SYMPOSIUM: NEW CONCEPTS AND DEVELOPMENTS IN T R A C E E L E M E N T N U T R I T I O N Variability in Mineral and Trace Element Content of Dairy Cattle Feeds R. S. ADAMS Dairy Science Extension The PennsylvaniaState University University Park 16802 ABSTRACT
QUANTITIES IN FEEDS
Trace element content of feeds is extremely variable compared to totat digestible nutrients or protein. Differences are wide between low and high values for many trace elements within a given type of feed. Coefficients of variation for forages range from 42 to 100%. Summary data are given for both major and trace elements. Problems in supplementation are discussed. Amounts for some d e m e n t s are skewed with relatively few samples around the mean and over 60% below the mean. Suggested mineral allowances for dairy cows are listed. Under current supplementation, zinc is the trace element most likely to be limiting and manganese the least likely. Iron, copper, cobalt, and iodine may be limiting in some cases. Needs of research and applied nutrition are presented.
The sharp contrast in variation among TDN, protein, and several elements is pointed out in Table 1. Even with allowances for extreme values due to error, contamination, etc., variability for trace elements within a major category of feed is much greater than that for TDN or protein. Also, the spread between low and high values is greater for trace than major elements, with the exception of calcium and sodium, which were not listed. Certainly a 30 to 50-fold range in trace element content is not unlikely within a given type of forage. Differences may be even greater among different types of forage or feedstuffs. Extremely high values, particularly for iron and aluminum, may reflect soil or other contamination in some cases.
INTRODUCTION Nutritionists have been concerned for years with the TDN (total digestible nutrients) or energy and protein contents of items used in feeding dairy cattle. To a lesser extent, there has been concern for amounts of calcium and phosphorus. However, too little attention has been paid to other elements, particularly t r a c e dements. Often trace mineral concerns stop with the recommendation to use a commercial product that has been trace mineralized. Due to the extreme variability among feeds as well as other factors, good trace element nutrition does not come this easy. I hope this presentation will demonstrate the great variation in trace element content which may occur. In addition, summary data on mineral analysis for various feeds will be provided and practical considerations in trace mineral supplementation will be discussed. Received December 13, 1974.
All mineral data, except for sulfur, taken from Penn State summaries have been determined with an emission spectrometer. Essentially the procedures are those reported in (1). This reference lists some of the important precautions to avoid high values from contamination during processing and analysis. Sulfur was determined with a Leco oxidizing unit. A procedure must be modified to include elemental sulfur as well as that in sulfate form. Another indication of large variability in trace element content of feeds may be found in Table 2. Here the mean coefficients of variation have been listed as taken from a summary of test data. Standard deviations as percents of means are higher for trace than maior dements, with the exception of sodium. Also, the coefficient of variation for calcium is relatively high for corn grain. Aluminum has the highest coefficient of variation among the trace elements. Both soil contamination and soil pH greatly affect aluminum values. Data in Tables 3 and 4 provide expectancies on both trace and major elements for commonly used forages and corn. Most of the samples
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SYMPOSIUM: NEW TRACE ELEMENT NUTRITION
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TABLE 1. Range in nutritive content of legume-grass forage, a
Item
Range
TDN, % Crude protein, % Calcium, % Phosphorus, % Magnesium, % Sulfur, % Manganese, ppm Iron, ppm Copper, ppm Zinc, ppm
51 6.6 .01 .07 .07 .04 6 10 2 8
Fold b difference -- 71 - 33.2 - 2.61 -- .74 -- .75 - .38 -- 265
1.4 5.0 261.0 10.6 10.7 9.5 44.2
-- 2599
259.9
-- 92 -- 300
46.0 37.5
aSummary of Penn State Forage Testing Service, 1969-73. bMaximum - minimum.
s u m m a r i z e d in t h e s e tables originated in P e n n sylvania a n d N e w York. T h e d a t a s h o u l d b e r e a s o n a b l y indicative of feeds p r o d u c e d in this region or u n d e r similar soil a n d o t h e r conditions. Sulfur d a t a are available o n a m u c h smaller p r o p o r t i o n o f t h e samples a n d are s u m m a r i z e d in T a b l e 5. S o m e w h a t similar d a t a for grains a n d byp r o d u c t i n g r e d i e n t s have b e e n p u b l i s h e d b y t h e N a t i o n a l R e s e a r c h C o u n c i l (9, 10). T h e data in Tables 6 and 7 for c o m m o n l y used c o n c e n t r a t e s have b e e n a d a p t e d f r o m t h e s e sources. T h e s e data were o b t a i n e d prior t o 1958. Also, few samples are r e p r e s e n t e d in s o m e m e a n values. This is true of t h o s e for trace e l e m e n t s , especially zinc a n d iodine. I n s u f f i c i e n t observations exist for s o m e i m p o r t a n t i n g r e d i e n t s such
as c o t t o n s e e d and s o y b e a n oil meals. Many factors may influence the mineral c o n t e n t of forages a n d o t h e r feeds. U n d e r w o o d (14) has suggested t h a t the m o s t i m p o r t a n t f a c t o r s are (a) genus, species, or s t r a i n of p l a n t , (b) t y p e of soil, (c) climatic or seasonal c o n d i t i o n s d u r i n g g r o w t h , a n d (d) stage o f m a t u r i t y of t h e p l a n t . D a t a on t h e s e a n d o t h e r f a c t o r s have b e e n p u b l i s h e d m o r e r e c e n t l y (13). T h e i n f l u e n c e of l o c a t i o n a n d soil via pH, p a r e n t material, a n d f e r t i l i z a t i o n has b e e n e s t a b l i s h e d in s o m e cases (2, 3, 4, 5, 7, 12, 13, 14). T h e s e are l a n d m a r k p u b l i c a t i o n s dealing w i t h applied m i n e r a l n u t r i t i o n . T h e e f f e c t of geographical origin o n t h e m o l y b d e n u m a n d s e l e n i u m c o n t e n t of feeds is well k n o w n . However, less d r a m a t i c b u t i m p o r -
TABLE 2. Mean coefficient of variation for elemental content, a Element
Forages
Corn grain
Phosphorus Potassium Calcium Magnesium Sulfur Sodium Manganese Iron Boron Copper Zinc Aluminum
25 32 28 33 29 128 75 68 42 57 63 100
22 33 196 17 24 318 116 83 58 62 39 172
Combined
(%) 25 32 73 30 28 170 84 71 46 58 57 116
aSummary of Penn State Forage Testing Service, 1969-73. Journal of Dairy Science Vol. 58, No. 10
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TABLE 3. Trace element content of various feeds, ppm in dry matter, a Item
Manganese
Legume forage (992) b Mean SD Low High
44.1 49.2 8.0 1080.0
Boron
Copper
Zinc
Aluminum
221.7 124.9 41.0 800.0
25.9 7.9 2.0 65.0
13.1 8.2 2.0 214.0
28.1 18.8 11.0 260.0
143.1 123.3 4.0 1000.0
48.1 21.3 6.0 265.0
222.0 142.7 10.0 2599.0
20.2 7.2 2.0 94.0
13.1 5.7 2.0 92.0
27.2 12.7 8.0 300.0
128.8 127.7 1.0 1500.0
57.3 40.0 7.0 1200.0
192.3 138.9 t9.0 2463.0
11.6 5.4 1.0 53.0
12.0 7.0 2.0 125.0
26.5 12.8 3.0 255.0
105.0 113.1 2.0 1271.0
Grass forage (352) Mean SD Low High
76.4 64.1 12.0 689.0
184.4 141.2 32.0 1200.0
8.3 3.8 .0 26.0
12.9 8.4 2.0 69.0
27.6 10.7 12.0 112.0
108.0 126.0 7.0 1200.0
Corn silage (7179) Mean SD Low High
38.1 20.8 1.0 267,0
200.1 131.1 5.0 1800.0
6.5 2.6 1.0 41.0
8.1 4.4 2.0 110.0
30.8 21.5 3.0 416.0
91.8 99.0 3.0 3500.0
Small grain forage (97) Mean SD Low High
62.6 41.0 9.0 276.0
298.8 155.9 40.0 900.0
8.0 4.3 1.0 27.0
11.9 7.7 2.0 36.0
33.2 25.5 14.0 212.0
181.8 166.5 1.0 1000.0
Sorghum-sudan forage (91) Mean SD Low High
69.1 65.2 9.0 571.0
320.5 278.2 67.0 2000.0
7.7 3.2 2.0 19.0
12.3 6.4 2.0 36.0
41.6 38.0 "15.0 315.0
173.6 157.8 23.0 691.0
Ear corn (324) Mean SD Low High
7.3 10.9 1.0 142,0
93.8 89.7 7.0 500,0
3.8 2.7 ,0 36.0
4.7 2.7 1.0 19.0
26.8 14.4 11.0 200.0
21.7 43.6 .0 500.0
4.8 4.0 1.0 29.0
69.0 48.5 10.0 464.0
3.6 1.6 1.0 10.0
3.7 2.5 .0 23.0
24.7 5.9 13,0 58.0
10.7 15.3 1.0 85.0
Mixed mainly legume (4014) Mean SD Low High Mixed mainly grass (4119) Mean SD Low High
Shelled corn (221) Mean SD Low High
Iron
aSummary of Penn State Forage Testing, 1969-73. hNumber of samples.
