Nutritive Diversity and Change
of Forage Plants for Deer
Case Study by Formosan Sika Deer (Cervus nippon taiouanus) in Dry Tropical
Forest in Taiwan
Distribution of Sika Deer
Sika Deer (Cervus nippon) has 13 subspecies in Asia and distributes from
Ussuri district of southeastern Siberia, Manchuria, Korea, eastern and southern China,
northern Viet Nam, Japan, Ryukyu Islands and Taiwan indigenously (Nowak 1991). In
addition, the Sika Deer are also introduced to many countries including Austria,
Czechoslovakia, Denmark, France, Germany, Poland, New Zealand, Great Britain, Ireland,
South Africa and USA (Corbet and Hill 1992). The largest native range of Sika Deer
is the South China, which had continuous range in eastern China from the Yangtze
basin south to northern Kwangtung. In the 19th century, it was not uncommon in a
district of the lower Yangtze including the basin of Poyang Lake (the second lake
in China). From this area the deer were named over a number of different "species"
(Common Name) based on individual variations in the intimate structure of the teeth
and in the form or degree of divergence of the antlers. This multiplicity of local
names gives us idea of the variability of the characters of this deer.
Shape and Size
Sika Deer has medium size between roe and red deer, and similar to fallow deer.
Based on the introduced populations in Maryland, US and England, UK: head and body
length is about 950-1400 mm, tail length is 75-130 mm, and height at the shoulder
is 640-811 mm (Nowak 1991). Males average 8.7% larger than females. Average weights
of dressed carcasses are 32.7 kg for males and 26.2 kg for females. The antlers
are narrow and erect, have 2-5 points each, and measure about 300-600 mm. The winter
coat is gray to almost black with spots at very close quarters. Summer coat is
usually chestnut red to pale yellow with pale but distinct white spots.
Habits
Usually associated with dense woodlands and scrubby vegetation. The Sika Deer prefers
forested areas with a dense understory, but it also adapts well to a variety of other
habitats. They appear to achieve their highest densities in habitats providing an
intimate mix of open field and dense woodland offering numbers of edges between forest
and grassland. They are opportunists and will apparently favor dense thickets whatever
the species composition. Activity occurs primarily at dusk and dawn but may also
be active during the daytime. The species is highly adaptable in diet, being predominantly
a grazer or sometimes a browser on trees and shrubs.
Mating occurs in Sept. and Oct, and the births usually in May and June. Females
are polyesterous. After the 30-week gestation, there is usually a single young weighing
4.5-7.0 kg. Weight increases until the age of 4-6 years in females and 7-10 years
in males (Nowak 1991).
Review of Formosan Sika Deer Status in Taiwan
Formosan Sika Deer (Cervus nippon taiouanus) is a Taiwanese endemic subspecies,
and the only extirpated deer in the Taiwan wilderness. They were once widespread
and abundant over the island of Taiwan. About 300-400 years ago it occur in the
plains and low hills below 300 meter in altitude. Because deer had an important economic
value and had been traditionally utilized in many ways, in the early history of development
in Taiwan, the migrants and indigenous people hunted deer for food and by-products.
In the late 1800's , as many as 50,000 Sika Deer skins a year went to Japan (Kano
1940), and the deer exports once peaked at 100,000 pelts per year (Kuo 1994). After
World War II, the native habitat was destroyed and fragmented by expanding agriculture
and development. By 1969 the combination of severe exploitation and habitat degradation
led to the extirpation of Sika Deer in the wild (McCullough 1973), and the survival
deer were left in captivity for exhibition and economic use. Since that, the Sika
Deer were delisted from the wildlife category in Taiwan government and treated as
a cattle.
METHODS
In 1982, there was a re-introduction project for Formosan Sika Deer in Kenting National
Park, Taiwan. Because in this recovery project, deer population will not be controlled
by predators and human harvest, the food supply in quality and quantity will almost
affect the deer numbers. A successful re-introduction project here may be primarily
judged by increasing population size over time, and a well self-sustainable and healthy
population in the wild.
We studied the food plants and its nutritive values of Sika Deer as part of the
recovery project. From April 1993 to Sept. 1994, we observed the spatial selection
of habitats and feeding habits in the Area I of Sheting re-introduction park, Kenting,
Taiwan. Each month we chose 3-6 days to observe the feeding behavior and the location
of Sika deer in the daytime (from 6 am to 6 pm), and once per month we observed deer
throughout the 1.5 year. Totally we recorded 45 deer-times, and 180 feeding hours
excluding the rest or roost periods.
Besides, we conducted a nutritive value survey testing of heat energy (kcal/kg),
protein (%), and ADF (acid detergent fiber) for certain essential forage and shelter
plants. Samplings in summer and winter were collected in Aug.1993 and Feb.1994 respectively.
