Manganese Utilization in the Chick: Effects of Corn, Soybean Meal, Fish Meal, Wheat Bran, and Rice Bran on Tissue Uptake of Manganese

Manganese Utilization in the Chick: Effects of Corn, Soybean Meal, Fish Meal, Wheat Bran, and Rice Bran on Tissue Uptake of Manganese KEVIN M. HALPIN and DAVID H. BAKER1 Department of Animal Sciences, University of Illinois, Urbana, Illinois 61801 (Received for publication June 12, 1985) ABSTRACT Experiments were conducted with young chicks to investigate the effect of various feed ingredients on manganese (Mn) bioavailability. Crossbred chicks were fed a Mn-deficient casein-dextrose diet supplemented with corn, soybean meal (SBM), fish meal (FM), wheat bran (WB), or rice bran (RB). Although these feed ingredients contain significant quantities of Mn, dietary addition of all five ingredients consistently depressed Mn deposition in key tissues (bone, gallbladder, and pancreas) of chicks fed excess inorganic Mn (1000 mg/kg provided as MnS0 4 • H 2 0 ) . Corn, SBM, FM, and WB also reduced tissue Mn levels at the chick's minimal dietary Mn requirement (14 mg/kg) when fed a casein-dextrose diet. In fact, as little as 1.0% WB, 2.5% FM, and 5.0% of a corn-SBM combination were capable of markedly reducing tissue Mn concentrations. Rice bran, however, appeared to provide bioavailable Mn when added to diets containing a level of Mn at or below the chick's requirement. (Key words: manganese, corn, soybean meal, fish meal, wheat bran, rice bran, tibia, gallbladder, pancreas) 1986 Poultry Science 65:995-1003 INTRODUCTION T h e i m p o r t a n c e of manganese (Mn) for p o u l t r y has been recognized for almost 50 years, ever since Wilgus and c o w o r k e r s d e m o n strated t h a t Mn could prevent perosis in t h e chicken (Wilgus et al, 1936). S u b s e q u e n t research has shown t h a t Mn is vital for g r o w t h , egg production, and p r o p e r d e v e l o p m e n t of t h e chick e m b r y o and is essential in t h e activation of n u m e r o u s enzymes ( U n d e r w o o d , 1977). Manganese s u p p l e m e n t a t i o n is especially imp o r t a n t in avian species because a b s o r p t i o n of dietary Mn is relatively inefficient in birds (Turk et al, 1982). T h u s , knowledge concerning t h e bioavailability of Mn from various sources is essential. A l t h o u g h inorganic salts have been c o m p a r e d as sources of dietary M n activity (Watson et al, 1 9 7 1 ; S o u t h e r n and Baker, 1 9 8 3 a ; Black et al, 1 9 8 4 a , b ) , little is k n o w n a b o u t t h e availability of Mn from organic sources. Feed ingredients c o m m o n l y used in p o u l t r y diets often contain significant quantities of Mn. In fact, w h e a t b r a n a n d rice b r a n are considered t o be rich sources of Mn, whereas fish meal and s o y b e a n meal contain m o d e r a t e a m o u n t s (Table 1). However, t h e availability of Mn from these sources is unknown.

1

To whom correspondence should be addressed.

Several e x p e r i m e n t s were t h u s c o n d u c t e d t o assess t h e effect of some c o m m o n p o u l t r y feed ingredients on Mn bioavailability. Tissue Mn u p t a k e a n d chick p e r f o r m a n c e were used as measures of Mn bioavailability (Watson et al, 1970; S o u t h e r n and Baker, 1983a; Black et al, 1984a,b). MATERIALS AND METHODS Male chicks, resulting from t h e cross of N e w Hampshire males a n d Columbian females, w e r e used in each study. All chicks were fed a corn-soybean meal starter diet ( 1 6 7 mg/kg Mn) during t h e first 7 days posthatching. On D a y 8 p o s t h a t c h , following an overnight fast, t h e chicks were weighed and allotted t o experim e n t a l groups so t h a t each group had a similar mean initial weight and weight distribution. Three replicate gorups of five chicks w e r e fed each of t h e e x p e r i m e n t a l diets from 8 t o 22 days posthatching. T h e chicks were h o u s e d in thermostatically controlled, wire-floored starter batteries, and a 24-hr constant light schedule was maintained. Feed a n d water were provided ad libitum t h r o u g h o u t each assay period. F e e d intake a n d weight gain were m o n i t o r e d at regular intervals. T h e basal diet (Table 2) used in each assay was a casein-dextrose diet formulated t o m e e t or exceed all n u t r i e n t r e q u i r e m e n t s of t h e growing chick w i t h t h e exception of Mn.

