tissu hepatique desseche; celle de leur plasma sanguins'etablit par ailleurs entre 22,8 et 28,3 ,mol/L. On n'enregistra pas de relation mathema- tique simple ...
Copper, Zinc and Manganese Concentrations in Equine Liver, Kidney and Plasma NADIA
Department of Veterinary Internal Medicine (Cymbaluk) and Department of Animal and Poultry Science (Christensen), University of Saskatchewan, Saskatoon, Saskatchewan 57N 0 WO
Five groups of horses were fed different diets of known trace mineral concentration for a minimum of six months. Copper (Cu), zinc (Zn) and manganese (Mn) concentrations were measured in livers of 125 yearling horses and kidneys of 81 yearling horses as an assessment of trace mineral status. Plasma Cu and Zn determinations were made for all horses. Mean hepatic Cu concentrations of horses fed diets containing 6.9 to 15.2 mg Cu!/kg dry matter (DM) feed were 0.27 to 0.33 ,tmol/g DM tissue. Plasma Cu concentrations ranged between 22.8 to 28.3 Amol/ L. There was no simple mathematical relationship between plasma and hepatic Cu concentrations. Mean hepatic Zn concentrations in horses fed diets containing 25.6 to 52.2 mg Zn/ kg DM feed were determined to be between 2.75 to 2.91 ,.mol/g DM tissue. Mean plasma Zn concentrations in groups of horses were between 11.7 to 13.5 ,umol/ L. Plasma Zn concentrations were not indicative of hepatic Zn concentration. Hepatic Mn concentrations ranged between 0.13 and 0.14 ,umol/g DM tissue. Renal Zn concentrations ranged between 1.55 to 1.63 ,umol/g DM tissue and did not differ with diet. Mean renal Mn concentrations were 0.09 ,umol/g DM tissue for all groups of horses. Renal Cu concentrations ranged from 0.36 to 0.47 ,umol/g DM tissue and differed with diet. Key words: Trace minerais, norse, tissues.
9:SU Mt s'etablissait a 0,09 ,imol/ g de tissu Teneur de foie, des reins et du plasma renal desseche et s'avera la meme pour de poulains, en cuivre, en zinc et en tous les groupes de poulains. Celle du cuivre varia de 0,36 a 0,47 ,umol/g de manganese Cette experience consistait a donner a tissu renal desseche et elle se revela cinq groupes de poulains, pendant au differente, d'une diete a l'autre. moins six mois, trois dietes variees dont on connaissait la teneur en Mots cles: oligoelements, cheval, cuivre, en zinc et en manganese. Elle tissus. visait aussi a determiner, a la fin de la periode experimentale, la concentra- I N T R O D U C T I o N tion des trois oligoelements precites Recently, dietary copper (Cu) and zinc dans 125 echantillons du foie et dans (Zn) imbalances have been implicated 81 echantillons des reins de ces as causes of musculoskeletal abnorpoulains, ainsi que la teneur en cuivre malities in horses (1,2,3,4). Mangaet en zinc du plasma sanguin de tous nese (Mn) deficiency has also been implicated in musculoskeletal abnorles poulains experimentaux. La teneur moyenne en cuivre de foie malities of equine newborns (5). des poulains dont la diete contenait de Recommended minimum concentra6,9 a 15,2/ mg de cuivre/ kg de matiere tions currently accepted as adequate seche varia de 0.27 a 0,33 Amol/g de for horses are 9 mg Cu, 40 mg Zn and tissu hepatique desseche; celle de leur 40 mg Mn per kg dry matter (DM) plasma sanguin s'etablit par ailleurs feed (6) but these values are not entre 22,8 et 28,3 ,mol/L. On conclusively established. Many feedn'enregistra pas de relation mathema- stuffs grown in western Canada may tique simple entre les concentrations contain Cu, Zn and Mn concentrations below these levels (7,8,9). Few plasmatique et hepatique en cuivre. La teneur moyenne en zinc du foie clinical abnormalities arising from des poulains dont la diete contenait de trace mineral deficiencies are reported 25,6 a 52.2 mg de zinc/ kg de matiere in horses in western Canada, yet Cu seche varia de 2,75 a 2,91 ,mol/g de deficiency is a cause of skeletal tissu hepatique desseche; celle de leur abnormalities in cattle of this region plasma sanguin s'etablit par ailleurs (10). Skeletal abnormalities are not entre 11,7 et 13,5 Amol/L et elle ne uncommon in young horses in western fournit aucun indice relatif a celle du Canada and dietary trace mineral imbalances must be considered in the foie. La teneur moyenne du foie en etiology. Thus, assessment of trace manganese varia de 0,13 a 0,14 ,umol/ mineral status in horses must be made. Diagnosis of trace mineral imbalang de tissu hepatique desseche. La teneur moyenne des reins varia ces in horses has largely been inferenen zinc de 1,55 a 1,63 ,umol/g de tissu tial. Few reports describe experimenrenrai desseche et ne diihfra pas ure celle Lai U1 nadLUr dlly -Uoccurri ng- CU, -Zrf - 33.6" 31.4" 22.5x Manganese (mg/ kg) a Expressed as a range obtained for three levels of phosphorus tested (see text). 'Values with different letters within the same row and comparison are different at P < 0.05.
