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Studies on the feeding of cupric sulfate pentahydrate, cupric citrate, and copper oxychloride to broiler chickens
Studies on the Feeding of Cupric Sulfate Pentahydrate, Cupric Citrate, and Copper Oxychloride to Broiler Chickens1 H. PETTIT EWING, GENE M. PESTI,2 REMZI I. BAKALLI, and JOSE FERNANDO M. MENTEN3 Department of Poultry Science, The University of Georgia, Athens, Georgia 30602-2772
(Key words: broiler, cupric sulfate pentahydrate, cupric citrate, copper oxychloride) 1998 Poultry Science 77:445–448
from organic and inorganic sources has been shown to differ (Ledoux et al., 1991), suggesting efficacy as a growth promotant may also differ. The purpose of these experiments was to test the ability of three commercially available copper sources to improve the growth performance of broiler chickens.
INTRODUCTION The broiler chick’s nutritional requirement for copper is approximately 8 mg/kg (NRC 1994). Copper is usually fed commercially at much higher pharmacological levels (100 to 300 mg/kg) because of its growthpromoting properties (Fisher et al., 1970; Fisher, 1973; Wang et al., 1987; Bakalli et al., 1995; Pesti and Bakalli, 1996). Traditionally, the source of copper has been copper sulfate pentahydrate due to cost and commercial availability. In recent years, additional copper sources have become available and the potential for commercial use as feed additives has expanded. It cannot be assumed that copper from different sources are completely interchangeable. The bioavailability of copper
MATERIALS AND METHODS In Experiment 1, 720 (Ross 208) chicks were purchased from a local hatchery.4 The chicks were divided into 24 groups of 30 chicks each and placed in 1.2 m × 3.6 m pens on pine shavings. The pens were grouped in a randomized block design to account for any error introduced by location in the house. There were 6 blocks of 4 treatments each. The basal ration was formulated to meet minimum nutritional requirements for starting broilers (Table 1; NRC, 1994) and contained 9.34 mg copper/kg diet by analysis. Copper (125 mg/kg) in the forms of copper sulfate pentahydrate (CuSO4·5H2O),5 copper oxychloride (CuCl2·3CuO·4H2O),5 or cupric citrate5 was added to the control to form the four treatments. The diets were fed fr om 1 d to 42 d of age.
Received for publication March 17, 1997. Accepted for publication October 20, 1997. 1Supported by state and Hatch funds allocated to the Georgia Agricultural Stations of The University of Georgia, an FAPESP Scholarship to J.F.M. Menten, and a gift from DuCoa, Inc., Highland, IL 62249. 2To whom correspondence should be addressed: [email protected]. uga.edu 3 Present address: Dept. Zootecnia, Univ. Sao Paulo, 13418-900 Piracicaba SP, Brazil. 4Seaboard Farms, Athens, GA 30606. 5Griffin Corp., Valdosta, GA 31603.
Abbreviation Key: AFCR = feed conversion ratio adjusted for mortality; FCR = feed conversion ratio.
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The feed conversion ratios (grams of feed:grams of gain of live birds) in the birds fed copper were not significantly different from those fed the basal diet (P > 0.05) unless corrections were made for the weights of the dead birds; the adjusted feed conversion ratios (grams of feed:grams of gain of live birds + grams of gain of mortalities) for the copper-treated birds in Experiments 1 and 2 were 5.2 and 7.6% lower, respectively, than the ratios of birds fed the basal diets. Plasma copper levels increased in supplemented chicks by 35% in Experiment 1 and 24% in Experiment 2. Liver copper levels in both experiments were increased by 26% with copper supplementation. Mortality was not affected by dietary treatment in either experiment (P > 0.05).
ABSTRACT Male commercial broiler strain chickens were fed either a control diet (based on corn and soybean meal) or the control diet supplemented with cupric sulfate pentahydrate, copper oxychloride, or cupric citrate in two experiments conducted in floor pens. In Experiment 1, feeding copper at 125 mg/kg diet for 42 d significantly increased broiler growth; and the response from cupric citrate was significantly better than either cupric sulfate or copper oxychloride. In Experiment 2, the inclusion of copper from cupric citrate was reduced to 63 mg/kg and the length of the experiment was increased to 56 d. Cupric sulfate pentahydrate and copper oxychloride treatments increased weight gain by 4.9% and cupric citrate increased weight gain by 9.1%.
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EWING ET AL. TABLE 1. Composition of the basal diets
Ground corn Soybean meal Poultry fat Poultry by-product meal Corn gluten meal Defluorinated phosphate Limestone Vitamin mix3 Salt D-L Methionine (98%) Trace mineral mix4 Coban5 BMD606
57.31 33.48 3.15 3 . . . 1.54 0.79 0.25 0.21 0.19 0.075 0.075 0.0065
Experiment 22 (19 to 56 d) (%) 62.75 24.80 3.375 3 3 1.42 0.935 0.25 0.235 0.145 0.075 0.075 . . .
