Introduction
There are numerous factors which must
be considered in designing optimal feeding
programs for any animal. There are no cut and
dried rules, especially when dealing with
species which have beenraised in captivity for
under two decades. Deer are quite different
from other more familiar domestic ruminants
in both their nutritional requirements and their
response to nutritional stress. This pamphlet
will present basic principles of cervid physiology and nutrition in order to clarify some of
the differences between them and domestic
species. Given this information, the approach
to feeding your deer can be done from a more
insightful perspective. Whenever possible
information specific to fallow deer will be
included, but most researchhas been done on
free ranging species; i.e.. white-tailed deer,
red deer and caribou. These sources,plus
extrapolation of cattle and sheep nutritional
principles, in conjunction with knowledge of
the biology, feeding behaviour and physiological characteristics of deer, have been used to
compile the following information.
Economic loss
Probably the most significant economic
losses on deer operations apart from trauma
associated with handling, are related to nutritional mismanagement. These problems often
arise from a lack of understanding of the
unique seasonalmetabolic adaptations and
nutritional requirements of deer.
Natural diets
c
c
~
It is importlnt to keep in mind the
botanical complexity of the diet of free ranging
deer. Plant availability, and nutritional value
of the plants vary considerably throughout the
year. In the wild, deer range over a large area
to choose the optimal nutritional combination.
This situation is in marked contrast to farming,
which involves limited speciesof plants and
usually one species of herbivore harvesting and
competing for what it needs. Deer are both
browsers and grazers. Fallow deer, if not
overstocked, will preferentially consume a diet
of75 to 90% grassesand forbes (leafy weeds),
leaving only 10 to 25% of the diet as browse.
This is so even though in the spring, leaves
and twigs have a higher digestible energy (DE)
and digestible protein (DP) than forbes or
grasses.
In general,deerhavethe ability to
digest higher fibre diets than do domestic
ruminants. This seemsto be a function of the
larger relative size of the omasum (the
forestomach compartment which grinds coarse
roughage).
Survival
What is it that allows fallow deer,
originally from the Mediterranean region, to
acclimatize successfully to a much more severe
Canadian climate? They have a remarkable
capacity for adaptation. Winter survival provides the most dramatic example of this adaptation. Temperate deer species are recognized
to undergo photoperiod and temperature mediated physiological changes.
Winter
Deer in winter are lesswell adaptedto
suddendeteriorationof climatic conditions
thancattle or sheepbecauseof their reduced
metabolism. Deerthyroid gland activity
(which mediates basal metabolic rate) decreasesduring cold weather. (It increases in
other ruminant species). This creates a physiological state similar to hibernation, but of
course much less extreme. Activity decreases
dramatically from summer ~d autumn levels.
Deer seek shelter and reduce foraging activity
to conserve body energy reserves during
winter. There is a 40 to 60% reduction of
voluntary feed intake during winter with
respectto maximumspringfeeding! The net
Publishedwith the support ofthe Saskatchewan
Agricluture DevelopmentFund
GF-F-3-01
energy required for maintenance, is lowest in
January. Increased energy demands such as
physical disturbances or lack of shelter at this
time are potentially very detrimental. Wind
and wet can also have a detrimental effect and
increase energy needs.
Spring
Metabolism begins to increase in
March, in response to increasing daylength.
By this time body reserves have been depleted
so the deer are more vulnerable than ever to a
negative energy balance. It is therefore towards the ~ of winter, that deer on a low
energy diet, exposed to a cold spell or a late
winter storm, are more likely to die than
during a cold spell in January. Emergency
feeding of starving deer at this time usually
cannot stop deaths becauseof the total depletion of theIr energy and protein reserves.
With this infonnation in mind, one can
appreciate that good summer and autumn
nutrition are critical for winter survival. Even
though deer experience winter anorexia, it is
still valuable to offer high energy winter supplement. This will help reduce energy wasted
on foraging and trying to get nutrition from
high fibre roughage. Also, if deer are known
to be somewhat down in condition, the provision of good wind and rain shelter will help
prevent winter death losses.
