Interrelationship of Dietary Phosphorus, Aluminum and Iron on Performance and Tissue Mineral Composition in Lambs

Transcription

1 Interrelatinship f Dietary Phsphrus, Aluminum and Irn n Perfrmance and Tissue Mineral Cmpsitin in Lambs I. V. Rsa, P. R. Henry and C. B. Ammerman J Anim Sci : The nline versin f this article, alng with updated infrmatin and services, is lcated n the Wrld Wide Web at:

2 INTERRELATIOHIP OF DIETARY PHOSPHORUS, ALUMINUM AND IRON ON PERFORMANCE AND TISSUE MINERAL COMPOSITION IN LAMBS 1,2 I. V. Rsa 3, P. R. Henry and C. B. Ammerman University f Flrida 4, Gainesville Summary A 76-d feeding trial was cnducted with 24 wether lambs (31 kg, initially) t study the interrelatinships amng dietary P, AI and Fe. A 2 X 2 x 2 factrial arrangement f treatments included tw cncentratins f supplemental P (0 r.25%) with added P as NaH2PO4, tw levels f supplemental Fe (0 r 760 ppm) with Fe added as ferric citrate and tw levels f supplemental AI (0 r 1,450 ppm) with A1 added as AIC13. 6H20. The basal diet cntained.17% P, 40 ppm Fe and 168 ppm AI. Phsphrus increased (P<.01) feed cnsumptin, but Fe (P<.01) and A1 (P<.05) decreased intake. Dietary treatments affected average daily gain (p<.01), with added P imprving and Fe r AI depressing gain. Additinal P imprved gain (P<.05) and intake (P<.01) in the presence f high AI and intake (P<.05) when dietary Fe was high. Serum P was increased (P<.01) by high dietary Fe and reduced (P<.01) by AI. High dietary P increased (P<.05) serum Mg. High dietary Fe increased (P<.01) hemglbin and hematcrit and increased (P<.01) Fe strage in liver, kidney, spleen and muscle but decreased (P<,01) kidney Zn cncentratin. High dietary AI increased (P<.01) liver Fe and kidney Zn levels but decreased kidney P and Mg (P<.05) and bne ash and Mg (P<.01). Based Flrida Agr. Exp. Sta. ]urna/ser. N The authrs acknwledge Internatinal Minerals and Chemical Crp., Mundelein, IL; Mrman Manufacturing C., Quincy, IL, and Occidental Chemical C., Hustn, TX fr funds in supprt f this research, and Pfier, Inc., New Yrk, NY fr supplying vitamins A and D. a Schlarship prvided by Empresa Brasileira de Pesquisa Agrpecuaria, Brasil. Present address: CNPGC/EMBRAPA Camp Grande, MS. Brasil. 4 Dept. f Anita. Sci. n these studies, additinal dietary P appeared beneficial in vercming the adverse effects f high dietary AI r Fe. (Key wrds: Aluminum, Phsphrus, Irn, Mineral Interrelatinships, Tissue Mineral Cncentratins, Sheep.) Intrductin The P requirement f a ruminant is rarely met by frage diets, therefre, supplementatin is necessary (Chen, 1980). Furthermre, P utiliatin can be adversely influenced by factrs including dietary AI and Fe. These elements can ccur in relatively high cncentratins in sil, which may be cnsumed by graing ruminants (Healy, 1970; Valdivia, 1977). High dietary AI has been suggested t interfere with P utiliatin in nnruminants by frming unabsrbable cmplexes in the gastrintestinal tract (Debald and Elvehjem, 1935; Jnes, 1938; Strer and Nelsn, 1968). Likewise, high amunts f dietary Fe have been demnstrated t affect P absrptin perhaps by frming insluble phsphates in the digestive tract (O'Dnvan et at., 1963; Standish et al., 1969). Althugh interference with P metablism by Fe has been well demn - strated in ruminants, infrmatin cncerning effects f high dietary AI is quite limited. Experiments with dietary A1 up t 1,200 ppm have prduced n adverse effects (Thmpsn et al., 1959; Valdivia et al., 1978). The present experiment was cnducted t investigate further the interrelatinships f dietary P, AI and Fe n perfrmance and tissue mineral cmpsitin in grwing Iambs. Experimental Prcedure Twenty- fur 6 - m- ld Flrida native wether lambs, averaging 31 kg initially, were randmly assigned t eight grups with a 1231 JOURNAL OF ANIMAL SCIENCE, Vl, 55, N. 5, 1982

