Effects of dietary copper on organ indexes, tissular Cu, Zn and Fe deposition and fur quality of growing-furring male mink (Mustela vison)
© Wu et al.; licensee BioMed Central. 2015
Received: 26 September 2014
Accepted: 9 January 2015
Published: 25 February 2015
The objectives of this study were to study the effects of different levels of dietary copper on organ indexes, tissular Cu, Zn and Fe deposition and fur quality of mink in the growing-furring periods. One hundred and five standard dark male mink were randomly assigned to seven groups with the following dietary treatments: basal diet with no supplemental Cu (Control); basal diet supplemented with either 6, 12, 24, 48, 96 and 192 mg/kg Cu from copper sulphate, respectively. The colour intensity scores displayed a linear trend (P = 0.057). The spleen Cu concentrations responded in a linear (P < 0.05) fashion with increasing level of Cu, but copper supplementation did not affect speen concentrations of Fe or Zn. Supplemental dose of Cu linearly increased (P < 0.05) liver Cu and Fe concentrations but did not alter (P > 0.10) liver Zn. Our results indicate that Cu plays an important role in the pigmentation in growing-furring mink, and supplemental dietary Cu in growing-furring mink improve hair colour, and copper has limited effects on liver mineral deposition.
Copper is a key trace mineral in mink nutrition in terms of its role in hemoglobin formation and normal pigmentation of fur. Copper, as an essential trace element, is required for plant, animal, and human health as well as for fur production of mink. Copper is a constituent of several metalloenzymes such as cytochrome oxidase, which functions in cellular respiration, and lysyl oxidase, important in connective tissue formation [1,2]. Copper is also a constituent of tyrosinase, an enzyme involved in melanin (the black pigment of skin, hair, and fur) [3-5]. The recommended level for copper in the mink diet is 4.5-6.0 mg/kg (NRC) . However, earlier studies by Aulerich and Ringer  indicated superior weight gains in male kits but not in female kits fed supplemental copper at the 50 mg/kg level. In two other studies, Aulerich et al.  and Bush et al.  it was noted that darker fur color occurred in male kits but not female kits with supplemental copper at the 200 mg/kg level. Studies at Cornell University with mink on purified diets suggested that 20 mg Cu/kg DM was adequate for growth and fur development .
Although copper has been found to play an important role in the nutrition and fur development of mink, the effects of copper supplementation on organ indexes, tissular Cu, Zn and Fe deposition and fur quality of mink has never been reported. Furthermore, the optimal dietary level of Cu in mink has not been established. Therefore, the objectives of the present study were to investigate the effects of dietary copper level on organ indexes, tissular Cu, Zn and Fe deposition and fur quality of mink in the growing-furring period. The optimum dietary copper requirement for mink was also estimated.
The animal protocol for this experiment was approved by the Animal Care Committee of the Institute of Special Economic Animal and Plant Science of the Chinese Academy of Agricultural Sciences (44.02。N, 126.15。E). Animals were maintained and processed in accordance with the CAAS Guide for the Care and Use of Laboratory Animals.
Animals, diets, management, and experimental design
Ingredient and chemical composition of basal diet
Ingredient [g/kg diet]
Corn gluten meal
Meat and bone meal
Chemical composition [g/kg]
Dry matter [g/kg]
Crude protein [g/kg DM]
Crude fat [g/kg DM]
Crude carbohydrate [g/kg DM]
Ash [g/kg DM]
Contents of mineral elementsa
Contents of amino acida [mg/kg]
Metabolizable energyb [MJ/kg DM]
% from protein
% from fat
% from carbohydrates
The animals were housed individually in open-sided sheds in mink growing cages (60 cm long × 40 cm wide × 50 cm high) with additional attached nest boxes (30 cm long × 40 cm wide × 30 cm high). All animals were vaccinated with distemper and canine parvovirus before the study started. Animals had access to ad libitum clean drinking water (contained less than 0.01 mg Cu/L by analysis). Animal had access to feed and tap water ad libitum throughout the study. Measured amount of treatment diets were offered twice daily at 08:00 and 16:00.
The chemical composition of the diets were analyzed by standard methods. Dry matter was determined by drying feed samples at 105°C to constant weight. The Cu, Fe and Zn content of feed and organs samples  were estimated in an air–acetylene flame on an atomic absorption spectrophotometer (Shimadzu Scientific Instruments, Kyoto, Japan).
Eight minks selected randomly from each group were pelted in accordance with normal farming practice. Mink were killed by gas (CO2) in a killing box, 20–30 mink may be placed in there, depending on box-size, according to the Welfare of Animals Kept for Fur Production. The abdominal cavity was opened and various organs obtained. The liver, spleen, heart, and kidney were weighed to determine the relative organ weight. Organ index was determined using a method described by Lu et al. . Organ index (g/kg) = weight of organ/empty-body weight.
