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DOMINION OF CANADA

THE HONORARY ADVISORY COUNCIL PCHaCTENTIFIC
AND INDUSTRIAL RESEARCH

BULLETIN No. «

SOME PROBLElVfS

OF THE

FOX-RAISING INDUSTRY

ANDREW HUNTER, NlA..||3c.»MAwaj.

PirofeMorofBiocheaiwtr^-lJyimri^.«^^ ■

Publuhed by the -'hrriff tf tfij TiiTi fiiniiiiaiii ijf ^ |Wvy Caonca
f or Scitatiik Mid btUrikl R«M«Gii

OTTAWA. 4^20

SOME PROBLEMS OF THE FOX-RAISING INDUSTRY.

iNfROUt'CriON.

The business of fox-breeding, which in the years before the
Great War was little more than a speculative adventure, is today
a solid commercial enterprise, success in which depends entirely
upon the number and qudlity of the pelts actually sold. In this
character it has already attained a truly surprising magnitude.
In Prince Edward Island alone there are about 275 fox farms with,
it is conservatively estimated, at least 4,000 pairs of breeding
foxes. During the season 1918-19 there were offered for sale,
at prices ranging mostly from $250 to $1,000, approximately
5,000 skins, and the total revenue of the Island from this source
must therefore have been little short of $1,000,000. When it is
considered that this province is not the only one in which foxes
are raised for their fur (ranches have been established also in New
Brunswick, Quebec, Ontario, Manitoba, etc.), and when it_is
further realized that the pelts produced arc practically all exporteid,
it becomes evident that the industry may justly claim not merely
a local, but a national im(K), Umce, which is very far indeed fron
oeing negligible. Needless to say, it has not reached this st. .
v/ithout encountering a variety of difficult problems. It is th
purpose of the following pages to inquire into the nature of these,
and to consider whether it would be profitable, and in what manner
it might be possible, to attempt their solution.

I. The Aver.\gk Yield and the Possibility of Its
Improvement.
It can hardly be doubted that under existing circumstances
the returns of the industry are on the average lower than they
need be. It is, to be sure, impossible to ascertain with exactness
either the total number of fox pups born in a given year, or the
total number raised to maturity; but the information available
would suggest that the 4,000 pairs of adult foxes in Prince Edward
Island raised successfully last year not much more than 5,000

7WH—1 1

pups. This would bean average yield jf only 1 -25 per pen. Since
the number at a birth is seldom less thaii 3, and is often from 5 to 7,
It is obvious thai -uch a figure indicates either a large percentage
of infertile matings, or very considerable lotwea among the growing
pups. The exact importance of the first factor cannot at present be
even roughly estimated, Hut as retrards the second it would appear
to be establiihed, upon the independent testimony of many exper-
ienced breeders, that from 40 to 60 per cent of the foxes accually
bom never reach maturity. The losses thus indicated are largely
avoidable, for there are individual ranches where the yield is very
much higher than the estimated average. In many it is over
2-5, and it appears that it may sometimes even exceed 4. .What
can be accomplished by some ranches ought not to be impossible
to any. It would be hard to say what may be ihe pr^ictical limit
of improvement, but it the actual yield l>e taken as 1-5, and the
generally attainable set no higher than 3, it would seem not
unreasonable to hope that the revenues of the industry might,
by scientific mana^ iient, at least l>e doubled.

II. Factors Responsible for the Low Rate of I.ncrease.

The factors responsible for the low average rat • of increase
are evidently very numerous, and are not always readily deter-
minable; but most of them appea.- to be classifiable under one or
other of the following heads:

1. Infectious Diseases.

2. Parasites.

.^. Food PoisoninR.

4. Imperfect Nutrition.

1. INFECTIOUS DISEASES.

Several ranches are known to have been visited by distemper
within the last few years, and it is suspected that others have
suffered without permitting their misfortune to become public.
While the loss thus caused to the industry as a whole represents
probably but a small fraction of the total revenue, a single outbreak
may spell at least temporary disaster for jhe individual.