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TABLE 1. Manganese concentration in various feed ingredients1 Ingredient

Manganese (mg/kg)

Corn Soybean meal, dehulled Fish meal, Menhaden Wheat bran Rice bran

4 4 4 4 2

7.2 36.1 37.3 163.9 404.3

± 1.0 ± 1.8 ±4.0 ± .4 ± 9.8

'As determined by atomic absorption spectrophotometry. 2

Number of analyses.

3

Corn, soybean meal, and fish meal data represent duplicate analyses on two separate samples, while wheat bran and rice bran represent quadruplicate and duplicate values, respectively, on the same sample. All data expressed as mean ± SEM.

Dietary additions to the basal diet were made at the expense of dextrose, with Mn being provided as MnS0 4 • H 2 O. A 5 X 2 factorial arrangement of treatments was employed in the first experiment to investigate the effect of feed ingredient supplementation on Mn utilization. Wheat bran (WB), which has a high Mn concentration relative to most feed ingredients, was added to the basal diet at 10%, whereas corn, soybean meal (SBM), and fish meal (FM) were each added at 20% of the diet. These dietary additions were made in the presence and absence of supplemental Mn, provided at a level of 14 mg/kg. This level of Mn supplementation is the minimal requirement of growing chicks fed a casein-dextrose diet (Southern and Baker, 1983b). Experiments 2 and 3 were conducted to assess the effect of feed ingredient supplementation on the bioavailability of excess dietary inorganic Mn. In Experiment 2, corn, SBM, FM, or WB was added to the basal diet as in Experiment 1. However, the basal diet used in this study was supplemented with 1000 mg Mn/kg, a level which dramatically increases tissue concentrations of Mn without being growth-depressing to the chick (Southern and Baker, 1983a). Graded levels (0, 1.0, 2.5, 5.0 and 10.0%) of each feed ingredient were added to the basal diet containing 1000 mg Mn/kg in Experiment 3. Experiments 4 and 5 were conducted to investigate the effect of rice bran (RB) sup-

plementation on Mn bioavailability. In Experiment 4, three levels of Mn (0, 14, and 1000 mg/kg) were fed at two levels of RB (0 and 10.0% of the diet), constituting a 3 X 2 factorial treatment design. A 3 X 3 factorial arrangement of treatments was employed in Experiment 5 to compare the effects of RB and WB supplementation on Mn utilization. At the termination of each experiment, chicks were killed by cervical dislocation, and tissues chosen for Mn analysis were removed from the three median weight chicks within each replicate. The tissues were then pooled by replicate, dried, and analyzed for Mn. The right tibia was taken in each experiment and ashed at 600 C for 24 hr before analysis. Bile was analyzed in Experiments 2 and 3, and pancreas Mn concentration was determined in Experiments 4 and 5. The pancreas and bile samples were dried at 100 C for 24 hr, weighed, and then wet ashed with H N 0 3 and H 2 0 2 (30%).

