Antlerogenesis - PowerPoint PPT Presentation
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Antlerogenesis
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One of the fastest tissue growth rates. Only other tissue that rivals this rate is some cancers. ... There is no way to predict quality of antlers. ... – PowerPoint PPT presentation
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Title: Antlerogenesis
1
Antlerogenesis
- How Antlers Grow
- Original Power Point Created by
- Andy Harrison
Modified by GA Agriculture Education Curriculum
Office July 2002
2
Nature of Antlers
- One of the fastest tissue growth rates
- Only other tissue that rivals this rate is some
cancers. - Has led to interest by the National Cancer
Society
3
Nature of Antlers
- Modified bones
- Structurally similar to normal bones
- NOT horns
- Horns are permanent structures that never shed
and are never replaced. - Antlers are temporary structures found only in
the deer family (Cervidae).
4
Nature of Antlers
- Begin to develop early in a bucks life
- Fawn bucks have small bony projections at a few
months old. - In order to produce antlers, there must be a
permanent base to grow them. - Located on frontal bones of skull called
pedicels
5
Nature of Antlers
- Fawn bucks rarely produce more than a small set
of pedicels. - Often called nubbin or button bucks
- During first 12 18 months, there are
physiological changes that cause antlers to
develop.
6
Nature of Antlers
- Function like any other bone
- Begin with the development of a protein framework
- Composed primarily of cartilage covered by skin
on the frontal portion of the skull - The skin contains small hairs that give the
velvety appearance - Amount of protein in diet very important for
growth
7
What Makes Antlers Develop
- Blood testosterone levels peak in rut
- Another smaller spike occurs just prior to time
of antler growth initiation - Not as dramatic as in rut period
- Brain response to longer day length may cause
spike. - An increase in serum testosterone levels changes
behavior
8
What Makes Antlers Grow
- Development begins almost immediately after
shedding of old antlers. - Scars quickly heal over - new buds appear within
couple of weeks. - Growth is slow at first.
9
What Makes Antlers Grow
- Bucks are typically in poor condition after rut
- AKA Post Rut Mortality
- Usually spend the spring season replenishing body
losses - Minimum of 16 protein needed to produce the best
antler growth - After body losses are replenished, focus is on
antlers
10
What Makes Antlers Grow
- Appearance is coded in some part of the brain
- Nervous system directs the building of antlers
- Growth progresses from tip of antler bud
- First formed as cartilage
- Later replaced by hardened bone
11
What Makes Antlers Grow
- During time of growth, bucks travel in social
groups of various numbers - If psychologically neutered at this time, bucks
are aware of size of developing antlers of other
bucks - May affect social hierarchy
- Social position may be affected by size of antlers
12
Antlers
- Bucks cannot shed summer coat until antler growth
is complete. - A grayish winter coat grows in as summer coat
sheds.
13
Antler Changes
- Just prior to pre-breeding period
- Soft framework of antlers begins to mineralize
- These minerals (calcium and phosphorous) were
deposited during the previous growing season.
14
Velvet Shed
- Some believe that a formation of a burr at
base of antlers shuts off blood supply. - Others believe that the depositing of minerals
causes hardening of arteries which cuts off
blood supply. - Velvet dies from lack of blood supply
- The actual reason may be a combination of both.
15
Velvet Shed
- The entire process takes only a few hours.
- Death shedding produce large quantities of
blood from blood vessels. - This stains the antlers to produce their
characteristic color. - Additional staining arises from rubbing on
vegetation.
16
Antlers
- Once velvet sheds, the buck rubs its antlers.
- Rubbing is influenced by hormones and from the
itching of dying tissue. - Remaining antlers are non-living tissue.
17
Antlers
- Many times portions are broken off in fighting.
- As rut progresses, testosterone levels decline.
This is due to - breeding
- physiological changes
- Dominant bucks are usually first to shed.
18
Antler Shed
- Abscission layer then forms at base, which cuts
off blood flow. - Related to dropping or depletion of testosterone
- Occurrence of antler shed depends on time of year
when rut ends.
19
Antler Growth
- Development of the antler bud is consistent in
all areas of country from March 15 to April 15. - By mid-May the antlers extend well above head.
- Brow tines develop in June.
- Each tine is developed before another pair
reaches completion.
20
Antler Growth
- In July ornamentation at base forms.
- In September antler growth is near completion
- Velvet shedding varies from range to range,
depending on breeding date. - In October antlers are fully hardened.
21
Antler Quality
- There is no way to predict quality of antlers.
- Some deer have the ability to reproduce pattern
if antlers are damaged. - Three factors that affect antler quality
- Age
- Nutrition
- Genetics
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