Plasma Cu concentrations of horses concentrations of 1.28 mmol/kg in 49 normal horses of undetermined age or differed according to diets fed but not nutritional history. However, both age in the same pattern observed for and dietary Cu intake may influence hepatic Cu concentrations (Table II). hepatic Cu concentrations in horses. Mean plasma Cu concentration of Fetal equine liver can contain oat-fed horses was lower (P < 0.05) between 2.0 to 9.1 ,umol Cu/g DM than obtained for all other groups. tissue (24). A postnatal decline occurs Barley-fed horses had higher plasma in hepatic Cu concentrations but mean Cu concentrations (P < 0.05) than all hepatic Cu concentrations of neonatal other groups except horses fed PF to eight-month old foals is 3.45 MAmol/ diet. g DM tissue (24). A 200-fold elevation Absolute plasma Cu values differed in hepatic Cu content occurs in ponies among groups but were not directly fed diets containing 791 mg Cu/ kg related to dietary Cu content. The DM feed as compared to ponies fed values obtained by us were similar to diets with Cu supplied as NRC plasma Cu concentrations of 22.4 recommended levels (19). ,umol/ L obtained for 16 horses by In the present study, absolute Cu Eamens et al (3). Meyer and Lemmer intakes by foals fed PF and PG diets (26) in a review of equine trace mineral RESULTS AND DISCUSSION was Cu twofold greater than by foals studies report plasma or serum Cu The most accurate evaluation of trace fed oat and barley diets yet hepatic Cu concentrations of 14.2 to 30.5 ,umol/ mineral status has been stated to be concentrations did not reflect these L. The wide range of plasma Cu feed analysis (11). The usefulness of differences. This suggested that horses concentrations cited in the latter study tissue trace mineral analyses for fed ad libitum diets containing 7 mg as compared to our observations may diagnostic purposes depends on Cu/ kg DM were able to maintain liver have arisen through differences in appropriate selection of tissue. Organs Cu concentrations as effectively as sample collection and preparation, that are primary sites of accumulation foals provided with twice the dietary age and breed of horse, or diet. of the trace mineral of interest can Cu concentration. This may also Equine plasma Cu concentrations provide relevant diagnostic informa- indicate differences in Cu availability are reported to be unresponsive to tion. Liver is the main tissue of Cu from diets and breed efficiencies in Cu dietary Cu supplementation (19). accumulation in most domestic lives- utilization. Statistical differences were However, a recent study reports a tock (12) including horses (19). Zinc obtained in hepatic Cu concentrations significant difference between serum may be diversely distributed through among groups of horses but these Cu concentrations of stabled and body tissues Dut liver nas Deen noted diiferences were not likely biologically pasture-ied norses, ana tnis adiierence to be an organ sensitive to dietary Zn significant. The similarity of our is attributed to possible dietary intake (20). Similarly, Mn can accum- observations with those of Schryver et influences (27). Mean serum Cu ulate in liver and kidney (12,20). al(22) suggests that normal hepatic Cu concentrations for stabled and pasLiver and plasma trace mineral concentrations for yearling horses are tured horses is reported to be 12.4 and concentrations in test horses are given about 0.31 ,mol Cu/g DM tissue. For 15.9 ,umol/L, respectively. The higher in Table II. Plasma Mn determina- interpretative purposes, the hepatic absolute values obtained in our study tions were not performed since the Cu concentrations of horses over one may be due to the use of plasma rather appropriate technique (21) was not year of age are more comparable to than serum in making Cu determinaavailable. Mean hepatic Cu concen- monogastric species (12) than to cattle tions. Paynter (28) using paired serum trations of horses fed PF and PG diets (25). and plasma samples from sheep and were lower (P < 0.05) than obtained for barley-fed horses. Hepatic Cu concentrations of horses fed oats and TABLE 11 cube diets did not differ from other TRACE MINERAL CONCENTRATIONS IN TISSUES OF YEARLING HORSES groups. Mean hepatic Cu concentrations of and Pelleted Pelleted yearling horses in our study were 0.27 Tissue Oats Mineral Cube Grain Barley Forage to 0.33 ,umol/g DM tissue and were LIVERb comparable to hepatic Cu concentra0.27Y 0.31 x,y 0.33x Copper 0.30x,y 0.27Y Zinc 2.78 2.77 2.79 2.75 2.91 tions obtained for one and two year 0.14 0.14 0.14 0.13 Manganese 0.13 old light breed horses fed diets containing 10 mg Cu/ kg DM feed PLASMAC 22.5x 25.3y Copper 28.3z 26.4Y,z 25.4Y (22). Hepatic Cu concentrations of Zinc 13.5X 11.7Y 1222x,y 11.7Y 13.4x seven horses of unspecified age and are means. aValues nutritional history ranged between bMeasured in,umol/g DM tissue. 