1Calculated composition: [Experiments 1 (1 to 42 d) and 2 (1 to 18 d)]: dry matter, 86.6%; crude protein, 21.4%; ME, 3,050 kcal/kg; methionine, 0.53%; cystine, 0.35% calcium, 0.99%; total phosphorus, 0.71%; sodium, 0.18%. 2Calculated composition: [Experiment 2 (19 to 56 d)]: dry matter, 86.6%; crude protein, 19.9%; ME, 3,171 kcal/kg; methionine, 0.48%; cystine, 0.34%; calcium, 0.98%; total phosphorus, 0.66%; sodium, 0.19%. 3Vitamin premix provides the following per kilogram: vitamin A, 5,500 IU from trans-retinyl acetate; cholecalciferol, 1,100 IU; vitamin E, 11 IU from all-rac-a-tocopherol acetate; riboflavin, 4.4 mg; Ca pantothenate, 12 mg; nicotinic acid, 44 mg; choline Cl, 220 mg; vitamin B12, 6.6 mg; vitamin B6, 2.2 mg; menadione, 1.1 mg (as menadione sodium bisulfate complex); folic acid, 0.55 mg; d-biotin, 0.11 mg; thiamine, 1.1 mg (as thiamine mononitrate); ethoxyquin, 125 mg. 4Trace mineral premix provides the following in milligrams per kilogram of diet: Mn, 60; Zn, 50; Fe, 30; Cu, 5; I, 1.5. 5Eli Lilly and Co., Indianapolis, IN 46285-0002. 6Alpharma, Fort Lee, NJ 07024.
Pen weights were taken on 1, 21, and 42 d to calculate rate of gain. Feed weight was recorded as added and residual feed was measured at 21 and 42 d to calculate feed conversion ratios. Mortality was recorded by pen number, date, and weight of carcass. After weights were taken at 42 d, two birds per pen were randomly selected to take blood and liver samples for plasma copper and liver copper analysis. In Experiment 2, 720 male (Ross 208) chicks from the same source4 were randomly divided into 24 groups of 30 chicks each and placed in pens on pine shavings. The basal diets were formulated to meet minimum nutritional requirements (Table 1; NRC, 1994). This experiment had a randomized block design. The four treatments were: basal, basal plus 125 ppm copper as copper sulfate pentahydrate, basal plus 63 ppm copper as cupric citrate, and basal plus 125 ppm copper as copper oxychloride. The decision to reduce the level of copper from cupric citrate was based on experiments indicating
6Perkin Elmer Corp., Norwalk, CT 06859-0012. 7National Institute of Standards and Technology,
30899-0001.
Gaithersburg, MD
RESULTS Results from Experiment 1 are shown in Table 2. The data from the 21-d weights (not shown) indicated no significant differences in body weight (P = 0.982) or FCR (P = 0.607) by treatment. All copper supplements improved total body weight gain over the basal diet at 42 d. Cupric citrate, at the same level of copper supplementation, produced significantly higher body weights than copper oxychloride or cupric sulfate pentahydrate. Cupric citrate was the only copper source that improved FCR at 42 d compared to the basal diet, but was not significantly better than the other two copper sources. A different conclusion could be drawn when the weight of mortalities was added to live bird weight to compute AFCR. The AFCR of the cupric citrate, cupric sulfate pentahydrate, and copper oxychloride fed broilers were found to be different from chicks fed the basal diet.
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Ingredient
Experiment 1 (1 to 42 d)1 Experiment 2 (1 to 18 d)
that cupric citrate has growth-promoting effects at this level (Pesti and Bakalli, 1996). The basal diets in this experiment included a starter ration (Table 1) containing 9.32 mg copper/kg diet by analysis used from 1 through 18 d, and a grower ration (Table 1) containing 10.71 mg copper/kg diet by analysis used from 19 through 56 d. Pen weights were taken on 1, 18, 35, and 56 d to calculate rate of gain. Feed weight was recorded as added and residuals weighed on 18, 35, and 56 d to calculate feed conversion ratios (FCR). On 56 d, two birds per pen were randomly selected to take plasma and liver samples for copper analysis. Mortality was recorded by pen number, date, and weight of carcass. The FCR are presented as recorded (FCR = weight of feed consumed per weight gain of survivors) and as adjusted for mortality (AFCR = weight of feed consumed)/(weight gain of survivors + weight gain of mortalities). The mortality adjustment was done because of a large number of birds that died in Experiment 2 (4.7% mortality on Days 46 and 47, and 12.8% mortality on Days 51 to 53) due to warm weather conditions. The FCR from Experiment 1 are also presented as AFCR. In Experiment 1, a 7% mortality rate occurred mostly due to a high incidence of slipped tendons. In both experiments birds with slipped tendons were culled when they could no longer stand to reach feed and water. Birds that were affected by slipped tendons but could still reach feed and water remained in the study. Total plasma copper levels were determined by methods described by Anonymous (1982) using a Perkin Elmer atomic absorption spectrophotometer 5000.6 The procedures and equipment were tested with Reference Standard 1577b.7 All data was analyzed by one-way ANOVA using the General Linear Models (GLM) procedure of SAS (SAS Institute, 1985). Blocks for location in the house had no significant effect, and were omitted from the statistical models. Significant treatment effects were separated by means using Duncan’s new multiple range test (Steel and Torrie, 1980).
