J. Anim Sci. 2007. 85:871-876. doi:10.2527/jas.2006-518
© 2007 American Society of Animal Science
Effects of tribasic copper chloride versus copper sulfate provided in corn-and molasses-based supplements on forage intake and copper status of beef heifers1
J. D. Arthington*,2 and
J. W. Spears
* University of Florida—IFAS, Range Cattle Research and Education Center, Ona 33865; and
and
Department of Animal Sciences and Interdepartmental Nutrition Program, North Carolina State University, Raleigh 27695
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Abstract
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The objective of this study was to investigate the effect of supplemental tribasic copper chloride (Cu2(OH3)Cl; TBCC) vs. Cu sulfate (CuSO4) on Cu status and voluntary forage DMI in growing heifers. Two 90-d experiments were conducted using 48 non-pregnant, crossbred heifers (24 heifers/experiment; 355 ± 10.7 and 309 ± 9.9 kg for Exp. 1 and 2, respectively). In each experiment, 3 supplemental Cu treatments were randomly allocated to heifers in individual pens consisting of (1) 100 mg of Cu/d from CuSO4, (2) 100 mg of Cu/d from TBCC, or (3) 0 mg of Cu/d. The 2 experiments differed by the form of supplement used to deliver the Cu treatments (corn- vs. molasses-based supplements for Exp. 1 and 2, respectively). Supplements were formulated and fed to provide equivalent amounts of CP and TDN daily but differed in their concentration of the Cu antagonists, Mo (0.70 vs. 1.44 mg/kg), Fe (113 vs. 189 mg/kg), and S (0.18 vs. 0.37%) for corn- and molasses-based supplements, respectively. All heifers were provided free-choice access to ground stargrass (Cynodon spp.) hay. Jugular blood and liver biopsy samples were collected on d 0, 30, 60, and 90 of each experiment. Heifer BW was collected on d 0 and 90. Heifer ADG was not affected by Cu treatment (average = 0.22 ± 0.11 and 0.44 ± 0.05 kg for Exp. 1 and 2, respectively; P > 0.20). In Exp. 1, heifers provided supplemental Cu, independent of source, had greater (P < 0.05) liver Cu concentrations on d 60 and 90 compared with heifers provided no supplemental Cu. In Exp. 2, average liver Cu concentrations were greater (P = 0.04) for heifers receiving supplemental Cu compared with heifers receiving no Cu; however, all treatments experienced a decrease in liver Cu concentration over the 90-d treatment period. Plasma ceruloplasmin concentrations did not differ in Exp. 1 (P = 0.83) but were greater (P = 0.04) in Exp. 2 for heifers receiving supplemental Cu compared with heifers receiving no Cu. In Exp. 1, voluntary forage DMI was greater (P < 0.05) for heifers provided supplemental Cu, independent of source, compared with heifers provided no Cu. In contrast, voluntary forage DMI was not affected (P > 0.10) by Cu supplementation in Exp. 2. These data imply that CuSO4 and TBCC are of similar availability when offered to growing beef heifers in both corn- and molasses-based supplements. However, corn- and molasses-based supplements appear to affect Cu metabolism differently. These impacts may affect voluntary forage DMI in growing beef heifers.
Key Words: copper • heifer • cattle • corn • molasses
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INTRODUCTION
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The Cu status of cattle fed molasses-based supplements is reduced compared with cattle fed corn-based supplements (Arthington and Pate, 2002
). This response is likely the result of greater S content of molasses vs. corn (Arthington and Pate, 2002). Sulfur is a recognized Cu antagonist alone (Suttle, 1974) or in conjunction with Mo (Mason, 1990).
Sources of Cu differ in their ability to be metabolized and utilized by cattle, especially in the presence of Cu antagonists (Kegley and Spears, 1994). Heifers that are Cu-deficient, because of consumption of high-S forages, experienced a faster rate of Cu repletion when provided organic Cu compared with an equivalent amount of Cu from CuSO4 (Arthington et al., 2002). In contrast, no differences in Cu status were detected when these sources were fed to Cu-adequate heifers provided molasses supplements (Arthington et al., 2003). Other investigators reported increased bioavailability of Cu from tribasic Cu chloride (TBCC) vs. CuSO4 when fed to steers consuming a diet with elevated concentrations of Mo, but not in steers consuming diets with minimal Mo concentrations (Spears et al., 2004).