It hardly needs to be said that the problem presented by
distemper is mainly one of prevention. From this point of view
the existing practice of many ranches is certainly capable of

improvement. It ..ught for instance to lie a matter of routine,
that every fox introduced from another l<x-ality should underKo
befo'" admitwion a rt-jfular ix-rifKl of quarantine. Not only «>,
but the foxi-s should Ik^ more riKiilly isolated than at present from
every contact, direct or iiidireit, with other aiiimul;* It is not
definitely known what sfH-cies are, and what are not, ca|>id>le of
harlmring or tran nitting the specific virus of distemper; Imt
it would obviously b«' ihc part of wisdom to exclude every kind
of animal, domesticated or wild, not only from the neighlKJurlKMHl
of the fox ranch, but also from the society of the keeper.

Should dislemix-r once make its appearance in a ranch the
most strenuous steps must Ite taken to prevent its spread. The
(Mily ho|K- of <|oing so, apart from the ust', as yet in its experimentul
stage, j)f protective vaccines, lies in the prompt and complete
isolation of the aflecfcd animals, and the thorough disinfection
of their jK'ns. Such a pr<Me<lure presup(>oscs of course the (Mis-
session by the infected ranch of a s|K'cial group of pens, separate<i
from its regular system, and capable of serving on (Hcasion as a
quarantine station, an isolation hospital, or a special nursery for
liackward pups. K\ery fox-breeder will probably admit the
desirability of such an arr.inncnuiit; but there are few as yet who
ha\e put it into o|K'ration.

2. INTESTINAL P.\R.\SITKS.

(a) Rolno Worms. - The majority of the fox pups on I'rince
Edwatd Islanil would appe.ir to become infected by the round
W' . several varieties of wliich have l)cen encountered hx-ally,
ail ; as soon as they are born. How far this almost univers.d
iniv.^iion is responsible, under existing conditions, for the high
percentage of loss among the youngest pups, it is not very easy
to say. It has l)ecome part of the regular routine of nearly every
ranch to administer to each |)up, at the end of the 3rd and 4th,
and again at alM)ut the eighth week of life, some or.« or other of
the various vermicidal preparations upon the marke. Many
ranchers state that .since this practice has been generally adopteil
the round worm no longer constitutes a serious problem; others
regard it still as their most formidable enemy. My own impres-
sion is that th" latter view is more probably the correct one, and
that many of .ne pups found dead in their nests, or carrietl out
700(M— 2 3

and buried by the mother, would, if the matter were iuve«tigated,
Iw found to have been killed by round wornm. Thin l» one of
many points which might well I made the subject of careful
imjuiry.

The pupa arc generally assumwi. probably quite iDrrecJly,
to acquire the infection during suckling, the teats of the mother
fox having l)ecome contaminated with the eggs of the parasite
through contact with such material as soil, feces, or the Ixrlding of
the nest. It is almost certain that the eggs of the rouixl worm
exist, and survive the winter, in the soil o.' every ranch where
the parasite has been prevalent; and it is probably of some signifi-
cance that early litters, lx)rn w hile fhi- snow '<r yet wxm the ground,
are, as experienced carctak. rs maintain, less liable to suflf<r from'
worms than the later oner- Unfortunately many of the state-
ments made regarding round worms in the domesticafwl fox ha\f
rested hitherto upon analogy rather than upon actual oi)scrvation.
\t is desirable that they should be tcMi-d upon the ground, and that
I ntccise mode in which the fox Iwcomes infected, together with
• he details of the parasites life- history in this particular host,
should l»e established once and for all in an authoritative manner.
Another aspect of the subject which deserves investigation
is the possibility of attacking the parasite not after, but Infore
it has gained entrance into the new Ixirn pup. If it were |)ossil)le
to destroy in the fall all the worms or eggs infesting the adult
foxes, the dens, and the soil of the ranch, there could be no infection
of pups in the following spring. This would 'h; a more logical
method of procedure than the one now prevailing; whellur it is a
practicable one can lie determined only by experiment.

The worms at.d their eggs, expelled as a result of trcatm.nt,
are frequently allowed to lie unmolested in the pens wherever
they happen to fall. In view of the highly resistant properties
of the eggs this would appear to lie a very careless proa><liire. It
should be possible to devise some way by which they could be
coll-rted in one spot, and iinmetliately destroyed. The observance
of such an elementary pn-caution would probably do sonuihinK
to diminish the probai-i'" i{ reinfection.