TABLE 2. Composition of manganese-deficient basal diet1

%

Ingredient Dextrose Casein Corn oil Mineral mixture, manganese-free2 Glycine DL-Methionine L-Arginine NaHCOj Vitamin mixture 3 Choline chloride DL-a-tocopheryl acetate, 20 mg/kg

to

100.00 20.00 3.00 5.30 2.00 .50 1.00 1.00 .20 .20 +

1 Contained 1.4 mg/kg Mn as determined by atomic absorption spectrophotometry. 2

Mineral mixture provided per kilogram of diet: CaC0 3 , 3.0 g; Ca3 ( P O J j , 28.0 g; K 2 HPO„, 9.0 g; NaCl, 8.8 g; MgS0 4 ^ H ^ O , 3.5 g; ferric citrate, .50 g ; Z n C 0 3 , .10g;CuSO 4 -SHjO, 20.0 mg; H 3 B 0 3 , 9.0 mg; Na a Mo0 4 '2HjO, 9.0 mg; KI, 40.0 mg; CoS0 4 -711,0, 1.0mg;Na 2 SeO 3 , .215 mg. 3 Vitamin mixture provided per kilogram of diet: thiamine-HCl, 20 mg; niacin, 50 mg; riboflavin, 10 mg; Ca-panthothenate, 30 mg; vitamin B u , .04 mg; pyridoxine-HCl, 6 mg; biotin, .6 mg; folic acid, 4 mg; inositol, 100 mg; para-aminobenzoic acid, 2 mg; vitamin K, 2 mg; ascorbic acid, 250 mg; cholecalciferol (200,000 IU/g), 600 IU; retinyl acetate (650,000 IU/g), 5200 IU.

MANGANESE UTILIZATION BY CHICKS

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TABLE 3. Effect of manganese and feed ingredient supplementation on chick performance (Experiment l)1' Manganese (mg/kg) 0 Dietary treatment

Gain 3

Basal (B) B + 20% corn B + 20% soybean meal (SBM) B + 20% fish meal (FM) B + 10% wheat bran (WB)

(g) 199 209 270 240 264

14 Gain/ feed3

Gain/ feed3

Gain 3

(g/kg) 633 661 707 714 683

(g/kg)

(g) 262 266 292 277 268

703 698 740 738 687

1 Data are means for three replicate groups of five male chicks during the period 8 to 22 days posthatching; average initial weight was 78.0 g. 2

Pooled SEM for gain and gain/feed were 5.9 and 8.5, respectively.

3

Manganese X SBM, Mn X FM, and Mn X WB interactions were significant (P<.05).

Manganese was determined in all tissues by atomic absorption spectrophotometry (PerkinElmer, Model 306). All data were analyzed by appropriate analysis of variance procedures (Steel and Torrie, 1980). Single degree-of-freedom comparisons were made to assess treatment differences. In Experiments 2 and 3, treatment means were compared by the least significant difference procedure only if the F-value for treatment was significant (P<.05).

RESULTS

Results of Experiment 1 are shown in Tables 3 and 4. Manganese supplementation significantly improved chick weight gain and feed efficiency. Supplementation of the caseindextrose diet with SBM, FM, or WB also enhanced performance, whereas the addition of corn was without effect. Because the gain and gain/feed responses to SBM, FM, or WB were greater in the absence than in the presence of

TABLE 4. Effect of manganese and feed ingredient supplementation on chick performance (Experiment

l)1'

Manganese (mg/kg) 0 Dietary treatment

Basal (B) B + 20% corn B + 20% soybean meal (SBM) B + 20% fish meal (FM) B + 10% wheat bran (WB)

14

Bone Mn3

Bone ash4

Bone Mn 3

(Mg/g bone)

(%)

(Mg/g bone)

(%)

2.42 1.82 2.55 1.86 2.64

38.2 40.1 40.0 42.0 40.3

4.25 3.41 4.20 2.79 3.60

39.2 40.9 40.0 41.3 39.5

Bone ash4

1 Data are means for three samples, each sample representing pooled tissue from three uniform chicks within a replicate. 2

Pooled SEM for bone Mn and bone ash were .14 and .80, respectively.

3

Manganese, corn, FM, Mn X FM, and Mn X WB effects were significant (P<.005).

"Corn and FM main effects were significant (P<.05).