0.16 to 0.82 ,umol/g DM tissue (23). CMeasured in ,mol/ L plasma. Eamens et al (3) report hepatic Cu XZValues within the same row and comparison with different superscripts are different at P < 0.05. Outliers were determined by the maximum normed residual (MNR) statistic (18). Of the total of 132 horses used in the combined studies, only 125 were available for tissue sampling. Another 12 cases were determined to have outlying values and were eliminated from the final statistical analyses. An outlying value for any measurement resulted in total deletion of the case from statistical analysis. The final sex distribution of horses used in the study was 60 colts and 53 fillies. The numbers of observations for each treatment group were: 24 in oats, 26 in cube, 20 in barley, 20 in PG and 18 in PF.
TABLE III TRACE MINERAL CONCENTRATIONSa IN KIDNEY OF YEARLING HORSES
Diet Oats Cube Barley
No. Zinc Copper 25 1.59 0.47x 28 0.41xIy 1.63 28 0.36Y 1.55 aValues are means and are measured in ,umol/g DM tissue. X-YValues within columns with different letters are different at P < 0.05.
cattle showed that serum Cu was lower than plasma Cu concentration and suggests that this could arise from the precipitation of ceruloplasmin Cu during clot aggregation. Yet, Eamens et al (3) found no differences between plasma and serum Cu concentrations in horses. Plasma Cu concentrations are used as indicators of hepatic Cu concentration and thus, Cu status of cattle (13), but we determined no significant relationship between these two biochemical indices in our study. Dietary Cu concentrations fed to foals in our study differed twofold and may have limited the hepatic-plasma response. Mean hepatic Zn concentrations among groups of horses did not differ (Table II). Horses fed cube and PF diets had lower (P < 0.05) plasma Zn concentrations than horses fed oats and PG diets. Plasma Zn concentration of barley-fed horses did not differ from other groups (Table II). Hepatic Zn concentrations for horses in our study were comparable to those obtained by Schryver et al (22) in yearling and two year old horses fed 50 mg Zn/ kg DM feed. Eamens et al (3) obtained values of 6.41 mmol Zn/kg liver but dietary Zn intakes were not reported in this study. Plasma Zn concentrations of horses in our study were between 11.3 to 13.5 ,mol/ L (Table II). These values were lower than serum Zn concentrations of 26.0 and 17.0 ,umol/ L recently reported for stabled and pasture-fed horses (27). Values of 9 to 16.5 ,umol Zn/ L in equine serum or plasma are reported by others (3,26). No correlation was obtained between hepatic and plasma Zn concentrations for the range of values in our study. There was no difference in hepatic manganese content among horses. Hepatic Mn concentrations were comparable to values obtained by
Manganese 0.09 0.09 0.09
Schryver et al (22) for one and two year old horses fed 50 mg Mn/kg DM feed. Renal trace mineral concentrations for 81 draft-cross horses are given in Table III. No differences were observed among the three groups of horses in renal Zn or Mn concentration but renal Cu concentration differed with diet. Barley-fed horses had lower renal Cu concentrations (P < 0.05) than oat-fed horses. Cubefed horses had renal Cu concentrations similar to oat or barley-fed horses. Renal Cu concentrations of horses in our study were comparable to those obtained by Eamens et al (3) but renal Zn concentrations were about 40% lower than in the latter study. Manganese concentrations in kidney were comparable to values obtained by Schryver et al (22). Dietary concentrations of Cu, Zn and Mn in the present study were 56 to 168% of current minimum levels specified for