Widely as the rounu worm is now distributtd amoiii; the
Island ranches, it would probably be an error to rejjard it as a
necessary evil. Ranches exist in whi<li it is all.gwl that worms

h.iv«- flcvcr Ihth seen, .uul in whu h ururtlinKly freaJmcnt h.i-

iiivtr Ik-.!! prattiswl; in othcru the i Kttion iit limited apparcntK

Id two or thriH! adjaftnt inn*. It in |K)!wiblc that a rancher

starting afresh rouKI l»y taking pro|)er pi.vaution.i, the nature o(

which will readily sugKest themselves, stock Tiis pens in su.h a

manner as to harl)or not a single worm, and could maintain them

indefmitdy in that condition. With this proWem, as with thai

of «listem|»cr. preventive measures should in he future as-sume a

pritlominant role. It shoukl, for instance ^romc a matter of

routine to examine for eggs the feces of an h-w fox, which it is

pr..(x.se<| to intr(«lucc into a ranch; anri in , ..,t! these are foumi, to

^^ul»jt•^t the animal Iwfore admission to the most efficacious coursi-

of treatment that can lie devisecl. I,alM)ratory control of .some sort

would of crnirse Ik: necessary to the complete success of such a plan.

(II) II(H)KW(.- \ .- The Health of Animals Hran< h of the

Dominion Department of Agriculture has recently found that

many domesticated foxes are infecte*! hy the hookworm.

Vh- presence of this |)arasite ( aniioi fail to have de'^terious eflfec is

upon tile health and vildity of the animal harlwring it. Just

how extensive and how- s. rious these effects may Ite remains t(»

l>e determined. In any rase it will l>e ncccs.sary in the future

for the fox breeder to pay attention to this hitherto unsuspected

enemy, and to initiate measures for effectively cf.ntrolling its

spread. He can hardly do so withoi-t the advice of an expert,

and the assistance afforded hy a readily accessible laboratorj'.

.1. KtKJD I'OISONlN(;.

.\(Hte food |)oisoning has on .several oci i>ions b> .1, res|K)nsibl<"
for serious losses among both young ar.i <ili.lt ,oxes. This coidd
(Hcur only when the rancher had not t'l'-n suficicnt care to
asi-ertain the fitness for con.su .lu'on of tlii /I'.at he was fcetling.
It would obviously be to the ' tit of the mdustry as a whole
if it adopted some gene1.1l co-oj>crafive system, whereby all meat
intended for foxes should be first inspected, and then properly
stored in <-old stor.ige plants at a sufificient number of readily
available centres.

4. IMl'ERlliCT XUTRITIO.V.

However important the factors of loss hitherto discussed,
their elimination would leave the average yield of the ranches still

far below its possible maximum. The fundamental problem of
the fox farmer, as of every breeder of animals, is one «.f nutrition;
and it is the failure fully to solve this problem that occasions at
present the most serious losses to the industry.

If a fox, or any other animal, is to be maintaine<l through
life in perfect nutritive condition, its diet must conform to each
and all of the following requirements. (I) It must furnish protein
(flesh-building food) in such quantity and also of t ich quality as
will make good the wear and tear of the IkmIv tissuf ., and provide,
in young animals, material for growth. (2) It must have an
a<leciuatc fuel value or energy content (commonly measured in
heat units or calories), a requirement best met by supplementing
the necessary protein with carbohydrates (starciiy foinis) and fats.
(.3) It must contain proper amounts of certain indispensable
mineral elements, such as phosphorus, calcium (lime), iron, and
the like. (4) It must include a sufficient supply of the .so-called
vitamines, es.sential accessories of unknown nature, the absence
of which leads to various t\|)cs of disordered nutrition, and of
which there are believed to exist at least three, (the "fat-solubl<-
•he '•water-soluble'', and the "antiscorlRitic").