447
EFFICACY OF COPPER SOURCES
TABLE 2. Influence of copper supplementation by source on the weight gain and feed conversion of broiler chickens, Experiment 11 Copper
FCR2 42 d
Weight gain 42 d
Source
Supplement
Mean
Basal Sulfate Oxychloride Citrate
(mg/kg) 0 125 125 125
2.477c 2.564b 2.551b 2.674a
SE
Mean
0.006 0.029 0.032 0.018
2.076a 1.995ab 2.006ab 1.915b
(kg)
SE
AFCR3 42 d Mean
(g feed intake:g gain) 0.035 2.017a 0.040 1.911b 0.028 1.946b 0.017 1.879b
Mortality
SE
Mean
0.022 0.016 0.031 0.015
5.5a 10.0a 6.1a 7.8a
SE (%) 1.65 3.55 1.03 2.22
a–cValues in columns with no common superscript differ significantly (P < 0.05) when tested by Duncan’s new multiple range test following analysis of variance. 1Values represent the means of six replicate pens of 30 cockerels each per source. 2Feed Conversion Ratio (FCR) = (feed consumption per pen)/(gain of live birds at weighing). 3Adjusted Feed Conversion Ratio (AFCR) = (feed consumption per pen)/(gain of live birds + gain of mortalities).
DISCUSSION Both studies confirm that copper sulfate pentahydrate, cupric citrate, and copper oxychloride are valid options for copper supplementation for growth promotion. Average body weights were increased for all forms of copper supplementation at 35 and 56 d of age (Experiment 2) and at 42 d of age (Experiment 1). In addition to improvements over the basal diet, the chicks fed cupric citrate also demonstrated improved weight gains over that of chicks fed copper oxychloride and cupric sulfate pentahydrate. The chicks consuming the diet containing cupric citrate outperformed chicks fed the other copper forms, even when supplemented at half the level of copper. This finding indicates an increased ability of cupric citrate to improve performance over other forms of copper supplementation. The plasma copper and liver copper levels of the birds fed cupric citrate were not different from those of birds fed the other sources at the same supplementation level or at half the level of the other sources (Table 4). Adding more than the 63 ppm copper from cupric citrate did not result in any increase in plasma copper, suggesting that homeostatic mechanisms either decreased copper absorption, transport to, and storage in some other tissue, excretion, or some combination of these. In commercial
TABLE 3. Influence of copper supplementation by source on the weight gain and feed conversion of broiler chickens, Experiment 21
Copper Source
Supplement
(mg/kg) Basal 0 Sulfate 125 Oxychloride 125 Citrate 63
Weight gain 35 d
FCR2 35 d
Mean SE
Mean SE
(kg) 1.739c 0.03 1.779b 0.01 1.794b 0.02 1.873a 0.02
(g 1.793a 1.678b 1.667b 1.614b
AFCR3 35 d
Weight gain 56 d
Mean SE
Mean SE
Mean SE
(kg) 3.245a 0.031 3.392b 0.019 3.415b 0.030 3.541c 0.057
(g 2.863a 2.636a 2.623a 2.653a
feed intake:g gain) 0.03 1.727a 0.03 0.01 1.628b 0.02 0.02 1.624b 0.01 0.02 1.556c 0.02
FCR 56 d
AFCR 56 d Mean SE
feed intake:g gain) 0.080 2.161a 0.032 0.185 2.023b 0.035 0.160 1.980b 0.013 0.196 1.985b 0.042
Mortality Mean SE 23.3a 20.0a 20.7a 22.7a
(%) 2.4 5.8 5.8 6.3
a–cValues in columns with no common superscript differ significantly (P < 0.05) when tested by Duncan’s new multiple range test following analysis of variance. 1Values represent the means of six replicate pens of 30 cockerels each per source. 2Feed Conversion Ratio (FCR) = (feed consumption per pen)/(gain of live birds at weighing). 3Adjusted Feed Conversion Ratio (AFCR) = (feed consumption per pen)/(gain of live birds + gain of mortalities).
