Bovine Mineral-Vitamin Balancers for Irish Maize Silage

BACKGROUND: Multiple mineral imbalances occur in most samples of Irish forage. Mineral levels in Irish bovine blood suggest the need for a pro-active national policy on generous mineral supplementation of all types of cattle, especially those in herds which have clinical or subclinical problems that could be due to deficiencies of Mg, Co, Cu, I and Se. See "Mineral-Vitamin Mixes for Cows and other Cattle" for recommendations on high-specification mineral-vitamin supplements for cattle on grass- or grass silage- based diets.

Forage maize is becoming popular as a winter-feed for Irish cattle. However, standard mineral supplements are not suitable for cattle on maize silage. Therefore, it was decided to compare the mineral composition of Irish maize silage with that of grass silage and to calculate the amount of supplementary minerals needed in ADDITION to high-specification cow minerals.

MAJOR AND TRACE ELEMENTS IN IRISH MAIZE SILAGE: The following two tables summarise the mean levels of major and trace elements in 115 samples of Irish forage maize ( supplied by Conor Butler, Farm Business Advisers, Fermoy) from the main maize-growing areas in Ireland in 2000. These values are compared with those of other samples of Irish forages (Levels of DM, Major Elements and Trace Elements in Irish Grass, Silage and Hay): 

Table 1: Major Elements in Irish Forages: Overall, our maize silage is deficient in N, Ca, Na, P, Mg and S for cows:
Major element levels (g/kg DM) in Irish forages and dairy concentrate

TArget in tdmi for lactating dairy cows

N: 25.60
Ca: 6.00
Na: 2.50
P: 3.60
Mg: 2.50
S: 2.50
K: 10.00

irish maize silage mean

N: 13.38
Ca: 2.07
Na: 0.92
P: 2.18
Mg: 1.34
S: 1.08
K: 11.87

irish grass silage mean

N: 24.05
Ca: 6.93
Na: 3.61
P: 3.12
Mg: 1.84
S: 3.13
K: 23.53

irish grazed grass mean

N: 35.07
Ca: 6.45
Na: 2.88
P: 4.00
Mg: 2.02
S: 3.87
K: 28.29

irish hay mean

N: 13.32
Ca: 5.78
Na: 2.22
P: 2.28
Mg: 1.58
S: 2.31
K: 20.49

typical high-spec dairy concentrate

N: 28.80
Ca: 9.0
Na: 2.5
P: 5.0
Mg: 2.5
S: ?
K: ?

maize silage shortfall from target

N: 12.22
Ca: 3.93
Na: 1.58
P: 1.42
Mg: 1.16
S: 1.42
K: -1.87

Table 2: Trace Elements in Irish Forages:
Trace element levels (mg/kg DM) in Irish forages

irish maize silage mean

Cu: 5.115
Mo. 0.228
Zn: 26.614
Mn: 25.737
Se: 0.032
I: 0.376

irish grass silage mean

Cu: 10.364
Mo. 1.477
Zn: 29.685
Mn: 103.452
Se: 0.093
I: 0.269

irish grazed grass mean

Cu: 9.217
Mo. 2.492
Zn: 30.830
Mn: 119.822
Se: 0.093
I: 0.261

irish hay mean

Cu: 5.843
Mo. 1.336
Zn: 18.825
Mn: 84.529
Se: 0.061
I: 0.225

Overall, our forages have many trace element imbalances and the problem is much worse with maize silage. Iodine levels in Irish maize silage are somewhat higher than in other forages, but are still deficient for cattle. However, the trace-element levels in high-specification minerals usually are generous enough to suit maize silage also. See "Mineral-Vitamin Mixes for Cows and other Cattle" for recommended specifications.

Vitamin E levels: We have no data for Irish maize silage but it probably has much less Vit E than grass silage. Maize silage, especially that with a high cob / starch content, needs a high supplement of Vit E.