To what degree these re(|uirenients are met, or fallen short of,
in one fox ranch or another, it is not at present possible to decide.
It is of course easy enough to obtain a list of the articles that make
up the foxes' menu; but to ascertain, item by item, the actual
foo<l consumption of the individual animal, (which is what really
counts), is quite another matter. Sucii information, as it has
hitherto been possible to collect, touches merely the qualitative
aspect of the problem. Any attempt, therefore, here made to
correlate the nutritional disorders reported with specific defects
of diet is to be regarded as purely preliminary in character.

The most striking feature of feeding practice, as it has come
under my observation, is its lack of uniformity. Kach ranch
seems to have worked out more or less indei)endently an indivi<lual
plan, and, so long as this operates with e\en mixlerate success,
it fears to risk a change. I'ailiire and success alike have been
largely the result of chance. The diets in use have in short been
developed largely at hapha/anl, and, generally speaking, with
few guiding princii)les other than tiie supposed habits of the wild
fox. It is assumed, rightly or wrongly, that the latter lives almost

)

««37783

exclusively upon flesh, and accordingly meat in one form or another
forms the principal ingredient of nearly every dietary. The
chief variety employed is horse-flesh, most of which is imported
from Montreal or Toronto; coming, as it does, from old and
exhausted animals, it is conspicuously devoid of fat. Other food
materials, entering into the dietary of one ranch or another, are
listed below;

Meat: (Ixisldes horse-flesh), U-ef, mutton, veal, pork, rabbit
and chicken. Fish: smelts, .s'alted fish (with the salt removed by
washing in water). Offal: liver, tripe, the entire viscera of small
animals. Cracklings. Eggs. Milk: whole or separate<l, raw or
()asteurized, coiidenswl or evaporated. Home-baked bread or
biscuit. Flour: graham flour, whole wheat, cornmcul. Porridge:
oatmeal, barley, rye, wheat, bran. Shredded wheat. Rice.
Fox biscuits of various makes, especially "c(Kl-li\er-oil" biscuits.
-Apples.

It is difliicult from a mere list of the sort given to form any
judgment of the general adecjuacy of the diets consumetl. Probably
they satisfy in general the first two re(|uirements that have Ijcen
laid down; there is considerable reason to doui)t whether they
fully meet the third and the fourth. It is to be remarked that the
majority of the articles named are drawn from two sources, namely
meat and the cereal grains. A diet absolutely restricted to these
would l)e decidedly deficient in certain mineral ingredients, for
instance calcium (lime), and wo-.ild moreover fail to provide a
proper supply of the indisjH-n.sable "vitamincs". The deficiencies
would be all the greater if the meat, like that chiefly fed to foxes,
were practically free from fat. They might be corrected in part
or in whole by the addition of fats, offal, green vegetables, eggs,
or milk. Fats and fatty portions of meat ought to apjiear in
the diet of foxes much more lil)erally than they do, not so much
.is vehicles for the fat solul>le vitamine, in which the brxly fat of
animals is not particularly rich, but in the general interest of a
well balancctl ration. Offal, such as liver and tripe, is a good
source of the fat-soluble vitamine, and might with advantage be
much more generally utilizcxl than it is. Greens would supply
not only \itamines but also calcium, though it is <l()ubtful whether
they could be fed to foxes in sufficient (luantity to afford any
iniportant supply of the latter. In existing practice they arc not

fed at all. Nevertheless the fox exhibits an appetite for a certain
amount of vegetable material, and is often observed to nibble
grass or the leaves of trees. This indicates in all probability a
real physiological need, and the deliberate provision of some leafy
niaterials from time to time might therefore be beneficial. Possibly
s»>me kinds of desiccated vegetable could be successfully utilized.
E^s are capable of supplying every requirement of a growing
animal, except possibly calcium, and will of course supply this
also if the shell is eaten. Milk, in sufficient quantity, will make
good any dietary deficiency whatsoever, and the more extensive
use of milk, when necessary suitably modified, would perhaps
solve not a few of the nutritional problems at present confronting
the fox raiser. It is true that milk already occupies a place in the
diet list of practically e%er>' ranch I have visitod. But it may be
questioned whether the amount fed is universally sufficient to
make good the defects of the meat and cereals which supply the
bulk of the nutriment. There exists among breeders some differ-
ence of opinion as to the liest form in which to administer milk to
foxes. The proper practice would probably be to use only faw
whole milk. To remove the fat is to remove an important nutrient,
in which the diet as a whole is already deficient, uini with it the
as.sociatcd fat-solubie accessory; while to heat the milk is to
destroy or diminish its vitamine content in general, and therefore
seriously to affect its gro'vth-promoting and protecti/e properties.