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supplemental Mn, significant Mn x SBM, Mn x FM, and Mn x WB interactions occurred. Supplemental Mn also increased tibia Mn concentration but had little effect on bone ash percent (Table 4). Surprisingly, the addition of corn or FM to the basal diet significantly reduced bone Mn levels, both in the presence and absence of supplemental inorganic Mn. Wheat bran also depressed tibia Mn concentration when added to the diet supplemented with 14 mg Mn/kg but not when added to the diet containing no supplemental Mn. This effect of WB resulted in a significant Mn X WB interaction. Soybean meal had little effect on the concentration of Mn in bone. Additions of corn and FM, while lowering bone Mn levels, significantly increased percentage of bone ash. In Experiment 2, supplementation of the basal diet containing 1000 mg Mn/kg with SBM or FM increased chick weight gain, and all four supplemental feed ingredients enhanced feed efficiency (Table 5). Corn, SBM, FM, and WB also markedly reduced Mn concentration in both bile and tibia when added to the basal diet containing excess Mn. Only supplemental FM significantly increased bone ash percent. The results of Experiment 3 are presented in Table 6. Addition of either WB or a corn-SBM mix (C-SBM) to the casein-dextrose diet con-

taining 1000 mg Mn/kg had little effect on chick performance, irrespective of the level added. Fish meal significantly improved chick performance but only when added at 5.0 or 10.0% of the diet. Feed ingredient supplementation, on the other hand, had dramatic effects on tissue Mn concentrations. Bile and bone Mn levels were markedly depressed when only 1.0% WB was added to the basal diet containing 1000 mg Mn/kg. Supplementation with WB at higher levels did not result in further reductions in tissue Mn levels beyond those obtained with 1.0% supplemental WB. Likewise, 2.5 and 5.0% supplemental FM were required to significantly depress bile and bone Mn concentrations, respectively. The C-SBM mix significantly reduced tissue Mn levels when added at 5.0% of the diet, with no further reduction occurring when the mix was added at 10.0%. Chick performance was improved by adding Mn to the casein-dextrose diet in Experiment 4 (Table 7). Rate and efficiency of gain of chicks fed diets supplemented with either 14 or 1000 mg Mn/kg, however, were similar, thereby supporting our previous requirement estimate of 14 mg Mn/kg. Rice bran supplementation also increased weight gain and gain/feed, with the greatest improvement in gain occurring in

TABLE 5. Effect of feed ingredient supplementation on performance and tissue manganese concentrations of chicks fed excess manganese (Experiment 2) Tissue analyses 2

Perform ance 1 Dietary t r e a t m e n t

Basal ( B ) 3 B + 20% corn B + 20% soybean meal (SBM) B + 20% fish meal (FM) B + 10% w h e a t b r a n (WB) Pooled SEM

Gain

Gain/feed

Bile Mn

Bone Mn

Bone ash

(g)

(g/kg)

(Mg/g dry tissue)

(Mg/g b o n e )

(%)

269a 282ab 298bc 305c 275a

672a 742C 747c 752C 708b

180.5b 84.3a 46.3 a 55.2a 51.0a

24.3d 18.1c 15.0b 11. l a 14.2b

40.7a 4 1 gab 40.8a 42.7b 41.5ab

22.55

.70

5.2

10.8

.40

a—d Means within a column not sharing a common superscript differ significantly (P<.05). Data are means for three replicate groups of five male chicks during the period 8 to 22 days posthatching; average initial weight was 78.4 g. 2 Data are means of three samples, each sample representing pooled tissue from three uniform chicks within a replicate. 1

3

Basal diet contained 1000 mg Mn/kg.

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MANGANESE UTILIZATION BY CHICKS

TABLE 6. Performance and tissue manganese concentrations of chicks fed graded levels of wheat bran (WB), fish meal (FM), or a corn-soybean meal (C-SBM) mix (Experiment 3) ]Performance

12

Tissue analyses3'4

'

Gain

Gain/feed

Bile Mn

Bone Mn

(g)

(g/kg)

(Mg/g dry tissue)

(Mg/g bone)

1. Basal (B) + 14.0 mg Mn/kg 2. B + 1000 mg Mn/kg

259 a 276ab

688abc 687abc

1.4a 150.0 e f

3.6 a 31. l e

3. 4. 5. 6.