The nutritive examinations were done by nutrition analysis lab in National Husbandry
Test Center in Taiwan.
RESULTS
Nutritive Change and Diversity in the Forest
We observed the favorable and unfavorable forage plants by deer browsing, and analyzed
its nutrient contents (Table 1).
Nutritive Change between Summer and Winter
1. In heat energy, most summer forages were better than winter. The only exceptions
were a4 and e1(fig 1).
2. In protein, , most summer forages were better than winter. There were exceptions
of a1, a6 and d1(fig 2).
3. ADF method is to estimate lignified nitrogen, lignin and cellulose by extracting
plant tissue with strong acid solutions. ADF method is also widely used as an easy
method to measure the fiber in a feed (Van Soest 1982). In ADF testing, the plants
in early autumn (Aug.1993) had more fiber content than spring (Feb.1994) (fig 3).
Nutritional Differences of Forages
1. The rich-energy forages were a33 (unfavorable acacia, predominant vegetation),
d1 (unfavorable citrus, native fence tree), a1 (much favorable, especially leaf and
fruit, exotic and neutralized legume as fodder plant), a15 (unfavorable mahogany,
native fence tree), and d18 (unfavorable verbena, shelter shrub). The poor-energy
forages were a4 (favorable mulberry) and c14 (favorable in specific season) (Fig
4).
2. The rich-protein forages were a1 (much favorable legume), a33 (unfavorable acacia),
d18 (unfavorable verbena), a41(unfavorable sandalwood), and d1 (unfavorable citrus).
The poor-protein forages included grasses (f1, f2) (Fig 5).
3. The rich-fiber (ADF) forages were e49 (unfavorable agave, exotic fiber plant as
cable raw material in World War II), c9 (favorable spurge vine), e38 (unfavorable
lily), a15 (unfavorable mahogany), and grasses (f1, f2). The poor-fiber forages
were a1 (much favorable legume), a4 (favorable mulberry), a6 (favorable loquat) and
c17 (favorable dog bane) (Fig 6).
4. Most plants in our survey had energy content from 3.6-4.2 kcal/kg, and protein
content from 7-15% (Fig 7).
DISCUSSION
Nutritive Storage
Forage quality or digestibility varies between plants, seasons, and locations (Klein
1962). The effective factors are climate (light, temp, moisture), soil quality,
species variation, and terrain difference (exposure, altitude, slope). There was
a positive correlation between nitrogen (protein) content of forages and their nutritive
quality, while a negative correlation exists between fiber content and nutritive
quality. Both nitrogen (protein) and fiber are reliable indicators of forage quality
(Klein 1965).
Basically, the deer favorable forages tended to have higher energy or protein, and
have less fiber content. On the other hand, the unfavorable forages tended to more
fiber which deer avoid browsing them. We found, for some reasons, deer didn’t feed
the rich-nutrient (energy or protein) forages as we supposed. Those plants almost
had a somewhat strong taste (e.g. d1, a15, a41) or certain defensive substances (e.g.
d18, a33)(table 2).
Nutritional Change
Nutrition of deer forages varies with physiological states and developments of forage
plants. Even though seasonal change of nutrients in tropical Taiwan was not so obvious,
we deduced that new growth in early summer had more heat and protein content than
matured leaves in winter, because young leaves accumulated both in protoplasm to
grow, and in winter or dry season, forage tended to have the low nutritive value.
In summer or wet season, the forage yield was maximum, and the nutritive values
were higher. In fall, the leaves predominated hydrolysis, increased fiber and lignify
the cell wall, so the ADF value was increasing in Aug.
Defensive Substances against the environment
The resistant substances of plants include lignin, cutin, and secondary compounds.
The function of those substances is to resist to wind, disease, and herbivore's
browsing. They reduce the nutritive value of the forage plant (Van Soest 1982), and
avoid deer’s over-browsing as to reserve their essential resource for plant growth
and reproduction
Secondary compounds, such as alkaloids, glycosides, saponins, tannin, terpenes,
phenols, etc., have a clear defensive rather than metabolic role. They have a metabolic
source and are often stored in fresh and vulnerable tissues that have not be defended
by physical structures like lignins and silica. Secondary compounds may always have
a greater effect on browsers (e.g. Sika Deer in Kenting) than grazers, because of
its high concentration and local distribution in plant parts (Table 2). For example,
wood plants and vines tend to be more highly defended towards browsers. (Bryant 1991)
About secondary compounds:
Alkaloids
Alkaloids is the heterocyclic nitrogenous compounds that exhibit the inhibitory activity
towards digestion. In our study area, there were certain rich-alkaloid plants: a1
(much favorable), a23 (favorable), and d18 (unfavorable). Although d18 (verbena)
also had better protein and heat content, but deer seemed to merely treat it as the
shelter plant and didn’t feed it. Sometimes the specific d18 fruit attracted deer
to browse it, but deer always took attention to prevent foraging the other parts.