An interesting observation among these studies relates to the impact of Cu supplementation on DMI. In one study (Arthington, 2005), heifers fed no supplemental Cu had lesser voluntary forage DMI compared with heifers provided supplemental CuSO4. Consequently, steers provided no supplemental Cu experienced a numeric tendency (P = 0.14) toward a lesser DMI compared with steers provided supplemental TBCC or CuSO4 (Spears et al., 2004). Further, heifers provided TBCC had greater voluntary forage DMI compared with heifers supplemented with an organic Cu source (Arthington et al., 2003).
Our objectives were to evaluate measures of Cu status and voluntary forage DMI in beef heifers provided 2 sources of supplemental Cu (TBCC and CuSO4) in supplements containing a low content of Cu antagonists (corn-based; Exp. 1) and supplements containing a high content of Cu antagonists (molasses-based; Exp. 2).
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MATERIALS AND METHODS
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Animal Care, Handling, and Diet
Animals utilized in both experiments were cared for by acceptable practices (FASS, 1999), and the protocol was approved by the University of Florida Institutional Animal Care and Use Committee. Liver biopsy collections were performed by a trained technician using techniques previously described (Arthington and Corah, 1995). Each experiment was conducted at the University of Florida Range Cattle Research and Education Center, Ona.
In Exp. 1, 24 nonpregnant, Brahman x British heifers (average initial BW = 355 ± 10.7 kg; average age 17 to 19 mo) were randomly assigned to individual pens (15 m2). Heifers were allowed to move freely within their assigned pen. After a 7-d acclimation period, 3 treatments were randomly assigned to the 24 pens (8 pens/treatment), consisting of (1) 100 mg of Cu/d from CuSO4, (2) 100 mg of Cu/d from TBCC (Cu2(OH3)Cl; Micronutrients Inc., Indianapolis, IN), or (3) 0 mg of Cu/d. Heifers received the same treatment throughout the duration of the experiment. Treatments were hand-mixed into a dry supplement consisting of 1.5 and 0.35 kg of corn and cottonseed meal, respectively. Heifers were provided ground stargrass (Cynodon spp.) hay in amounts adequate to ensure ad libitum consumption throughout the duration of the experiment. Nutrient composition of the supplements and hay is provided in Table 1, and the concentration of Cu antagonists is provided in Table 2.
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Table 2. Dietary contribution of Cu and Cu antagonists (Mo, Fe, and S) from supplements and hay in Exp. 1 and 2, DM basis
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Forage DMI was assessed daily by the collection of orts. Average DMI, expressed as a percentage of individual heifer BW, was pooled over nine 10-d intervals. Individual heifer BW was collected at the beginning and conclusion of the study, after a 16-h withdrawal from feed and water. Heifer BW within the designated DMI intervals was calculated by assuming a uniform ADG over the 90-d experimental period. Liver biopsy and jugular blood samples were collected from all heifers on d 0, 30, 60, and 90.
In Exp. 2, 24 nonpregnant Brahman x British heifers (average initial BW = 309 ± 9.9 kg; average age 15 to 18 mo) were randomly assigned to the same pens used in Exp. 1. After a 7-d acclimation period, the same Cu treatments used in Exp. 1 were fed thrice weekly (Monday, Wednesday, and Friday) for 90 d in a molasses-based supplement consisting of 4.1 kg of sugarcane-derived, blackstrap liquid molasses (United States Sugar Corporation, Clewiston, FL) blended with 0.81 kg of cottonseed meal. Heifers received the same treatment throughout the duration of the experiment. Heifers in Exp. 2 were provided with ad libitum access to stargrass hay that was derived from a different season. For this reason, the nutrient content of the hay differed between Exp. 1 and 2. The nutrient composition of the supplement components and hay is provided in Table 1
, and the concentration of Cu antagonists is provided in Table 2. Voluntary forage DMI was assessed over three 14-d intervals conducted at the beginning (d 15), middle (d 47), and end (d 76) of the study. As in Exp. 1, liver biopsy and jugular blood samples were collected from all heifers on d 0, 30, 60, and 90.
