Page 9 - MWC 02-25-2021s

Are Your Cows Too Big? The Midwest Cattleman · February 25, 2021 · P9

Match inventory to available feed resources.

By Glenn Selk, Oklahoma State University Emeritus Extension Animal Scientist

Mature weight and milk The start of a new year would be
production of many commer- a good time to honestly review
cial beef cows are both greater our cow herd weights and stock-
than they were 30-40 years ago. ing rates. The year 2021 would be
Many ranchers have not recently an excellent time to begin the pro-
weighed the adult cows in their cess of better matching the cows
herd to know what average ma- to the forage base at our ranch.
ture weight to expect. Therefore,
most commercial ranchers would
underestimate the mature size
of their cows. To expect large,
heavy-milking cows to be in mod-
erate body condition at calving
and maintain condition through
breeding, they must receive more
feed than smaller, lighter-milking
cows.
Fig. 1 uses the 1996 Nation-
al Research Council’s guidelines
to show the energy needs of two
different body types and levels of
milk production. These energy re-
quirements would be representa-
tive for cows calving in February
and March and weaned in Octo-
ber. The top line represents the
energy needs of 1,250-pound (lb.)
heavy-milking beef cows vs. the
lower line, which represents the
needs of 1,100-lb. moderate-milk-
ing beef cows. The values graphed
are the megacalories (Mcal) per
day required to maintain body
weight throughout the year.
The larger heavier-milking cow
requires about 34% more energy
on the average for an entire year.
Consequently, an operation that
was carrying 100 of the smaller
cows must carry only 66 of the
larger cows in order to use the
same quantity of forage from that
farm or ranch. She also will need
34% more winter hay and supple-
ment to maintain body condition.
In some commercial herds, there
are cows much larger than the
1,250-pounders depicted in this
graph.
As we take inventory at the be-
ginning of 2021, this is a time to
reconsider herd numbers and cow
size to better fit the stocking rates
required. Reduced stocking rates
will be necessary if range and pas-
ture condition has deteriorated in
recent years. Diminished forage
availability will lead to poorer
cow body condition, more supple-
ment and hay feeding, or both.