7.9
4 4 . 3 ± 2.8 4 0 . 4 ± 6.1 33.3 ± 2.8
LEDOUX ET AL.
1384 REFERENCES
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Anonymous, 1982. Analytical Methods for Atomic Absorption Spectrophotometry. The Perkin-Elmer Corp., Norwalk, CT. Brown D. R., L. L. Southern, and D. H. Baker, 1985. A comparison of methods for organ-weight data adjusted in chicks. Poultry Sci. 64:366-369. Christmas, R. B., and R. H. Harms, 1979. The effect of supplemental copper and methionine on the performance of turkey poults. Poultry Sci. 58:382-384. Christmas, R. B., and R. H. Harms, 1984. The value of protein, methionine or other nutrients for the alleviation of copper toxicity in the broiler chick diet. Nutr. Rep. Int. 29:1217-1222. Dalvi, R. R., andC. McGowan, 1984. Experimental induction of chronic aflatoxicosis in chickens by purified aflatoxin B,, and its reversal by activated charcoal, phenobarbital and reduced glutathione. Poultry Sci. 63:485^91. Jensen, L. S., and D. V. Maurice, 1979. Influence of sulfur amino acids on copper toxicity in chicks. J. Nutr. 109:91-97. Leeson, S., and J. D. Summers, 1980. Production and carcass characteristics of the broiler chicken. Poultry Sci. 59:786-798. Madhusudhan, K. T., H. P. Ramesh, T. Ogawa, K. Sasaoka, and N. Singh, 1986. Detoxification of commercial linseed meal for use in broiler rations. Poultry Sci. 65:164-171. Martin, W. G., 1972. Sulphate metabolism and taurine synthesis in the chick. Poultry Sci. 51:608-612.
Nam, D. S., I. K. Han, and J. D. Kim, 1984. Effects of supplemental copper and excess dietary methionine on the growing performance of broiler chicks. Korean J. Anim. Sci. 26:621-630. Pearce, J., N. Jackson, and M. H. Stevenson, 1983. The effects of dietary intake and of dietary concentration of copper sulphate on the laying domestic fowl: Effects on some aspects of lipid, carbohydrate and amino acid metabolism. Br. Poult. Sci. 24:337-348. Plavnik, I., and S. Hurwitz, 1983. Organ weights and body composition in chickens as related to the energy and amino acid requirements: Effects of strain, sex and age. Poultry Sci. 62:152-163. Robbins, K. R., and D. H. Baker, 1980a. Effect of highlevel copper feeding on the sulfur amino acid need of chicks fed corn-soybean meal and purified crystalline amino acid diets. Poultry Sci. 59:1099-1108. Robbins, K. R., and D. H. Baker, 1980b. Effect of sulfur amino acid level and source on the performance of chicks fed high levels of copper. Poultry Sci. 59:12461253. Statistical Analysis Systems Institute, Inc., 1982. SAS User's Guide: Statistics. 1982 ed. SAS Inst., Cary, NC. Southern, L. L., D. H. Baker, and D. D. Schmeisser, 1984. Eimeria acervulina infection during aflatoxicosis in the chick. Nutr. Rep. Int. 29:35^15. Stevenson, M. H., J. Pearce, and N. Jackson, 1983. The effects of dietary intake and of dietary concentration of copper sulphate on the laying domestic fowl: Effects on laying performance and tissue mineral contents. Br. Poult. Sci. 24:327-335.
1987 Poultry Science 66:1379-1384 INTRODUCTION
It is well established that dietary concentrations of Cu in excess of 250 mg/kg often result in reduced feed intake and growth of broilers (Jensen and Maurice, 1979; Robbins and Baker, 1980a,b; Christmas and Harms, 1984). This reduction in performance has traditionally been attributed to Cu toxicosis per se. However, Jensen and Maurice (1979) and Christmas and Harms (1979, 1984) were able to show that the growth-depressing effect of Cu could be alleviated with supplemental methionine (MET). Robbins and Baker (1980a) demonstrated that supplemental amino acids, minerals, and vitamins could overcome the growth depression observed when chicks were fed 500 mg/kg Cu in a purified diet. These results led Christmas and Harms (1984) to postulate that the growth de-
1 Florida Agricultural Experiment Stations Journal Series Number 7754. 2 Department of Animal Science. 3 Department of Poultry Science. "To whom correspondence should be addressed.
pression observed in chicks fed high levels of Cu may be the result of two separate factors: 1) a nutrient deficiency resulting from reduced feed intake, and 2) Cu toxicosis per se. This study was conducted to investigate the influence of high dietary Cu in combination with supplemental MET and selected nutrient supplementation (SN) on broiler performance and tissue Cu concentrations.
