J. Anim. Sci. 2003. 81:318-322
© 2003 American Society of Animal Science
Effects of breed (Angus vs Simmental) and copper and zinc source on mineral status of steers fed high dietary iron1,2
L. A. Mullis,
J. W. Spears3 and
R. L. McCraw
Department of Animal Science and Interdepartmental Nutrition Program, North Carolina State University, Raleigh 27695-7621
3 Correspondence:
phone: 919-515-4008; fax: 919-515-4463; E-mail:
Jerry_Spears{at}ncsu.edu.
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Abstract
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Forty-four Angus (n = 24) and Simmental (n = 20) steers, averaging 301 kg initially, were used to determine the effects of breed and Cu and Zn source (SO4 or proteinate (Prot) form) on Cu and Zn status of steers fed high dietary iron (Fe). Steers were stratified by weight within breed and randomly assigned to treatments. Treatments consisted of: 1) CuSO4 + ZnSO4, 2) CuSO4 + ZnProt, 3) CuProt + ZnSO4, and 4) CuProt + ZnProt. Copper and Zn sources were added to provide 5 mg Cu and 25 mg supplemental Zn/kg DM. All steers were individually fed a corn silage-based diet supplemented with 1,000 mg Fe (from FeSO4)/kg DM. Liver biopsy samples were obtained at the beginning and end of the 149-d study. Serum samples were collected initially and at 28-d intervals for determination of ceruloplasmin activity and Zn and Cu concentrations. Copper and Zn source did not affect performance, serum or liver Cu and Zn concentrations, or ceruloplasmin activity. Copper status decreased (P < 0.01) in all steers with time, and increasing the level of supplemental Cu from 5 to 10 mg/kg DM on d 84 did not prevent further drops in serum Cu and ceruloplasmin. Simmental steers had lower (P < 0.05) serum and liver Cu concentrations, and serum ceruloplasmin activity throughout the study. These results indicate that neither CuSO4 nor CuProt were effective at the supplemental concentrations evaluated in alleviating the adverse effect of high Fe on Cu status. Simmental steers had lower Cu status than Angus, suggesting a higher Cu requirement.
Key Words: Cattle • Copper • Iron • Zinc
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Introduction
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Ruminants consuming forage-based diets are often exposed to high levels of Fe through water, forage, and/or soil ingestion. High dietary Fe has been shown to greatly reduce Cu status in cattle (Standish et al., 1971; Campbell et al., 1974; Humphries et al., 1983) and sheep (Prabowo et al., 1988). Steers supplemented with 1000 mg Fe/kg DM also had reduced liver Zn concentrations (Standish et al., 1971), suggesting that bioavailability of Zn is also reduced by high dietary Fe. Because of coordinate covalent bonding between the metal and organic functional groups, chelated forms of Cu and Zn may interact less than inorganic forms with Fe, and, thus, be more bioavailable in the presence of high dietary Fe. Research suggests that Cu bioavailability from a Cu complex (Cu lysine) did not differ from CuSO4 in lactating dairy cows fed high Fe (Chase et al., 2000). Studies have not been conducted to compare bioavailability of Cu or Zn from chelated or proteinate forms relative to inorganic forms in cattle fed high Fe diets. Previous research indicated that Cu proteinate was more bioavailable than CuSO4 in cattle fed diets high in the Cu antagonist, Mo (Kincaid et al., 1986; Ward et al., 1996).
Copper requirements of cattle may vary depending on breed. Ward et al. (1995) reported that Simmental cows and their calves had lower plasma Cu concentrations than Angus. We hypothesized that Cu and Zn proteinate would be more bioavailable than SO4 forms in the presence of high Fe and that liver, as well as plasma Cu concentrations, would be lower in Simmental than in Angus steers. The present study was conducted to 1) compare the bioavailability of Cu and Zn from proteinate forms relative to SO4 forms in steers fed high dietary Fe and 2) compare Cu status of growing Angus and Simmental steers fed high Fe diets.