3 1232 ROSA ET AL. 2 2 x 2 factrial arrangement f treatments in a cmpletely randmied design. The treatments cnsisted f a basal diet (table 1), in which crnstarch was partially replaced by minerals t prvide the desired mineral cncentratins (dry basis):.17 (basal) r.42% ttal P, supplemental P added as NaH2PO4 ; 0 r 760 ppm added Fe as ferric citrate (basal 40 Ppm Fe) and 0 r 1,450 ppm added A1 as AIC13,6HO (basal 168 ppm AI). Calcium was adjusted in all diets t prvide a cnstant Ca t P rati f 1.3:1. Animals were hused individuauy in elevated pens with sltted flrs during a 76-d trial; experimental diets and tap water were supplied ad libitum. The water cntained < 1 ppm AI and Fe and < 10 ppm P. Lambs were initially dewrmed s and allwed t adjust t basal diets fr 10 d. Individual weights were taken n tw successive days at the beginning and end f the experiment. Bld samples were btained via jugular puncture at the beginning and at the end f the experiment. At the end f the trial, all lambs were killed by exsanguinati0n and liver, spleen, kidney, heart, lngissimus muscle and metacarpal bne were remved and fren fr subsequent analysis. Calcium, Me, Fe, Cu, Zn and Mn in feed and tissues were analyed by atmic absrptin spectrphtmetry 6 accrding t prcedures recmmended by the manufacturer (Perkin- Elmer, 1973). Phsphrus in feed and tissues was determined by the clrimetric methd described by Harris and Ppat (1954). Hemglbin was determined by the hematin methd (Chen and Smith, 1919) and hematcrit by the micrhematcrit methd. Bnes were cleaned f all sft tissue, dried at 100C fr 24 h, and defatted in a Sxhlet extractr fr 48 h. Minerals were analyed as described previusly. Statistical evaluatins f data were made by analysis f variance prcessed by cmputer prgrams f Statistical Analysis System (Barr et al., 1976) with the same basic mdel used fr perfrmance, tissue and bld data. Results and Discussin Animal Perfrmance. Daily dry matter intake was increased (P<.01) by additinal S Levamislc, Pitman - Mre, Inc., Washingtn Crssing, NJ ~Perkin,Elmer 306, Perkin-Elmer Crp., Nrwalk, CT TABLE 1. COMPOSITION OF BASAL DIET Item % Ingredient cmpsitin a Crnmeal (IFN ) 44.0 Cttnseed hulls (IFN ) Crnstarch (IFN ) Crn il (IFN ) Sybean meal (IFN ) Alfalfa meal (IFN ) 2.0 Urea (281% equivalent prtein) Salt, trace mineraliedb 1.5 1,0 Calcium carbnate (IFN ).3 SUlfur, flwers Vitamin A and D c.1 + Ttal 100;0 Chemical cmpsitin d Crude prtein, % P,% Ca, % Mg, %.2~.12 AI, ppm 168,0 Fe, ppm 40.0 aas - fed basis. banalysis in percentage as fllws: NaCI, 96.0; Zn,.30; Mn,.24; Fe,.22; Cu,.025 ; I,,007; C,.007. CVitamins added per kg f diet: 2,200 IU vitamin A palmitate, 440 IU vitamin Ds, ddry matter basis. P (1,04-9 vs 1,259 g) but decreased by Fe (P<.01; 1,280 vs 1,027 g) and Al (P<,OS; 1,224 vs 1,084 g; table 2). Phsphrus and Al interacted (P<.05) n vluntary feed intake, with additinal P partially vercming the adverse effect f high dietary Al. Additin f supplemental P t the basal diet imprved (P<.01) average daily gain frm 105 t 148 g. High dietary Fe and A1 decreased (P<.01) average daily gain frm 156 t 97 g and 159 t 95 g, respectively. There was a P x At interactin (P<.0$) n daily gain~ with added dietary P cunteracting the depressing effect f high dietary A1. There was als a P x Fe interactin (P<.05) n intake with added dietary P partially vercming the depressing effects f Fe. There were n effects f dietary treatments n feed cnversin. The psitive respnse t P prbably can be attributed t a greater supply f P in a diet that is brdqrline r deficient in the element, because NRC (1975)recmmends.23% dietary P fr ptimum perfrmance in grwing lambs. Thmpsn et al. (1959) reprted n deleterius effects in lambs by feeding diets cntaining

