What do my Cows need now?

March, 2012
Randy Gornto, Highlands County Livestock Agent, UF/IFAS

There are a few questions you need to answer to determine what the cow needs and if you need to supplement.

Rough requirements of a cow at  1000 lbs body weight, as a mature cow, in a condition score of 6
Gestation/Maintenance       .88 lbs protein and 7.74 lbs of TDN (total digestible Nutrients)
Last 1/3 Gestation                 1.10 lbs protein and 9.36 lbs of TDN
Lactation                                 1.90 lbs protein and 10.75 lbs of TDN

Questions:

  • What is the average weight of my cows?
  • What is the condition score of my cows?
  • Where are the cows in their Cycle? (Maintenance, last 1/3 gestation, or lactation)
  • What do I have available to feed my cows? (standing forage, Hay, nothing)
  • What is the quality of my pasture? (standing forage, hay, ect.) Keep in mind that standing forage continues to decline in nutritional value as the season continues. So take samples as needed.
    You need to provide supplement to meet whatever the limiting factor like protein, TDN or Mineral.
An example:
my hay tested out at 6% protein and 52 TDN
My cows are about 1000# she can consume about 2% of her body weight per day or about 20# if she is lactating she will consume about 2.2% or 22#.
Lets say she is in lactation according to the requirements she need about 1.9# protein and 10.74# of TDN.
She gets about 1.32# protein from the hay or forage 22# forage X 6% protein = 1.32# protein
She gets 11.44# of TDN from the hay or forage 22# forage X 52% TDN = 11.44# TDN
My limiting element is protein which is about .57 of a pound short so it would take 3# of a 20% protein product to meet her needs per day or 2# of a 32% product.

If my hay is 3% protein and 48 TDN it will take more to meet her needs. This is a two edge problem because the cow can’t process as much of the poor quality forage in a 24 hr period let say to keep it simple she consumes 20#
20# forage X 3% protein = .6 lb of protein
20# forage X 48% TDN = 9.6# of TDN
She is lactating so she needs 1.90# protein so she is short 1.3 lbs of protein
She needs 10.74# of TDN so she is short 1.15# of TDN
To meet protein need at this point it would take 6.5# of 20% protein product or 4.6# of a 32% protein product.
On the TDN side she is 1.15# short which depending on the TDN level of the product being fed you would need 1.8# of a 65%TDN product or 1.7# of a 72%TDN product.
Your most limiting need is still protein and if you feed to meet that need you should get more than enough TDN out of the product to meet cow need.


Conclusion
You need to determine the need (protein, TDN and/or mineral) and develop a program to meet those needs. If you would like help in developing a program for your cattle contact the University of Florida Livestock Extension Agent in your county.

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