Home' NZ Dairy Farmer : April 2010 Contents ANIMAL HEALTH
30 The Dairyman APRIL 2010
WATER-soluble B vitamins and
choline are indispensable nutrients
for all mammalian species and are
obligatory for the regulation of metabolic
processes. The functions of these com-
pounds are wide ranging and affect all
aspects of health and productivity.
These vitamins have been reasonably well
studied in monogastric species but less so in
ruminants, as it has been largely assumed
that microbes are capable of producing suffi-
cient quantities of B vitamins to supply host
animals. Although the rumen microbes may
be capable of producing B vitamins, there
may be conditions when the production of
these nutrients is not adequate to support
ever-increasing levels of production.
The purpose of this article is to evaluate
the information available and to determine if
the data suggest that ruminants may, under
certain situations, benefit from the inclusion
of water-soluble vitamins in their diets.
The concept of providing B vitamins to
ruminants is not new. The possible need for
B vitamin supplementation was questioned
as early as the 1940s and 50s. Much of our
understanding of B vitamin requirements for
ruminants is based on this and other early
There appeared to be a renewed interest in
B vitamins for ruminants in the 1990s, which
has continued until the present.
With monogastric animals, estimating
vitamin requirements generally involves a
dose response protocol. Predicting the
dietary B vitamin needs of ruminants is a
more daunting task. First, feeding a vitamin-
free diet does not result in a lack of the par-
ticular vitamin in the duodenum, and it is
sometimes difficult to obtain supplies low
enough to elicit a short-term response.
Second, altering the dietary supply may
not necessarily reflect the amount absorbed.
Microbes have the ability to not only pro-
duce water-soluble vitamins but also to
To be confident of the vitamin dosage,
vitamins need to be injected, duodenally
infused or rumen protected.
As with other nutrients, the cow requires
water-soluble vitamins for maintenance,
growth, milk production and reproduction.
Stress and high water turnover may further
affect requirements. As with other nutrients,
milk generally places the largest demands
upon total needs.
The National Research Council committee
recognised the recent important, new infor-
mation on water-soluble vitamins. NRC
(2001) approximates the water-soluble vita-
min requirements of lactating cows based on
milk and maintenance. With this system,
milk values represent net output with no cor-
rection for digestibility or postabsorptive
Maintenance values were extrapolated
from swine and do include digestibility and
efficiency adjustments. NRC (2001) con-
cluded that folic acid and pantothenic acid
are the most likely to be limiting for cows
producing 35 kg of milk.
It is not known if the water-soluble vita-
min composition of milk is consistent as a
means of species preservation or if the milk
acts as a depository for vitamins when levels
are high. A number of compounds in milk
are at equilibrium with blood (urea, for
example). The B-vitamin composition of
milk was obtained from three sources (Davis
and Drackley, 1998; Roy 1980; U.S.
Department of Agriculture, 2000).
The similarities in the values might sug-
gest that all originated from the same older
sources of information. Nail et al. (1980)
found that supplementing humans with
either thiamin or riboflavin increased output
in urine but not in milk. However, Deuchler
et al. (1998) determined that increasing the
duodenal supply of choline resulted in
increasing levels of choline in milk.
Likewise, Girard and Matte (2005) found
significant increases in vitamin B12 when
cows were injected with this vitamin.
Certainly, more information concerning the
vitamin composition of milk as well as
sources of variation in the composition
would be helpful for further research in this
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Dr. Essi Evans is chief executive officer of
Essi Evans Technical Advisory Services
Inc., Bowmanville, Ontario, Canada.
The growing body of information on dairy cows' use of B vitamins indicates that there are opportunities to improve production,
reproduction and general well-being with judicious supplementation. In some cases, vitamins will need to be provided in a form that
protects them against rumen destruction to permit the cow to take advantage of their properties.
Are vitamins essential for your cows?
By ESSI EVANS
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