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Results from Experiment 2 are shown in Table 3. As in Experiment 1 at 21 d, there were no significant differences in FCR (P = 0.370) or body weight gain (P = 0.97) at 18 d of age. Body weight gain at 35 and 56 d was increased by supplementing all three copper sources. However, cupric citrate at 63 mg copper/kg diet produced significantly higher body weights at 35 and 56 d than the other two copper sources fed at 125 mg copper/kg diet. Feed conversion at 35 d was improved by all three copper sources. Adjusting the 35-d FCR separated the chicks fed cupric citrate from chicks fed the other copper sources. Initial calculation of the FCR from 0 to 56 d demonstrated no difference between any copper supplement and the basal diet. Adjusting the FCR for mortality (AFCR) decreased the standard error enough to distinguish the FCR of the copper-supplemented chicks from the chicks fed the basal diet. Plasma and liver copper levels from Experiments 1 and 2 are presented in Table 4. In Experiment 1, equal copper supplementation (125 mg copper/kg diet) from each source increased the plasma and liver copper levels to about the same degree. In Experiment 2, even with decreased copper from cupric citrate (63 vs 125 mg/kg), all copper sources increased plasma and liver copper concentrations to a similar degree.
448
EWING ET AL. TABLE 4. Influence of copper by source and level or plasma copper and liver concentration of broiler chickens1 Copper Source
Experiment 1 Supplement
Mean
Experiment 2
SE
Mean
SE
(mg/100 mL)
(mg/kg) 0 125 125 125 63
11.7b 15.6a 15.8a 16.0a . . .
0.49 1.18 1.14 1.17 . . . (mg/g
13.2b 16.2a 16.4a . . . 16.6a DM)
0.40 0.14 0.15 . . . 0.15
Liver Cu Basal Sulfate Oxychloride Citrate Citrate
0 125 125 125 63
11.9b 15.1a 15.0a 14.9a . . .
0.36 0.38 0.34 0.10 . . .
9.6b 12.0a 11.9a . . . 12.3a
0.48 0.51 1.06 . . . 0.37
a,bValues in columns with no common superscript differ significantly (P < 0.05) when tested by Duncan’s new multiple range test following analysis of variance. 1Values represent the means, two cockerels tested per pen, from six replicate pens per source.
operations, this improved utilization of copper from cupric citrate should allow for lower feeding levels of copper, thus reducing the risk of environmental contamination. Adjusting the FCR for mortality (AFCR) changed the apparent differences in performance due to copper sources. As would be expected, the higher mortalities seen as age and size of the birds increased caused the mortality adjustment to be more dramatic as the age of the birds increased (Experiment 2). Although the mortality was independent of treatment in both experiments, the mortality adjustment decreased the standard error enough to make differences more apparent. This effect is best seen in the FCR data for the 56-d-old birds in Experiment 2. The FCR (calculated as typical for the industry) demonstrated no significant difference between the control group and any of the copper-supplemented groups. The mortality adjustment improved all the ratios a similar amount (0.613 to 0.702; change in FCR for AFCR vs nonadjusted FCR); however, the standard errors were reduced by greater than 50%. The differences seen in the AFCR closely match the differences seen in body weight gain. In a commercial operation, it is not practical to adjust FCR for mortality. Therefore, the data in Experiments 1 and 2 suggest that under commercial conditions, average body weight gain is a better indicator of the effectiveness of copper supplementation than FCR (because calculation of AFCR is not routinely practiced in the industry). Copper oxychloride is being used by several broiler producers without evidence in the published literature on its effectiveness as a copper source. The data presented here indicate that copper oxychloride is a viable copper source compared to the industry standard copper sulfate when growth is used as the response criterion; however, the growth responses to copper sulfate or copper oxychloride are not comparable to
cupric citrate, as reported earlier (Pesti and Bakalli, 1996).