rant differences may exist within a state, c o u n t y , c o m m u n i t y , or even o n a farm. F o r example, zinc in Pennsylvania forages m a y vary appreciably d e p e n d i n g u p o n location, as illusJournal of Dairy Science Vol. 58, No. 10
t r a t e d in Table 8. Forages g r o w n in Regions 2 and 5 t e n d to c o n t a i n m o r e zinc. T h e reasons are n o t a p p a r e n t here, b u t o b s e r v a t i o n o f m a n y tests over years suggests t h a t forages g r o w n
SYMPOSIUM: NEW TRACE ELEMENT NUTRITION
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TABLE 4. Major element content of various feeds, percent in dry matter, a Item
Phosphorus
Potassium
Calcium
Magnesium
Sodium
Legume forage (992) b Mean SD Low High
.30 .05 .14 .56
2.55 .61 .21 4.93
1.18 .27 .03 2.23
.24 .07 .10 .58
.024 .017 .001 .100
Mixed mainly legume (4014) Mean SD Low High
.29 .06 .07 .74
2.26 .60 .42 9.63
1.02 .28 .01 2.61
.22 .07 .07 .75
.018 .015 .000 .110
Mixed mainly grass (4119) Mean SD Low High
.23 .06 .05 .81
1.79 .55 .30 4.70
.65 .28 .10 2.73
.18 .06 .03 .79
.013 .016 .000 .390
Grass forage (352) Mean SD Low High
.22 .07 .09 .56
1.68 .61 .24 4.04
.49 .20 .10 1.58
.16 .06 .04 .42
.014 .019 .000 .110
Corn silage (7179) Mean SD Low High
.23 .05 .01 .93
1.07 .27 .02 3.28
.27 .11 .01 1.88
.18 .05 .01 .55
.005 .014 .000 .350
Small grain forage (97) Mean SD Low High
.32 .09 .14 .76
2.29 .81 .49 5.30
.44 .20 .06 1.22
.16 .05 .07 .29
.030 .031 .001 .100
Sorghum-sudan forage (91) Mean SD Low High
.24 .06 .07 .44
1.73 .74 .12 4.00
.48 .23 .12 1.83
.28 .12 .06 .58
.008 .012 .001 .071
.28 .08 .14 1.14
.49 .18 .26 2.96
.05 .10 .01 1.15
.12 .02 .01 .25
.007 .020 .000 .100
.31 .05 .19 .59
.42 .13 .24 1.41
.03 .06 .01 .72
.12 .02 .06 .20
.003 .010 .000 .100
Ear corn (324) Mean SD Low High Shelled corn (221) Mean SD Low High
aSummary of Penn State Forage Testing, 1969-73. bNumber of samples.
closer to industrial centers may be higher in some trace elements. Perhaps s o m e of this may be due to air pollution, use of industrial b y - p r o d u c t s o n soils, a n d r u n - o f f f r o m disposal
sites for industrial wastes. Forages grown in an area w i t h slate m i n e s m a y s o m e t i m e s c o n t a i n 80 t o 2 2 0 p p m zinc. T h i s is 3 to 7 t i m e s h i g h e r t h a n e x p e c t e d zinc. M o l y b d e n u m t o x i c i t y h a s Journal of Dairy Science Vol. 58, No. 10
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T A B L E 5. Sulfur c o n t e n t of various feeds, dry m a t t e r basis, a
Item
No. samples
Legume forage Mixed mainly legume Mixed mainly grass Grass forage Corn silage Small grain forage Sorghum-sudan Ear corn Shelled corn
39 121 71 4 249 1 3 18 8
Mean
Low
High
Standard deviation
%
%
%
+-%
.26 •23 .20 .20 .14 .21 .10 .13 .14
.14 .04 .12 .14 .04 . . .08 .08 .10
.43 .38 .35 •29 .22 . . .14 .22 .19
.07 .06 .06 .07 .04
.
.
.
.
. .03 .04 .03
a s u m m a r y of Penn State Forage Testing, 1969-73.
T A B L E 6. Zinc p p m in forages by major land resource areas in Pennsylvania. a Corn silage
Legume-Grass hay
Grass-Legume hay
Region b
No. samples
ppm
No. samples
ppm
No. samples
ppm
1 2 3 4 5
879 278 295 1478 974
31 37 30 29 30
328 189 123 874 355
27 32 25 26 31
679 115 158 351 214
24 30 25 27 31
a c o n t e n t on a dry m a t t e r basis for samples tested from 1969 to 1973. bRegions are described as follows: (1) Glaciated Allegheny Plateau and Catskill Mountains (Northwest and Northeast), (2) Central Allegheny Plateau, (3) Eastern Allegheny Plateau and Mountains, (4) Northern Appalachian Ridge and Valleys (South Central), and (5) Northern P i e d m o n t (Southeast).
T A B L E 7. Trace mineral c o n t e n t of various concentrates, dry m a t t e r basis, a Item
Manganese
Iron
Copper
Zinc
Cobalt
Iodine
(ppm) Barley No. samples Mean Low High Beet pulp, dried No. samples Mean Low High Brewers' grains, dried No• samples Mean Low High Citrus pulp, dried No. samples Mean Low High
(73) 18.2 2.4 29.9
(41) 60.0 40,0 100.0
(33) 8.6 1.3 20.0
(3) 17.1 11.9 20.9
(27) .117 .000 .321
(39) 38.5 12.1 77.9
(27) 331.0 85.0 600.0
(31) 13.9 8.4 22.7
(1) 7.0 . . . . . . . .
(26) .112 023 116
(29) 40.7 21.1 56.1
(22) 271.6 100.0 410.0
(16) 23.1 5.5 45.3
. . . .
.. . . . . . . . . .
(15) 067 044 110
(16) 7.5 1.1 19.4
(14) 183.1 94.0 303.0
(8) 6.3 2.0 14.5
(1) 16.0 . . . . . . . .
(4) .236 066 704
Journal of Dairy Science Vol. 58, No. 10
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T A B L E 7. ( C o n t i n u e d ) T r a c e m i n e r a l c o n t e n t o f v a r i o u s c o n c e n t r a t e s , d r y m a t t e r basis, a Item
Manganese
Iron
Copper
Zinc
Cobalt
Iodine
(2) 19.6 12.1 26.8
(460) •022 .002 .299
(16) •344 .064 •7 0 4
(ppm) Corn, dent No. samples Mean Low High C o r n distillers w sol. No. samples Mean Low High Corn gluten feed No. samples Mean Low High C o t t o n s e e d m e a l , solv. No. samples Mean Low High H o m i n y f e e d , yel. No. samples Mean Low High Oats No. samples Mean Low High Molasses, c a n e No. samples Mean Low High Sorghum No. samples Mean Low High S o y b e a n m e a l , solv. No. samples Mean Low High Steamed bone meal No. samples Mean Low High Wheat bran No. samples Mean Low High Wheat std. raids No. samples Mean Low High
(568) 5.7 .7 53.9
(518) 20.0 10.0 100.0
(463) 2.4 .9 9.0
(10) 30.9 15.6 67.3
(8) 334.1 200.0 600.0
(2) 67.1 56.1 78.5
. . . .
.. (2) . . . 120 . . . . . . . . . .
(45) 26.3 8.8 42.2
(32) 514.0 260.0 955.0
(33) 52.7 13.0 89.3
. . . .
. . . . . . . . . . .
(26) 097 022 286
(5) 21.8 16•2 30.1
(3) 167.0 110.0 246.0
(3) 23.3 16.3 32.6
. . . .
.. . . . . . . . . .
(3) 086 033 176
(17) 17.8 11.4 30.6
(12) 109.0 10.0 260.0
(5) 10.7 7.9 13.9
. . . .
.. . . . . . . . . .
(3) 061 048 066
(199) 42.9 20.0 203.5
(88) 80.0 20.0 300.0
(73) 6.6 2.4 25.7
. . . .
.. . . . . . . . . .
(19) 064 000 321
(9) 56.6 12.8 83.8
(9) 251.0 130.0 429.0
(8) 80.0 33.4 137.1
•.. . . . . . . . ...
(4) 1.213 224 3.485
(42) 16.2 .0 27.3
(44) 50.0 .0 180.0
(38) 10.8 2.0 19.1
(2) 15.4 11.8 18.9
(22) .304 .040 .737
(7) 30.8 24.9 33.9
(9) 147.0 110.0 240.0
(8) 16.0 13.6 18.3
. . . .
(6) 103 031 176
(57) 31.9 2.0 92.4
(63) 882.4 159.0 2829.0
(56) 17.1 .9 33.4
(36) 446.0 51.3 1835.9
(44) 129.9 90.0 164.3
(29) 193.0 88.0 270.0
(30) 13.8 4.4
(20) 132.0 103.4 157.7
(13) 115.9 83.0 192.0
(10) 11.1 22.2 28.2
29.9
. . . . . . . . . . .
.
(24) 108 031 178
... . . . . . . . . . . . .
(10) 094 079 130
.
. °
, . .
° . .
(17) .065 .044 .110
. .. . . . . . . . . .
,
.
aAdapted from National Academy of Science, National Research Council Publications No. 449 and 585. J o u r n a l o f D a i r y S c i e n c e Vol. 5 8 , N o . 10
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TABLE 8. Major mineral content of various concentrates, dry matter basis, a Item
Phosphorus
Potassium
Calcium
Magnesium
Sulfur
Sodium
Chlorine
(234) .14 .01 .23
(213) .19 .10 .35
(10) .02 .01 .06
(14) .13 .09 .17
(%) Barley No. samples Mean Low High Beet pulp, dried No. samples Mean Low High Brewers' grains, dried No. samples Mean Low High Citrus pulp, dried No. samples Mean Low High Corn, dent No. samples Mean Low High Corn distillers w sol. No. samples Mean Low
(331) .47 .28 .92
(233) .63 .33 .99
(57) .11 .05 .17
(8) .23 .15 .39
(56) .75 .36 1.03
(14) .30 .06 .43
(4) .22 .13 .31
(6) .19 .11 .23
(1) .04 ... ...
