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Dairy Feeding During Drought

Ideal nutrient content of various silages.

June 2017

J. W. Schroeder, Extension Dairy Specialist Emeritus

One of the prime concerns for dairy producers should be forage quality and supply. Buying good forage in large quantities often is more difficult than purchasing grain or concentrates.

High quality forage is an important factor in obtaining efficient milk production and normal milk composition and quality, as well as good cow health and reproduction. Whenever possible, the forage ration should contain a minimum of 60 percent TDN on a dry matter basis. In addition, it should be relatively low in toxic factors such as nitrates and mold poisons. It should also be reasonably palatable.

One option is to harvest small grains and corn as whole-plant silage. This may increase yields of nutrients per acre and replenish forage supplies. Even drought-stricken corn may make silage with a relatively high energy content, as indicated in Table 1. When little or no grain development occurs, let the corn approach maturity dates equivalent to recommended stages of ensiling. For example, poorly pollinated corn should be allowed to reach 45-55 days after silking to increase sugar levels.

It is important to harvest the crop before the whole-plant moisture level falls below 60-63 percent to ensure reasonably normal fermentation and minimize silo gas formation. Often, moisture levels in the whole plant may run higher than normal when grain development is lacking. Moisture content may drop and grain may mature quickly once many leaves die. Stunted plants with good ear development may have a lower moisture level than normal. Finer settings are needed to obtain adequate chop of dry matter. Add water if necessary. Coarser settings are needed to avoid chopping material too fine that is relatively high in moisture content.

Forage sorghums, sundangrass and their crosses may be grown for emergency forage. These require close management to make good quality pasture or silage.

Table 1. Expected nutrient content of various silages.
Dry Matter Basis
Material Matter Protein TDN CA P Mg K S
Percentage (%)
Corn silage
Average 34 8.5 67 0.27 0.23 0.18 1.07 0.14
Pre-silk 10 12.4 61
Silk 15 11.3 63
Milk 21 7.0 66
Dent 28 8.3 69
Over-ripe 45 9.1 63
Few ears 25 9.9 61
Stover silage 27 7.2 58 0.33 0.10 0.18 1.63 0.17
Pea vine 25 13.1 56 1.31 0.24 0.34 0.93 0.30
Soybean 28 17.7 54 1.25 0.49 0.34 0.93 0.30
Small grain 36 11.5 59 0.44 0.32 0.16 2.29 0.17
Sorghum, sudan 33 9.5 60 0.48 0.24 0.28 1.73 0.10
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