Feed, Plasma, and Liver Analysis
The nutrient content of supplement components and hay was analyzed by commercial laboratories (hay, corn, and cottonseed meal at Dairy One Laboratory, Ithaca, NY, and molasses at SDK Laboratories, Hutchinson, KS). Liver samples were analyzed (SDK Laboratories) using inductively coupled plasma, atomic emission spectroscopy. Blood was collected by jugular venipuncture into heparin-coated, evacuated tubes. Plasma was harvested from blood after centrifugation at 2,400 x g for 20 min and then frozen at –20°C until analyzed for ceruloplasmin concentration using colorimetric procedures (Demetriou et al., 1974).
Statistical Analysis
Statistical analyses of liver Cu and plasma ceruloplasmin concentrations and forage DMI were achieved by ANOVA for a repeated measures experiment within a completely randomized design using PROC MIXED (SAS Inst. Inc., Cary, NC). The model statement contained the effects of treatment and time and the interaction of treatment x time. Data were analyzed using the pen x treatment interaction as the random effect. For liver Cu analyses, d 0 values were used as a covariate in the model to test subsequent sampling dates. Statistical analysis for the overall change in liver Cu and ceruloplasmin concentrations and ADG was achieved by analysis of variance for a completely randomized design using PROC MIXED of SAS. The model statement contained the effect of treatment. Data were analyzed using the pen x treatment interaction as the random effect. Pen was used as the experimental unit for both experiments.
When treatment or treatment x day interactions were significant, differences among treatments were compared using single-df orthogonal contrasts. Contrasts for both experiments were (1) no Cu vs. Cu and (2) TBCC vs. CuSO4. All values are reported as least squares means.
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RESULTS AND DISCUSSION
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In Exp. 1, liver Cu concentrations increased (P < 0.01) in heifers receiving Cu supplements from d 0 to 90, but no differences among Cu sources were detected (P = 0.49). Liver Cu concentrations for heifers receiving no supplemental Cu did not change (P = 0.17) from d 0 to 90. This resulted in greater (P < 0.05) liver Cu concentrations for Cu-supplemented heifers on d 30, 60, and 90 compared with heifers receiving no supplemental Cu (Figure 1). This response is similar to that reported previously (Arthington and Pate, 2002), whereas heifers provided supplemental CuSO4 in a corn/cottonseed meal carrier experienced a net increase in liver Cu concentration over 84 d of supplementation compared with no change in heifers provided no supplemental Cu. The corn-based supplement fed in Exp. 1 contained minimal concentrations of S and Mo (Table 2), which are the primary Cu antagonists for cattle (McDowell, 2003). Spears et al. (2004) also reported no differences in liver Cu accumulation for steers provided supplemental CuSO4 or TBCC in a basal diet that contained a minimal concentration of Mo (1.18 mg/kg).
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Figure 1. The effect of Cu source on liver Cu concentrations in Exp. 1 and 2. Day 0 values were used as a covariate for analysis of subsequent sampling days. For Exp. 1 and 2, pooled SEM = 20.2, 27.1, and 18.4, and 8.9, 8.7, and 12.7 mg/kg for d 30, 60, and 90, respectively. Values are provided on a DM basis. Treatment x day interaction (P < 0.01 and P < 0.60 for Exp. 1 and 2, respectively). *Single df orthogonal contrast comparing Cu vs. no Cu, P < 0.05.