(37) .54 .36 .68
(5) .09 .04 .18
(37) .29 .14 .65
(7) .15 .03 .31
(4) .34 .05 .51
(1) .28 . . . . . . . .
(4) .20 06 26
(38) .13 .09 .24
(4) .69 .10 1.41
(38) 2.18 1.24 3.55
(20) .18 .02 .50
. . . .
"(571) .03 .00 .35
(88) .14 .08 .90
(38) .14 .10 .19
(53) .01 .00 .O6
(72) .06 .02 .O9
(8) .71 .22 1.13
(22) .19 .I1 .28
(13) .27 .09 .38
(5) .33 .24 .40
(3) .39 .18 .79
(3) .19 .17 .19
(29) .66 .62 1.33
(59) .51 .03 1.08
(31) .32 .29 .87
(26) .24 .06 1.40
(3) 1.05 1.03 1.10
(7) 1.24 .06 1.04
(3) 1.61 1.03 2.20
(14) .16 .07 .26
(4) .64 .37 .82
(3) .06 01 11
(2) .04 .04 .05
(586) .31 .09 .24 (22) .74 .43 1.02
High Corn gluten feed No. samples (82) Mean .85 Low .38 High 1.20 Cottonseed meal, solv. No. samples (16) Mean 1.20 Low .65 High 1.70
(88) .33 .20 .73
(325) .09 .03 .41
b e e n f o u n d in plants and animals l o c a t e d in t h e vicinity o f zinc and m o l y b d e n u m smelters. S o m e o f the e x t r e m e l y high trace e l e m e n t s in Table 3 were o b t a i n e d in forages f r o m farms with animal health p r o b l e m s w h i c h a p p a r e n t l y resulted f r o m intake o f industrially c o n t a m i n a t e d forages. S U P P L E M E N T A T I O N PROBLEMS
Neither universal p r o d u c t s nor general reco m m e n d a t i o n s can insure t h a t all cows on all farms will receive p r o p e r a m o u n t s o f mineral e l e m e n t s at all times. Yet, this is w h a t s o m e Journal of Dairy Science Vol. 58, No. l0
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. . . .
(1) .23 . . . . . . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
d a i r y m e n are led t o believe for various reasons. F u r t h e r , s o m e f a r m e r s believe t h a t h o m e - p r o d u c e d feeds will c o n t a i n a d e q u a t e a m o u n t s o f m o s t e l e m e n t s , if t h e y fertilize according to soil tests or get good yields. U n f o r t u n a t e l y , s o m e mineral n u t r i t i o n p r o b l e m s result f r o m a differential r e q u i r e m e n t o f the animal over t h a t o f plants or f r o m low availability of .an e l e m e n t t o the animal (7). P r o p e r use o f forage and feed testing with mineral analyses c o m b i n e d with c u s t o m f e e d p r o g r a m m i n g offers t h e b e s t a p p r o a c h t o reas o n a b l y g o o d mineral n u t r i t i o n . T h e use of
SYMPOSIUM: NEW T R A C E ELEMENT N U T R I T I O N
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T A B L E 8. (Continued) Major mineral c o n t e n t o f various concentrates, dry matter basis, a Item
Phosphorus
Potassium
Calcium
Magnesium
Sulfur
Sodium
Chlorine
(%) Hominy feed, yel. No. samples Mean Low High 0 ats No. samples Mean Low High Molasses, cane No. samples Mean Low High Sorghum No. samples Mean Low High Soybean meal, solv. No. samples Mean Low High Steamed bone meal No. samples Mean Low High Wheat bran No. samples Mean Low High Wheat std. mids No. samples Mean Low High
(22) .57 .30 .87 (273) .39 .05 1.02 (32) ,11 .01 .25 (235) .35 .10 .52 (34) .75 .50 1.09
(1) .57 . . . . . . (83) .42 .22 .89 (9) 3.20 2.16 3.64 (16) .38 .28 .50
. .
(22) .06 02 12
(2) .04 .02 .06
. . . .
(227) .11 .04 .48
(77) .19 .03 .29
(15) .23 .15 .31
(18) .07 .01 .16
(19) .47 .16 .87
(15) .46 .10 .97
(5) .23 .10 .53
(4) 3.69 2,60 4.35
(227) .05 .01 .53
(23) .19 .02 .25
(6) .18 .15 .21
(9) .05 .01 .09
(7) .10 .07 .14
(35) .36 .23 .96
(8) _30 .00 ,45
(1) .48 . . . . . . . .
(6) .38 04 62
(1) ,00 , •• •..
(109) 30.44 22.75 36.65
(45) ,64 .11 1.19
(40) .23 .07 .91
(18) .48 .40 .55
... ... ... ...
(9) .07 .01 A1
(7) .05 .02 .10
(35) 1.20 .32 2.20
(6) 2,20 2.00 2.30
.. (1) . . . 14 . . . . . . . . . . . . . . . .
(109) 14.28 8.34 18.35
118 ... ...
(86) 1.31 .10 1.91
(11) 1.39 .93 1.77
(84) .16 .07 .56
(10) .62 .50 .80
(9) .25 .19 .36
(53) 1.01 .73 1.35
(33) 1.09 1.06 1.37
(30) .17 .07 .50
(34) .41 .40 .56
(32) (1) .06 .25 . . . . . . . . . . . . . .
. •• .••
(19) .11 .05 .19
(3) .03 03 04
aAdapted f r o m National A c a d e m y of Science, National Research Council Publications No. 449 and 585.
multiple product lines designed to provide f l e x i b i l i t y in m i n e r a l c o n t e n t o f f i n i s h e d f e e d s affords a satisfactory means of improving mineral n u t r i t i o n . T h e u s e o f m a n u f a c t u r e d p r o t e i n concentrates without added minerals, at least t h e m a j o r o n e s , p r o v i d e s still a n o t h e r a l t e r n a tive. T r a c e m i n e r a l t e s t s m u s t be u s e d w i t h c a u t i o n in f e e d p r o g r a m m i n g . E x t r e m e v a l u e s m a y o c c u r d u e t o c o n t a m i n a t i o n b e f o r e or a f t e r sampling, faulty procedures, and improperly
o p e r a t e d or m a l f u n c t i o n i n g e q u i p m e n t . T h u s , it is b e s t t o u s e v a l u e s t h a t a r e c o n s i s t e n t w i t h past test reports from a farm when unreasonable values are encountered. It is e x t r e m e l y i m p o r t a n t to use sound assumptions, good expectancy data, and reasonable allowances for developing either general recommendations or universal formulas for supplements, Should one base supplementation on average values for forage and concentrates? Or should values be used that range from Journal of Dairy Science Vol. 58, No. 10
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one-half to more than one standard deviation below average? In regard t o trace e l e m e n t s , it a p p e a r s best to use a value t h a t at least a p p r o a c h e s o n e s t a n d a r d deviation b e l o w m e a n values. This t h e o r e t i c a l l y w o u l d m a k e t h e reco m m e n d a t i o n s a d e q u a t e a b o u t 84% of t h e time. As i l l u s t r a t e d in T a b l e 9, values for a given e l e m e n t m a y n o t fit a n o r m a l d i s t r i b u t i o n curve. T h e y m a y be s k e w e d w i t h relatively few samples close t o t h e m e a n a n d c o n s i d e r a b l y m o r e values falling b e l o w t h e m e a n t h a n a b o v e it. T h e m i n i m u m allowances w h i c h we p r e f e r to use in general feed p r o g r a m m i n g are in T a b l e 10. P h o s p h o r u s allowances a p p r o x i m a t e t h o s e of t h e 1971 N R C p u b l i c a t i o n (11). M o s t t r a c e mineral a l l o w a n c e s agree w i t h t h o s e of J a c o b son et al. (8). Q u a n t i t i e s of t r a c e m i n e r a l s n e e d e d in t h e grain m i x t u r e to b a l a n c e a c o m m o n l y used r a t i o n are in T a b l e 11. Likewise, a m o u n t s of m i n o r e l e m e n t s n e e d e d in a trace m i n e r a l salt to be used in s u p p l e m e n t i n g a c o r n a n d s o y b e a n oil meal m i x t u r e are given. A s s u m p t i o n s include feeding a c o w weighing 545.5 kg a n d p r o d u c i n g 22.7 kg of m i l k t e s t i n g 4% fat. In a d d i t i o n , 65% of the t o t a l dry m a t t e r was f u r n i s h e d b y a
TABLE 9. Distribution of iron in mixed mainly legume forages, a
ppm 30 60 90 120 150 180 210 240 270
- 60 -- 90 -- 120 - 150 -- 180 -- 210 - 240 - 270 - 300 3OO - 330 330 -- 36O 360 - 390 39O -- 42O 420 - 45O 450 -- 480 480 -- 510
Percent of samples 1.5 5.9 5.2 19.3 14.8 11.1 2.2 3.0 1.5 5.9 .7 2.2 4.4 1.5 1.5 19.3
a135 samples randomly selected from 1973-74 testing year at Penn State. Mean 255.9 + 150.1 ppm; range 38 to 500 ppm. Skewed positively with 61.5% of the samples below the mean and 38.5% above the mean. Journal of Dairy Science Vol. 58, No. 10
TABLE 10. Mineral allowances for dairy cows. a Element
Amount
Calcium, % Phosphorus, % Potassium, % Magnesium, % Sulfur, % Manganese, ppm Iron, ppm Copper, ppm Zinc, ppm Cobalt, ppm Iodine, ppm
.68 -- .76 .38 .70 .22 .20 44 150 11 70 1 2
aLevels expressed on a dry matter basis. forage r a t i o n consisting of 50% c o r n silage a n d 50% m i x e d m a i n l y l e g u m e forage o n a d r y m a t t e r basis. If m e a n e x p e c t a n c i e s are used, o n e c o u l d feed r e a s o n a b l y c e r t a i n t h a t needs were b e i n g m e t o n l y 50% of t h e t i m e or less. W h e n an e x p e c t a n c y of o n e s t a n d a r d d e v i a t i o n b e l o w m e a n is used, one m a y be m e e t i n g needs a b o u t 84% of the time. F o r c o m p a r i s o n , trace m i n e r a l s in a p o p u l a r m a n u f a c t u r e d dairy feed a n d a widely used trace m i n e r a l salt are s h o w n in p a r e n t h e s e s . M a n g a n e s e usually a p p r o a c h e s or exceeds needs in p r o d u c t s used for s u p p l e m e n t a t i o n . T h i s p r o b a b l y is a carry-over f r o m p o u l t r y n u t r i t i o n , r a t h e r t h a n t h e r e s u l t of g o o d f o r m u l a t i o n f o r dairy p u r p o s e s . Zinc s u p p l e m e n t a t i o n is m o s t likely i n a d e q u a t e . Iron m a y be lacking in s o m e fortifications. Copper, cobalt, a n d i o d i n e m a y be i n s u f f i c i e n t in s o m e cases. Classical c o b a l t , c o p p e r , and, to a lesser e x t e n t , i o d i n e deficiencies have b e e n f o u n d in P e n n s y l v a n i a d e s p i t e usual s u p p l e m e n t a t i o n w i t h t h e s e e l e m e n t s . This is n o t surprising in view of t h e i n f o r m a t i o n in T a b l e 11 a n d elsewhere in this paper. Supplementation may be inadequate to meet m i n i m u m needs. Also, various factors or imbalances m a y increase r e q u i r e m e n t s for c e r t a i n elements. F o r e x a m p l e , goitrogens m a y increase iodine r e q u i r e m e n t . Availability of m i n e r a l s in forages m a y also vary f r o m t i m e t o t i m e , as in the case of m a g n e s i u m . While s o m e dairy h e r d s m a y suffer f r o m a lack of minerals, o t h e r s m a y be over-supplemented with major and trace elements to the p o i n t of decreased p r o f i t s a n d r e d u c e d p e r f o r m ance, It is n o t u n c o m m o n to find d a i r y m e n w h o provide trace m i n e r a l s u p p l e m e n t a t i o n via
