Animal Husbandry Mimeograph
Series No. 55-13 May, 1956 *-
THE VALUE OF ESTRNORWAY (FRACTION OF CITRUS OILS) AS A GROIN, j!
STIMULANT AND PARASITE CONTROL FOR WEANLING PIGS
H. D. Wallace, David Aronson, Don C. Tomlin, Billy Bass
G. E. Combs and L. E. Swansonr-
(Animal Husbandry and Nutrition Department and Veterinary Science Departm
A constant search is underway for new compounds which may be useful in
swine feeding. Recent interest in the possible feeding value of certain citrus
oils prompted this investigation. The product used in these experiments
consisted of d-limonene and various derivatives.
The experiments were designed to obtain information on the value of the
oil under different environmental conditions, namely in drylot (on concrete),
in drylot (access to soil), and on pasture. The product was also tested
both in the absence and presence of antibiotic, and in one experiment two
levels of the oil were compared.
The experimental animals (purebred Duroc, Hampshire X Duroc, and
purebred Spotted Poland China) were divided into treatment groups according
to weight, breed and previous history.
The basal rations fed in the experiments are described in Table I. The
basal ration fed in Experiment I was fortified with 2000 I.U. of vitamin A,
10 micrograms of B12, and .45 gm. of Lederle Fortafeed 2-490 per pound. No
vitamin fortification was provided the pigs of Experiment II since they were
fed on pasture. The pigs of Experiment III were given the vitamin mixture
described in Table I.
IWallace, Associate Animal Husbandman; Aronson, Tomlin and Bass, Research
Assistants; Combs, Assistant Animal Husbandman, Department of Animal Husbandry
and Nutrition. Swanson, Parasitologist, Department of Veterinary Science.
Table I. Basal Rations
Experiment Number I 2 3
Ground yellow corn
Trace Mineralized salt*
* The trace mineralized salt used in Experiments I and 2 consisted of 1842 gm.
MnSO4*H20; 796 gm. FeSO4-H20; 250 gm. CuSO4*5H20; 20 gm. CcC03; and 100 Ibs.
iodized salt. The trace mineralized salt mixture used in Experiment 3
contained in addition to the above ingredients 350 gm. of ZnSO4'H20.
Vitamin A (10,000 l.U./gm.)
Vitamin 02 (9,000 l.U./gm.)
Vitamin E (44 I.U./gm.)
Vitamin B12 (I gm.= i mg. BI2)
Choline Chloride (25 percent)
The citrus oil was mixed with the total ration at levels indicated in
Table 0. These-tevels approximated daily intake of i ounce,or Ilounce per
pig. All rations were self-fed. Ample shade and water were provided the
animals at all times.
The various experimental regimes and feeding results are summarized in
Several of the animals from Experiments I and II were slaughtered at
the termination of the tests and worms present in the gastrointestinal tract
were counted. The results are shown in Table 3.
Results and Discussion
in Experiment I, which was conducted in concrete pens, the average daily
gains of the pigs receiving citrus oil was 1.39 Ibs. compared to 1.29 for the
controls (Table 2). Feed consumption was greater for the treated pigs, however,
the feed required per pound of gain was approximately the same for the two
lots. Since there were only 6 pigs per group these results were not conclusive
but did suggest that further study was justified. We also noticed in this
experiment that the treated pigs were passing roundworms regularly while no
worms were observed in the control pen.
Experiment II was conducted on pasture and the pigs were considerably
heavier initially than in the other two experiments. In this test the control
pigs actually out performed both treated lots by a small margin in terms of
average daily gains. It appeared that feed intake may have been adversely
affected by the feeding of I oz. per head per day of citrus oil, whereas the
lower level had practically no affect on feed intake.
In Experiment III it was desired to study the value of the citrus oil in
the absence of antibiotic. The average daily gains of the controls and
treated animals were practically the same. The control animals ate more
feed but were slightly less efficient in converting it to weight gains.
The citrus oil appeared to influence the palatability of the rations in
all experiments. The lower level of oil used in Experiment I and fed over
a relatively short period seemed to stimulate appetite. In Experiment II
the lower level of oil affected feed intake only slightly while the higher
level markedly reduced it. In Experiment III the higher level of oil again
reduced overall palatability of the ration as measured by feed intake. The
oil seemed to stimulate appetite in the early phases of all experiments but
TABLE 2 THE VALUE OF CITRUS OIL IN THE RATION OF GROWING-FATTENING SWINE
Experiment Number I II II
Environmental Drylot (Concrete pens) Pasture (Native Grasses) ;Drylot (Access to soil)
Terramycin 20 gm. 10 gm. None
added per ton of feed
Lot Number 1 2 I 2 3 1 2
Citrus Oil added
per 100 Ibs. of feed None 284 gm. None 284 gm. 568 gm. None 568 gm.
Number of pigs 6 6 9 9 8* It II
Av. initial wt., Ibs. 24.7 24.5 62.7 62.7 63.6 27.0 27.2
Av. daily gain, lbs. 1.29 1.39 1.74 1.68 1.65 1.52 1.48
Feed consumed per pig
per day, Ibs. 3.36 3.65 5.77 5.80 5.50 4.89 4.67
Feed consumed per lb.
gain, Ibs. 2.60 2.61 3.32 3.46 3.32 3.22 3.15
Days on experiment 56 56 663 63 63 91 91
,i ,I i
second week of experiment
* One pig died during
- cause undetermined.
TABLE 3. PARASITES PRESENT IN GASTROINTESTINAL
TRACT AT TERMINATION OF EXPERIMENTS
Pig Number and Treatment Ascarids
181 (control) 10
166 (control) 116
177 (1 oz. citrus oil/day) 6
119 ( oz. citrus oil/day) 51
Wh i s
(G oz. citrus oil/day)
(1 oz. citrus oil/day)
(I oz. citrus oil/day)
(I oz. citrus oil/day)
Animal Husb. Exp. Sta.
then feed intake tended to drop off markedly toward the end of the tests in lots
receiving the high level of oil.
The parasite counts presented in Table 3 are not extensive enough to
permit definite conclusions. It is interesting that none of the treated pigs
were excessively infected while three of the four control animals studied
carried quite a large number of worms. If there was a worming effect from
the feeding of the citrus oil, it was not important in terms of the gains
and feed conversion of the experimental pigs.
Three experiments involving a total of sixty weanling pigs have been
conducted to determine the feeding value of a citrus oil product (d-limonene
and various derivatives).
The results as measured in terms of average daily gain, feed intake,
feed conversion, and parasite populations indicate that the product has
no beneficial affect when fed to healthy pigs which are receiving a well
To Mar-Tay, Inc. Orlando, Florida we are indebted for supplying the
citrus oil. The Chas. Pfizer and Co., Terre Haute, Indiana, provided the
terramycin and certain of the B-vitamins used. The Fortafeed 2-49C Vitamin E
and certain other B-vitamins were contributed by Lederle Laboratories,
Pearl River, New York. The Vitamin A was supplied by Nopco Chemical Co.,
Harrison, New Jersey, and the Vitamin D by Dawes Laboratories, Inc.,