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In Exp. 2, initial (d 0) average liver Cu concentrations were greater for Cu supplemented vs. heifers receiving no supplemental Cu; nevertheless, all treatments experienced a decline (P < 0.01) in average liver Cu concentration from d 0 to 90, with no significant treatment x time interaction (Figure 1). The differences between Exp. 1 and 2 are likely a result of the presence of Cu antagonists in the supplement + hay used in Exp. 2, particularly Mo and S (Table 2). Although the Mo content of molasses is greater than corn, Cu is also greater, resulting in similar Cu:Mo ratios (wt/wt = 9.54 vs. 8.61 for Exp. 1 and 2, respectively). The dietary Cu:Mo ratio is often used to characterize the antagonistic influence of Mo on Cu, although this method has limitations in that it does not consider the impact of S as a Cu antagonist (Underwood and Suttle, 1999). Sulfur is likely the most relevant Cu antagonist in ruminants because it can influence Cu absorption alone (Suttle, 1974) or in combination with Mo in the formation of thiomolybdates (Mason, 1990). Even though the Cu treatments resulted in a diet containing almost 3 times the minimum Cu concentration suggested for beef cattle (10 ppm; NRC, 1996), the concentration was not sufficient to overcome the antagonism of S found primarily in the molasses, but also in the hay (Table 2). Similar changes in liver Cu concentrations were noted in a previous study where grazing heifers were provided supplemental CuSO4 in a molasses-based carrier (Arthington and Pate, 2002). In the current study, no apparent differences in liver Cu concentrations were observed between heifers provided supplemental TBCC or CuSO4. These results differ from those reported by Spears et al. (2004) where actual liver Cu concentrations did not differ between steers provided equivalent amounts of Cu from CuSO4 or TBCC for 98 d. However, multiple linear regression analysis (Littell et al., 1995) revealed a greater relative bioavailability for TBCC, relative to CuSO4. In the current study, we were unable to utilize a similar bioavailability analysis because of the presence of only 2 levels of supplementation (0 and 100 mg of Cu/d). One explanation for the differences between these studies may be related to the source of Cu antagonist being considered. In the current study, the primary antagonist was S, compared with Mo in their model (Spears et al., 2004). In their study, dietary Mo concentrations were 11.9 mg/kg compared with only 1.4 mg/kg in the current study. Dietary S concentrations did not differ substantially between studies (0.37 vs. 0.45% for the current study and Spears et al. 2004, respectively). These differences may have been sufficient to influence the Cu-binding properties of thiomolybdates (Mo x S complex; Mason, 1990), potentially creating differences in measures of availability among dietary Cu sources.
There were no significant treatment x time interactions for plasma ceruloplasmin concentrations in either experiment; however, the change in plasma ceruloplasmin tended (P = 0.08) to be greater for TBCC-supplemented heifers in Exp. 1 (Table 3). In Exp. 2, average plasma ceruloplasmin concentrations were greater (P = 0.04) for Cu-supplemented heifers vs. heifers receiving no supplemental Cu. Additionally, change in plasma ceruloplasmin concentration tended (P = 0.10) to be greater for heifers receiving no supplemental Cu vs. heifers receiving CuSO4 or TBCC (Table 2). Measures of ceruloplasmin activity can be used as an alternative to direct measurement of plasma or serum Cu because more than 90% of blood Cu is incorporated into the ceruloplasmin protein (Cousins, 1985). One potential shortcoming of this technique relates to the acute phase properties of ceruloplasmin, whereas ceruloplasmin concentrations will increase following stimulation from inflammatory signals (Cousins, 1985).
In Exp. 1, voluntary forage DMI was less for heifers receiving no supplemental Cu vs. heifers receiving CuSO4 or TBCC (Figure 2). In this experiment, voluntary forage DMI was reported as an average over nine 10-d intervals. In Exp. 2, voluntary forage DMI was assessed differently than Exp. 1; forage DMI was measured on 3 equally spaced 14-d intervals beginning on the third week of the study and continuing every 2 wk until the conclusion of the study (Table 4). In Exp. 2, no differences in forage DMI, relative to the presence of Cu or source, were detected. Because we did not begin to measure voluntary forage DMI until the start of wk 3 of Exp. 2, it is possible that we missed a difference that might have been present at the start of the study. In Exp. 1, the difference between Cu-supplemented and nonsupplemented heifers was apparent in the first 10-d interval, suggesting that the influence of Cu on voluntary forage DMI was the result of a fairly immediate impact on the animal. This theory is further supported by another study conducted at the same approximate time as the current study. In that study (Arthington, 2005), there was no difference in average voluntary forage DMI in Cu-supplemented vs. nonsupplemented heifers over a 12-wk period. However, in the first 2 wk of the study, heifers provided no supplemental Cu had a lesser voluntary forage DMI compared with heifers provided supplemental CuSO4. In that study, heifers were provided molasses-based supplements similar to those used in Exp. 2.