4 DIETARY P, AI AND Fe FOR LAMBS 1233 TABLE 2. EFFECT OF DIETARY PHOSPHORUS, IRON AND ALUMINUM ON FEED INTAKE, GAIN AND FEED CONVERSION IN LAMBS a Treatment. (added minerals) b Avg initial Avg dry matter Avg daily P, % Fe,ppm AI, ppm weight, kg intake, g gain, g , , , O ,O O 1, O 1,O , , I , , , P P<.O1 P<.O1 Fe P<.01 P<.01 A! P<.01 P<.05 P X Fe P<.05 P X Al P<.01 P<.05 Fe X A1 P X Fe X AI Feed/unit gain aeach value represents the mean SE f three lambs. bbasal diet cntained.17% P, 40 ppm Fe and 168 ppm AI. C = P>.IO. 1.0% aluminum sulfate (810 ppm Al). Valdivia (1977) reprted that inclusin f AI at 2,000 ppm in the diet f lambs depressed gain and feed intake. Additin f P, hwever, t the high AI diet imprved intake and gain, Standish et al. (1969) bserved depressin f gain and feed intake in steers by as little as 400 ppm dietary Fe. Standish and Ammerman (1971) fed 1,600 ppm dietary Fe t Iambs and bserved an adverse effect f Fe n gain, which may have resulted frm reduced dietary intake. In anther trial with steers, Standish et al. (1971) reprted the same adverse effect f high dietary Fe (1,000 ppm) n feed intake and gain. Feeding additinal P (.23%) tended t cunteract the adverse effects f high Fe but this was nt statistically significant. Bld Cbaracteristics. Excess dietary Fe (760 ppm added) increased (P<.01) inrganic P in serum, while high dietary AI reduced (P<.01) serum P level (table 3). There was an Fe X A1 interactin (P<.01) n serum P; the reductin in serum P caused by high dietary AI was cunteracted partially by added dietary Fe. Serum Ca was nt affected by dietary minerals, but serum Mg was increased (P<.05) when P was added t the diets. High dietary AI tehded t depress serum Mg, but nt signifi- candy. Bld hemglbin and hematcrit were increased (P<.01) by dietary Fe but ther dietary treatments had n effect n these bld characteristics. Similar increases in serum P related t high dietary Fe were reprted t ccur in chicks (Dr and Elvehjem, 1935) and rats (Harmn et al., 1968). Standish et al. (1969), wh bserved a similar effect f high dietary Fe in steers, suggested that increased plasma P culd be related mre clsely t a reduced feed intake, Standish et al. (1971) fund a reductin in serum P f sheep by feeding 1,000 ppm Fe at the 45th d f a trial, but this effect was nt apparent at the 77th d. The reductin in serum P caused by high dietary A1 in the present study has been reprted in previus studies with nnruminant animals (Jnes, 1938; Street, 1942; Alsmeyer et al., 1963) and was attributed t a decreased P absrptin resulting frm P cmplexatin with AI in the digestive tract. In ruminants, Thmpsn et al. (1959) reprted n effect f 1.0% dietary aluminum sulfate n serum P and ther characteristics studied in sheep. The authrs suggested that ruminants were less susceptible t excess dietary AI than nnruminants due t cnsiderable quantities

5 1234 ROSA ET AL. r~ t~ ~ ' ~ II I I I I. ~. ~ ' ~ F-, 0 < m M 0 m M I II ~ ~ M m I I 0~ ZZZZZZZ ~ [.-, +1 I~ r~ [-., r r~ ~a d, ~ 0 0 [.-, XX ~X X X