We believed the reason might be its bitter taste from alkaloids, glycosides and
saponins. By the way for a1 and a23, it is interested how the deer digestion system
with its rumen microbes adapt to absorb the nutrients with high alkaloid contents
in physiology and behavioral ecology.
Essential oils
Essential oils represent a diverse group of organic substances in plants that
are volatile and soluble in organic solvents. They have low molecular weight such
like ester, ether, phenols and terpenes and also exhibit antimicrobial activity.
When those plants are browsed, rumen organisms would change or make some adjustments
(Schwart 1980).
Legume (e.g. a1) is the essential forage for deer either in the captivity or in the
wild. Legume also has widely terpenoid throughout the plant body, which includes
saponins and steroids (table 2) and would be somewhat toxic, although rumen bacteria
might have ability to partially detoxify them. Some terpenoids also have potential
to cause stable foam formation and to promote RBC hemolysis (Van Soest 1982).
We observed deer primarily fed much a1 legume either in dry or wet season, and obtained
highly energy and protein contents from this quality forage. Deer may regulate the
intake amount with different feeding patterns and behavioral controls to avoid its
overdosed terpoid toxicity.
Tannin
Tannin may be effective as toxins, rather than a defensive compound by its protein
precipitating ability (Robbins 1987). Because of the high content of tannin in a33
(acacia), Sika Deer didn’t browse this predominant vegetative plant even though it
was high in energy and protein contents. In addition, other forages with more or
less tannin content might be browsed in a limited dose (a23, d3), or avoid tasting
the highly protective plant parts with tannin, such as a1 bark and a6 fruit (table
2).
Literature Cited
Bryant, J.P. et al. 1991. Interactions between woody plants and browsing mammals
mediated by secondary metabolites. Annual review of ecological systematics 22:431-436.
Corbet, G.B. and J.E. Hill. 1992. The mammals of the indomalayan region: a systematic
review. Oxford Univ. Press. NY. 255p.
Faix, J.J. 1974. Ph.D. Thesis, Cornell Univ., Ithaca, NY.
Kano, T. 1940. Zoogregraphical status of Tsugitaka Mountain of Taiwan Shibusawa.
Inst. Ethnogr. Res., Tokyo. 145p.
Kuo, Guol-way. 1994. The study of field behavior and habitat use of Formosan Sika
Deer (Cervus nippon taiouanus). M.S. thesis. National Taiwan Normal University,
Taipei, Taiwan.
Klein, D.R. 1962. Rumen contents analysis as an index of range quality. Trans N.
Am. Wildlf Conf. 27:150-62.
Klein, D.R. 1965. Ecology of deer range in Alaska. Ecol. Monogr. 35:259- 284.
McCullough, D. R. 1974. Status of larger mammals in Taiwan. Tourism Bureau, Taipei,
Taiwan, R. O. C. 35p.
Nowak, R.M. 1991. Walker’s Mammals of the World. 5th Eds. Volume II. Johns Hopkins
Univ. Press. Baltimore and London. 1379p.
Robbins, C.T. et al. 1987. Role of tannins in defending plants against ruminants:
reduction in protein avaiability. Ecology 68(1):98-107.
Schwart, C.C., et al. 1980. Juniper oil yield, terpenoid concentration and anti-microbial
effects on deer. Journal of Wildlife Management 44(1):107-113.
Schwart, C.C., et al. 1980. Deer preference for juniper forage and volatile oiltreated
food. Journal of Wildlife Management 44(1):114-120.
Van Soest, P.J. 1982. Nutritional ecology of the ruminant: ruminant metabolism, nutritionak
strategies, and cellulolytic fermentation and the chemistry of forages and plant
fibers. Cornell Univ. Press.137p.