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Figure 2. The effect of Cu source on voluntary forage DMI in Exp. 1. Greatest SEM = 0.06. Treatment x day interaction (P < 0.05). *Single df orthogonal contrast comparing Cu vs. no Cu, P < 0.05.
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Table 4. Effect of copper source on voluntary forage DMI in heifers provided molasses-based supplements in Exp. 2
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A link between Cu nutrition and voluntary forage intake is unclear. Hubbert et al. (1958) suggested that relatively low concentrations of Cu were toxic to ruminal microbes contained in a culture system. In contrast, Lopez-Guisa and Satter (1992) suggested that supplementation of Cu above 10 mg/kg, which is the current recommendation (NRC, 1996), might improve the digestion of low-quality forages. In one study, Ward and Spears (1997) reported a greater DMI among weaned bull calves fed a corn silage receiving diet fortified with CuSO4 (7.8 mg of Cu/kg) vs. no Cu supplementation. Alternative forms of Cu supplementation may also affect forage utilization in cattle. Steers receiving supplemental Cu via a Cu oxide bolus were found to have reduced apparent digestibility of forage NDF and CP (Arthington, 2005). This response may be related to subclinical Cu toxicity associated with the Cu oxide bolus. On the other hand, diets deficient in Cu may also create a scenario suitable for reduced forage utilization because it is reasonable to expect the microbial population of the rumen to have a requirement for Cu in addition to other microminerals. More research efforts are needed to further examine the impact of Cu nutrition on forage intake and utilization in cattle.
There were no differences (P > 0.85) in initial BW among treatments in Exp. 1 and 2 (average initial BW ± SEM = 355 ± 10.7 and 309 ± 9.9 kg for Exp. 1 and 2, respectively). The provision of supplemental Cu had no impact on heifer ADG in either experiment (ADG ± SEM = 0.22 ± 0.24 and 0.44 ± 0.05 kg for Exp. 1 and 2, respectively). Although research investigating the influence of dietary Cu on BW gain of beef cattle has been somewhat variable, our research with growing cattle consuming forage diets that are marginal or deficient in Cu typically results in increased BW gain in response to supplemental Cu. Heifers provided organic and inorganic Cu supplements tended (P = 0.11) to have a greater BW gain compared with heifers receiving no supplemental Cu (Arthington et al., 2003). Similarly, heifers provided supplemental Cu (15 and 60 ppm via CuSO4) experienced greater BW gain compared with heifers provided no supplemental Cu (Arthington, 2005). Further, Spears et al. (2004) reported a greater BW gain for steers provided 5 and 10 ppm supplemental Cu compared with steers consuming the basal diet with no supplemental Cu.
Results of these experiments imply that supplementation of CuSO4 and TBCC result in similar measures of Cu status among growing heifers consuming low to moderate quality forage diets and supplemented with either corn- or molasses-based feeds. Heifers consuming molasses-based supplements experience a net decrease in liver Cu accumulation even when provided supplemental Cu at 2 times NRC (1996) recommendations. Further, Cu nutrition appears to affect voluntary forage DMI in growing cattle; however, the response is variable and may be influenced by the presence of Cu antagonists, the form of Cu provided, or both.
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Footnotes
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1 Appreciation is expressed to Davi Brito de Arau 'jo and Toni Wood for their assistance during this experiment. The authors also wish to thank Micronutrients Inc. (Indianapolis, IN) for their partial financial support of these studies. 
2 Corresponding author: jdarthington{at}ifas.ufl.edu
Received for publication July 31, 2006.
Accepted for publication October 17, 2006.
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LITERATURE CITED
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Arthington, J. D. 2005. Effects of copper oxide bolus administration or high-level copper supplementation on forage utilization and copper status in beef cattle. J. Anim. Sci. 83:2894–2900.[Abstract/Free Full Text]
Arthington, J. D., and L. R. Corah. 1995. Liver biopsy procedures for determining the trace mineral status in beef cows; Part II (Video, AI 8134). Extension TV, Dep. Communications. Coop. Ext. Ser., Kansas State Univ., Manhattan.