SYMPOSIUM: NEW TRACE ELEMENT NUTRITION
1547
TABLE 11. Possible elemental quantities for supplementary feeding. Basis:
Mean
One standard deviation below mean
Element
Concentrate mixa
Trace mineral salt b
Concentrate mixa
Trace mineral salt b
Manganese Iron Copper Zinc Cobalt Iodine
(ppm) 39 31 10 123 2.3 3.1
(%) .310 .000 .044 .934 .023 .028
(ppm) 78 (76) c 245 (363). 19 (10) 143 (105) 2.3 ( ...) 4.0 (...)
(%) .690 1.800 .130 1.112 .023 .037
(.600) d (.200) (.060) (.010) (.015) (.016)
aTotal of the element (natural + supplemental) necessary to balance the forage ration using the grain mixture or complete dairy feed as the vehicle. bElement necessary in a trace mineral salt to provide needed supplementation when used at 1% in a cornsoybean oil meal mixture. CIn a popular manufactured dairy feed. din a popular trace mineral salt.
as many as 6 to 8 sources. To illustrate, some dairymen using a grains plus supplement mixture may furnish supplementary trace minerals via each of the following means: (a) manufactured dairy concentrate, (b) trace mineral salt in mix, (c) trace mineralized phosphorus supplement in mix, (d) liquid protein supplement free-choice, (e) trace mineral salt free-choice, (f) commercial mineral supplement free-choice, and (g) nonprotein nitrogen (NPN) corn silage made with a commercial additive. This kind of supplementation should be discouraged for numerous reasons. Trace mineral supplementation via one or two sources in forced feeding and one in free-choice feeding should be adequate in most cases, if well-formulated products are used. We have encountered herds with appetite and other problems where 5 to 7% of the grain mixture consisted of supplementary mineral compounds and premixes, as recommended by some computer programs. NEEDS
Additional information is necessary in several areas, as follows: (a) More research is needed to develop improved allowances for use in feed programming and formulation of commercial products. (b) Further studies are necessary on the use of chelated minerals from both the basic and applied standpoints, (c) Guarantees or specification sheets for
manufactured feeds and concentrates should be expanded to include mineral content in all cases, not just for pre-mixes, super-concentrates, or feeds tagged under the feed control laws of certain states. (d) Improved compilations of the content of mineral and other nutrients in feeds are vital to aid in improving the nutrition of farm animals. Further elaboration on the fourth point is justified. Compilations which provide as full information as possible on well-described feeds should be published on a more regular basis. The format preferably should include standard deviations and coefficients of variation. The efforts of the National Research Council in the past (9, 10) are to be commended. The current effort being made by the International Feedstuffs Institute at Utah State University (6) also is commendable. It provides the basis upon which a more satisfactory job of compilation and publication could be accomplished. To date, however, funding and voluntary efforts appear inadequate to serve the needs of the animal industry in today's world. A more deliberate effort may be needed to make certain that the number of samples included in a meaningful compilation approach a minimum of 100 to 150 for any particular analysis of an important feed. Further compilations probably should be published at least every 5 yr to keep values abreast of changing technology in production and processing. Preferably, only data within such a limited period Journal of Dairy Science Vol. 58, No. 10
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should be included. Additional regionalization of data based on k n o w n differences in mineral c o n t e n t of feeds or special environmental conditions is necessary. While a large, highly specific as well as detailed compilation is necessary for certain situations, the greater need is for one that covers in detail only the i m p o r t a n t forages and concentrates in somewhat broader categories. Such a version is badly needed by applied nutritionists and essential to improvements in feeding. More a t t e n t i o n m u s t be paid to mineral nutrition, especially trace elements, in feeding dairy cattle. T o o m a n y people in feed trade and educational circles have not put sufficient emphasis on mineral nutrition. This has encouraged m a n y entrepreneurs, well meaning and otherwise, to market minerals directly to dairymen and livestock farmers. Because of the inherent inefficiencies of this approach, the costs of these minerals to farmers has b e e n considerably higher than necessary. Nevertheless, s o m e good has been done in m o r e closely meeting nutritional needs and in encouraging greater efforts on the part of researchers and the feed trade. There is no substitute for a ration t h a t is well balanced f r o m the chemical and physical standpoints. A balanced ration is essential to good p e r f o r m a n c e under b o t h farm and research conditions. Whenever possible, experimental rations should be isomineralized as well as isocaloric, isonitrogenous, and otherwise nutritionally adequate. Poorly f o r m u l a t e d rations can result in faulty conclusions or severely limit the usefulness of the research in practical feeding. SUMMARY
The trace element c o n t e n t of feeds is extremely variable. Differences b e t w e e n high and low values for a given t y p e of feed are wide for m a n y elements. There is a lack o f data for certain elements in some widely used feeds. Zinc is the element m o s t likely to be inadequate under current s u p p l e m e n t a t i o n practices. Manganese is the least likely to be limiting. Cobalt, copper, iodine, and iron are apt to be provided in insufficient a m o u n t s with current practices. ACKNOWLEDGMENTS
The a u t h o r wishes to acknowledge the technical assistance of Barrie Moser and William Journal of Dairy Science Vol. 58, No. 10
Stout, as well as the cooperation of the dedicated staff of the Penn State Forage Testing Service. In addition, partial financial support for s u m m a r y w o r k by Agway, Inc., of Syracuse, NY and the Animal F e e d Supplements group of Borden Chemical of Norfolk, V A is appreciated greatly. REFERENCES
1 Baker, Dale E., G. W. Gorsline, C. B. Smith, W. I. Thomas, W. E. Grube, and J. L. Ragland. 1964. Technique for rapid analyses of corn leaves for eleven elements. Agron. J. 56:133. 2 Becker, R. B., P. T. Dix Arnold, W. G. Kirk, George K. Davis, and R. W. Kidder. 1953. Minerals for dairy and beef cattle. FL Agr. Exp. Sta. Bull. 513. 3 Beeson, K. C. 1945. The occurrence of mineral nutritional diseases of plants and animals in the United States. Soil Sci. 60:9. 4 Cunha, T. J., R. L. Shirley, H. L. Chapman, Jr., C. B. Ammerman, G. K. Davis, W. G. Kirk, and J. F. Hentges, Jr. 1964. Minerals for beef cattle in Florida. FL Agr. Exp. Sta. Bull. 683. 5 French, C. E., C. B. Smith, H. R. Fortmann, R. P. Pennington, G. A. Taylor, W. W. Hinish, and R. W. Swift. 1957. Survey of ten nutrient elements in Pennsylvania forage crops. I. Red Clover. PA Agr. Exp. Sta. Bull. 624. 6 Harris, Lorin E. 1970. Nutritive research techniques for domestic and wild animals. I. An international record system and procedure for analyzing samples. International Feedstuffs Institute. Utah State University, Logan. 7 Hodgson, J. F., R. M. Leach, Jr., and W. H. Allaway. 1962. Micro-nutrients in soils and plants in relation to animal nutrition. Agr. Food Chem. 10:171. 8 Jaeobson, D. R., R. W. Hemken, F. S. Button, and R. H. Hatton. 1972. Mineral nutrition, calcium, phosphorus, magnesium, and potassium interrelationships. J. Dairy Sci. 55:935. 9 National Research Council, U. S. 1956. Composition of concentrate by-product feeding stuffs. Publ. 449. Washington, DC. 10 National Research Council, U. S. 1958. Composition of cereal grains and forages. Publ. 585. Washington, DC. 11 National Research Council, U. S. 1971. Nutrient requirements of dairy cattle. Publ. 3. Washington, DC. 12 Ralston, A. T., I. A. Dyer, W. H. Abbitt, M. F. Adams, and M. E. Ensminger. 1961. Influence of location and season on the trace mineral status of beef cattle in Washington. WA Agr. Exp. Sta. Bull. 623. 13 Reid, R. L., Amy J. Post, and G. A. Jung. 1970. Mineral composition of forages. WV Agr. Exp. Sta. Bull. 589T. 14 Underwood, E. J. 1962. Trace elements in human and animal nutrition. Academic Press, New York City.