MATERIALS AND METHODS
Subjects were 576 1-day-old Cobb feathersexed female chicks used in a 3 x 2 x 2 factorial arrangement of treatments. The basal diet (Table 1) contained 12 mg Cu/kg (by analysis). Treatments included 0, 400, or 800 mg Cu/kg as copper sulfate (CuSCy5H20), Oor .4% MET, and 0 or 20% SN (Table 1) added to the basal diet. Six replicate pens of eight chicks were assigned to each of the 12 treatments. Chicks were housed in electrically-heated Petersime batteries. Chicks were allowed ad libitum access to feed and water and were maintained on a 24-h constant-light schedule.
1379
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ABSTRACT An experiment was conducted with 576 female Cobb feather-sexed chicks to study the influence of methionine (MET) and selected nutrient (SN) supplementation on the performance of chicks fed high Cu levels. Day-old chicks were allotted randomly to pens for the 22-day experiment. A 3 x 2 x 2 factorial arrangement of treatments was used which included Cu at 0, 400, and 800 mg/kg, MET at 0 and .4%, and SN at 0 and 20%. A significant (P<.001) Cu x MET x SN interaction was found for gain. Supplemental MET reversed the growth depression observed in birds fed 400 but not 800 mg/kg Cu. Additions of 400 and 800 mg/kg Cu to the basal diet depressed (P<.001) feed consumption by 8.6 and 19.4%, respectively. Hepatic Cu concentrations increased linearly (P<.001) with increasing dietary Cu and were not influenced (P>. 10) by supplemental MET or SN. Liver weights increased linearly (P<.001) with increasing dietary Cu and were higher (P<.05) for chicks on diets supplemented with SN, but lower (P<.05) for those with diets supplemented with MET. The interaction of MET x SN was significant (P<.001) for serum Cu; chicks supplemented with SN in conjunction with MET had the lowest (P<.05) serum Cu concentrations. Serum glutamicoxaloacetic transaminase (SGOT) activity was not influenced (P>. 10) by dietary Cu, but SN supplementation resulted in a 10% elevation (P<.001) in SGOT activity. Results indicated that the reduction in performance caused by high dietary Cu may not always be due to Cu per se, but may be due to nutrient deficiency as a result of reduced feed intake. (Key words: copper, methionine, nutrients, performance, chicks)
1380
LEDOUX ET AL. TABLE 1. Composition of basal diet1
Ingredients
Percent
Ground yellow corn Soybean meal, dehulled (48.5% crude protein) Corn oil Limestone, ground Dicalcium phosphate (18.5% P, 22% Ca) Salt, iodized Microingredients5 Filler, washed sand 3 ' 4
45.60 41.00 6.60
1.30 1.45 .40 .50 3.15
Total 1
100.00
As-fed basis.
2
3 Selected nutrients added per kilogram of diet: folic acid, 1.21 mg; pyridoxine hydrochloride, 6.6 mg; biotin, .22 mg; lysine, 150 g; potassium magnesium sulfate, 1 g; salt, 20% increase; phosphorus, 20% increase; calcium, 20% increase; microingredients, 20% increase. 4
Selected nutrients and dietary additions substituted for equivalent weights of washed sand.
On Day 22, chicks were weighed individually and feed consumption was determined per pen. Three chicks from each pen were randomly selected, killed by cervical dislocation, and their livers excised, blotted dry, weighed, then frozen in heat-sealed polyethylene bags for subsequent mineral analysis. Blood was collected by anterior cardiac puncture from two chicks per pen selected randomly from the remaining five chicks for determination of serum Cu and serum glutamic-oxaloacetic transaminase (SGOT) activity. Feed and tissue Cu were determined by flame atomic absorption spectrophotometry on a Perkin-Elmer Model 5000 spectrophotometer with an AS-50 Autosampler (Anonymous, 1982). The SGOT activity was estimated using Fisher GOT Kits (Fisher Scientific Company, Fair Lawn, NJ). Data were analyzed by analysis of variance procedures by the general linear models procedure of the Statistical Analysis System Institute, Inc. (1982). RESULTS
Mean body weight gain, feed consumption, and feed conversion of chicks fed each diet for 22 days are presented in Table 2. There was a significant (P<.001) Cu x MET x SN interaction for gain. This resulted from differences in response to supplemental MET and SN at each dietary Cu level. With no added Cu, there were no differences (P<.10) in gain due to supple-