equine diets. Although statistical differences were found in trace mineral concentrations for some of the analyzed tissues these differences are not likely of biological significance. The similarities in tissue trace mineral concentrations among groups of horses suggested that at ad libitum feed intakes, sufficient trace mineral is obtained for growth even though dietary concentrations may not meet current NRC specifications. Thus, the growing horse may be more tolerant of a wider range of trace mineral intakes than expected. This further emphasizes the need for an accurate nutritional history which should include absolute feed intakes and dietary trace mineral concentrations. The data presented here are based on long-term feeding situations and the values obtained provide reference values for tissue trace
mineral concentrations for horses of known nutritional history, age and breed. A C K N OW L E D G M E N T S
Technical assistance of K. Skilnyk, M. Farmer, S. Hodgson and J. Anthony was appreciated. The assistance of R.J. Coleman, L. Burwash and J.D. Milligan, Horse Industry Branch, Alberta Agriculture is gratefully acknowledged. REFERENCES 1. BRIDGES CH, WOMACK JE, HARRIS ED,
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of ponies to high levels of dietary copper. J Anim Sci 1975; 41: 1645-1649. 20. GEORGIEVSKII VI. The physiological role of microelements. In: Georgievskii VI, Annenkov RN, Samokhin VI, eds. Mineral nutrition of animals. London: Butterworths & Co., 1981: 171-224. 21. SHEARER DA, CLOUTIER RO, HIDIROGLU M.
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BOOK REVIEW Pathology of Domestic Animals, Third Edition. Edited by K.V.F. Jubb, Peter C. Kennedy and Nigel Palmer. Vol. I: 574 pages, Vol. II: 582 pages, Vol. III: 527 pages. Published by Academic Press Incorporated, Publishers, Orlando, Florida. 1985. Price Vol. I, $91.00, Vol. II, $83.50, Vol. III, $91.00.
This third edition replaces the previous edition published in 1970 and provides much-needed up-dated information. Three volumes replace the previous two volumes; while the text has been expanded, the print has been reduced in size. The authorship has also been expanded to include Nigel Palmer and there are contributions (chapters) from a number of coauthors so that the book is now truly a multiauthored text. This is clearly a strength rather than a weakness. The number of photographs has increased; these are useful and of high quality. 210
The book consists of a series of chapters which address the lesions and diseases which occur in each of the 16 body systems. The format is similar (but not identical) in all chapters and bold-faced type is used for headings and some key words. The text is not referenced directly, rather the reference sources are listed at the end of each chapter. References are grouped according to disease or lesion, a feature which is helpful to the reader. Coverage of the various systems is comprehensive and up-to-date although the most recent references are from 1983. There is much new material as in the chapter on skin, where there is major emphasis placed on pattern analysis in dermatohistopathology. Numerous disease entities that have emerged over the past 15 years are discussed. Many chapters have a preamble on general considerations for that system. The reader will find this useful and it is an area that could be expanded. For some, espe-
cially the undergraduate student, the volume of the information presented may be overwhelming. Some parts of the text are long and detailed, leaving the reader searching for the pertinent facts. While some chapters have lists, charts or diagrams, the expanded use of such devices would provide the reader with welcome relief. Extended use of bold-face type would provide the reader with additional signposts. The major strength of this text relates to its comprehensive coverage. While the book is expensive, it will have wide usage in veterinary medicine. Undergraduate students will find this a useful reference text. They will not find it easy to read but they will find that the descriptions are accurate and the pertinent facts are there. Graduate students and teachers in veterinary pathology as well as diagnostic veterinary pathologists should have C.E. these volumes on their desks. Doige.