QUANTITIES IN FEEDS
Trace element content of feeds is extremely variable compared to totat digestible nutrients or protein. Differences are wide between low and high values for many trace elements within a given type of feed. Coefficients of variation for forages range from 42 to 100%. Summary data are given for both major and trace elements. Problems in supplementation are discussed. Amounts for some d e m e n t s are skewed with relatively few samples around the mean and over 60% below the mean. Suggested mineral allowances for dairy cows are listed. Under current supplementation, zinc is the trace element most likely to be limiting and manganese the least likely. Iron, copper, cobalt, and iodine may be limiting in some cases. Needs of research and applied nutrition are presented.
The sharp contrast in variation among TDN, protein, and several elements is pointed out in Table 1. Even with allowances for extreme values due to error, contamination, etc., variability for trace elements within a major category of feed is much greater than that for TDN or protein. Also, the spread between low and high values is greater for trace than major elements, with the exception of calcium and sodium, which were not listed. Certainly a 30 to 50-fold range in trace element content is not unlikely within a given type of forage. Differences may be even greater among different types of forage or feedstuffs. Extremely high values, particularly for iron and aluminum, may reflect soil or other contamination in some cases.
INTRODUCTION Nutritionists have been concerned for years with the TDN (total digestible nutrients) or energy and protein contents of items used in feeding dairy cattle. To a lesser extent, there has been concern for amounts of calcium and phosphorus. However, too little attention has been paid to other elements, particularly t r a c e dements. Often trace mineral concerns stop with the recommendation to use a commercial product that has been trace mineralized. Due to the extreme variability among feeds as well as other factors, good trace element nutrition does not come this easy. I hope this presentation will demonstrate the great variation in trace element content which may occur. In addition, summary data on mineral analysis for various feeds will be provided and practical considerations in trace mineral supplementation will be discussed. Received December 13, 1974.
All mineral data, except for sulfur, taken from Penn State summaries have been determined with an emission spectrometer. Essentially the procedures are those reported in (1). This reference lists some of the important precautions to avoid high values from contamination during processing and analysis. Sulfur was determined with a Leco oxidizing unit. A procedure must be modified to include elemental sulfur as well as that in sulfate form. Another indication of large variability in trace element content of feeds may be found in Table 2. Here the mean coefficients of variation have been listed as taken from a summary of test data. Standard deviations as percents of means are higher for trace than maior dements, with the exception of sodium. Also, the coefficient of variation for calcium is relatively high for corn grain. Aluminum has the highest coefficient of variation among the trace elements. Both soil contamination and soil pH greatly affect aluminum values. Data in Tables 3 and 4 provide expectancies on both trace and major elements for commonly used forages and corn. Most of the samples
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SYMPOSIUM: NEW TRACE ELEMENT NUTRITION
1539
TABLE 1. Range in nutritive content of legume-grass forage, a
Item
Range
TDN, % Crude protein, % Calcium, % Phosphorus, % Magnesium, % Sulfur, % Manganese, ppm Iron, ppm Copper, ppm Zinc, ppm
51 6.6 .01 .07 .07 .04 6 10 2 8
Fold b difference -- 71 - 33.2 - 2.61 -- .74 -- .75 - .38 -- 265
1.4 5.0 261.0 10.6 10.7 9.5 44.2
-- 2599
259.9
-- 92 -- 300
46.0 37.5
aSummary of Penn State Forage Testing Service, 1969-73. bMaximum - minimum.
s u m m a r i z e d in t h e s e tables originated in P e n n sylvania a n d N e w York. T h e d a t a s h o u l d b e r e a s o n a b l y indicative of feeds p r o d u c e d in this region or u n d e r similar soil a n d o t h e r conditions. Sulfur d a t a are available o n a m u c h smaller p r o p o r t i o n o f t h e samples a n d are s u m m a r i z e d in T a b l e 5. S o m e w h a t similar d a t a for grains a n d byp r o d u c t i n g r e d i e n t s have b e e n p u b l i s h e d b y t h e N a t i o n a l R e s e a r c h C o u n c i l (9, 10). T h e data in Tables 6 and 7 for c o m m o n l y used c o n c e n t r a t e s have b e e n a d a p t e d f r o m t h e s e sources. T h e s e data were o b t a i n e d prior t o 1958. Also, few samples are r e p r e s e n t e d in s o m e m e a n values. This is true of t h o s e for trace e l e m e n t s , especially zinc a n d iodine. I n s u f f i c i e n t observations exist for s o m e i m p o r t a n t i n g r e d i e n t s such
as c o t t o n s e e d and s o y b e a n oil meals. Many factors may influence the mineral c o n t e n t of forages a n d o t h e r feeds. U n d e r w o o d (14) has suggested t h a t the m o s t i m p o r t a n t f a c t o r s are (a) genus, species, or s t r a i n of p l a n t , (b) t y p e of soil, (c) climatic or seasonal c o n d i t i o n s d u r i n g g r o w t h , a n d (d) stage o f m a t u r i t y of t h e p l a n t . D a t a on t h e s e a n d o t h e r f a c t o r s have b e e n p u b l i s h e d m o r e r e c e n t l y (13). T h e i n f l u e n c e of l o c a t i o n a n d soil via pH, p a r e n t material, a n d f e r t i l i z a t i o n has b e e n e s t a b l i s h e d in s o m e cases (2, 3, 4, 5, 7, 12, 13, 14). T h e s e are l a n d m a r k p u b l i c a t i o n s dealing w i t h applied m i n e r a l n u t r i t i o n . T h e e f f e c t of geographical origin o n t h e m o l y b d e n u m a n d s e l e n i u m c o n t e n t of feeds is well k n o w n . However, less d r a m a t i c b u t i m p o r -
TABLE 2. Mean coefficient of variation for elemental content, a Element
Forages
Corn grain
Phosphorus Potassium Calcium Magnesium Sulfur Sodium Manganese Iron Boron Copper Zinc Aluminum
25 32 28 33 29 128 75 68 42 57 63 100
22 33 196 17 24 318 116 83 58 62 39 172
Combined
(%) 25 32 73 30 28 170 84 71 46 58 57 116
aSummary of Penn State Forage Testing Service, 1969-73. Journal of Dairy Science Vol. 58, No. 10
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TABLE 3. Trace element content of various feeds, ppm in dry matter, a Item
Manganese
Legume forage (992) b Mean SD Low High
44.1 49.2 8.0 1080.0
Boron
Copper
Zinc
Aluminum
221.7 124.9 41.0 800.0
25.9 7.9 2.0 65.0
13.1 8.2 2.0 214.0
28.1 18.8 11.0 260.0
143.1 123.3 4.0 1000.0
48.1 21.3 6.0 265.0
222.0 142.7 10.0 2599.0
20.2 7.2 2.0 94.0
13.1 5.7 2.0 92.0
27.2 12.7 8.0 300.0
128.8 127.7 1.0 1500.0
57.3 40.0 7.0 1200.0
192.3 138.9 t9.0 2463.0
11.6 5.4 1.0 53.0
12.0 7.0 2.0 125.0
26.5 12.8 3.0 255.0
105.0 113.1 2.0 1271.0
Grass forage (352) Mean SD Low High
76.4 64.1 12.0 689.0
184.4 141.2 32.0 1200.0
8.3 3.8 .0 26.0
12.9 8.4 2.0 69.0
27.6 10.7 12.0 112.0
108.0 126.0 7.0 1200.0
Corn silage (7179) Mean SD Low High
38.1 20.8 1.0 267,0
200.1 131.1 5.0 1800.0
6.5 2.6 1.0 41.0
8.1 4.4 2.0 110.0
30.8 21.5 3.0 416.0
91.8 99.0 3.0 3500.0
Small grain forage (97) Mean SD Low High
62.6 41.0 9.0 276.0
298.8 155.9 40.0 900.0
8.0 4.3 1.0 27.0
11.9 7.7 2.0 36.0
33.2 25.5 14.0 212.0
181.8 166.5 1.0 1000.0
Sorghum-sudan forage (91) Mean SD Low High
69.1 65.2 9.0 571.0
320.5 278.2 67.0 2000.0
7.7 3.2 2.0 19.0
12.3 6.4 2.0 36.0
41.6 38.0 "15.0 315.0
173.6 157.8 23.0 691.0
Ear corn (324) Mean SD Low High
7.3 10.9 1.0 142,0
93.8 89.7 7.0 500,0
3.8 2.7 ,0 36.0
4.7 2.7 1.0 19.0
26.8 14.4 11.0 200.0
21.7 43.6 .0 500.0
4.8 4.0 1.0 29.0
69.0 48.5 10.0 464.0
3.6 1.6 1.0 10.0
3.7 2.5 .0 23.0
24.7 5.9 13,0 58.0
10.7 15.3 1.0 85.0
Mixed mainly legume (4014) Mean SD Low High Mixed mainly grass (4119) Mean SD Low High
Shelled corn (221) Mean SD Low High
Iron
aSummary of Penn State Forage Testing, 1969-73. hNumber of samples.