Balancers for Irish maize silage: The data show that our maize silage has very low crude protein (84 g/kg DM); it needs a CP supplement of 76 g/kg maize silage DM for lactation, or 56 g/kg maize silage DM for other cattle. Maize silage also has very low S. To ensure optimum protein metabolism in the rumen, cattle eating a high proportion of maize silage in their diet need an extra 1.5 g S/kg maize silage DM from other sources.

It also is low in Na, Ca, P and Mg for dairy-cow lactation. Mineral balancers for maize silage need more Na, Ca, P and Mg than balancers for grass silage. The supplement of Na, Ca, P, Mg and Vitamin E needed, in addition to standard mineral-vitamin supplements was calculated, as shown in Table 3.

TABLE 3: BALANCER FOR MILKING COWS ON MAIZE SILAGE: From data in Table 1, we can calculate:
Major elements inputs (g/cow/d)

input from 11 kg average maize silage dm

Ca: 22.77
Na: 10.12
P: 23.98
Mg: 14.74

input from 6 kg high-spec dairy conc dm

Ca: 54.00
Na: 18.00
P: 30.00
Mg: 15.00

input from 11 kg maize dm + 6 kg conc dm

Ca: 76.77
Na: 28.12
P: 53.98
Mg: 29.74

target input for milking cows from 17 kg ideal diet dm

Ca: 102.00
Na: 42.50
P: 61.20
Mg: 42.50

deficit from total dietary target (g/cow/d)

Ca: 25.23
Na: 32.38
P: 37.22
Mg: 27.76

deficit expressed as g/kg maize silage dmi

Ca: 2.29
Na: 2.94
P: 3.38
Mg: 2.52

From that calculation, in ADDITION to high-specification Lactation Minerals, which usually are included in the dairy concentrate, as in Table 1, lactating cows on maize silage need 31.5 (say 30)g of the supplement in Table 4 (g/kg maize silage DMI).

Table 4: Additional supplement for milking cows on Maize Silage

Sodium phosphate anhydrous (20% Na, 27% P)

Per kg maize silage DMI: 12.53 g
Kg/tonne of balancer mineral: 397.53

salt (39% na)

Per kg maize silage DMI: 6.96 g
Kg/tonne of balancer mineral: 220.81

limestone flour (33% ca)

Per kg maize silage DMI: 6.95 g
Kg/tonne of balancer mineral: 220.49

calcined magnesite (50% mg)

Per kg maize silage DMI: 5.05 g
Kg/tonne of balancer mineral: 160.22

vitamin e*

Per kg maize silage DMI: 30 i.u.
Kg/tonne of balancer mineral: 0.95

total

Per kg maize silage DMI: 31.52 g
Kg/tonne of balancer mineral: 1000.00

* Assuming that 1 i.u. Vit E = 1 mg

For example, lactating cows on 6.8 kg standard dairy concentrate (6 kg concentrate DM, which includes standard Lactation Minerals), but whose intake of maize silage varies from 0 to 11 kg DM/d (with a corresponding decrease in DMI from grass silage or grass) need a daily supplement of the balancer in Table 4, as follows:

DMI (kg/d) from maize silage

0
1
2
3
4
5
6
7
8
9
10
11

Maize balancer mineral (Table 4) needed by milking cows (g/cow/d)
0
30
60
90
120
150
180
210
240
270
300
330

MAIZE BALANCER FOR DRY COWS: From data in Table 1, and using target dietary values for dry cows of 3 g Ca, 2 g Na, 3 g P and 2.5 g Mg/kg TDMI, we can calculate:
Major element inputs (g/cow/d)

Input from 10 kg average maize silage DMI

Ca: 20.70
P: 21.80
Na: 9.20
Mg: 13.40

input from 100 g high-spec dry cow mineral

Ca: 0.00
P: 7.00
Na: 13.00
Mg: 15.00

subtotal input

Ca: 20.70
P: 28.80
Na: 22.20
Mg: 28.40

target input for dry cows from 10 kg adequate diet dmi

Ca: 30.00
P: 30.00
Na: 20.00
Mg: 25.00

deficit from total dietary target (g/cow/d)

Ca: 9.30
P: 1.20
Na: -2.20
Mg: -3.40

deficit expressed as g/kg maize silage dmi

Ca: 0.93
P: 0.12
Na: -0.22
Mg: -0.34

From that calculation, dry cows need the balancer in Table 5, at a rate of 3.3 g/kg DMI from maize silage in ADDITION to 100 g high-specification Dry-Cow minerals. Note: Dry cows need no further Mg supplement.