REFERENCES Anonymous, 1982. Analytical Methods for Atomic Absorption Spectrophotometry. The Perkin-Elmer Corp., Norwalk, CT. Bakalli, R. I., G. M. Pesti, W. L. Ragland, and V. Konjufca, 1995. Dietary copper in excess of nutritional requirement reduces plasma and breast muscle cholesterol in chickens. Poultry Sci. 74:360–365. Fisher, C., 1973. Use of copper sulfate as a growth promoter for broilers. Feedstuffs: July 16, 24–25. Fisher, C., D. Wise, and D. G. Filmer, 1970. The effect of copper on the growth of broilers and the interaction of copper with zinc and iron. Proc. 14th World’s Poult. Congr. Madrid, Spain 2:759–764. Ledoux, D. R., P. R. Henry, C. B. Ammerman, P. V. Rao, and R. D. Miles, 1991. Estimation of the relative bioavailability of inorganic copper sources for chicks using tissue uptake of copper. J. Anim. Sci. 69:215–222. National Research Council, 1994. Nutrient Requirements of Poultry. 9th rev. ed. National Academy Press, Washington, DC. Pesti, G. M., and R. I. Bakalli, 1996. Studies on the feeding of cupric sulfate pentahydrate and cupric citrate to broiler chickens. Poultry Sci. 75:1086–1091. SAS Institute, 1985. SAS Users Guide: Statistics. Version Five Edition. SAS Institute Inc., Cary, NC. Steel, R.G.D., and J. D. Torrie, 1980. Pages 137–171 in: Principles and Procedures of Statistics: A Biometrical Approach. 2nd ed. McGraw-Hill Book Co., New York, NY. Wang, J. S., S. R. Rogers, and G. M. Pesti, 1987. Influence of choline and sulfate on copper toxicity and substitution of and antagonism between methionine and copper supplements to chick diets. Poultry Sci. 66:1500–1507.
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Plasma Cu Basal Sulfate Oxychloride Citrate Citrate
(Key words: broiler, cupric sulfate pentahydrate, cupric citrate, copper oxychloride) 1998 Poultry Science 77:445–448
from organic and inorganic sources has been shown to differ (Ledoux et al., 1991), suggesting efficacy as a growth promotant may also differ. The purpose of these experiments was to test the ability of three commercially available copper sources to improve the growth performance of broiler chickens.
INTRODUCTION The broiler chick’s nutritional requirement for copper is approximately 8 mg/kg (NRC 1994). Copper is usually fed commercially at much higher pharmacological levels (100 to 300 mg/kg) because of its growthpromoting properties (Fisher et al., 1970; Fisher, 1973; Wang et al., 1987; Bakalli et al., 1995; Pesti and Bakalli, 1996). Traditionally, the source of copper has been copper sulfate pentahydrate due to cost and commercial availability. In recent years, additional copper sources have become available and the potential for commercial use as feed additives has expanded. It cannot be assumed that copper from different sources are completely interchangeable. The bioavailability of copper
MATERIALS AND METHODS In Experiment 1, 720 (Ross 208) chicks were purchased from a local hatchery.4 The chicks were divided into 24 groups of 30 chicks each and placed in 1.2 m × 3.6 m pens on pine shavings. The pens were grouped in a randomized block design to account for any error introduced by location in the house. There were 6 blocks of 4 treatments each. The basal ration was formulated to meet minimum nutritional requirements for starting broilers (Table 1; NRC, 1994) and contained 9.34 mg copper/kg diet by analysis. Copper (125 mg/kg) in the forms of copper sulfate pentahydrate (CuSO4·5H2O),5 copper oxychloride (CuCl2·3CuO·4H2O),5 or cupric citrate5 was added to the control to form the four treatments. The diets were fed fr om 1 d to 42 d of age.
Received for publication March 17, 1997. Accepted for publication October 20, 1997. 1Supported by state and Hatch funds allocated to the Georgia Agricultural Stations of The University of Georgia, an FAPESP Scholarship to J.F.M. Menten, and a gift from DuCoa, Inc., Highland, IL 62249. 2To whom correspondence should be addressed: [email protected]. uga.edu 3 Present address: Dept. Zootecnia, Univ. Sao Paulo, 13418-900 Piracicaba SP, Brazil. 4Seaboard Farms, Athens, GA 30606. 5Griffin Corp., Valdosta, GA 31603.
Abbreviation Key: AFCR = feed conversion ratio adjusted for mortality; FCR = feed conversion ratio.
445
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The feed conversion ratios (grams of feed:grams of gain of live birds) in the birds fed copper were not significantly different from those fed the basal diet (P > 0.05) unless corrections were made for the weights of the dead birds; the adjusted feed conversion ratios (grams of feed:grams of gain of live birds + grams of gain of mortalities) for the copper-treated birds in Experiments 1 and 2 were 5.2 and 7.6% lower, respectively, than the ratios of birds fed the basal diets. Plasma copper levels increased in supplemented chicks by 35% in Experiment 1 and 24% in Experiment 2. Liver copper levels in both experiments were increased by 26% with copper supplementation. Mortality was not affected by dietary treatment in either experiment (P > 0.05).
ABSTRACT Male commercial broiler strain chickens were fed either a control diet (based on corn and soybean meal) or the control diet supplemented with cupric sulfate pentahydrate, copper oxychloride, or cupric citrate in two experiments conducted in floor pens. In Experiment 1, feeding copper at 125 mg/kg diet for 42 d significantly increased broiler growth; and the response from cupric citrate was significantly better than either cupric sulfate or copper oxychloride. In Experiment 2, the inclusion of copper from cupric citrate was reduced to 63 mg/kg and the length of the experiment was increased to 56 d. Cupric sulfate pentahydrate and copper oxychloride treatments increased weight gain by 4.9% and cupric citrate increased weight gain by 9.1%.
