88
Vitamin A Requirement of Farm Mammals
Summary of data on minimum vitamin A and carotene
requirements of various species
Species
Cattle .. ..
Sheep .. ..
Swine .. ..
Horse .. ..
Rat .. ..
Rat .. ..
Daily intake per kg. bodyweight
Vitamin A
γ
5.1—6.4
4.3—6.3
4.4—5.7
4.2—5.3
4 6—5.3
3.8—4.6?
I. U.
21—27
17—26
18—24
17—22
—
18—22
Carotene
γ
26—33
25—35
25—39
20—30
15—20
—
I. U.
43—55
42—58
42—65
33—50
25—33
—
1 Data based on cod liver oil that was used in cattle,
sheep, swine and horse experiments.
2 Data based on U.S.P. Reference cod liver oil.
that green growing pasture grasses are
needed to maintain the production of
butterfat high in vitamin A.
LOSS OF CAROTENE (PROVITAMIN A) DURING
PREPARATION AND STORAGE OF FODDER
Carotene is easily oxidized in the pre
sence of air and light and the rate of
oxidation is accelerated by heat.
Hartman [1931] found in the natural
curing processes of hay in sunlight that,
with the bleaching of the chlorophyll,
carotene is rapidly oxidized and the vita
min A value reduced markedly. When the
leaves of plants dry up and become brown
their vitamin A value is completely lost
[Coward, 1925]. Wide variations in the
vitamin A value of hay depending on the
method of curing have been demonstrated
by many workers. Russell [1929] showed
that a sample of alfalfa hay artificially
dried had as much as 7 times the vitamin
A value of field cured samples. On the
basis of this work, 7 to 10 per cent
dehydrated alfalfa meal, notwithstanding
its greater cost, was recommended as
addition to poultry food in the absence of
fresh greens.
Generally speaking, artificially dried
hays are higher in carotene content than
field cured; marked variations exist is
both. Kisselbach and Anderson [1931]
and Guilbert [1934] found in some case
no significant differnce. Hauge an
Aitkenhead [1931] studied the question
and concluded that enzymes were impor
tant causes of loss of the vitamin during
curing. The possibility of using ant
oxidants in stabilizing the vitamins
worth considering if it can be done within
economic limits.
Guilbert [1934] has outlined a modifi
cation of existing methods for the estima
tion of carotene in forage. He [1933]
used this method in studies of factors
affecting the carotene content of alfab
hay and meal. Tests were made on the
effect of vacuum drying for 3 hours at 10
C. Four fresh leaf samples showed 48.0
52.0, 46.0 and 60.3 mg. per cent, respectiv-
ly, while the corresponding vacuum dr
samples contained 48.4, 51.3, 46.6 and 57
mg. per cent. In similar tests on the
effect of autoclaving for 1 hour at 17
pressure, the loss of carotene varied from
33 to 67.5 per cent. Samples subjects
to sun drying lost as much as 69.5 per cet
of the carotene content. A sample per
viously dried in vacuo exposed under gla
to the sun at the same time lost 67.4 per
cent of its carotene. Enzymes were show
to play a part in the destruction of the
substance. In one test, where leaves we
exposed at 38° C. over water and toluen
for 24 hours and then vacuum dried,
loss of 49 per cent occurred. In a contr
vacuum dried sample there was no loss.
Environmental temperature during
storage is important. Sherwood and
Fraps [1932] demonstrated the loss
vitamin A potency in cattle foods during
ordinary storage, whereas Russell, Taylar
and Chichester [1934] found that, wh
stored in vacuo at 0±5°C, alfalfa sample
sustained no loss of carotene. The latt
workers were of the opinion that the ra
of carotene loss in cured plants might be
greater during the early days of storage
than after a few months had elapsed
Fraps and Treichler [1933] indicate the
reverse to be the case. Guilbert [1933]
made tests on alfalfa stored at 3 different
temperatures.
Samples in stopper