Table 5. Supplement for Dry Cows on Maize Silage

Limestone flour (33% Ca)

g/kg maize DMI: 2.82
kg/tonne of Dry-Cow maize balancer: 857.14

sodium phosphate anhydrous (20% na, 27% p)

g/kg maize DMI: 0.44
kg/tonne of Dry-Cow maize balancer: 133.74

vitamin e*

g/kg maize DMI: 0.03
kg/tonne of Dry-Cow maize balancer: 9.12

total

g/kg maize DMI: 3.29
kg/tonne of Dry-Cow maize balancer: 1000.00

* Assuming that 1 i.u. Vit E = 1 mg

For example, dry cows on 100 g high-spec Dry-Cow Minerals, but whose intake of maize silage varies from 0 to 10 kg DM/d (with a corresponding decrease in DMI from grass silage or grass) need a daily supplement of the balancer in Table 5, as follows:

DMI (kg/d) from maize silage

0
1
2
3
4
5
6
7
8
9
10

Maize balancer mineral (Table 5) needed by dry cows (g/cow/d)
0
3.3
6.6
9.9
13.2
16.5
19.8
23.1
26.4
29.7
33.0

MAIZE BALANCER FOR WEANLINGS, FINISHERS AND OTHER DRYSTOCK: From data in Table 1, and using target dietary values for finishers of 5 g Ca, 2 g Na, 4 g P and 20 g Mg/kg TDMI, we can calculate:
Major element inputs (g/head/d)

input from 8 kg average maize silage dmi

Ca: 48.00
Na: 20.00
P: 28.00
Mg: 20.00

input from 3 kg beef nuts dmi, containing 110 g high-spec drystock material

Ca: 27.40
Na: 17.40
P: 25.00
Mg: 6.70

subtotal input

Ca: 75.40
Na: 37.40
P: 53.80
Mg: 26.70

target input for finishers from 11 kg adequate diet dmi

Ca: 55.00
Na: 22.00
P: 44.00
Mg: 22.00

deficit from total dietary target (g/head/d)

Ca: -20.40
Na: -15.40
P: -9.80
Mg: -4.70

deficit expressed as g/kg maize silage dmi

Ca: -2.55
Na: -1.93
P: -1.23
Mg: -0.59

From that calculation, as there are no deficits, drystock need no additional mineral supplement for maize silage if they are on a the high-specification beef nut containing Drystock minerals. However, the mineral inclusion in the concentrate allowance should be fortified with extra Vitamin E, i.e., the mineral should have >690 i.u./kg, instead of the more usual >418 i.u./kg.

SUMMARY 

1. Irish maize silage has very low crude protein (84 g/kg DM); it needs a CP supplement of 76 g/kg DM for lactation, or 56 g/kg DM for other cattle. 

2. Maize silage also has low levels of Na, Ca, P, Mg and S for dairy-cow lactation. Mineral balancers for maize silage need more Na, Ca, P and Mg than balancers for grass silage. To ensure optimum protein metabolism in the rumen, cattle eating a high proportion of maize silage in their diet need an extra 1.5 g S/kg maize silage DM from other sources.

3. Maize silage also has low Cu, I, Zn and Mn levels and very low Se levels. However, trace-element inputs from high-specification minerals (see "Mineral-Vitamin Mixes for Cows and other Cattle") usually are generous enough to suit maize silage also. 

4. We have no data for Vitamin E levels in Irish maize silage but it probably has much less Vit E than grass silage. Maize silage, especially that with a high cob / starch content, needs a high supplement of Vit E.

Phil Rogers MRCVS, Lucan, Dublin, Ireland​
Fax: 353-46-26154 Tel: 353-46-26740 (Lab)
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