Reproductive Performance
Earlier pamphlets have given target
weights at various ages and times during the
annual cycle. These are weights at which farm
managers can be assured that they are approaching maximal productivity. Puberty
occurs in fallow deer at about 28 kg. Although
they are theoretically able to breed at this
weIght, production records show that to
achieve conception and fawning rates of over
75% for yearling does, pre-rut weights should
be at least 38 kg. The mature does should be
42 to 50 kg and have weaning rates of over
90%. Competent nutritional management
helps reach these goals. As in domestic ruminants, late gestation demands a high plane of
nutrition. Unlike domestic ruminants, deer
tend to sacrifice fetal growth to maintain their
own body condition if undernourished. In
contrast, cattle and sheepdevelop 'pregnancy
toxaemia', a life threatening metabolic disease,
in order to maintain fetal growth! In deer
therefore, poor nutrition will show up as
increased numbers of stillbirths and high
perinatal mortality, even though the does
may not appear to be in poor condition.
GF-F-3-02
In spring in the prairiesnutritional needsof the deer
may exceedpastureavailability if green-upis late.
Supplementswill beneededin thesecircumstances.
There may be more subtle effects of
nutrition on maternal behaviour. According to
studies on red deer in Scotland, mismothering
is much more likely to occur in poorly fed
females.
Undernourishment during a single
summer can effect the entire herd for a several
years. Does that are underweight at breeding
time may not conceive. These relationships
are illustrated in the pamphlet GF-F-2 "Maximizing your fawn crop". Even if they do
conceive, their fawns will be born light, as a
direct relationship between maternal weight at
breeding, and fawn weight has been shown.
The birth weight of fawns is directly related to
survival, and to weaning weight. A single
kilogram of increased weight at birth can lead
to 3 or 4 kg increase at weaning. The heavier
the weaning weight, the heavier the female
fallow deer will be at 15 months of age, and
therefore the more likely to conceive -and of
course, the heavier she is at breeding time, the
higher the chancesof conception, and the
higher the weight of her fawn the next summer, and so on and so on.
Feeding the bucks
Mature bucks have high spring and
summer nutritional demands to make up for
the cumulative weight loss which would have
begun the previous rutting seasonand continued throughout the winter. Beginning in
spring, bucks also invest large amounts of
energy in antlerogenesis. Th~ size of antlers
dependsa great deal on nutritional factors.
Winter feed restriction does not affect antler
size provided unrestricted feed is available
during the growth phase. Mineral requirements for antlerogenesis are almost equal to
those of lactation. Twenty to 40% of the
mineral required for antler growth comes from
mobilizing skeletal reserves, as the best diet
can only provide 60 to 80% of whatis re-
quired.
The following tables give the approximate dietary energy and protein requirements
for deer. These values can be used by feed
companies to formulate balanced rations for
your deer. The energy units are given in
megajoules.
Feeding for Growth
Preweaning growth rates of fallow
fawns have been measured at 175g/d for
bucks, 150g/d for does. These rates can be
30% lower if the dams are not receiving top
quality feed to meet lactational demands.
Fawns should be onto their supplemental feed
by late summer in order to minimize the stress
associatedwith weaning. A creep feeder
systemcan be built to exclude the does, bucks
and yearlings, while preparing the fawns for
winter with preferential feed. Prof Dr. Herman
Bogner's design in Yon Kerckerinck's book
'Deer farming in North America', has creep
openings of 18 cm wide X 59 cm high for
fallow fawns.
Even though weaners should have
supplemehtary feed all winter, their protein
requirements are rather low, dropping from the
spring/summer level of 18%, to about 12%.
