Beef/Cattle Extension Program
Supplementing Winter Rations with Grain: Good or Bad
By Erasmus Okine, Department
of Animal Science, University of Alberta, Edmonton
take home message is that when it is cold, the
cow needs better quality feedstuffs, such as good-quality
Maintaining our cows through the various stages of
pregnancy, especially through the winter months, has
some unique challenges, especially when feeding low
A forage is considered low in quality when it has digestible
energy of less than 1 Mcal/lb and less than 7% crude
protein. Examples would be late cut weathered hay or
Feeding straw when the weather is very cold
A 1213-lb mature cow, six months pregnant needs about
30 Megacalories of digestible energy per day. Even if
the weather is not cold, the cow can eat a maximum of
about 18 pounds of straw on a dry matter basis (about
21 pounds as-fed). The amount of digestible protein
needed by the bugs in the rumen to digest the straw
is about 0.65 lb, of which only 62% is supplied from
the 18.7 pounds of straw. This cow will lose half a
body condition score in about 33 days.
At -13°F, the amount of energy required to maintain
the cow goes up to approximately 41 Megacalories per
day. The cow will attempt to increase straw intake by
about 20% and may get impacted. Even at the increased
intake of 22 pounds of dry matter the amount of digestible
protein supplied is only 39% of what is required. The
cow will lose half a body condition score in about 20
Energy and protein supplements
All nutritionists agree that the most important consideration
to get a cow through the winter is the provision of
adequate energy and protein. Cows can not survive harsh
winters and be productive on straw alone. However, in
recent times there have been reports suggesting that
feeding barley grain as an energy supplement is not
a good idea.
Those against feeding grain say that feeding cows grain
could actually serve to reduce energy intake through
a decrease in the digestibility of straw. On the other
hand the recommendation usually given is that feeding
a protein supplement is the way to go. Let us illustrate
the basis of this recommendation with numbers in Table
||1 lb.Protein Supplement (20% range pellet)
||3 lb. Energy Supplement (barley grain)
|Forage intake(dry matter)
|Digestible energy intake from forage
|Digestible energy from supplement
|Total digestible energy intake
|Metabolizable energy intake from forage (82% of
|Metabolizable energy intake from supplement
|Total metabolizable energy intake
Data adapted from Beef Today: January 20, 1999.
On the other hand, the assumption is that feeding one
pound of a protein supplement increases straw intake
by about three pounds. Using those assumptions, the
digestible energy intake from adding grain is about
20.28 versus 22.26 Megacalories per day from adding
the protein supplement. The conclusion drawn is that
feeding grain with straw may not be a good nutritional
management in winter when the animal is cold stressed.
What are the facts?
Fact Number 1: In a cold stress situation the
cow does not use the digestible energy system! She will
use what is called the metabolizable energy system.
Feedstuffs that cause less wastage of energy (less methane
production and energy loss in urine) become extremely
useful to the cow. For example, straw loses about 18%
of its energy value as methane and urine. Barley grain
loses about 13% or even less. A protein supplement such
as the range pellet loses about 16% as methane and urine
energy. When you take these wastage factors into consideration,
you move from the digestible energy into the metabolizable
energy system. The metabolizable energy system measures
the total amount of energy actually available to the
Fact Number 2: More recent research data indicates
that the so-called substitution effect is not one-to-one.
The substitution rate is actually only 43% instead of
100% when you supplement low quality forage with grain.
What this means is that when you add three pounds of
grain to straw, only 1.3 pounds of straw will not be
eaten out of the 20 pounds offered. In other words 18.7
pounds of straw will be consumed.
When these two facts are added together, the total metabolizable
energy intake from feeding straw only, straw and protein,
and straw and grain becomes 14.76, 18.28 and 18.11 Megacalories
per day, respectively. Note that the difference between
supplementing with protein and grain is about 0.17 Megacalories
per day and that is nothing to write home about.
The take home message is that when it is cold, the cow
needs better quality feedstuffs, such as good-quality
hay. If you do not have good-quality hay, your choices
are supplementing your straw with either grain or a
protein supplement or both.
My recommendation is that when it is very cold, feed
some grain. It is a faster and often cheaper method
of increasing the energy intake of your cows.
For more information contact Erasmus Okine at (403)