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Materials and Methods
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Care, handling, and sampling of animals used in this study were approved by the North Carolina State University Institutional Animal Care and Use Committee (#92-165). Forty-four Angus (n = 24) and Simmental (n = 20) steers (301 ± 6.6 kg initial BW), approximately 9 mo of age, were stratified by weight within breed and then randomly assigned to one of four treatments. Treatments were arranged as a 2 x 2 factorial consisting of 1) CuSO4 + ZnSO4, 2) CuSO4 + Zn proteinate (DuCoa, Highland, IL), 3) Cu proteinate (DuCoa) + ZnSO4 and 4) Cu proteinate + Zn proteinate. Copper and Zn sources were added to provide 5 mg supplemental Cu and 25 mg supplemental Zn/kg diet DM. Plasma Cu decreased rapidly the first 84 d of the study, and because of this supplemental Cu was increased from 5 to 10 mg/kg after 84 d. There were 11 animals (5 Simmental, 6 Angus) per treatment.
Steers were fed a diet that consisted of 90% corn silage (30.7% DM, 7.0% CP, 3.5 mg Cu, 26 mg Zn, and 334 mg Fe/kg DM) and 10% of a protein, mineral, and vitamin supplement on a DM basis (Table 1
). All diets were supplemented with 1,000 mg Fe/kg DM from FeSO4. Analyzed concentrations of Zn, Cu, and Fe in experimental diets are shown in Table 2. Steers were housed in covered, slotted floor pens and individually fed by electronic feeders (American Calan, Northwood, NH). Steers were fed once daily with feed allotments based on what an animal would consume in a 24-h period. Weights and serum samples were obtained initially and at 28-d intervals throughout the 149-d study. Blood was taken via jugular venipuncture into vacuum tubes (Vacutainer 6526, Becton Dickinson, Rutherford, NJ) designated for trace mineral analysis. Serum was frozen until analyzed for ceruloplasmin activity and Cu and Zn concentrations. Liver biopsy samples (Erwin et al., 1956) were taken at the beginning and end of the study for Cu, Zn, and Fe analysis.
Analytical Procedures.
For determination of serum Cu and Zn concentrations, serum was diluted 1:3 with deionized water and aspirated into the flame of an atomic absorption spectrophotometer (Model 5000, Perkin Elmer, Norwalk, CT). Standards were prepared in 10% glycerin. Serum ceruloplasmin activity was determined by the method of Houchin (1958) and is reported as absorbance units at 525 nm. Liver biopsy samples were dried at 100°C for 72 h and then wet-ashed in a microwave digester (Model MDS-81D, CEM, Matthews, NC). Samples were placed into Teflon-lined digestion vessels to which 10 mL of trace mineral grade nitric acid was added and were allowed to digest for 1 h at room temperature. Sealed vessels were then placed in the microwave digester at 49% power setting for 45 min, 35% power for 45 min, and 0 power for 10 min. Vessels were vented, 2 mL of 30% hydrogen peroxide was added, and unpressurized samples were then placed back in the microwave digester for 5 min at 50% power. Feed samples were ashed in the same manner; however, feed samples were only allowed to digest for 30 min and were placed in the microwave for 5 min at 50% power, 15 min at 70% power, and 10 min at 0 power. After addition of hydrogen peroxide, samples were placed back in the microwave for 3 min at 50% power and 2 min at 0 power. Ashed samples were analyzed for Cu, Zn, and Fe by atomic absorption spectrophotometry.
Statistical Analysis.
Data were analyzed by least squares ANOVA using the GLM procedures of SAS (SAS Inst. Inc., Cary, NC). Plasma and liver data were analyzed by repeated measures in the GLM procedure of SAS using the main effects of treatment, breed, treatment x breed, time, treatment x time, breed x time, and treatment x breed x time. The model for performance data included treatment, breed, and treatment x breed. Single degree of freedom contrasts were used to partition treatment effects of Cu source, Zn source, and Cu source x Zn source.
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Results and Discussion
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Serum Cu concentrations were not affected by Cu source (Table 3) or a treatment x breed interaction. Serum Cu concentrations declined (time effect; P < 0.01) throughout the study, even though supplemental Cu was increased to 10 mg/kg diet at d 84. Phillippo et al. (1987) reported that when 500 mg Fe/kg diet in the form of saccharated ferrous carbonate was fed to calves plasma Cu concentrations were reduced to 0.14 µg/mL by d 168 of the study. Prabowo et al. (1988) found that plasma Cu concentrations decreased in lambs supplemented with 300, 600, or 1,200 mg Fe/kg diet as ferrous carbonate.