446
EWING ET AL. TABLE 1. Composition of the basal diets
Ground corn Soybean meal Poultry fat Poultry by-product meal Corn gluten meal Defluorinated phosphate Limestone Vitamin mix3 Salt D-L Methionine (98%) Trace mineral mix4 Coban5 BMD606
57.31 33.48 3.15 3 . . . 1.54 0.79 0.25 0.21 0.19 0.075 0.075 0.0065
Experiment 22 (19 to 56 d) (%) 62.75 24.80 3.375 3 3 1.42 0.935 0.25 0.235 0.145 0.075 0.075 . . .
1Calculated composition: [Experiments 1 (1 to 42 d) and 2 (1 to 18 d)]: dry matter, 86.6%; crude protein, 21.4%; ME, 3,050 kcal/kg; methionine, 0.53%; cystine, 0.35% calcium, 0.99%; total phosphorus, 0.71%; sodium, 0.18%. 2Calculated composition: [Experiment 2 (19 to 56 d)]: dry matter, 86.6%; crude protein, 19.9%; ME, 3,171 kcal/kg; methionine, 0.48%; cystine, 0.34%; calcium, 0.98%; total phosphorus, 0.66%; sodium, 0.19%. 3Vitamin premix provides the following per kilogram: vitamin A, 5,500 IU from trans-retinyl acetate; cholecalciferol, 1,100 IU; vitamin E, 11 IU from all-rac-a-tocopherol acetate; riboflavin, 4.4 mg; Ca pantothenate, 12 mg; nicotinic acid, 44 mg; choline Cl, 220 mg; vitamin B12, 6.6 mg; vitamin B6, 2.2 mg; menadione, 1.1 mg (as menadione sodium bisulfate complex); folic acid, 0.55 mg; d-biotin, 0.11 mg; thiamine, 1.1 mg (as thiamine mononitrate); ethoxyquin, 125 mg. 4Trace mineral premix provides the following in milligrams per kilogram of diet: Mn, 60; Zn, 50; Fe, 30; Cu, 5; I, 1.5. 5Eli Lilly and Co., Indianapolis, IN 46285-0002. 6Alpharma, Fort Lee, NJ 07024.
Pen weights were taken on 1, 21, and 42 d to calculate rate of gain. Feed weight was recorded as added and residual feed was measured at 21 and 42 d to calculate feed conversion ratios. Mortality was recorded by pen number, date, and weight of carcass. After weights were taken at 42 d, two birds per pen were randomly selected to take blood and liver samples for plasma copper and liver copper analysis. In Experiment 2, 720 male (Ross 208) chicks from the same source4 were randomly divided into 24 groups of 30 chicks each and placed in pens on pine shavings. The basal diets were formulated to meet minimum nutritional requirements (Table 1; NRC, 1994). This experiment had a randomized block design. The four treatments were: basal, basal plus 125 ppm copper as copper sulfate pentahydrate, basal plus 63 ppm copper as cupric citrate, and basal plus 125 ppm copper as copper oxychloride. The decision to reduce the level of copper from cupric citrate was based on experiments indicating
6Perkin Elmer Corp., Norwalk, CT 06859-0012. 7National Institute of Standards and Technology,
30899-0001.
Gaithersburg, MD
RESULTS Results from Experiment 1 are shown in Table 2. The data from the 21-d weights (not shown) indicated no significant differences in body weight (P = 0.982) or FCR (P = 0.607) by treatment. All copper supplements improved total body weight gain over the basal diet at 42 d. Cupric citrate, at the same level of copper supplementation, produced significantly higher body weights than copper oxychloride or cupric sulfate pentahydrate. Cupric citrate was the only copper source that improved FCR at 42 d compared to the basal diet, but was not significantly better than the other two copper sources. A different conclusion could be drawn when the weight of mortalities was added to live bird weight to compute AFCR. The AFCR of the cupric citrate, cupric sulfate pentahydrate, and copper oxychloride fed broilers were found to be different from chicks fed the basal diet.