6 DIETARY P, A1 AND Fe FOR LAMBS 1235 f rganic acids in the rumen, which wuld cmplex AI, preventing, at least partially, P precipitatin in the digestive tract. Valdivia et al. (1978) reprted n changes in plasma P f steers by the feeding f up t 1,200 ppm AI. In an experiment with sheep, hwever, Valdivia (1977) reprted a significant decrease in plasma P when 2,000 ppm AI (as chlride) were supplied in the diet. The increase in bld hemglbin and hematcrit by feeding high dietary Fe is in agreement with results reprted fr swine (Furuguri, 1972) and calves (Thmas et al., 1954; Kng et al., 1970). Standish et al. (1969, 1971) and Standish and Ammerman (1971) reprted n effect f up t 1,600 ppm dietary Fe n bld hemglbin and hematcrit in steers and sheep. Tissue Minerals. Irn was the nly mineral in liver that was affected by dietary treatments (table 4). High dietary Fe increased (P<.01) Fe cncentratin in liver. Added dietary P reduced (P<.01) hepatic Fe levels while high dietary AI increased (P<.01) liver Fe cncentratin. Phsphrus interacted (P<.01)with Fe by depressing Fe accumulatin in the liver resulting frm high dietary Fe. An interactin (P<.01) between Fe and AI was manifested by the dietary excess f bth elements cmbining t prduce an increase in liver Fe. Again, antagnistic dietary effects f P and A1 were indicated (P<.01), with high dietary P depressing liver Fe accumulatin induced by excess dietary AI. A three-way interactin (P<.01) was als detected with high Fe and A1 prducing an increase in liver Fe and high dietary P antagniing this effect. High dietary AI depressed (P<.05) P cncentratin in kidney (12,204 vs 11,491 ppm; table 5). Kidney Mg was decreased (P<.01) by high AI diets. Either high dietary P r Fe decreased kidney Mg in the presence f lw dietary cncentratins f the ther element and this effect was reversed when bth elemerits were present at high cncentratins (P Fe interactin, P<.05). The additin f P r Fe t the diet decreased (P<.01) kidney Zn, but high dietary A1 increased (P<.01) kidney Zn cncentratin. High dietary AI increased Zn cncentratin in kidney in the presence f lw dietary P, but added dietary P reversed this effect (P AI interactin, P<.01). Irn cncentratin in kidney was increased (P<.01) by dietary Fe frm 349 t 678 ppm. Kidney Cu was increased (P<.01) by additin f dietary AI and there was als TABLE 4. EFFECT OF DIETARY PHOSPHORUS, IRON AND ALUMINUM ON LIVER MINERAL COMPOSITION IN LAMBS a Treatment b Mineral cncentratin (ppm dry matter basis) P, % Fe, ppm Al, ppm P Ca Mg Zn Fe Cu Mn ,301 1, , , ,187 1, ,450 8,206 1, ,450 8, ,450 9, ,450 9,376 1, , , , , P P<.01 Fe P~.O1 AI P<.01 P X Fe P~.O1 P X AI N8 P<.01 Fe X A1 P<.01 P X Fe X A1 P<.01 aeach value represents the mean + SE f three animals. bbasal diet cntained.17% P, 40 ppm Fe and 168 ppm AI. c = P>.IO.

7 1236 ROSA ET AL. a P A1 interactin (P<.05) in which additinal P vercame the increase in kidney CU brught abut by dietary A1. Skeletal muscle exhibited an efficient hmestatic mechanism fr minerals (table 6); hwever, there was an increase (P<.01) f Fe in muscle frm 65 t 81 ppm when high Fe diets were fed. Als, a P X Fe interactin (P<.05) n muscle Fe was detected, with high dietary P decreasing Fe accumulatin resulting frm excess dietary Fe. The remaining minerais analyed in the muscle were nt affected (P>.10) by dietary treatments. Cardiac muscle, like skeletal muscle, is knwn t pssess a rather efficient mechanism fr cntrlling mineral accumulatin when excesses are supplied in the diet (table 7). The nly effect f dietary treatment n heart minerals was a decrease (P<.05) in heart Mn cncentratin caused by added dietary P. High dietary Fe decreased (P<.01) Ca cncentratin in spleen frm 223 t 198 ppm (table 8). Magnesium and Mn cncentratins in