Serum Cu concentrations were affected by a time x breed (P < 0.01) interaction (Figure 1). Although both breeds of steers grazed the same pastures before the experiment began, Simmental steers tended to have lower (P < 0.10) serum Cu levels on d 0. On d 28 and subsequent sampling days, Simmental steers had lower (P < 0.05) serum Cu concentrations than Angus. In agreement with the present study, Simmental cows and their calves had lower plasma Cu concentrations than Angus when fed low Cu diets (Ward et al., 1995). By d 140, both Angus and Simmental had serum Cu concentrations that were indicative of severe Cu deficiency (Underwood, 1977). Angus steers had mean concentrations of 0.30 ± 0.03 mg/L, whereas Simmental steers had mean Cu concentrations of 0.15 ± 0.04 mg/L at the end of the study.
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Figure 1. Effect of breed on serum Cu concentration in Angus and Simmental Steers. Pooled SEM: d 0 = 0.04; d 28 = 0.04 (Angus), 0.05 (Simmental); d 56 = 0.04; d 84 = 0.05; d 112 = 0.04; d 140 = 0.03 (Angus), 0.04 (Simmental. Breed x time interaction (P < 0.01). *P < 0.05, **P < 0.01.
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Zinc source did not affect serum Zn concentrations (Table 4). Serum Zn concentrations remained within the normal range (Underwood, 1977) throughout the study. Zinc concentrations in serum were higher (time effect: P < 0.01) at later sampling dates (d 84, 112, and 140) than at earlier sampling dates (d 0, 28, and 84). Serum Zn was also affected by a breed x time interaction (P < 0.05). Simmental steers had lower (P < 0.01) serum Zn concentrations than Angus on d 0, 28, and 56 (Figure 2). After d 56, there were no differences in serum Zn concentrations among breeds.
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Figure 2. Effect of breed on serum Zn concentration in Angus and Simmental steers. Pooled SEM: d 0 = 0.03; d 28 = 0.02; d 56 = 0.03 (Angus), 0.04 (Simmental); d 84 to 140 = 0.02 (Angus), 0.03 (Simmental). Breed x time interaction (P < 0.01). *P < 0.05, **P < 0.01.
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Ceruloplasmin activity in serum dropped steadily (time effect; P < 0.01) throughout the experiment but was not affected by Cu or Zn source (Table 5). The decrease in ceruloplasmin would be expected since the majority of Cu in serum is present in ceruloplasmin (Underwood, 1977). Ceruloplasmin activity was affected by a time x breed (P < 0.01) interaction. Simmental steers had lower (P < 0.05 on d 28 and 140; P < 0.01 on d 56, 84, and 112) ceruloplasmin activities throughout the study with the exception of d 0 (Figure 3). On d 140, Simmental steers were approaching nondetectable activities of ceruloplasmin.
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Figure 3. Effect of breed on serum ceruloplasmin activity in Angus and Simmental steers. Pooled SEM: d 0 to 140 = 0.01. Breed x time interaction (P < 0.01). *P < 0.05, **P < 0.01.
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Copper and Zn source did not affect liver Fe, Zn, or Cu concentrations (Table 6). In contrast lactating dairy cows supplemented with Cu proteinate had higher liver Fe concentrations than those receiving CuSO4 (Du et al., 1995). Final liver Fe concentrations were much greater (P < 0.01) than initial liver iron concentrations due to the high load of iron being ingested. Previous studies (Humphries et al., 1983; Bremner et al., 1987) have demonstrated that feeding high concentrations of Fe from bioavailable sources will elevate liver Fe concentrations. Final liver Cu concentrations were much lower (P < 0.01) than initial liver Cu concentrations. All treatments had liver Cu concentrations at the end of the study that were below 20 mg/kg DM, which is indicative of severe Cu deficiency (Underwood, 1977). Liver Zn was not affected by treatment or time. There was no effect of breed on liver iron and Zn concentrations (Table 7). Liver Cu concentrations were affected by breed (P < 0.01) and a breed x time interaction (P < 0.01). Simmental steers had lower liver Cu concentrations than Angus, but the difference between breeds was greater on d 0 than on d 140. The lower liver Cu concentrations in Simmental steers may relate to increased biliary Cu excretion. Gooneratne et al. (1994) reported that biliary Cu excretion was much greater in Simmental than in Angus heifers.