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Ingredient
Experiment 1 (1 to 42 d)1 Experiment 2 (1 to 18 d)
that cupric citrate has growth-promoting effects at this level (Pesti and Bakalli, 1996). The basal diets in this experiment included a starter ration (Table 1) containing 9.32 mg copper/kg diet by analysis used from 1 through 18 d, and a grower ration (Table 1) containing 10.71 mg copper/kg diet by analysis used from 19 through 56 d. Pen weights were taken on 1, 18, 35, and 56 d to calculate rate of gain. Feed weight was recorded as added and residuals weighed on 18, 35, and 56 d to calculate feed conversion ratios (FCR). On 56 d, two birds per pen were randomly selected to take plasma and liver samples for copper analysis. Mortality was recorded by pen number, date, and weight of carcass. The FCR are presented as recorded (FCR = weight of feed consumed per weight gain of survivors) and as adjusted for mortality (AFCR = weight of feed consumed)/(weight gain of survivors + weight gain of mortalities). The mortality adjustment was done because of a large number of birds that died in Experiment 2 (4.7% mortality on Days 46 and 47, and 12.8% mortality on Days 51 to 53) due to warm weather conditions. The FCR from Experiment 1 are also presented as AFCR. In Experiment 1, a 7% mortality rate occurred mostly due to a high incidence of slipped tendons. In both experiments birds with slipped tendons were culled when they could no longer stand to reach feed and water. Birds that were affected by slipped tendons but could still reach feed and water remained in the study. Total plasma copper levels were determined by methods described by Anonymous (1982) using a Perkin Elmer atomic absorption spectrophotometer 5000.6 The procedures and equipment were tested with Reference Standard 1577b.7 All data was analyzed by one-way ANOVA using the General Linear Models (GLM) procedure of SAS (SAS Institute, 1985). Blocks for location in the house had no significant effect, and were omitted from the statistical models. Significant treatment effects were separated by means using Duncan’s new multiple range test (Steel and Torrie, 1980).
447
EFFICACY OF COPPER SOURCES
TABLE 2. Influence of copper supplementation by source on the weight gain and feed conversion of broiler chickens, Experiment 11 Copper
FCR2 42 d
Weight gain 42 d
Source
Supplement
Mean
Basal Sulfate Oxychloride Citrate
(mg/kg) 0 125 125 125
2.477c 2.564b 2.551b 2.674a
SE
Mean
0.006 0.029 0.032 0.018
2.076a 1.995ab 2.006ab 1.915b
(kg)
SE
AFCR3 42 d Mean
(g feed intake:g gain) 0.035 2.017a 0.040 1.911b 0.028 1.946b 0.017 1.879b
Mortality
SE
Mean
0.022 0.016 0.031 0.015
5.5a 10.0a 6.1a 7.8a
SE (%) 1.65 3.55 1.03 2.22
a–cValues in columns with no common superscript differ significantly (P < 0.05) when tested by Duncan’s new multiple range test following analysis of variance. 1Values represent the means of six replicate pens of 30 cockerels each per source. 2Feed Conversion Ratio (FCR) = (feed consumption per pen)/(gain of live birds at weighing). 3Adjusted Feed Conversion Ratio (AFCR) = (feed consumption per pen)/(gain of live birds + gain of mortalities).
DISCUSSION Both studies confirm that copper sulfate pentahydrate, cupric citrate, and copper oxychloride are valid options for copper supplementation for growth promotion. Average body weights were increased for all forms of copper supplementation at 35 and 56 d of age (Experiment 2) and at 42 d of age (Experiment 1). In addition to improvements over the basal diet, the chicks fed cupric citrate also demonstrated improved weight gains over that of chicks fed copper oxychloride and cupric sulfate pentahydrate. The chicks consuming the diet containing cupric citrate outperformed chicks fed the other copper forms, even when supplemented at half the level of copper. This finding indicates an increased ability of cupric citrate to improve performance over other forms of copper supplementation. The plasma copper and liver copper levels of the birds fed cupric citrate were not different from those of birds fed the other sources at the same supplementation level or at half the level of the other sources (Table 4). Adding more than the 63 ppm copper from cupric citrate did not result in any increase in plasma copper, suggesting that homeostatic mechanisms either decreased copper absorption, transport to, and storage in some other tissue, excretion, or some combination of these. In commercial
TABLE 3. Influence of copper supplementation by source on the weight gain and feed conversion of broiler chickens, Experiment 21
Copper Source
Supplement
(mg/kg) Basal 0 Sulfate 125 Oxychloride 125 Citrate 63
Weight gain 35 d
FCR2 35 d
Mean SE
Mean SE
(kg) 1.739c 0.03 1.779b 0.01 1.794b 0.02 1.873a 0.02
(g 1.793a 1.678b 1.667b 1.614b
AFCR3 35 d
Weight gain 56 d
Mean SE
Mean SE
Mean SE
(kg) 3.245a 0.031 3.392b 0.019 3.415b 0.030 3.541c 0.057
(g 2.863a 2.636a 2.623a 2.653a
feed intake:g gain) 0.03 1.727a 0.03 0.01 1.628b 0.02 0.02 1.624b 0.01 0.02 1.556c 0.02
FCR 56 d
AFCR 56 d Mean SE
feed intake:g gain) 0.080 2.161a 0.032 0.185 2.023b 0.035 0.160 1.980b 0.013 0.196 1.985b 0.042
Mortality Mean SE 23.3a 20.0a 20.7a 22.7a
(%) 2.4 5.8 5.8 6.3
a–cValues in columns with no common superscript differ significantly (P < 0.05) when tested by Duncan’s new multiple range test following analysis of variance. 1Values represent the means of six replicate pens of 30 cockerels each per source. 2Feed Conversion Ratio (FCR) = (feed consumption per pen)/(gain of live birds at weighing). 3Adjusted Feed Conversion Ratio (AFCR) = (feed consumption per pen)/(gain of live birds + gain of mortalities).