Arthington, J. D., and F. M. Pate. 2002. Effect of corn- versus molasses-based supplements on trace mineral status in beef heifers. J. Anim. Sci. 80:2787–2791.[Abstract/Free Full Text]
Arthington, J. D., F. M. Pate, and J. W. Spears. 2003. Effect of copper source and level on performance and copper status of cattle consuming molasses-based supplements. J. Anim. Sci. 81:1357–1362.[Abstract/Free Full Text]
Arthington, J. D., J. E. Rechcigl, G. P. Yost, L. R. McDowell, and M. D. Fanning. 2002. Effect of ammonium sulfate fertilization on bahiagrass quality and copper metabolism in grazing beef cattle. J. Anim. Sci. 80:2507–2512.[Abstract/Free Full Text]
Cousins, R. J. 1985. Absorption, transport, and hepatic metabolism of Cu and Zn: Special reference to metallothionein and ceruloplasmin. Physiol. Rev. 65:238–309.[Free Full Text]
Demetriou, J. A., P. A. Drewes, and J. B. Gin. 1974. Ceruloplasmin. Page 857 in Clinical Chemistry. D. C. Cannon and J. W. Winkelman, ed. Harper and Row, Hagerstown, MD.
FASS. 1999. Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching. 1st rev. ed. Fed. Anim. Sci. Soc., Savoy, IL.
Hubbert, F., Jr., E. Cheng, and W. Burroughs. 1958. Mineral requirement of rumen microorganisms for cellulose digestion in vitro. J. Anim. Sci. 178:559–568.
Kegley, E. B., and J. W. Spears. 1994. Bioavailability of feed-grade copper sources (oxide, sulfate, or lysine) in growing cattle. J. Anim. Sci. 72:2728–2734.[Abstract]
Littell, R. C., A. J. Lewis, and P. R. Henry. 1995. Statistical evaluation of bioavailability assays. Pages 5–33 in Bioavailability of nutrients for Animals. C. G. Ammerman, D. H. Baker, and A. J. Lewis, ed. Academic Press, San Diego, CA.
Lopez-Guisa, J. M., and L. D. Satter. 1992. Effect of copper and cobalt addition on digestion and growth in heifers fed diets containing alfalfa silage or corn crop residue. J. Dairy Sci. 75:247–256.[Abstract]
Mason, J. 1990. The biochemical pathogenesis of molybdenum-induced copper deficiency syndromes in ruminants: Towards the final chapter. Ir. Vet. J. 43:18–22.
McDowell, L. R. 2003. Copper and Molybdenum. Page 235 in Minerals in Animal and Human Nutrition. 2nd ed. Elsevier Science, Amsterdam, the Netherlands.
NRC. 1996. Nutrient Requirements of Beef Cattle. 7th ed. Natl. Acad. Press, Washington, DC.
Spears, J. W., E. B. Kegley, and L. A. Mullis. 2004. Bioavailability of copper from tribasic copper chloride and copper sulfate in growing cattle. Anim. Feed Sci. Technol. 116:1–13.[CrossRef]
Suttle, N. F. 1974. Effects of organic and inorganic sulphur on the availability of dietary copper to sheep. Br. J. Nutr. 32:559–568.[CrossRef][Medline]
Underwood, E. J., and N. F. Suttle. 1999. The Mineral Nutrition of Livestock. 3rd ed. CABI Publishing, Wallingford, UK.
Ward, J. D., and J. W. Spears. 1997. Long-term effects of consumption of low-copper diets with or without supplemental molybdenum on copper status, performance, and carcass characteristics of cattle. J. Anim. Sci. 73:3057–3065.
Weiss, W. P., H. R. Conrad, and N. R. S. Pierre. 1992. A theoretically-based model for predicting total digestible nutrient values of forages and concentrates. Anim. Feed Sci. Technol. 39:95–110.
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Abstract
INTRODUCTION