mental MET or SN. At 400 mg/kg added Cu, chicks fed MET gained 10% more (P<.001) than those not receiving MET, resulting in a restoration in growth equal to that observed in control birds. For chicks fed 800 mg Cu/kg diet, there was an interaction (P< .001) between MET and SN, with chicks fed MET in the presence or absence of SN having higher gains, while chicks fed SN in the absence of MET gained less (345 g) than those not fed SN (380 g). Additions of 400 and 800 mg Cu/kg to the basal diet depressed (P<.001) feed consumption by 8.6 and 19.4%, respectively (Table 2). Within dietary Cu concentrations there were no differences (P>.10) in intake, indicating that SN and MET failed to affect intake. The interaction for Cu x MET was significant (P<.05) for feed efficiency (Table 2). In the absence of MET, birds fed 400 and 800 mg Cu/kg were less efficient than control birds (no added Cu). However, in the presence of MET, birds fed 400 mg Cu/kg were as efficient as control birds, while those fed 800 mg Cu/kg were less efficient. Liver Cu concentrations and liver weights (g/100 g body weight) as influenced by dietary treatments are shown in Table 3. Liver Cu concentrations were not influenced (P>.10) by MET or SN supplementation. However, increasing dietary Cu concentration resulted in a linear increase (P<.001) in liver Cu. Liver weights increased linearly (P<.001) with increasing di-
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Supplied per kilogram of diet: vitamin A palmitate, 6,600 IU; vitamin D 3 , 2,000 ICU; menadione dimethylpyrimidinol bisulfite, 2.2 mg; riboflavin, 4.4 mg; pantothenic acid, 13.2 mg; niacin, 39.6 mg; choline chloride, 500 mg; vitamin B 1 2 , .022 mg; ethoxyquin, 125 mg; manganese, 60 mg; iron, 50 mg; copper, 6 mg; iodine, 1.1 mg; zinc, 35 mg.
0 400 800
Feed conversion, g feed/g gain3
± 7.3 ± 10.0 ± 8.0
1.58 ± 1.69 ± 1.87 ±
.01 .05 .08
5
4
3
Each value represents the mean ± standard error of six pens, eight chicks per pen.
Significant interaction of copper X methionine (P<.05).
Significant effect of copper (P-C001).
± ± ±
+ ± ±
8.10 1.20 .73
7.6 8.1 7.9
1.54 ± .02 1.54 ± .02 1.67 ± .02
37.9 37.5 30.7
543 537 405
.4% MET
0 Added nutrients
39.7 ± .54 36.3 ± .66 32.0 ± 2.20
552 474 380
OMET
'Significant interaction of copper X methionine X selected nutrients (P<.001).
Each value represents the mean ± standard error of 48 chicks.
0 400 800
Daily feed consumption, g3
1
0 400 800
(mg/kg)
Added Cu
Body weight gain, g1
Production parameter
TABLE 2. Body weight gain, feed consumption, and feed conversion of broiler chicks fed 0, 400, o 0 and .4% added methionine (MET) and 0 and 20% added selected nut
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LEDOUX ET AL.
1382
etary Cu and were higher (P<.05) for chicks supplemented with SN, but lower (P<.05) for those supplemented with MET. Table 4 contains a summary of the influence of dietary treatments on serum Cu and SGOT activity. There was a significant (P<.001) MET X SN interaction for serum Cu. Chicks fed diets supplemented with both MET and SN had lower serum Cu concentrations than those fed no supplement or those fed either MET or SN alone. The SGOT activity, used in this study as an indicator of Cu toxicosis per se, was not influenced (P>. 10) by dietary Cu or MET. Selected nutrient supplementation, however, caused a 10% elevation (P<.001) in SGOT activity for those receiving excess Cu.
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Addition of MET to the basal diet (zero added Cu) resulted in no improvement in gain, indicating that the basal diet was not deficient in sulfuramino acids (SAA). Depressions in intake and gain with increasing dietary Cu observed in this study are congruent with those found in previous reports (Christmas and Harms, 1979, 1984; Jensen and Maurice, 1979; Robbins and Baker, 1980a,b). The ability of MET to alleviate the growth depressing effect of Cu has also been reported previously (Jensen and Maurice, 1979; Christmas and Harms, 1979, 1984). In the present study MET completely restored growth and feed efficiency in chicks fed 400 mg/kg Cu and improved growth by 14.2% for those fed 800 mg/kg Cu. The failure of SN and success of MET in reversing the growth depression in chicks fed 400 mg/kg Cu may indicate that SAA become the first-limiting factor in corn-soybean diets containing high Cu concentrations. Evidence of this is provided by the way chicks fed 800 mg/kg Cu responded to MET and SN supplementation. Supplemental MET improved gains by 6.2%, and addition of SN in the presence of added MET produced a further improvement in gain of 8.2%. These results confirm findings of Robbins and Baker (1980a,b) who reported that chicks fed high dietary levels of Cu (>250 mg/kg) have an increased SAA requirement. Using a semi-purified diet, Robbins and Baker also demonstrated that cysteine was more effective than cystine or MET in reversing growth depression in chicks fed high dietary Cu levels. The increase in hepatic Cu concentrations observed in this study is consistent with that ob-
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in SO in rri OS SO
COPPER AND NUTRIENT INTERACTION
1383
TABLE 4. Serum Cu and glutamic oxaloacetic transaminase (SGOT) concentrations of broiler chicks fed 0, 400 or 800 ppm Cu in combination with 0 and .4% added methionine (MET) and 0 and 20% added selected nutrients 0 Added nutrients Parameter
A d d e d Cu
OMET
.4% MET
20% A d d e d n u t r i e n t s OMET
.4% M E T
(mg/kg) Serum copper, g / 1 0 0 m L
SGOT, IU/L 1 ' 3 - 4
,,!