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Results from Experiment 2 are shown in Table 3. As in Experiment 1 at 21 d, there were no significant differences in FCR (P = 0.370) or body weight gain (P = 0.97) at 18 d of age. Body weight gain at 35 and 56 d was increased by supplementing all three copper sources. However, cupric citrate at 63 mg copper/kg diet produced significantly higher body weights at 35 and 56 d than the other two copper sources fed at 125 mg copper/kg diet. Feed conversion at 35 d was improved by all three copper sources. Adjusting the 35-d FCR separated the chicks fed cupric citrate from chicks fed the other copper sources. Initial calculation of the FCR from 0 to 56 d demonstrated no difference between any copper supplement and the basal diet. Adjusting the FCR for mortality (AFCR) decreased the standard error enough to distinguish the FCR of the copper-supplemented chicks from the chicks fed the basal diet. Plasma and liver copper levels from Experiments 1 and 2 are presented in Table 4. In Experiment 1, equal copper supplementation (125 mg copper/kg diet) from each source increased the plasma and liver copper levels to about the same degree. In Experiment 2, even with decreased copper from cupric citrate (63 vs 125 mg/kg), all copper sources increased plasma and liver copper concentrations to a similar degree.
448
EWING ET AL. TABLE 4. Influence of copper by source and level or plasma copper and liver concentration of broiler chickens1 Copper Source
Experiment 1 Supplement
Mean
Experiment 2
SE
Mean
SE
(mg/100 mL)
(mg/kg) 0 125 125 125 63
11.7b 15.6a 15.8a 16.0a . . .
0.49 1.18 1.14 1.17 . . . (mg/g
13.2b 16.2a 16.4a . . . 16.6a DM)
0.40 0.14 0.15 . . . 0.15
Liver Cu Basal Sulfate Oxychloride Citrate Citrate
0 125 125 125 63
11.9b 15.1a 15.0a 14.9a . . .
0.36 0.38 0.34 0.10 . . .
9.6b 12.0a 11.9a . . . 12.3a
0.48 0.51 1.06 . . . 0.37
a,bValues in columns with no common superscript differ significantly (P < 0.05) when tested by Duncan’s new multiple range test following analysis of variance. 1Values represent the means, two cockerels tested per pen, from six replicate pens per source.
operations, this improved utilization of copper from cupric citrate should allow for lower feeding levels of copper, thus reducing the risk of environmental contamination. Adjusting the FCR for mortality (AFCR) changed the apparent differences in performance due to copper sources. As would be expected, the higher mortalities seen as age and size of the birds increased caused the mortality adjustment to be more dramatic as the age of the birds increased (Experiment 2). Although the mortality was independent of treatment in both experiments, the mortality adjustment decreased the standard error enough to make differences more apparent. This effect is best seen in the FCR data for the 56-d-old birds in Experiment 2. The FCR (calculated as typical for the industry) demonstrated no significant difference between the control group and any of the copper-supplemented groups. The mortality adjustment improved all the ratios a similar amount (0.613 to 0.702; change in FCR for AFCR vs nonadjusted FCR); however, the standard errors were reduced by greater than 50%. The differences seen in the AFCR closely match the differences seen in body weight gain. In a commercial operation, it is not practical to adjust FCR for mortality. Therefore, the data in Experiments 1 and 2 suggest that under commercial conditions, average body weight gain is a better indicator of the effectiveness of copper supplementation than FCR (because calculation of AFCR is not routinely practiced in the industry). Copper oxychloride is being used by several broiler producers without evidence in the published literature on its effectiveness as a copper source. The data presented here indicate that copper oxychloride is a viable copper source compared to the industry standard copper sulfate when growth is used as the response criterion; however, the growth responses to copper sulfate or copper oxychloride are not comparable to
cupric citrate, as reported earlier (Pesti and Bakalli, 1996).
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Plasma Cu Basal Sulfate Oxychloride Citrate Citrate