spleen were nt affected (P>.10) by dietary treatments. Added dietary P decreased (P<.05) spleen Zn. Irn strage in spleen was increased (P<.01) by high dietary Fe, frm 981 t 7,510 ppm. Dietary Fe als increased (P<.05) Cu cncentratin frm 4.3 t 5.8 ppm. An interactin (P<.0$)f P x A1 n Cu in spleen was bserved, with added dietary P decreasing spleen Cu cncentratins resulting frm high dietary AI. Dietary P prduced a 3.9% increase (P<.01) in bne ash (table 9). Cnversely, high dietary A1 caused a 2.3% reductin (P<.01) in that characteristic. Phsphrus cntent in bne ash was increased (P<.01) by dietary P frm 16.8 t 17.2%. High dietary A1 had a tendency t depress bne P percentage, but this effect was nt significant. An interactin (P<.05) f P A1 was detected, with added dietary P increasing bne Ca, while high A1 in the diet antagnied this effect. Bne Mg was increased (P<.01) by high dietary P but decreased (P<.01) by dietary AI. An interactin (P<.01) between P and A1 n bne Mg was bserved and manifested by high dietary P partially cunteracting the adverse effect f added AI. Dyle and Spaulding (1978) suggested that Fe in excess f requirements fr metablic prcesses in the animal bdy is stred in several tissues, with highest cncentratins in liver, Treatment (added minerals) b TABLE 5. EFFECT OF DIETARY PHOSPHORUS, IRON AND ALUMINUM ON KIDNEY MINERAL COMPOSITION IN LAMBS g Mineral cncentratin (ppm dry matter basis) P,% Fe, ppm A1, ppm P Ca Mg Zn Fe Cu Mn , , , , ,450 11, ,450 11, ,450 11, , ,450 11, P P<.01 Fe P<.O1 P<.01 AI P<.05 P<.01 P<.01 P<.01 P X Fe P<.05 P=.08 P X AI P<.O1 P =.08 P<.05 P<.05 Fe X AI P X Fe X AI P<.05 : P<.05 aeach value represents the mean + SE f three animals. bbasal diet cntained.17% P, 40 ppm Fe and 168 ppm A1. c = P>.10.

8 DIETARY P, A AND Fe FOR LAMBS 1237, Treatment (added minerals) b TABLE 6. EFFECT OF DIETARY PHOSPHORUS, IRON AND ALUMINUM ON MUSCLE MINERAL COMPOSITION IN LAMBS a Mineral cncentratin (ppm dry matter basis) P, % Fe, ppm AI, ppm P Ca Mg Zn Fe Cu Mn , , , , * ,450 6, * ,450 6, ,450 7, ,450 6, P Fe P=.08 P<.01 AI P =.09 P =.06 P =.09 P X Fe P<.05 P X AI Fe X A1 P X Fe X AI aeach value represents the mean SE f three lambs. bbasal diet cntained.17% P, 40 ppm Fe and 168 ppm AI. c = P>.10. TABLE 7. EFFECT OF DIETARY PHOSPHORUS, IRON AND ALUMINUM ON HEART MINERAL COMPOSITION IN LAMBS a Treatment (added minerals) b Mineral cncentratin (ppm dry matter basis) P, % Fe, ppm A1, ppm P Ca Mg Zn Fe Cu Mn , , , , ,450 8, ,450 8, ,450 8, ,450 9, P Fe AI P=.09 P X Fe P X AI Fe X AI P Fe A1 P<.05 aeach value represents the mean + SE f three lambs. bbasal diet cntained.17% P, 40 ppm Fe and 168 ppm A1. c=p>.io.

9 1238 ROSA ET AL. TABLE 8. EFFECT OF DIETARY PHOSPHORUS, IRON AND ALUMINUM ON SPLEEN MINERAL COMPOSITION IN LAMBS a Treatment (added minerals) b Mineral cncentratin (ppm dry matter basis) P, % Fe, ppm AI, ppm P Ca Mg Zn Fe Cu Mn , :~ , , ,686+ 1, , , ,450 11, , ,450 11,352+1, ,450 10, ,704+ 1, ,450 10, , , P P=.06 ' P<.05 Fe P<.01 P<.O1 P<.05 Al P X Fe P=.09 P X Al P<.05 P<.05 Fe X AI P=.08 P Fe X AI aeach value represents the mean + SE f three lambs. bbasal diet cntained.17% P, 40 ppm Fe and 168 ppm AI. c =P>.lO. TABLE 9. EFFECT OF DIETARY PHOSPHORUS, IRON AND ALUMINUM ON BONE COMPOSITION IN LAMBS a Treatment (added minerals) b Mineral cncentratin (% ash basis) P, % Fe, ppm A1, ppm Ash, % P Ca Mg , O 1, , , P P<.O1 P<.O1 P<.O1 Fe AI P<.01 P =.09 P<.O 1 P X Fe P X AI P<.05 P<.O1 Fe X AI P X Fe X AI aeach value represents the mean + SE f three lambs. bbasal diet cntained.17% P, 40 ppm Fe and 168 ppm A1. c = P>.10.