273ab 274ab 281bc 280bc

676ab 666 a 696bcd 700bcd

69.7bc 59.3bc 57.9bc 51.7 b

19.1bc 17.0 b 18.0 b c 16.3 b

Dietary treatment

As 2 As 2 As 2 As 2

+1.0% WB + 2.5% WB +5.0% WB + 10.0% WB

7. 8. 9. 10.

As 2 + 1.0% FM As 2 + 2.5% FM As 2 +5.0% FM As 2 + 10.0% FM

28?bcd 283bcd 295cd 300 d

688abc 710cde 711cde 731e

165.6 f 77.4cd 740bcd 70.7bcd

29.3 e 25.7de 22.9 c d 15.5 b

11. 12. 13. 14.

As 2 + 1.0% C-SBM5 As 2 + 2.5% C-SBM As 2 + 5.0% C-SBM As 2 + 10.0% C-SBM

279bc 274ab 275ab 288bcd

682ab 687abc 682ab 716de

103.6 d e 141.0 e f 84.7cd 68.8 b c

25.0 d e 26.4 d e 19.3 b c 17.6 b

a—f Means within a column not sharing a common superscript differ significantly (P<.05). 1 Data are means for three replicate groups of five male chicks during the period 8 to 22 days posthatching; average initial weight was 80.6 g. 2 Pooled SEM for gain and gain/feed were 6.1 and 8.5, respectively. 3 Data are means of three samples, each sample representing pooled tissue from three uniform chicks within a replicate. 4 Treatment variances were heteroscedastic; thus, data were transformed using the equation log (Y + 1) before statistical analysis was performed. 5 Corn-SBM ratios were similar to that found in a typical 23% protein diet, i.e., 57.33% corn and 42.67% SBM.

the Mn-unsupplemented birds. This RB effect resulted in a significant Mn X RB interaction for gain. Supplemental Mn also markedly increased tissue Mn levels. The effects of RB supplementation, however, were variable, depending on the level of dietary Mn fed. Rice bran had little effect on pancreas Mn when added to the Mn-unsupplemented diet, but the bran lowered pancreatic Mn in Mn-adequate chicks, resulting in a significant Mn X RB interaction. A similar interaction occurred for bone Mn, as RB increased tibia Mn concentrations at the two lower levels of Mn supplementation but depressed the concentration of Mn in bone of birds fed 1000 mg Mn/kg. Bone ash percent was increased by Mn supplementation in this experiment. The effects of RB and WB supplementation on Mn bioavailability were compared in Experiment 5 (Table 8). Performance improved linearly as graded levels of Mn (0, 7, 14 mg

Mn/kg) were added to the basal diet. Chick weight gain was also increased by RB at all levels of Mn, and by WB at the two lower levels of Mn, but only RB significantly improved feed efficiency. Both types of bran, therefore, increased gain to a greater extent at the more deficient levels of Mn, resulting in significant Mn X RB and Mn X WB interactions. Tissue Mn concentrations also increased linearly with increasing levels of Mn supplementation. The overall effect of adding bran to the basal diet was an increase in pancreas and bone Mn concentrations, although RB and WB differed significantly in their main effects. Rice bran supplementation increased tissue Mn concentrations at all three levels of supplemental inorganic Mn, with the greater responses occurring at the more deficient levels of Mn. Wheat bran also increased Mn concentration in tissues of birds fed the Mn-unsupplemented diet, but the magnitude of response was lower

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TABLE 7. Effect of manganese and rice bran supplementation on chick performance and tissue manganese concentrations (Experiment 4) Performance 1

Tissue analyses2

Supplemental Mn

Rice bran

Gain3>4'5

Gain/ feed3-4

Pancreas Mn3'4-5

Bone Mn3'4-5

Bone ash3

(mg/kg)

(% of diet)

(g)

(g/kg)

(Mg/g dry tissue)

(Mg/g

(%)

0 14 1000

0 0 0

215 267 271

649 690 683

9.2 15.4 22.6

1.4 3.9 29.3

46.6 48.2 49.1

0 14 1000

10 10 10

275 289 288

715 735 722

10.4 8.7 13.5

4.1 4.6 13.5

48.3 49.0 48.4

Pooled SEM6

4.3

10.8

2.01

.53

1 Data are means for three replicate gorups of five male chicks during the period 8 to 22 days posthatching; average initial weight was 73.8 g. 2 Data are means of three samples, each sample representing pooled tissue from three uniform chicks within a replicate. 3 4

Manganese main effect was significant (P<.06). Rice bran main effect was significant (P<.05).