rant differences may exist within a state, c o u n t y , c o m m u n i t y , or even o n a farm. F o r example, zinc in Pennsylvania forages m a y vary appreciably d e p e n d i n g u p o n location, as illusJournal of Dairy Science Vol. 58, No. 10
t r a t e d in Table 8. Forages g r o w n in Regions 2 and 5 t e n d to c o n t a i n m o r e zinc. T h e reasons are n o t a p p a r e n t here, b u t o b s e r v a t i o n o f m a n y tests over years suggests t h a t forages g r o w n
SYMPOSIUM: NEW TRACE ELEMENT NUTRITION
1541
TABLE 4. Major element content of various feeds, percent in dry matter, a Item
Phosphorus
Potassium
Calcium
Magnesium
Sodium
Legume forage (992) b Mean SD Low High
.30 .05 .14 .56
2.55 .61 .21 4.93
1.18 .27 .03 2.23
.24 .07 .10 .58
.024 .017 .001 .100
Mixed mainly legume (4014) Mean SD Low High
.29 .06 .07 .74
2.26 .60 .42 9.63
1.02 .28 .01 2.61
.22 .07 .07 .75
.018 .015 .000 .110
Mixed mainly grass (4119) Mean SD Low High
.23 .06 .05 .81
1.79 .55 .30 4.70
.65 .28 .10 2.73
.18 .06 .03 .79
.013 .016 .000 .390
Grass forage (352) Mean SD Low High
.22 .07 .09 .56
1.68 .61 .24 4.04
.49 .20 .10 1.58
.16 .06 .04 .42
.014 .019 .000 .110
Corn silage (7179) Mean SD Low High
.23 .05 .01 .93
1.07 .27 .02 3.28
.27 .11 .01 1.88
.18 .05 .01 .55
.005 .014 .000 .350
Small grain forage (97) Mean SD Low High
.32 .09 .14 .76
2.29 .81 .49 5.30
.44 .20 .06 1.22
.16 .05 .07 .29
.030 .031 .001 .100
Sorghum-sudan forage (91) Mean SD Low High
.24 .06 .07 .44
1.73 .74 .12 4.00
.48 .23 .12 1.83
.28 .12 .06 .58
.008 .012 .001 .071
.28 .08 .14 1.14
.49 .18 .26 2.96
.05 .10 .01 1.15
.12 .02 .01 .25
.007 .020 .000 .100
.31 .05 .19 .59
.42 .13 .24 1.41
.03 .06 .01 .72
.12 .02 .06 .20
.003 .010 .000 .100
Ear corn (324) Mean SD Low High Shelled corn (221) Mean SD Low High
aSummary of Penn State Forage Testing, 1969-73. bNumber of samples.
closer to industrial centers may be higher in some trace elements. Perhaps s o m e of this may be due to air pollution, use of industrial b y - p r o d u c t s o n soils, a n d r u n - o f f f r o m disposal
sites for industrial wastes. Forages grown in an area w i t h slate m i n e s m a y s o m e t i m e s c o n t a i n 80 t o 2 2 0 p p m zinc. T h i s is 3 to 7 t i m e s h i g h e r t h a n e x p e c t e d zinc. M o l y b d e n u m t o x i c i t y h a s Journal of Dairy Science Vol. 58, No. 10
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ADAMS
T A B L E 5. Sulfur c o n t e n t of various feeds, dry m a t t e r basis, a
Item
No. samples
Legume forage Mixed mainly legume Mixed mainly grass Grass forage Corn silage Small grain forage Sorghum-sudan Ear corn Shelled corn
39 121 71 4 249 1 3 18 8
Mean
Low
High
Standard deviation
%
%
%
+-%
.26 •23 .20 .20 .14 .21 .10 .13 .14
.14 .04 .12 .14 .04 . . .08 .08 .10
.43 .38 .35 •29 .22 . . .14 .22 .19
.07 .06 .06 .07 .04
.
.
.
.
. .03 .04 .03
a s u m m a r y of Penn State Forage Testing, 1969-73.
T A B L E 6. Zinc p p m in forages by major land resource areas in Pennsylvania. a Corn silage
Legume-Grass hay
Grass-Legume hay
Region b
No. samples
ppm
No. samples
ppm
No. samples
ppm
1 2 3 4 5
879 278 295 1478 974
31 37 30 29 30
328 189 123 874 355
27 32 25 26 31
679 115 158 351 214
24 30 25 27 31
a c o n t e n t on a dry m a t t e r basis for samples tested from 1969 to 1973. bRegions are described as follows: (1) Glaciated Allegheny Plateau and Catskill Mountains (Northwest and Northeast), (2) Central Allegheny Plateau, (3) Eastern Allegheny Plateau and Mountains, (4) Northern Appalachian Ridge and Valleys (South Central), and (5) Northern P i e d m o n t (Southeast).
T A B L E 7. Trace mineral c o n t e n t of various concentrates, dry m a t t e r basis, a Item
Manganese
Iron
Copper
Zinc
Cobalt
Iodine
(ppm) Barley No. samples Mean Low High Beet pulp, dried No. samples Mean Low High Brewers' grains, dried No• samples Mean Low High Citrus pulp, dried No. samples Mean Low High
(73) 18.2 2.4 29.9
(41) 60.0 40,0 100.0
(33) 8.6 1.3 20.0
(3) 17.1 11.9 20.9
(27) .117 .000 .321
(39) 38.5 12.1 77.9
(27) 331.0 85.0 600.0
(31) 13.9 8.4 22.7
(1) 7.0 . . . . . . . .
(26) .112 023 116
(29) 40.7 21.1 56.1
(22) 271.6 100.0 410.0
(16) 23.1 5.5 45.3
. . . .
.. . . . . . . . . .
(15) 067 044 110
(16) 7.5 1.1 19.4
(14) 183.1 94.0 303.0
(8) 6.3 2.0 14.5
(1) 16.0 . . . . . . . .
(4) .236 066 704
Journal of Dairy Science Vol. 58, No. 10
•
o .
SYMPOSIUM: NEW TRACE ELEMENT NUTRITION
1543
T A B L E 7. ( C o n t i n u e d ) T r a c e m i n e r a l c o n t e n t o f v a r i o u s c o n c e n t r a t e s , d r y m a t t e r basis, a Item
Manganese
Iron
Copper
Zinc
Cobalt
Iodine
(2) 19.6 12.1 26.8
(460) •022 .002 .299
(16) •344 .064 •7 0 4
(ppm) Corn, dent No. samples Mean Low High C o r n distillers w sol. No. samples Mean Low High Corn gluten feed No. samples Mean Low High C o t t o n s e e d m e a l , solv. No. samples Mean Low High H o m i n y f e e d , yel. No. samples Mean Low High Oats No. samples Mean Low High Molasses, c a n e No. samples Mean Low High Sorghum No. samples Mean Low High S o y b e a n m e a l , solv. No. samples Mean Low High Steamed bone meal No. samples Mean Low High Wheat bran No. samples Mean Low High Wheat std. raids No. samples Mean Low High
(568) 5.7 .7 53.9
(518) 20.0 10.0 100.0
(463) 2.4 .9 9.0
(10) 30.9 15.6 67.3
(8) 334.1 200.0 600.0
(2) 67.1 56.1 78.5
. . . .
.. (2) . . . 120 . . . . . . . . . .
(45) 26.3 8.8 42.2
(32) 514.0 260.0 955.0
(33) 52.7 13.0 89.3
. . . .
. . . . . . . . . . .
(26) 097 022 286
(5) 21.8 16•2 30.1
(3) 167.0 110.0 246.0
(3) 23.3 16.3 32.6
. . . .
.. . . . . . . . . .
(3) 086 033 176
(17) 17.8 11.4 30.6
(12) 109.0 10.0 260.0
(5) 10.7 7.9 13.9
. . . .
.. . . . . . . . . .
(3) 061 048 066
(199) 42.9 20.0 203.5
(88) 80.0 20.0 300.0
(73) 6.6 2.4 25.7
. . . .
.. . . . . . . . . .
(19) 064 000 321
(9) 56.6 12.8 83.8
(9) 251.0 130.0 429.0
(8) 80.0 33.4 137.1
•.. . . . . . . . ...
(4) 1.213 224 3.485
(42) 16.2 .0 27.3
(44) 50.0 .0 180.0
(38) 10.8 2.0 19.1
(2) 15.4 11.8 18.9
(22) .304 .040 .737
(7) 30.8 24.9 33.9
(9) 147.0 110.0 240.0
(8) 16.0 13.6 18.3
. . . .