10 DIETARY P, AI AND Fe FOR LAMBS 1239 spleen and red bne marrw. In investigatins with ruminants, Standish et al. (1969, 1971) and Standish and Ammerman (i971) cnsistently bserved an increased Fe cntent in liver, spleen and kidney when high dietary Fe was supplied t steers r sheep. High dietary Fe als increased Fe cncentratins in heart and muscle in steers and in heart in sheep. Irn increases in liver f steers were threefld with 1,600 ppm dietary Fe (Standish et al., 1969), and 10-fld in sheep fed the same cncentratin f dietary Fe (Standish and Ammerman, 1971). An antagnism between Fe and P was evidenced in certain tissues: additin f P t the high Fe diets reduced Fe cncentratin in liver t abut ne-half. In spleen, hwever, the secnd mst imprtant site f Fe accumulatin in this study, P did nt affect Fe cncentratin. Decreased liver Fe cncentratin related t high dietary P is in agreement with findings f several authrs and related t the bservatin by Brck and Diamnd (1934) that Fe cmbines with P in the intestinal tract t frm cmpunds that are difficult t absrb. A metablic antagnism between P and Fe characteried by reduced liver Fe accumulatin has been reprted by Harmn et al. (1968) in rats and by Standish et al. (1971) in steers. The synergistic effect between AI and Fe Jan be related t the metablic antagnism f bth elements with P. Because it is well established that P can cmbine with either A1 r Fe and make them unavailable fr absrptin and vice versa, it seems reasnable t infer that increasing either Fe r AI in a diet high in P wuld permit mre f each element t be available fr absrptin in the digestive tract. Valdivia (1977) reprted increased Fe in liver and spleen f sheep when high dietary Al (2,000 ppm) was fed, even thugh cncentratins f dietary Fe were in a range cnsidered nrmal. In ur study a depressing effect f high dietary Al n cncentratins f P and Mg in kidney was bserved. A depressin f Mg cncentratin in kidney f sheep was als related t high dietary Al (2,000 ppm; Valdivia, 1977). In the present study high dietary P r Fe decreased Zn cncentratin in kidney, while high dietary Al had the ppsite effect. Zinc cncentratin was reduced in spleen by diets high in P. Similar results were reprted by Valdivia (1977) wh bserved a reductin in kidney Zn by increasing dietary P and an increase in Zn cncentratin in kidney and liver when high dietary AI was fed. Standish et al. (1971) reprted that reduced Zn cncentratins in liver and increased cncentratins in spleen f steers were related t high dietary Fe (1,000 ppm). High dietary Al decreased (P<.01) Mg cncentratin in bne and kidney. Similarly, Valdivia (1977) reprted a reductin f Mg in kidney and serum when high dicta W A1 was fed. These findings are f imprtance in view f a recent reprt (Allen et al., 1980) n the presence f high cncentratins f Alin pasture influencing the ccurrence f grass tetany. When high dietary Al (1,450 ppm) was prvided, bne ash as well as bne Mg were reduced. Valdivia (1977) bserved decreased bne ash percentage in sheep fed 2,000 ppm dietary Al. In the present study, antagnistic effects between P and Al were bserved n bne Mg, Ca and P, which were depressed by high dietary Al. Irn interference with P utiliatin, manifested by lw bne ash and bne P, has been reprted fr nnruminants (O'Dnvan et al., 1963; Furuguri, 1972). In the present experiment, a similar effect n bne cmpsitin was nt detected with the relatively lw cncentratin f Fe utilied (760 ppm) as cmpared with cncentratins used with nnruminants (abve 2,000 ppm). These findings suggest that excessive levels f dietary Al r Fe increase the dietary requirement fr P and that elevated levels f dietary P help alleviate the adverse effects f excessive Al and Fe. This may have special imprtance under graing cnditins in which quantities f sil are cnsumed. Literature Cited Allen, V. G., D. L. Rbinsn and F. G. Hembry Aluminum in the etilgy f grass tetany. J. Anim. Sci. 51 (Suppl. 