When cow's milk is used for the feeding of very young foxes,
it ought, we may assume, to be so modified as to approximate in
composition the milk supplied by the vixen. Unfortunately the
exact composition of the vixe milk is not known. There is on
rtrord i)ut one analysis, and ti.at a very imperfect one, of a sample
which may or may not hove represented a fair average. So far
as it goes it indicates a much higher fat and a much lower sugar
c(jntent than cow's milk. This is quite in accord with what is
known of the milk of small animals in general. It would therefore
seem reasonable to use for the growing pup cow's mil': of the
highest obtainable fat content, and L\'en to enrich thi by the
addition of a suitable amount of cream. But before the fox
breeder can be furnished with authoritative guidance in the adap-
tation of cow's milk to the successive stages of the young animal's
growth, it will be necessary to secure more comprehensive and

accurate data upon the composition of vixen's milk, not only in
regard to organic but also inorganic constituents. The immediate
need of such data should not be forgotten in any experimental
work which may be planned in the future.

The dietary imperfections, to the probable existence of which
att«ntion has been drawn, are likely to be most conspicuous during
the winter season. The reason for thinking so is that milk is never
included in the diet until after the pups are born in the early
spring. This situation is the more unfortunate since a diet of
meat and cereals alone furnishes a particularly jxHir provision for
the requirc.iients of pregnancy and lactation. If the practical
difficulties that have hitherto excluded milk from the diet of the
pregnant female cannot be overcome, other sources of calcium
and of the fat-soluble accessory become an absolute necessity.
Eggs (with the shell) would provide both, bone-meal might be
useful in supplying the former, and the latter could be derived
from the liberal use of liver, tripe and other glandular materials.
Many of the most successful ranchers have been led by experience
to include one or more of these articles of diet in their winter
regime. In others the situation is perhaps saved to some extent
by the use of cod-liver oil biscuits.

Reference has been made to the possibility of a deficiency of
calcium in the diet of the foxes. The other inorganic constituents
of the food also demand attention. Many caretakers appear to
be very much afraid of giving their foxes too much common salt,
and it would not be surprising if this fear led c casionally to a
deficiency of sodium. It might be a go<xl plan to leave the solution
of this question to the fox itself, by placing in each pen a lump of
rock salt.

A human subject restricted to the articles which have Ijeen
actually used in feeding foxes would stand a considerable chance
of being attacked by scurvy. The only fcxjdstuflfs in the list
already given, which contain the "anti-scorbutic" vitamine, are
milk, which is not particularly rich in it, and probably apples.
Scurvy is a disease from which flesh-eating animals are not positively
known to suffer; it is none the less possible and indeed likely that
they require for the maintenance of perfect niitrition a supply
of the antiscorbutic element present in green vegetables, fruits,
and many tubers. If such a requirement does actually exist, it is

in most ranches rather imperfectly met. Although apples are fed
liberally in certain of the more successful ones, in the majority
they are used very sparingly if at all. There is much to Ije sai<l
for their regular inclusion in the diet.

After this general discussion of feeding practice in the fc;
industry it remains to consider which, if any, among the actually
prevalent sources of damage or loss may Ik* in whole or in part
the consequence of imperfect nutrition. The list of reporteil
complaints in which a nutritive defect of some st)rt may with reason
be suspected to lie a factor is, as a matter of fact, quite large. It
would include, e.g., rickets, lonvulsions, sore eyes, still births, the
abandoning or even the killing and eating by the mother of her
young, premature cessiition of milk supply, early death of the young,
failure to grow, failure t«) reprcxlucc, and imperfect development
of fur.