Fur properties evaluated on dried skins. Leather thickness was measured 15 cm anterior from the tail root along the middle of the back with a modified micrometer. Overall quality was visually assessed on a scale ranging from 1 to 10 (best), and silkiness was visually assessed on a scale ranging from 1 to 4 (most silky and glossy), Colour intensity [1 (light)–4 (dark)] was measured by the optic technique of the Finnish Fur Sales. Underfur density was examined in skin biopsies. The skin biopsies were prepared as described by Rasmussen and Damgaard  for histology.
Where Yij is the observation; μ is the general mean; di is the effect of Cu level (i = 1,…,7); εij is the random error.
Tukey tests were used to detect statistical significance between treatment groups. Linear and quadratic effects due to copper level were determined. Significant differences were accepted if P ≤ 0.05.
Effects of copper supplementation on organ indexes in growing-furring male mink
Quality of skins
Effects of dietary copper on quality of skins in growing-furring mink
Overall quality (score)
Colour intensity (score)
Underfur hairs per mm2 skin
Leather thickness (mm)
Tissular Cu, Zn and Fe deposition
Effect of Cu supplementation on tissular Cu, Zn and Fe deposition in growing-furring mink
Liver (DM basis, mg/kg)
Spleen (DM basis, mg/kg)
Heart (DM basis, mg/kg)
Kidney (DM basis, mg/kg)
We found that the liver weights of the pelted males were not affected by supplemental dietary copper. Results of the present study are consistent with observations of Aulerich et al. .
In the present study, hair colour of the mink fed with the various concentrations of Cu was evaluated because fur colour is an important characteristic in dark mink. Copper, as a constituent of tyrosinase, plays a key role in a normal pigmentation of fur in mink [4,16-18]. Previous study [8,19] has reported that relatively high levels (100–200 mg/kg) of supplemental Cu may have a beneficial effect on intensifying hair colour of dark mink. Bush et al.  also demonstrated that darker fur colour occurred in male kits but not female kits with supplemental copper at the 200 mg/kg level. One of the clinical signs of Cu deficiency in mink is hypochromotrichia and some mink farmers have reported feeding supplemental dietary Cu to intensify fur colour in dark mink .
Because the liver is one of the main organs involved in the storage and metabolism of Cu, liver Cu concentration might be considered indicative of an animal’s Cu status. Copper concentrations in the liver were in accordance with normal for most adult non-ruminant animals (15 to 30 mg Cu/kg DM), and were within the broad range reported by Fisher  and Aulerich et al. . These data suggest that mink may be similar to sheep and swine in that liver Cu stores increase in proportion to dietary Cu intake . Stejskal et al.  found that copper was concentrated in the livers and tended to increase with age for mink. Heart copper concentrations also can increase in mink fed high dietary copper, but to a lesser extent than liver. Arredondo  reported that copper deficiency generates cellular iron deficiency. It is noteworthy that feeding supplemental dietary copper to decrease Fe concentrations in the liver. Ceruloplasmin oxidizes Fe2+ prior to transferrin binding . The absence of ceruloplasmin does not produce marked changes in Cu metabolism. It does, however, produce a gradual accumulation of Fe in the liver and other tissues . During severe Cu deficiency, Fe transport within the body is adversely affected, and Fe tends to accumulate in many tissues. Generally, Cu deficiency is accompanied by a hypochromic microcytic anemia similar to that produced by Fe deficiency.
Our results indicate that Cu plays an important role in the pigmentation in growing-furring mink, and supplemental dietary Cu in growing-furring mink improve hair colour. Data also indicate that copper has limited effects on liver mineral deposition.
The funding for this study was from Special Fund for Agro-scientific Research in the Public Interest (No.200903014). The staff of State Key Laboratory for Molecular Biology of Special Economical Animals is gratefully acknowledged for their valuable help in carrying out these experiments.