1):44 -. Alsmeyer, W. L., B. G. Harmn, D. E. Becket, A. H. Jensn and H. W. Nrtn Effects f dietary aluminum and irn n phsphrus utiliatin. J. Anim. Sei. 22:1116 (Abstr.). Barr, A.J., J.H. Gdnight, J.P. Sail and J.T. Helwig A User's Guide t SAS (Statistical Analysis Systems). SAS Inst. Incrp., Raleigh, NC. Brck, J. F. and L. K. Diamnd Rickets in rats by irn feeding. J. Pediat. 4:442. Chen, R.D.H Phsphrus in rangeland ruminant nutritin: A review. Livestck Prd. Sci. 7:25. Chen, B. and A. H. Smith The elrimetric

11 1240 ROSA ET AL. determinatin f hemglbin. J. Bil. Chem. 39:489. Debald, H. J. and C. A. Elvehjem The effect f feeding high amunts f sluble irn and aluminum salts. Amer. J. Physil. 111 : 118. Dyle, J. J. and J. E. Spanlding Txic and essential trace elements in meat - A review. J. Anim. Sci. 47:398. Furuguri, K Effect f elevated dietary level f irn n irn stre in liver, sme bld cnstituents and phsphrus deficiency in yung swine. J. Anim. Sei. 34:573. Harmn, B. G., D. E. Becket, A. H. Jensen and H. W. Nrtn Effect n Na 2 EDTA in diets f different irn levels n utiliatin f calcium, phsphrus and irn by rats. J. Anim. Sci. 27:418. Harris, W. D. and P. Ppat Determinatin f the phsphrus cntent f lipids. Amer. Oil Chem. Sc. J. 31:124. Healy, W. B Ingested sil as a pssible surce f elements fr graing animals. Prc. New Zealand Sc. Anim. Prd. 30:11. Jnes, J. H The metablism f calcium and phsphrus as influenced by the additin t the diet f salts f metals which frm insluble phsphates. Amer. J. Physil. 124:230. Kng, L. J., M. B. Wise and E. R. Barrick Effect f elevated dietary levels f irn n the perfrmance and bld cnstituents f calves. J. Anita. Sci. 31:422. NRC Nutrient Requirements f Dmestic Animals, N. 5. Nutrient Requirements f Sheep. Fifth Revised Ed. Natinal Academy f Sciences - Natinal Research Cuncil, Washingtn, DC. O'Dnvan, P. B., R. A. Pickett, M. P. Plumlee and W. M. Beesn Irn txicity in the yung pig. J. Anim. Sci. 22:1075. Perkin-Eimer Analytical Methds fr Atmic Absrptin Spectrphtmetry. The Perkin- Elmer Crp., Nrwalk, CT. Standish, J. F. and C. B. Ammerman Effect f excess dietary irn as ferrus sulfate and ferric citrate n tissue mineral cmpsitin f sheep. J. Anim. SCI. 33:481. Standish, J. F., C. B. Ammerman, A. Z. Palmer and C. F. Simpsn Influence f dietary irn and phsphrus n perfrmance, tissue mineral cmpsitin and mineral absrptin in steers. J. Anita. SCI. 33:171. Standish, J. F., C. B. Ammerman, C. F. Simpsn, F. C. Neal and A. Z. Palmer Influence f graded levels f dietary irn, as ferrus sulfate, n perfrmance and tissue mineral cmpsitin f steers. J. Anim. Sci. 29:496. Strer, N. L. and T. S. Nelsn The effect f varius aluminum cmpunds n chick perfrmance. Pui. Sci. 47:244. Street, H. R, The influence f aluminum sulfate and aluminum hydrxide upn the absrptin f dietary phsphrus by the rat. J. Nutr. 24: 111. Thmas, J. W., M. Okamt, W. C. Jacbsn and L. A. Mre A study f hemglbin levels in the bld f yung dairy calves and the alleviatin f anemia by irn. J. Dairy SCI. 37:805. Thmpsn, A., S. L. Hansard and M. C. Bell The influence f aluminum and inc upn the absrptin and retentin f calcium and phsphrus in lambs. J. Anim. Sci. 18:187. Valdivia, R Effect f dietary aluminum n phsphrus utiliatin by ruminants. Ph.D. Thesis. Univ. f Flrida, GainesviUe. Valdivia, R., C. B. Ammerman, C. J. Wilcx and P. R. Henry Effect f dietary aluminum n animal perfrmance and tissue mineral levels in grwing steers. J. Anita. Sci. 47: 1351.