A32-Lancaster Farming, Saturday, November 18, 2000
Speakers at this week’s dairy cattle nutrition workshop
were, from left, Bill Weiss, professor of dairy science, Ohio
State; Gabriella Varga, professor of animal nutrition, Penn
State; and Jud Heinrichs, professor of dairy and animal
science, Penn State.
Dairy Conference Reviews
Importance Of Forage
Quality, New NRC Book
(Continued from Page At)
also vary significantly, the nutri
tion expert said, in chemical
composition.
“Even corn grain has signifi
cant variations,” he said.
The new book, out in Janu
ary, will further define nutrient
values depending on feed used.
The book has “big changes in
energy values,” noted Weiss.
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“Use this to balance diets.”
Some recommendations in the
1989 edition included feed
values that were calculated too
high.
By-product composition
values, including for cottonseed,
have changed. Cottonseed hulls
are a lot higher in fiber yet have
poor digestibility.
And nutritionists should be
aware that total digestible nu-
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Virginia Ishler, extension assistant at Penn State, hands out corn silage samples
during the workshop.
trient (TDN) values are an “ex
tremely poor measurement of
energy content of feeds high in
protein and high in fat,” Weiss
noted.
Two feeds with the same
TDN can have very different net
energy for lactation (NEL)
values, Weiss said.
TDN is not equal to NEL. In
the 2000 book, TDN values are
“completely disconnected from
NELs,” said Weiss.
In the new book, higher pro
tein feeds have more energy. If
the nutritionist would feed
higher protein, the dairy animal
would have “higher net ener
gies,” he said.
Overall, Weiss noted, it will
require more energy to produce
milk in 2000 than 1989.
Different dietary require
ments will consider new feed
energy values and “bioavailabil-
ity” of certain nutrients. The
bioavailability requirement con
siders how much the heifer or
cow has to “absorb,” Weiss said,
not simply how much she is fed.
On supplementary vitamins,
vitamin A values increase 50
percent over the old 1989 values.
Vitamin D values don’t change.
Vitamin E values reveal a big in
crease, simply as a way to pre
vent mastitis.
Body weight after calving is
the most significant correlation
to how much milk a cow will
produce, particularly the end
portion of the growth period, ac
cording to Jud Heinrichs, Penn
State professor of dairy and
animal science.
Heinrichs also reviewed some
NRC guide book changes, im
portant in combination with
general management.
Heinrichs noted some keys to
lifetime profitability based on
the dollar amount of input at
heifer raising compared to the
milking cow.
It could be possible to de
crease the amount of time to
calving while increasing rate of
gain.
If calved at 22 months, the
rate of gain stands at 1.7-1.8
pounds per day maximum,
Heinrichs noted. Through man
agement and diet, in addition to
genetic selection, nutritionists
could get more rapid rates of
gain and calve younger than 22-
24 months.
For now, Heinrichs noted that
dairy nutrition research is look
ing at ways to increase the
growth and development of the
rumen. The vast majority Of the
growth in the animal comes
(Turn to Pag* A 33)
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