5

Manganese X rice bran interaction was significant (P-C06).

6 Pooled SEM for bone Mn is not reported, as the treatment variances were heteroscedastic. Data were therefore log transformed prior to statistical analysis.

TABLE 8 Effect of rice bran (RB) or wheat bran (WB) on performance and tissue manganese concentrations of chicks fed various levels of manganese (Experiment 5) Perform; ince 1

Tissue analyses2

Supplemental Mn

Level and type of bran

Gain 3

Gain/ feed4

Pancreas Mn3

Bone Mn 3

Bone ash

(mg/kg)

(% of diet)

(g)

(g/kg)

(Mg/g dry tissue)

(Mg/g bone)

(%)

0 7 14

0 0 0

194 220 244

646 667 697

2.0 5.7 7.6

1.7 2.8 3.7

48.4 50.4 48.8

0 7 14

10% RB 10% RB 10% RB

257 260 260

725 710 726

8.2 8.8 8.0

4.0 4.1 5.0

48.6 49.8 50.4

0 7 14

10% WB 10% WB 10% WB

227 240 237

657 667 697

5.1 6.2 7.3

2.6 2.8 2.9

50.1 49.5 48.9

Pooled SEM

4.5

10.5

.43

.17

.72

1 Data are means for three replicate groups of five male chicks during the period 8 to 22 days posthatching; average initial weight was 59.1 g. 2 Data are means of three samples, each sample representing pooled tissue from three uniform chicks within a replicate. 3 4

Manganese X RB and Mn X WB interactions were significant (P<.005). Manganese X RB interaction was significant (P<.05).

MANGANESE UTILIZATION BY CHICKS

than that resulting from RB supplementation. Also, WB did not significantly affect pancreas Mn concentration when added to diets containing 7 or 14 mg Mn/kg. Wheat bran, moreover, had no effect on bone Mn concentration when added to the diet containing 7 mg Mn/kg and significantly reduced the concentration of Mn in the tibia of birds fed the higher level of Mn. Thus, significant Mn X WB interactions occurred for pancreas and bone Mn concentrations. The dietary treatments did not significantly affect bone ash percent.

DISCUSSION

Chick growth was enhanced by Mn supplementation of the casein-dextrose diet up to a level of 14 mg/kg supplemental Mn. No further improvement in performance was observed when the diet was supplemented with 1000 mg Mn/kg, nor was growth depressed at that level. These findings coincide with previous work from our laboratory wherein the minimal Mn requirement was determined to be 14 mg/kg in chicks fed a casein-dextrose diet (Southern and Baker, 1983b). Manganese has also been shown to be relatively atoxic in that a growth depression was not observed in chicks fed a C-SBM diet except at exceptionally high (3000 to 5000 mg/kg) levels of Mn supplementation (Southern and Baker, 1983a). Whether due to enhanced palatability or some other reason, supplementation of the casein-dextrose basal diet with the natural feed ingredients frequently improved chick performance. This enhanced performance was observed even in the presence of excess supplemental Mn (1000 mg/kg), although the greatest response to feed ingredient supplementation occurred at deficient levels of Mn. Thus, the performance data may indicate that at least a portion of the Mn present in corn, SBM, FM, WB, and RB is available to the chick. Tissue Mn accumulation, however, is probably a better marker of Mn uptake than rate or efficiency of weight gain (Watson et al, 1970; Southern and Baker, 1983a, Black et al, 1984a,b). These researchers have established that bone Mn concentration is the most sensitive criterion in determining Mn bioavailability. Bile Mn concentration has also been shown to reflect excess dietary Mn intake (Southern and Baker, 1983a). Bile flow is the primary route of Mn excretion, although excretion also occurs via the pancreatic juice (Underwood, 1977).