Over-winter growth rates fall significantly to
FALLOW DEER
Daily Metabolizable Energy (ME ) Requirements in megajoules (MJ)
NOTE: thesefigures are calculatedfor animals in New Zealand. They may behigher in winter in colder
regions of Canada,or when wet windy conditionsprevail
Fall weight (kg) Autumn
Winter
Spring
Summer
Maturedoes
45-55
12.9-15
13.9-16.1
15.8-17.5 21.6-23.4
Maturebucks
85-105
20.7-24.3
19.6-23.0
20.3-24.1 20.3-24.1
Young does
18
9.7
10.4
11.3
11.3
Yearling does
38
11.3
13.1
15.2
20.7
Yearling bucks
47
13.3
15.4
16.0
15.0
DatafromJL. Adam1988 Growth. In: ProgressiveFallow Farming.
AllenJL. & G.W.Asher (eds)Ruakura.New Zealand.p. 51
"" -"-
GF-F-3-03
50 and 25g/d for buck and doe fawns respectively, given an adequatediet. This is related
to the numerous physiological events discussed
in the introduction of the pamphlet. Extrapolations from other deer species indicate the ME
requirements (MJ) for young fallow deer over
autumn, winter and spring/summer are approximately 70, 80 and 90% of that required
by the mature animals
in spite
smaller
SIze. of their
-
receivingadequatenutrition!
Minerals and vitamins
We have not addressedthe topic of
mineral and vitamin needs, but they should not
be forgotten. In most cases,these needs can be
met by usin~ the same figures as would be
seenin a dairy ration. There are however a
coupleof exceptions.
Deer are flighty, and
somewhatsuscepti-
In the autumn,
weanling deer have
less than 4% body fat
(steers have 12%,
lambs 18%). The
best way to prepare
them for winter
seemsto be with prerut weaning. The
weaner mob would
be exposed to less
social stress associated with rutting
activity, and they
would have less
competition for feed
than if run with the
adults. An added
advantage of pre-rut
weaning is that the
does have several
weeks after lactation
to maximize their
pre-rut weight.
It is well known that deer, regardless of
feed availability, have variable feed intake
according to seasonalinfluences, resulting in
great changes in body growth and condition.
For young deer in which the goal is to maximize growth over the fIrst 15 to 17 months,
i.e.. by puberty, managers must attempt to
avoid any winter weight loss or even a sustained slow-down in growth rate. Even though
deer have a tremendous capacity for compensatory growth over the spnng and summer
period, young deer which experienced nutritional stress during their fIrst autumn and
winter, never catch up in size to those which
did not suffer a deficiency.
During the autumn, fawns lay down fat
deposits to ensure winter survival. They
compensate for inadequate nutrition by stunting growth. Because of this, necropsy findings
of moderate fat deposits found in small fawns,
does not necessarily mean that they were
GF-F-3-04
@
recycled
paper
ble to capture myopathy if not handled
with care. Dr. Duane
Ullrey's research at
Michigan State has
shown that high
levels of vitamin E
can play an important role in protecting deer from this
affliction. Current
recommendations
are for a minimum
of 200 international
units of this vitamin
per kg of feed. This
does mean an increased cost for the
ration, but a single
preventable death
will more than
override any savings.
A mineral supplement of some sort must be offered. For instanceoats and hay in Canada are very low in
copper levels, and a suitable mineral will
prevent problems from deficiency of this and
other essential trace minerals.
References
1. Denholm,L.I. 1984. Nutrition of farmeddeer.
DeerRefresherCourse. The Post-graduateCommittee
in VeterinaryScience,U. of Sydney. Pp 662-707
2. Hofmann,R.R. 1985.Digestive physiology of the
deer.In: Biology of DeerProduction,The Royal Society
of New Zealand.Bulletin No. 22. pp.393-408
3. Loudon,A.S.I., Milne I.A. 1985.Nutrition and
growth of youngred deer.In: Biology of DeerProduction, The Royal Societyof New Zealand.pp. 423-427
4. Yerex, D., Spiers,I. 1987.Modem DeerFarm
Management.AmpersandPublishingAssociatesLtd.
Catterton,New Zealand. pp. 49-68
Photocredits:J. Smits