(6) 103 031 176
(57) 31.9 2.0 92.4
(63) 882.4 159.0 2829.0
(56) 17.1 .9 33.4
(36) 446.0 51.3 1835.9
(44) 129.9 90.0 164.3
(29) 193.0 88.0 270.0
(30) 13.8 4.4
(20) 132.0 103.4 157.7
(13) 115.9 83.0 192.0
(10) 11.1 22.2 28.2
29.9
. . . . . . . . . . .
.
(24) 108 031 178
... . . . . . . . . . . . .
(10) 094 079 130
.
. °
, . .
° . .
(17) .065 .044 .110
. .. . . . . . . . . .
,
.
aAdapted from National Academy of Science, National Research Council Publications No. 449 and 585. J o u r n a l o f D a i r y S c i e n c e Vol. 5 8 , N o . 10
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TABLE 8. Major mineral content of various concentrates, dry matter basis, a Item
Phosphorus
Potassium
Calcium
Magnesium
Sulfur
Sodium
Chlorine
(234) .14 .01 .23
(213) .19 .10 .35
(10) .02 .01 .06
(14) .13 .09 .17
(%) Barley No. samples Mean Low High Beet pulp, dried No. samples Mean Low High Brewers' grains, dried No. samples Mean Low High Citrus pulp, dried No. samples Mean Low High Corn, dent No. samples Mean Low High Corn distillers w sol. No. samples Mean Low
(331) .47 .28 .92
(233) .63 .33 .99
(57) .11 .05 .17
(8) .23 .15 .39
(56) .75 .36 1.03
(14) .30 .06 .43
(4) .22 .13 .31
(6) .19 .11 .23
(1) .04 ... ...
(37) .54 .36 .68
(5) .09 .04 .18
(37) .29 .14 .65
(7) .15 .03 .31
(4) .34 .05 .51
(1) .28 . . . . . . . .
(4) .20 06 26
(38) .13 .09 .24
(4) .69 .10 1.41
(38) 2.18 1.24 3.55
(20) .18 .02 .50
. . . .
"(571) .03 .00 .35
(88) .14 .08 .90
(38) .14 .10 .19
(53) .01 .00 .O6
(72) .06 .02 .O9
(8) .71 .22 1.13
(22) .19 .I1 .28
(13) .27 .09 .38
(5) .33 .24 .40
(3) .39 .18 .79
(3) .19 .17 .19
(29) .66 .62 1.33
(59) .51 .03 1.08
(31) .32 .29 .87
(26) .24 .06 1.40
(3) 1.05 1.03 1.10
(7) 1.24 .06 1.04
(3) 1.61 1.03 2.20
(14) .16 .07 .26
(4) .64 .37 .82
(3) .06 01 11
(2) .04 .04 .05
(586) .31 .09 .24 (22) .74 .43 1.02
High Corn gluten feed No. samples (82) Mean .85 Low .38 High 1.20 Cottonseed meal, solv. No. samples (16) Mean 1.20 Low .65 High 1.70
(88) .33 .20 .73
(325) .09 .03 .41
b e e n f o u n d in plants and animals l o c a t e d in t h e vicinity o f zinc and m o l y b d e n u m smelters. S o m e o f the e x t r e m e l y high trace e l e m e n t s in Table 3 were o b t a i n e d in forages f r o m farms with animal health p r o b l e m s w h i c h a p p a r e n t l y resulted f r o m intake o f industrially c o n t a m i n a t e d forages. S U P P L E M E N T A T I O N PROBLEMS
Neither universal p r o d u c t s nor general reco m m e n d a t i o n s can insure t h a t all cows on all farms will receive p r o p e r a m o u n t s o f mineral e l e m e n t s at all times. Yet, this is w h a t s o m e Journal of Dairy Science Vol. 58, No. l0
. . . .
. . . .
(1) .23 . . . . . . . .
. . . .
. . . .
. . . .
. . . .
. . . .
. . . .
d a i r y m e n are led t o believe for various reasons. F u r t h e r , s o m e f a r m e r s believe t h a t h o m e - p r o d u c e d feeds will c o n t a i n a d e q u a t e a m o u n t s o f m o s t e l e m e n t s , if t h e y fertilize according to soil tests or get good yields. U n f o r t u n a t e l y , s o m e mineral n u t r i t i o n p r o b l e m s result f r o m a differential r e q u i r e m e n t o f the animal over t h a t o f plants or f r o m low availability of .an e l e m e n t t o the animal (7). P r o p e r use o f forage and feed testing with mineral analyses c o m b i n e d with c u s t o m f e e d p r o g r a m m i n g offers t h e b e s t a p p r o a c h t o reas o n a b l y g o o d mineral n u t r i t i o n . T h e use of
SYMPOSIUM: NEW T R A C E ELEMENT N U T R I T I O N
1545
T A B L E 8. (Continued) Major mineral c o n t e n t o f various concentrates, dry matter basis, a Item
Phosphorus
Potassium
Calcium
Magnesium
Sulfur
Sodium
Chlorine
(%) Hominy feed, yel. No. samples Mean Low High 0 ats No. samples Mean Low High Molasses, cane No. samples Mean Low High Sorghum No. samples Mean Low High Soybean meal, solv. No. samples Mean Low High Steamed bone meal No. samples Mean Low High Wheat bran No. samples Mean Low High Wheat std. mids No. samples Mean Low High
(22) .57 .30 .87 (273) .39 .05 1.02 (32) ,11 .01 .25 (235) .35 .10 .52 (34) .75 .50 1.09
(1) .57 . . . . . . (83) .42 .22 .89 (9) 3.20 2.16 3.64 (16) .38 .28 .50
. .
(22) .06 02 12
(2) .04 .02 .06
. . . .
(227) .11 .04 .48
(77) .19 .03 .29
(15) .23 .15 .31
(18) .07 .01 .16
(19) .47 .16 .87
(15) .46 .10 .97
(5) .23 .10 .53
(4) 3.69 2,60 4.35
(227) .05 .01 .53
(23) .19 .02 .25
(6) .18 .15 .21
(9) .05 .01 .09
(7) .10 .07 .14
(35) .36 .23 .96
(8) _30 .00 ,45
(1) .48 . . . . . . . .
(6) .38 04 62
(1) ,00 , •• •..
(109) 30.44 22.75 36.65
(45) ,64 .11 1.19
(40) .23 .07 .91
(18) .48 .40 .55
... ... ... ...
(9) .07 .01 A1
(7) .05 .02 .10
(35) 1.20 .32 2.20
(6) 2,20 2.00 2.30
.. (1) . . . 14 . . . . . . . . . . . . . . . .
(109) 14.28 8.34 18.35
118 ... ...
(86) 1.31 .10 1.91
(11) 1.39 .93 1.77
(84) .16 .07 .56
(10) .62 .50 .80
(9) .25 .19 .36
(53) 1.01 .73 1.35
(33) 1.09 1.06 1.37
(30) .17 .07 .50
(34) .41 .40 .56
(32) (1) .06 .25 . . . . . . . . . . . . . .
. •• .••
(19) .11 .05 .19
(3) .03 03 04
aAdapted f r o m National A c a d e m y of Science, National Research Council Publications No. 449 and 585.