1001

Thus, the pancreas represents a soft tissue that can easily be used as a sensitive criterion of Mn bioavailability. In Experiment 1, tibia Mn concentration was low in chicks fed the basal diet unsupplemented with inorganic Mn. Moreover, addition of 20% corn or FM to this diet actually reduced bone Mn level still further, while 20% SBM or 10% WB neither increased nor decreased bone Mn (Table 4). When the basal diet was supplemented with 14 mg Mn/kg (MnS0 4 *H 2 0), bone Mn concentration increased in all cases. In this series of diets, all four feed ingredients depressed bone Mn concentration, although the depression due to SBM was not statistically significant. These results thus indicate that the Mn present in these four feed ingredients is unavailable to the chick. Furthermore, it appears that these feed ingredients may reduce the availability of Mn from inorganic sources in the diet. To further investigate the depressing effect of these four feedstuffs on tissue Mn concentrations, the study was repeated in Experiment 2 but using a higher level of dietary Mn (1000 mg Mn/kg). Tibia and bile Mn concentrations were again dramatically reduced upon adding corn, SBM, FM, or WB to the basal diet containing 1000 mg Mn/kg from MnS04" H 2 0 . Thus, although these feed ingredients contributed significant quantities of oral Mn, they actually reduced the amount of Mn deposited in key tissues. These data may appear to contradict the performance data. It should be noted, however, that a considerable portion of the growth response to the addition of these feed ingredients is likely related to palatability and thus unrelated to provision of Mn. Indeed, chicks fed diets containing excess dietary Mn also responded to feed ingredient supplementation (cf. Tables 5, and 7). It is also possible that gain responses to these feed ingredients might be considerably reduced, or even eliminated, if longer term assays were performed, assuming the ingredients would continue to reduce the amount of Mn deposited in bone and other key tissues over time. The mechanism by which the feed ingredients employed herein depress tissue Mn concentration has not yet been elucidated; however, data from Experiment 3 indicate that tissue Mn levels were reduced even at low supplemental levels of each feed ingredient. Only 1.0% supplemental WB was required to dramatically depress tissue Mn concentration. Similarly, 5.0% of a C-SBM mix significantly reduced

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HALPIN AND BAKER

tissue Mn level, whereas 2.5 and 5.0% additions of supplemental FM were required to depress bile and bone Mn concentrations, respectively. Other researchers have suggested that natural feed ingredients may reduce the bioavailability of dietary Mn. Davis et al. (1962) concluded that isolated soybean protein interferes with the utilization of Mn, thereby increasing the dietary Mn requirement. Holmes and Roberts (1963) reported that inclusion of rapeseed meal at 30% of the diet increased the incidence of perosis in growing chickens. Subsequently, Seth and Clandinin (1973) postulated that the tannins in rapeseed meal may form complexes with Mn, thereby increasing the incidence of perosis. However, increasing the level of Mn in the rapeseed meal-containing ration did not lower the incidence of perosis. Some of the factors present in natural feed ingredients that might negatively impact bioavailability of a trace element such as Mn are: a) phytic acid, b) fiber, and c) calcium. All of these factors are represented in one way or another in the four feed ingredients evaluated herein. Corn, SBM, and WB contain significant quantities of phytate, while FM does not. On the other hand, FM contributes considerable calcium to the diet, whereas the other three ingredients have a relatively low calcium concentration. Finally, WB contributes a plethora of fiber to the diet, but the other three ingredients do not. Thus, there seems to be no common denominator that can explain the tissue Mn-lowering effects of these feed ingredients. The results of Experiment 4 indicate that RB also depressed Mn deposition in key tissues of chicks fed excess inorganic Mn (1000 mg/ kg). However, in contrast to the other feed ingredients tested, RB significantly increased tissue Mn concentrations when added to the Mn-unsupplemented basal diet. Moreover, RB supplementation enhanced tissue Mn deposition in Experiment 5 at all three levels of Mn supplementation (at or below the Mn requirement). In contrast to the results of Experiment 1, WB also increased tissue Mn concentrations when added to the Mn-unsupplemented diet in Experiment 5. Wheat bran, however, was without effect when added to the diet supplemented with 7.0 mg Mn/kg, and it significantly reduced tibia Mn concentration at the 14.0 mg/kg level of Mn supplementation. Thus, it appears that all five ingredients-corn, SBM, FM, WB, and RB-consistently

