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Virginia Cooperative Extension - Knowledge for the CommonWealth

Don't Skip the Little Things

Dairy Pipeline: February 2009

M. Chase Scott, Extension Agent
Southwest Virginia
(276) 223-6040;

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We’ve all heard the theory of limitation in reference to plant nutrients and productivity – that old illustration of a barrel that can only hold as much water as the lowest “stave” allows. We commonly relate this analogy to soil fertility and assign the staves as N, P, K, PH, etc. This same analogy can be used in reference to the functionality of the dairy cow and assign not only protein and energy to the “staves,” but also Ca, P, Mg, etc. In times of declining milk prices it is easy to “cut corners” and “save a little here and there,” by not keeping the mineral supplement feeders full to all groups of cattle, but one must consider the potential long term impacts. These may include reduced fertility and consequent increases in days open and days to first calving. Reduced feed efficiency in relation to milk production can have an all too familiar impact on a dairy operation's bottom line. Just as we submit soil samples for testing before fertilizing and liming a field, we should test forages and home grown feeds before feeding them to dairy cows. The table below details the mineral requirements for cows at various stages of lactation and production.

  Milk Cows
  Dry Cow Fresh Early Middle Late
Early Close-up 0 to 21d 22 to 80d 80 to 200d >200d
DMI (lbs) 30 22 >35 53 48 44
Major Minerals in % of DM
Ca 0.6 0.7 (*1.0) 1.0 0.9 0.7 0.6
P 0.26 0.3 0.45 0.4 0.36 0.32
Mg 0.16 0.3 (*0.4) 0.33 0.3 0.25 0.2
K 0.65 0.65 1 1 0.9 0.9
Na 0.1 0.05 0.33 0.3 0.2 0.2
Cl 0.15 0.15 (*0.8) 0.3 0.25 0.25 0.25
S 0.16 0.2 (*0.4) 0.25 0.25 0.22 0.22
*When anionic salts are used: mineral/anionic salts (%)
Adapted from “Nutrient Utilization in the Dairy Cow”
Illini DairyNet. By Dr. Mike Hutjens (April 2003)

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