Table 1. Plant list in nutritive
tests
(Nutritive test date: S=summer samples in Aug. 1993; W=winter samples in Feb. 1994)
(ID, scientific name, test date, browsing amount, common name of the forage plant)
Trees
a1. Leucaena glauca (L.) Benth. (leaf, fruit) W,S ++++ legume
a2. Macaranga tanarius (L.) Muell.-Arg. W,S +++ spurge
a3. Pittosporum pentandrum (Blanco) Merr. W,S ++ (Pittosporaceae)
a4. Broussonetia papyrifera (L.) L'Herit. ex Vent. W,S +++ mulberry
a6. Eriobotrya deflexa (Hemsl.) Nakai W,S ++ rose - loquat
a8. Trema orientalis (L.) Blume W,S + elm
a15. Aglaia formosana (Hayata) Hayata W - mahogany
a23. Terminalis catappa L. W ++ (Combrefaceae)
a31. Ficus wightiana Wall. ex Benth. W + mulberry - ficus
a33. Acacia confusa Merr. W - legume - acacia
a41. Champereia manillana (Blume) Merr. W + sandalwood
a43. Bambusa dolichoclada Hayata W + bamboo
Vines
c1. Ipomoea obscura (L.) Ker-Gawl. W +++ morning glory
c3. Passiflora suberosa L. W,S ++ passionflower
c4. Trachelospermum gracilipes Hook. f. W ++ dos bane
c7. Gymnema alternifolium (Lour.) Merr. W +++ milkweed
c9. Mallotus repandus (Willd.) Muell.-Arg. W ++ spurge
c12. Merremia gemella (Burm. f.) Hall. f. W ++ morning glory
c14. Piper kawakamii Hayata W,S + (Piperaceae)
c15. Parsonia laevigata (Moon) Alston W + dog bane
c17. Trachelospermum jasminoides (Lindl.) Lemaire W + dog bane
Shrubs
d1. Murraya paniculata (L.) Jack. W,S - rue / citrus
d3. Ardisia cornudentata Mez W + (Myrsinaceae)
d4. Pandanus odoratissimus L. f.
var. sinensis (Warb.) Kanehira W + (Pandanaceae)
d18. Lantana camara L. W - verbena
d28. Hibiscus taiwanensis Hu W - mallow
Herbs
e1. Hypoestes cumingiana Benth. & Hook. W,S ++++ acanthus
e2. Stachytarpheta jamaicensis (L.) Vahl. W + verbena
e38. Ophiopogon formosanum Ohwi W + lily
e47. Lygodium japonicum (Thunb.) Sw. W ++ fern (Schizaeaceae)
e49. Agave sisalana Perr. ex Enghlm. W + agave
e51. Cyperus alternifolius L.
subsp. flabelliformis (Rottb.) Kukenthal W + sedge
Grasses
f1. Miscanthus floridulus (Labill.) Warb.
ex Schum. & Laut. W,S +++ grass
f2. Imperata cylindrica (L.) Beauv.
var. major(Nees)Hubb.ex Hubb. & Vaughan W,S ++ grass
Table 2. Distributions of second compounds in deer
forage plants in Taiwan
(plant parts: lf=leaf, fr=fruit, sd=seed, bk=bark,al=all plant, rt=root, st=stem)
ID, (secondary compounds class), distributed parts - specific substances, local concentration (if available)
Trees
a1 (alkaloids)lf,fr-mimosine, leucenol (saponins)lf sd-sitosterol4.6% (tannin)bk6.25%
sd lf
a3 (saponins)al-hederagenin,barrigenol (tannin)al 0.4% al-edergenin
a6 (glycosides)lf,sd-amygdalin1.4% (saponins)lf sd (tannin)lf fr 0.17% (others)
lf-As 0.012%(fresh);0.022%(old) fr-pectin 1.03% sd-HCN 0.004% fr-Na, K 0.22%, Fe
0.02%
a23 (alkaloids)al,fr-trigonelline (tannin)al bk 6.26% rt 7.77% (others)al-Mg(much),
K(rare,3.87%) al-phytosterol fr-glucosazon, pentosan al-pyridine 0.1%(K salt,
etc)
a31 (glycosides)lf-flavonic glycoside, coumarin (others)rt,st-phenoid
a33 (tannin)al:5-16%(age=10-30 yr)
Vines
c1 (glycosides)sd-pharbitin 2.0%, gibberellin glucoside 7%
c3 (others)al-theine, leucodelphinidin
c4 (glycosides)al (others)al-acetamide, inositol dimethyl ether,arctin
c7 (others)al-sarcostin,metaplexigenin,benzoylramanone,deacylcynanchogenin,utendin,pergularin,lanoxin
c14 (others)al-piperidine, piperidene, futoenone, futoxide
c17 (glycosides)al-flaronglycoside (others)al-lanoxin, tracheloside, acetamide,
inositol dimethyl ether, arctin, metairesinoside
Shrubs
d1 (others)bk-mexoticinlf-isopentyl limettin, exoticin, heptamethoxy flavone, cadinene,
flavone, coumarin, engenol, imperatorin, murralogin, meranzin, imurrangatin, noracrolnlcine
d3 (tannin)al (others)al-bergennin, querectin, myricitrin
d4 (others)lf-phenol
d18 (alkaloids)al (glycosides)al-lanoxin (saponins)al (others)al-flavoid
d28 (glycosides)fl-anthocyanin,f lavonic glycoside
Herbs
e2 (glycosides)al (others)al-phenol 0.0028%
e47 (others)al-phenol
Grass
f2 (glycosides)al (others)al- K 0.75%