During recent years there have Ix'cn ronductetl in different
lal)oratories a great variety of experiments in which rats, guinea
pigs, swine, or other animals have been subjectetl for longer or
shorter peric.'s to the influence of variously restrictetl diets.
Among the results of these experiments one may find, singly or
in various combinations, every one of the abnormal conditions
just mentioned. This does not necessarilv mean that these arc
always to Ik; attributed to a dietary factor. The habit of killing
and eating the young, for example, may Ije merely a vice, inherited
or acquired, in which case there is nothing to be done but to destroy
the animal. What the experiments referreti to demonstrate is
that this, and the other conditions named, may be, and doubtless
often are, the consequence of improper feeding. It is probable
that most of them would become much less common if the foxes
could be assured a diet which supplied continuously each and all
of the factors essential to perfect nutrition.

Incidentally it may be pointed out that we do not know
definitely the normal duration of lactation in the fox, nor its
normal growth curve. These furnish problems that .should not be
forgotten in any experimental study of the growing fox's nutrition.

III. Further Cons!dkr.\tioxs Affectino the Returns of

THE I>fDUSTRY.

The problem of reaching and maintaining a maximum return
involves more than the successful rearing to maturity of every
fox that may happen to l)e } rn. It is of equal importance that
the number born should be as great as the nature of the case
makes possible. This implies that in any complete study of the
problems of fox-raising questions of fertility and fecundity must
be taken into account. These are undoubteilly in part q;:«stion8
of nutrition, but other factors— hereditary, psychical, climato-
logical, etc.,— are also in varying degrees involved, and it would
be desirable to have their relative importance more exactly eluci-
dated.

A not irrelevant ,|iiestion is that of proper age fcr the first
reproductive effort of the adolescent am. i.kl. It has l)ecome the
practice to mate the foxes selected for breeding purjxises at the
earliest possible moment, that is, in the winter following their
birth, while they are yet less than a year old. It is very doubtful
vhether this is a practice to be recommended, and it should Iw
cinsidered whether it would not in the long run Ite more economical
to postpone mating till the animals reach their second w inter. A
series of co;iiparative tests might be plannetl to throw light upon
this problem.

Again, mere numbers is not enough. The final aim of the
fox-'" idustry is the production, not sa much of perfectly nourished
and healthy animals, as of valuable pelts. These are by no means
necessarily the same thing. A red fox may be physiologically as
perfect an animal as it is possible to conceive- in the market value
of its fur it may be far surpassed by a pure-bred silver fox exhib-
iting the worst deformities of rickets. The fox in captf.ity is
bred in short for certain special characters, and a failure to present
these in perfection is as definitely a source of loss to the owner,
as eariy death from malnutrition. Beside the fundamental
problem of nutrition we must place therefore the fundamen::al
problem of breeding and inheritance. The more important
aspects of this problem, as related t<j the fox industry', will be
discussed in another publication of tho Research Council.

IV. Recommendations.

The preceding [taraKriphs have indicated the existence, in
connection with the fo\-hreeding industry, of a large \a;:?*y of
unsolved problems. Tneir final solution nust await the outcv^n^e
of appropriately planned experiments. The information collected
is however already sufficient to suggest certain improvements in
existing practice. These may for conven'ence be thrown together
here in the form of recommendations addressed to the fox-breeder.

1. An endeavour should be made to supply in the diet more
fat, a certain amount of green vegetables, and especially more
milk, the fat of which ought not to be removed. A special
endeavour should be made to feed milk during the winter, in which
attempt the ix)ssible usefulness of whole milk powder should be
remembered. The winter diet should also contain liberal amounts of
tripe, liver, and eggs. Raw apples should be fed whenever it is
possible to obtain them, as well as, if they prove acceptable to the
foxes, raw potatoes or turnips.

2. A lump of rock salt should be placed in each pen.

3. The adult fox-.^s should I)e treated for worms in the fall,
and an endeavour should be made to exterminate all eggs in the
pens before mating takes place.

4. All wild or domestic animals should be rigidly excluded
from the neighbourhood of the pens.

5. Each ranch should maintain a small quarhntine station
and isolation hospital.

6. Cold storage plants should be provided for the different
sections of the island, and provision should be made for the
careful inspection of all meat fed to foxes.

7. It would probably be wise to abandon the practice of mating
young foxes ai ^heir first year of life.

8. The fox-breeders should form an association for the regis-
tration of their valuable animals, and each should maintain a

ontinuous record of the actual performance of its stock.