Copper and Zn source did not significantly affect steer performance (Table 8). The level of Fe added in the present study would be expected to reduce performance based on previous studies (Standish et al., 1969; 1971). Steer performance was also not affected by breed.
In conclusion, no differences in Cu and Zn status were noted between steers fed proteinate and SO4 forms of these metals. Although the proteinate sources were expected to be better utilized in the presence of high dietary iron, the tremendous amount of dietary iron most likely overwhelmed any differences in bioavailability. Simmental steers appear to have a higher copper requirement than Angus based on serum and liver Cu concentrations and ceruloplasmin activity.
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Implications
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Results of this study indicate that 1,000 mg of supplemental iron per kilogram diet has a deleterious effect on copper status of cattle. Neither copper sulfate nor copper proteinate at the supplemental concentrations (5 or 10 mg/kg diet) evaluated were effective in preventing the adverse effect of high iron on copper status. Simmental steers consistently had lower copper status than Angus cattle, suggesting that Simmental have a higher copper requirement.
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Footnotes
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1 Use of trade names in this publication does not imply endorsement by the North Carolina Agric. Res. Serv., or criticism of similar products not mentioned. 
2 Supported in part by a gift from DuCoa, Highland, IL.
Received for publication March 11, 2002.
Accepted for publication August 19, 2002.
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Literature Cited
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Bremner, I., W. R. Humphries, M. Phillippo, M. J. Walker, and P. C. Morrice. 1987. Iron-induced copper deficiency in calves: Dose-response relationships and interactions with molybdenum and sulfur. Anim. Prod. 45:403–414.
Campbell, A. G., M. R. Coup, W. H. Bishop, and D. E. Wright. 1974. Effect of elevated iron intake on the copper status of grazing cattle. N. Z. J. Agric. Res. 17:393–399.
Chase, C. R., D. K. Beede, H. H. Van Horn, J. K. Shearer, C. J. Wilcox, and G. A. Donovan. 2000. Responses of lactating dairy cows to copper source, supplementation rate, and dietary antagonist (iron). J. Dairy Sci. 83:1845–1852.[Abstract]
Du, Z., R. W. Hemken, and T. W. Clark. 1995. Copper proteinate may be absorbed in chelated form by lactating Holstein cows. Pages 315–319 in Biotechnology in the Feed Industry. T. P. Lyons and K. A. Jacques, ed. Nottingham University Press, Nottingham, UK.
Erwin, E. S., I. A. Dyer, T. O. Meyer, and K. W. Scott. 1956. Uses of aspiration biopsy technique. J. Anim. Sci. 15:428–434.[Abstract/Free Full Text]
Gooneratne, S. R., H. W. Symonds, J. V. Bailey, and D. A. Christensen. 1994. Effects of dietary copper, molybdenum and sulfur on biliary copper and zinc excretion in Simmental and Angus cattle. Can. J. Anim. Sci. 74:315–325.
Houchin, O. B. 1958. A rapid colorimetric method for the quantitative determination of copper oxidase activity (ceruloplasmin). Clin. Chem. 4:519.[Abstract]
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Kincaid, R. L., R. M. Blauwiekel, and J. D. Cronrath. 1986. Supplementation of copper sulfate or copper proteinate for growing calves fed forages containing molybdenum. J. Dairy Sci. 69:160–164.[Abstract/Free Full Text]
Phillippo, M., W. R. Humphries, and P. H. Garthwaite. 1987. The effect of dietary molybdenum and iron on copper status and growth in cattle. J. Agric. Sci. 109:315–320.
Prabowo, A., J. W. Spears, and L. Goode. 1988. Effects of dietary iron on performance and mineral utilization in lambs fed a forage-based diet. J. Anim. Sci. 66:2028–2035.
Standish, J. F., C. B. Ammerman, A. Z. Palmer, and C. F. Simpson. 1971. Influence of dietary iron and phosphorus on performance, tissue mineral composition and mineral absorption in steers. J. Anim. Sci. 33:171–178.
Standish, J. F., C. B. Ammerman, C. F. Simpson, F. C. Neal, and A. Z. Palmer. 1969. Influence of graded levels of dietary iron as ferrous sulfate, on performance and tissue mineral composition of steers. J. Anim. Sci. 29:496–503.
Underwood, E. J. 1977. Trace Elements in Human and Animal Nutrition. 4th ed. Academic Press, New York.
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Abstract
Introduction
