BY LORETTA SORENSEN
…is now in session
Did you know that grazing beef
cattle take about 30,000 bites a
day during an eight-hour session?
ust as beef producers gain weight faster on pie than
salad (EDITOR: Such a thinly veiled hint, Loretta ), cattle
gain weight more rapidly and easily on high quality, leafy,
“It won’t matter what type of forage
you’re feeding, if the quality
isn’t there, you won’t get the results
you want,” Dan Undersander, emeritus
forage agronomist, University of
Wisconsin-Madison, says. “Grazing
forage at the right stage can mean
the difference between feed with 20%
protein or 6% to 8% protein.”
In grazing mixed alfalfa/hay pastures,
maturity stage – and optimum
grazing time – should be based on the
alfalfa maturity stage. Clover-grass
mixtures should be judged for maturity
based on the stage of the grass.
The reason forage quality changes
as plants mature is due to the production
of fl owers, heads and seeds. That
process takes energy from the plant
which otherwise was used at early
growth stages to produce leaves.
The main developmental stages of
grass plants are vegetative, transition,
In the vegetative stage, leaf blades
are the primary result of grass shoots.
As daylight hours and temperatures
increase, grass plants respond by transitioning
to “fl oral bud” stage. During
this stage, grass stems begin to elongate,
causing the grass to be high
enough to graze.
Much of the reproductive stage
occurs unseen until a seed head
emerges. Boot stage – one part of the
reproduction stage - is defi ned as the
period when the plant seed head is
enclosed but ready to emerge.
Cool season grasses begin growing
when soil temperature reaches between
40 and 45 degrees (F.). Optimal growth
temperature range is 65-75 degrees (F.).
As temperatures increase beyond this
range, cool season grasses begin losing
quality. During peak growth stages,
cool season grasses provide a higher
percentage of crude protein than
warm season varieties.
Warm season grasses produce more
leaves than stems early in their life
cycle and more stems than leaves as
they mature. Immature leaf tissue is
low in fi ber with high levels of soluble
proteins, fats, carbohydrates and oils.
All those nutrients meet or exceed
nutrient demands of grazing cattle.
As most grasses mature, they produce
more stems that are high in
indigestible fi ber and low in digestible
nutrients. Total Digestible Nutrients
(TDN) is the term for the total sum of
digestible fi ber, protein, lipid and carbohydrates
of a cattle feedstuff or diet.
Depending on a cow’s gestation
stage, crude protein and TDN change.
Nutritional needs are highest postpartum,
when cows must lactate, repair
reproductive tracts, resume heat
cycles, breed, increase activity and (if
young) grow and mature. Not receiving
adequate nutrition can result in
delayed breeding and/or deteriorating
Plant leaves have short lives. During
its prime middle age, a grass leaf produces
more energy than it consumes
and exports the excess to other parts
of the plant. During this stage, the
“boot” stage, the leaf has the greatest
dry weight and is at its nutritional
peak. The dying back stage of the leaf
begins shortly after it reaches it growth
peak. During the dying process, the
leaf cell contents are redistributed to
other parts of the plant, reducing the
nutritional value of older leaves.
Once more than half the leaf surface
is removed by grazing (or mowing),
30 I WORKING RANCH I MARCH 2019