multiple product lines designed to provide f l e x i b i l i t y in m i n e r a l c o n t e n t o f f i n i s h e d f e e d s affords a satisfactory means of improving mineral n u t r i t i o n . T h e u s e o f m a n u f a c t u r e d p r o t e i n concentrates without added minerals, at least t h e m a j o r o n e s , p r o v i d e s still a n o t h e r a l t e r n a tive. T r a c e m i n e r a l t e s t s m u s t be u s e d w i t h c a u t i o n in f e e d p r o g r a m m i n g . E x t r e m e v a l u e s m a y o c c u r d u e t o c o n t a m i n a t i o n b e f o r e or a f t e r sampling, faulty procedures, and improperly
o p e r a t e d or m a l f u n c t i o n i n g e q u i p m e n t . T h u s , it is b e s t t o u s e v a l u e s t h a t a r e c o n s i s t e n t w i t h past test reports from a farm when unreasonable values are encountered. It is e x t r e m e l y i m p o r t a n t to use sound assumptions, good expectancy data, and reasonable allowances for developing either general recommendations or universal formulas for supplements, Should one base supplementation on average values for forage and concentrates? Or should values be used that range from Journal of Dairy Science Vol. 58, No. 10
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ADAMS
one-half to more than one standard deviation below average? In regard t o trace e l e m e n t s , it a p p e a r s best to use a value t h a t at least a p p r o a c h e s o n e s t a n d a r d deviation b e l o w m e a n values. This t h e o r e t i c a l l y w o u l d m a k e t h e reco m m e n d a t i o n s a d e q u a t e a b o u t 84% of t h e time. As i l l u s t r a t e d in T a b l e 9, values for a given e l e m e n t m a y n o t fit a n o r m a l d i s t r i b u t i o n curve. T h e y m a y be s k e w e d w i t h relatively few samples close t o t h e m e a n a n d c o n s i d e r a b l y m o r e values falling b e l o w t h e m e a n t h a n a b o v e it. T h e m i n i m u m allowances w h i c h we p r e f e r to use in general feed p r o g r a m m i n g are in T a b l e 10. P h o s p h o r u s allowances a p p r o x i m a t e t h o s e of t h e 1971 N R C p u b l i c a t i o n (11). M o s t t r a c e mineral a l l o w a n c e s agree w i t h t h o s e of J a c o b son et al. (8). Q u a n t i t i e s of t r a c e m i n e r a l s n e e d e d in t h e grain m i x t u r e to b a l a n c e a c o m m o n l y used r a t i o n are in T a b l e 11. Likewise, a m o u n t s of m i n o r e l e m e n t s n e e d e d in a trace m i n e r a l salt to be used in s u p p l e m e n t i n g a c o r n a n d s o y b e a n oil meal m i x t u r e are given. A s s u m p t i o n s include feeding a c o w weighing 545.5 kg a n d p r o d u c i n g 22.7 kg of m i l k t e s t i n g 4% fat. In a d d i t i o n , 65% of the t o t a l dry m a t t e r was f u r n i s h e d b y a
TABLE 9. Distribution of iron in mixed mainly legume forages, a
ppm 30 60 90 120 150 180 210 240 270
- 60 -- 90 -- 120 - 150 -- 180 -- 210 - 240 - 270 - 300 3OO - 330 330 -- 36O 360 - 390 39O -- 42O 420 - 45O 450 -- 480 480 -- 510
Percent of samples 1.5 5.9 5.2 19.3 14.8 11.1 2.2 3.0 1.5 5.9 .7 2.2 4.4 1.5 1.5 19.3
a135 samples randomly selected from 1973-74 testing year at Penn State. Mean 255.9 + 150.1 ppm; range 38 to 500 ppm. Skewed positively with 61.5% of the samples below the mean and 38.5% above the mean. Journal of Dairy Science Vol. 58, No. 10
TABLE 10. Mineral allowances for dairy cows. a Element
Amount
Calcium, % Phosphorus, % Potassium, % Magnesium, % Sulfur, % Manganese, ppm Iron, ppm Copper, ppm Zinc, ppm Cobalt, ppm Iodine, ppm
.68 -- .76 .38 .70 .22 .20 44 150 11 70 1 2
aLevels expressed on a dry matter basis. forage r a t i o n consisting of 50% c o r n silage a n d 50% m i x e d m a i n l y l e g u m e forage o n a d r y m a t t e r basis. If m e a n e x p e c t a n c i e s are used, o n e c o u l d feed r e a s o n a b l y c e r t a i n t h a t needs were b e i n g m e t o n l y 50% of t h e t i m e or less. W h e n an e x p e c t a n c y of o n e s t a n d a r d d e v i a t i o n b e l o w m e a n is used, one m a y be m e e t i n g needs a b o u t 84% of the time. F o r c o m p a r i s o n , trace m i n e r a l s in a p o p u l a r m a n u f a c t u r e d dairy feed a n d a widely used trace m i n e r a l salt are s h o w n in p a r e n t h e s e s . M a n g a n e s e usually a p p r o a c h e s or exceeds needs in p r o d u c t s used for s u p p l e m e n t a t i o n . T h i s p r o b a b l y is a carry-over f r o m p o u l t r y n u t r i t i o n , r a t h e r t h a n t h e r e s u l t of g o o d f o r m u l a t i o n f o r dairy p u r p o s e s . Zinc s u p p l e m e n t a t i o n is m o s t likely i n a d e q u a t e . Iron m a y be lacking in s o m e fortifications. Copper, cobalt, a n d i o d i n e m a y be i n s u f f i c i e n t in s o m e cases. Classical c o b a l t , c o p p e r , and, to a lesser e x t e n t , i o d i n e deficiencies have b e e n f o u n d in P e n n s y l v a n i a d e s p i t e usual s u p p l e m e n t a t i o n w i t h t h e s e e l e m e n t s . This is n o t surprising in view of t h e i n f o r m a t i o n in T a b l e 11 a n d elsewhere in this paper. Supplementation may be inadequate to meet m i n i m u m needs. Also, various factors or imbalances m a y increase r e q u i r e m e n t s for c e r t a i n elements. F o r e x a m p l e , goitrogens m a y increase iodine r e q u i r e m e n t . Availability of m i n e r a l s in forages m a y also vary f r o m t i m e t o t i m e , as in the case of m a g n e s i u m . While s o m e dairy h e r d s m a y suffer f r o m a lack of minerals, o t h e r s m a y be over-supplemented with major and trace elements to the p o i n t of decreased p r o f i t s a n d r e d u c e d p e r f o r m ance, It is n o t u n c o m m o n to find d a i r y m e n w h o provide trace m i n e r a l s u p p l e m e n t a t i o n via
SYMPOSIUM: NEW TRACE ELEMENT NUTRITION
1547
TABLE 11. Possible elemental quantities for supplementary feeding. Basis:
Mean
One standard deviation below mean
Element
Concentrate mixa
Trace mineral salt b
Concentrate mixa
Trace mineral salt b
Manganese Iron Copper Zinc Cobalt Iodine
(ppm) 39 31 10 123 2.3 3.1
(%) .310 .000 .044 .934 .023 .028
(ppm) 78 (76) c 245 (363). 19 (10) 143 (105) 2.3 ( ...) 4.0 (...)
(%) .690 1.800 .130 1.112 .023 .037
(.600) d (.200) (.060) (.010) (.015) (.016)
aTotal of the element (natural + supplemental) necessary to balance the forage ration using the grain mixture or complete dairy feed as the vehicle. bElement necessary in a trace mineral salt to provide needed supplementation when used at 1% in a cornsoybean oil meal mixture. CIn a popular manufactured dairy feed. din a popular trace mineral salt.
as many as 6 to 8 sources. To illustrate, some dairymen using a grains plus supplement mixture may furnish supplementary trace minerals via each of the following means: (a) manufactured dairy concentrate, (b) trace mineral salt in mix, (c) trace mineralized phosphorus supplement in mix, (d) liquid protein supplement free-choice, (e) trace mineral salt free-choice, (f) commercial mineral supplement free-choice, and (g) nonprotein nitrogen (NPN) corn silage made with a commercial additive. This kind of supplementation should be discouraged for numerous reasons. Trace mineral supplementation via one or two sources in forced feeding and one in free-choice feeding should be adequate in most cases, if well-formulated products are used. We have encountered herds with appetite and other problems where 5 to 7% of the grain mixture consisted of supplementary mineral compounds and premixes, as recommended by some computer programs. NEEDS
Additional information is necessary in several areas, as follows: (a) More research is needed to develop improved allowances for use in feed programming and formulation of commercial products. (b) Further studies are necessary on the use of chelated minerals from both the basic and applied standpoints, (c) Guarantees or specification sheets for
manufactured feeds and concentrates should be expanded to include mineral content in all cases, not just for pre-mixes, super-concentrates, or feeds tagged under the feed control laws of certain states. (d) Improved compilations of the content of mineral and other nutrients in feeds are vital to aid in improving the nutrition of farm animals. Further elaboration on the fourth point is justified. Compilations which provide as full information as possible on well-described feeds should be published on a more regular basis. The format preferably should include standard deviations and coefficients of variation. The efforts of the National Research Council in the past (9, 10) are to be commended. The current effort being made by the International Feedstuffs Institute at Utah State University (6) also is commendable. It provides the basis upon which a more satisfactory job of compilation and publication could be accomplished. To date, however, funding and voluntary efforts appear inadequate to serve the needs of the animal industry in today's world. A more deliberate effort may be needed to make certain that the number of samples included in a meaningful compilation approach a minimum of 100 to 150 for any particular analysis of an important feed. Further compilations probably should be published at least every 5 yr to keep values abreast of changing technology in production and processing. Preferably, only data within such a limited period Journal of Dairy Science Vol. 58, No. 10
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ADAMS
should be included. Additional regionalization of data based on k n o w n differences in mineral c o n t e n t of feeds or special environmental conditions is necessary. While a large, highly specific as well as detailed compilation is necessary for certain situations, the greater need is for one that covers in detail only the i m p o r t a n t forages and concentrates in somewhat broader categories. Such a version is badly needed by applied nutritionists and essential to improvements in feeding. More a t t e n t i o n m u s t be paid to mineral nutrition, especially trace elements, in feeding dairy cattle. T o o m a n y people in feed trade and educational circles have not put sufficient emphasis on mineral nutrition. This has encouraged m a n y entrepreneurs, well meaning and otherwise, to market minerals directly to dairymen and livestock farmers. Because of the inherent inefficiencies of this approach, the costs of these minerals to farmers has b e e n considerably higher than necessary. Nevertheless, s o m e good has been done in m o r e closely meeting nutritional needs and in encouraging greater efforts on the part of researchers and the feed trade. There is no substitute for a ration t h a t is well balanced f r o m the chemical and physical standpoints. A balanced ration is essential to good p e r f o r m a n c e under b o t h farm and research conditions. Whenever possible, experimental rations should be isomineralized as well as isocaloric, isonitrogenous, and otherwise nutritionally adequate. Poorly f o r m u l a t e d rations can result in faulty conclusions or severely limit the usefulness of the research in practical feeding. SUMMARY
The trace element c o n t e n t of feeds is extremely variable. Differences b e t w e e n high and low values for a given t y p e of feed are wide for m a n y elements. There is a lack o f data for certain elements in some widely used feeds. Zinc is the element m o s t likely to be inadequate under current s u p p l e m e n t a t i o n practices. Manganese is the least likely to be limiting. Cobalt, copper, iodine, and iron are apt to be provided in insufficient a m o u n t s with current practices. ACKNOWLEDGMENTS
The a u t h o r wishes to acknowledge the technical assistance of Barrie Moser and William Journal of Dairy Science Vol. 58, No. 10
Stout, as well as the cooperation of the dedicated staff of the Penn State Forage Testing Service. In addition, partial financial support for s u m m a r y w o r k by Agway, Inc., of Syracuse, NY and the Animal F e e d Supplements group of Borden Chemical of Norfolk, V A is appreciated greatly. REFERENCES
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