- Delhaize E, Loneragan JF, Webb J. Development of three copper metalloenzymes in clover leaves. Plant Physiol. 1985;78:4–7.View ArticlePubMed CentralPubMedGoogle Scholar
- Cobine PA, Pierrel F, Winge DR. Copper trafficking to the mitochondrion and assembly of copper metalloenzymes. Biochim Biophys Acta. 2006;1763:759–72.View ArticlePubMedGoogle Scholar
- Rolff M, Schottenheim J, Decker H, Tuczek F. Copper-O2 reactivity of tyrosinase models towards external monophenolic substrates: molecular mechanism and comparison with the enzyme. Chem Soc Rev. 2011;40:4077–98.View ArticlePubMedGoogle Scholar
- Sendovski M, Kanteev M, Ben-Yosef VS, Adir N, Fishman A. First structures of an active bacterial tyrosinase reveal copper plasticity. J Mol Biol. 2011;405:227–37.View ArticlePubMedGoogle Scholar
- Lopez-Serrano D, Solano F, Sanchez-Amat A. Involvement of a novel copper chaperone in tyrosinase activity and melanin synthesis in Marinomonas mediterranea. Microbiology. 2007;153:2241–9.View ArticlePubMedGoogle Scholar
- NRC. Nutrient requirements of mink and foxes. 2nd rev. Washington, DC: Natl. Acad. Press; 1982.Google Scholar
- Aulerich R, Ringer R. Feeding copper sulfate: could it have benefits in nutrition of mink. Fur Rancher. 1976;56:4.Google Scholar
- Aulerich RJ, Ringer RK, Bleavins MR, Napolitano A. Effects of supplemental dietary copper on growth, reproductive performance and kit survival of Standard dark mink and the acute toxicity of copper to mink. J Anim Sci. 1982;55:337–43.PubMedGoogle Scholar
- Bush CR, Restum JC, Bursian SJ, Aulerich RJ. Responses of growing mink to supplemental dietary copper and biotin. Scientifur. 1995;19:141–7.Google Scholar
- McCarthy B, Travis H, Krook L, Warner R. Pantothenic acid deficiency in the mink. J Nutr. 1966;89:392–8.PubMedGoogle Scholar
- Hansen N, Finne L, Skrede A, Tauson A. Energy supply for the mink and the fox. In: NJF Report. Copenhagen, Denmark: Nordic Association of Agricultural Scientists; 1991. p. 59.Google Scholar
- Jariwala M, Suvarna S, Kumar GK, Amin A, Udas A. Study of the concentration of trace elements Fe, Zn, Cu, Se and their correlation in maternal serum, cord serum and colostrums. Indian J Clin Biochem. 2013;29:181–8.View ArticlePubMedGoogle Scholar
- Lu CD, Schoknecht PA, Ellis KJ, Shypailo R, Su DR, Pond WG. Differential compensatory organ growth in young pigs after short-term rehabilitation from protein deficiency. Nutr Res. 1996;16:627–37.View ArticleGoogle Scholar
- Rasmussen PV, Borsting CF. Effects of variations in dietary protein levels on hair growth and pelt quality in mink (Mustela vison). Can J Anim Sci. 2000;80:633–42.View ArticleGoogle Scholar
- Statistical Analysis System (SAS). SAS/STAT user’s guide: version 9.0. Cary, North Caroline: SAS Institute Inc; 2002. p. OpenURL.Google Scholar
- Fatemi Naieni F, Ebrahimi B, Vakilian HR, Shahmoradi Z. Serum iron, zinc, and copper concentration in premature graying of hair. Biol Trace Elem Res. 2012;146:30–4.View ArticlePubMedGoogle Scholar
- Guclu BK, Kara K, Beyaz L, Uyanik F, Eren M, Atasever A. Influence of dietary copper proteinate on performance, selected biochemical parameters, lipid peroxidation, liver, and egg copper content in laying hens. Biol Trace Elem Res. 2008;125:160–9.View ArticlePubMedGoogle Scholar
- Prohaska JR, Gybina AA. Intracellular copper transport in mammals. J Nutr. 2004;134:1003–6.PubMedGoogle Scholar
- Wu X, Liu Z, Zhang T, Yang Y, Yang F, Gao X. Effects of dietary copper on nutrient digestibility, tissular copper deposition and Fur quality of growing-furring mink (mustela vison). Biol Trace Elem Res. 2014;158:166–75.View ArticlePubMedGoogle Scholar
- Bleavins MR, Aulerich RJ, Ringer RK. Hexachlorobenzene‐induced effects on the lymphocyte blastogenic response to concanavalin a in the mink and European ferret. Environ Toxicol Chem. 1983;2:411–8.View ArticleGoogle Scholar
- Fisher GL. Function and homeostasis of copper and zinc in mammals. Sci Total Environ. 1975;4:373–412.View ArticlePubMedGoogle Scholar
- Suttle N, Mills C. Studies of the toxicity of copper to pigs. Br J Nutr. 1966;20:149–61.View ArticlePubMedGoogle Scholar
- Stejskal SM, Aulerich RJ, Slanker MR, Braselton WE, Lehning EJ, Napolitano AC. Element concentrations in livers and kidneys of ranch mink. J Vet Diagn Invest. 1989;1:343–8.View ArticlePubMedGoogle Scholar
- Arredondo M, Nunez MT. Iron and copper metabolism. Mol Aspects Med. 2005;26:313–27.View ArticlePubMedGoogle Scholar
- Miyajima H. Aceruloplasminemia, an iron metabolic disorder. Neuropathology. 2003;23:345–50.View ArticlePubMedGoogle Scholar
- Harris ZL, Takahashi Y, Miyajima H, Serizawa M, MacGillivray R, Gitlin JD. Aceruloplasminemia: molecular characterization of this disorder of iron metabolism. Proc Natl Acad Sci U S A. 1995;92:2539–43.View ArticlePubMed CentralPubMedGoogle Scholar
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.