0 400 800 0 400 800
38.7 ± 4.4 38.1 ± 3.2 4 4 . 3 ± 3.7 139 119 117
±7.9 ± 7.7 ±4.9
32.8 ± 3.0 37.9 ± 2.8 38.9 ± 2.9 123 117 113
Each value represents the mean ± standard error of 12 chicks.
2
Significant interaction of methionine X selected nutrients (P<.001).
3
Significant effect of selected nutrients (P<.001).
138 135 127
±6.3 ±5.7 ± 7.4
18.1 ± 1.3 2 0 . 7 ± 1.5 2 5 . 6 ± 2.1 135 138 137
±6.2 ±5.9 ± 8.3
4
One IU represents the oxidation of one micromole of nicotinamide adenine dinucleotide reduced per minute at 30 C.
served in previous research (Jensen and Maurice, 1979; Robbins and Baker, 1980a,b; Nam etal., 1984). The influence of MET supplementation on hepatic Cu concentration remains disputed. Jensen and Maurice (1979) found that .4% MET significantly reduced hepatic Cu concentrations in birds fed 500 and 750 mg/kg Cu. In studies by Robbins and Baker (1980a,b), supplemental MET reduced hepatic Cu concentrations at 250 but not at 500 mg Cu/kg. Recently Nam etal. (1984) reported that additional MET failed to reduce hepatic Cu in birds fed 500 and 1,000 mg Cu/kg even when MET was added at 2% of the diet. Results of the present study confirm findings of Robbins and Baker (1980a,b) and Nam et al. (1984) and may indicate that MET does not reduce absorption of Cu in chicks as has been suggested by Jensen and Maurice (1979). Other workers (Pearce et al., 1983; Stevenson et al., 1983) indicated that high dietary concentrations of Cu fed to laying hens resulted in decreased liver weights. This reduction in liver weight was attributed to reduced feed intake, since force-fed birds showed an increase in liver weights. In this study liver weights indicated that in broiler chicks, unlike laying hens, increasing dietary Cu resulted in an increase in liver weights. These results, however, should be interpreted with caution as previous reports have demonstrated that small chicks have a higher liver weight when expressed as a percentage of body weight than large chicks of equal
age regardless of dietary treatments imposed (Leeson and Summers, 1980; Plavnik and Hurwitz, 1982; Southerner al., 1984; Brown et al., 1985). Therefore, it appears that, as with the layers, observed differences were the result of reduced feed intake. The significantly lower serum Cu concentrations observed in chicks fed MET in conjunction with SN may, in part, be the result of an interrelationship between MET and sulfate (included as a component of SN). Martin (1972) reported that dietary sulfate was utilized by chicks to synthesize taurine and that in the presence of MET there was increased synthesis. Taurine as an essential component of bile salts may well play a role in enhancing biliary excretion of Cu, resulting in lower serum Cu levels. In an attempt to determine if Cu toxicosis per se was occurring, activity of the serum enzyme glutamic-oxaloacetic transaminase (GOT) was determined. A marked rise in GOT activity is indicative of organ damage and would provide evidence of Cu toxicosis per se. Failure of dietary Cu to affect SGOT activity, indicated that Cu toxicosis per se was not occurring, and although SN supplementation resulted in increased SGOT activity, levels were well within normal ranges reported in the literature (Dalvi and McGowan, 1984; Madhusudhan et al., 1986). It is concluded that the reduction in performance observed in this study was primarily due to a copper-mediated reduction in feed intake and not to copper toxicosis per se.
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1
± 7.6 ±5.3 ±7.9
4 4 . 3 ± 2.8 4 0 . 4 ± 6.1 33.3 ± 2.8
LEDOUX ET AL.
1384 REFERENCES
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