depressed tissue Mn deposition when added to diets containing excess Mn (1000 mg/kg). These feed ingredients, with the exception of RB, also reduced tissue Mn levels at the chick's dietary Mn requirement of 14 mg/kg. Rice bran, however, appeared to provide bioavailable Mn when added to diets containing a level of Mn at or below the chick's requirement. Wheat bran may also increase Mn deposition in key tissues of chicks fed diets unsupplemented with inorganic Mn, although this response was not observed in Experiment 1. These studies may partially explain why the Mn requirement in a C-SBM diet is relatively high (60 mg/kg) for the growing chick (National Research Council, 1984). Corn and SBM may reduce the bioavailability of the supplemental inorganic Mn in this practical-type diet. Further studies are underway to determine the mechanism by which these feed ingredients reduce tissue Mn levels. In addition, the long-term effects of depressed Mn deposition are being assessed. REFERENCES Black, J. R., C. B. Ammerman, P. R. Henry, and R. D. Miles, 1984a. Tissue manganese uptake as a measure of manganese bioavailability. Nutr. Rep. Int. 29:807-814. Black, J. R., C. B. Ammerman, P. R. Henry, and R. D. Miles, 1984b. Biological availability of manganese sources and effects of high dietary manganese on tissue mineral composition of broiler-type chicks. Poultry Sci. 63:1999-2006. Davis, P. N., L. C. Norris, and F. H. Kratzer, 1962. Interference of soybean proteins with the utilization of trace minerals. J. Nutr. 77:217-223. Holmes, W. B., and R. Roberts, 1963. A perotic syndrome in chicks fed extracted rapeseed meal. Poultry Sci. 42:803-809. National Research Council, 1'984. Nutrient Requirements of Poultry. Nutrient Requirements of Domestic Animals. 8th. ed. Natl. Acad. Sci., Washington, DC. Seth, P.C.C., and D. R. Clandinin, 1973. Effect of including rapeseed meal in the ration of broilertype chickens on the incidence of perosis and the ineffectiveness of supplemental manganese. Poultry Sci. 52:1158-1160. Southern, L. L., and D. H. Baker, 1983a. Excess manganese ingestion in the chick. Poultry Sci. 62:642-646. Southern, L. L., and D. H. Baker, 1983b. Eimeria acervulina infection in chicks fed deficient or excess levels of manganese. J. Nutr. 113:172— 177. Steel, R.G.D., and J. H. Torrie, 1980. Principles and Procedures of Statistics. A Biometrical Approach. 2nd. ed. McGraw-Hill Book Co., New York, NY. Turk, D. E., D. S. Gunji, and P. Molitoris, 1982. Coccidial infections and manganese absorption.

MANGANESE UTILIZATION BY CHICKS Poultry Sci. 61:2430-2434. Underwood, E. J., 1977. Trace Elements in Human and Animal Nutrition. 4th ed. Academic Press, New York, NY. Watson, L. T., C. B. Ammerman, S. M. Miller, and R. H. Harms, 1970. Biological assay of inorganic manganese for chicks. Poultry Sci. 49:1548— 1554.

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Watson, L. T., C. B. Ammerman, S. M. Miller, and R. H. Harms, 1971. Biological availability to chicks of manganese from different inorganic sources. Poultry Sci. 50:1693-1700. Wilgus, H. S., L. C. Norris, and G. F. Heuser, 1936. The role of certain inorganic elements in the cause and prevention of perosis. Science 84: 252-253.