C2-Lancaatar Fanning, Saturday, Octobar 21, 1995
SOURCES OF
EGGSHELL STRENGTH
Dr. Carol V. Gay
Professor Of
LAND PRIDE ESj
CUTS FARM MAINTENANCE
DOWN TO SIZE.
15’ ROTARY CUTTER
• 15’folding unit
• Reinforced 10 gauge deck
• Wings fold up for 96” transport width
• Mowing height from 2” to 14”
• Cuts material up to 2” thick
The Land Pride family... quality from the ground up.
Bangor Implement
6 Flicksville Road
Bangor, PA 18013
610-588-5922
Betts Er r^ment
3139 Windy Bush Road.Rt 232
New Hope, PA 18938
215-598-7501
C.B. Hoober &
Son, inc.
Mam Street
Intercourse, PA 17534
717-768-8231
Cannonsburg Supply
& Equipment Co.
RD 247
Cannonsburg, PA 15317
412-746-2500
Deerfield Ag &
Turf Center, Inc.
RR 2 Box 212
Watsontown, PA 17777
717-538-3557
Oetlan
Equipment, Inc,
141 East Mam St
Silverdale, PA 18962
215-257-5177
Dunkle & Grieb Inc
RR 2, Box 14
Centre Hall, PA 16828
814-364-1421
Caldwell Tractor &
Equipment, Inc.
48u U S Route 46
Fairfield, N J 07006
201-227-6772
Rodio Tractor Sales
North White Horse Pike
Hammonton, N.J 08037
609-561-0141
The avian egg is a notably well-
Pennsylvania
Eckroth Bros
Farm Equipment
Rd 2, Box 24A
New Rmgold, PA 17960
717-943-2131
Hines Equipment
RT 220, Belwood, PA
814-742-8171
Keller Brothers
R 7 Box 405
Lebanon PA 17042
717-949-6501
1950 Fruitville Pike
Lancaster, PA 17601
717-569-2500
Lost Creek
Implement, Inc.
Route 35, Box 123
Oakland Mill, PA 17076
717-463-2161
M.S. Yearsly & Sons
West Chester, PA
610-696-2990
Marshall
Machinery, Inc.
Route 642
Honesdale, PA 18431
717-729-7117
Nicarry
Equipment Co.
RD2, Rt 61,3 Miles S.
of Leesport, Reading, PA
610-926-2441
New Jersey
Frank Rymon & Sons, Inc
RD 3, Box 355
Washington, N J. 07882
908-689-1464
Warren County Service Center
228 Route 94
Blairtown, N.J.
908-362-6916
Molecular And
Cell Biology
And Poultry Science
' A <*’ •** 't
Norman D. Clark &
Son, Inc.
Honey Grove, PA
717-734-3682
Pikeville
Equipment Inc.
RO 2, Oysterdale Road
Oley, PA 19547
610-927-6277
Sollenberger’s
Equipment, Inc
80 State St.
Everett, PA 15537
814-652-6990
Stoltzfus Farm
Service
Cochranville, PA
610-593-2407
Stouffer Bros Inc.
1066 Lincoln Way West
Chambersburg, PA 17201
717-263-8424
Thomas L. Dunlap
Rt 220, Mam St Exit
Jersey Shore, PA 17740
717-398-1391
Tractor Parts Co.
335 Central Road
Bloomsburg, PA 17815
717-784-0250
Triple H
Eguipment, Inc.
2368 Robert Fulton Hwy.
Peach Bottom, PA 17563
717-548-3775
designed structure. Sources ot
eggshell strength include overall
shape, shell membrane quality,
and composition and design of the
calcified shell.
At ovulation, a spherical yolk is
literally engulfed by the funnel
shaped end of the oviduct (I’ve
seen movies of this). During pas
sage through the first 12-inch sec
tion of oviduct, called the mag
num, the yolk is encapsulated in a
thick mass of egg white. During
passage down the loose, stretch
able oviduct, the egg takes on its
characteristic oblong shape.
Shape is a very important factor
in eggshell strength. Since an egg
is rounded in all directions, high
stress points, where fractures
would easily occur, are avoided.
Obviously, the strongest shape
would be a perfect sphere. In fact,
some birds, such as ostriches,
humming birds and Japanese
quail, lay more nearly spherical
eggs. The spherical shape allows
these birds to make thinner shelled
eggs relative to egg size, conserv
ing body materials.
Approximately two hours after
ovulation, the egg has traversed
the magnum and the white has
completely formed. The egg then
enters the isthmus region of the
oviduct. In this region the shell
membranes (there are two) are
formed over the egg white, a pro
cess that takes about an hour and a
half.
Shell membranes arc well
known to all who have peeled hard
boiled eggs I find it quite dis
couraging when trying to whip up
a platter of grand-looking deviled
eggs, to have the membranes so
firmly attached to the white that
whites get tom. (I would like to
hear from readers who know of
tricks to prevent this" problem.
Please call me at 814-865-6722.)
Shell membranes consist of a
crisscrossed network of protein
fibers that look like a multilayered
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filter when magnified I.OOOX by a
scanning electron microscope.
These fibers arc linked to each
other by chemical bonds to form a
very tough sheet. The shell mem
branes are thinner in older birds.
Upon entry into the shell gland,
fluid is added through the shell
membranes. This causes the egg
white to swell and push the shell
membranes into a fully distended
position. Next, calcium carbonate
is secreted by the shell gland. Clus
ters of calcium carbonate crystals
form at fairly precise distances
from each other on the outer sur
face of the shell membrane. From
these clusters, columns of calcium
carbonate grow outward and para
llel to each other to form a calcified
layer. Only microscopic spaces
exist among the tightly packed col
umns of crystals. It is not known
what controls the spacing of the
first crystals formed from which
the columns grow.
Tough Growing Year
Requires Harvest Management
COLUMBUS, Ohio—An early
killing frost in late September
slammed the last nail in the coffin
of what was a very tough growing
season for Ohio’s com growers,
said an Ohio State University
agronomist.
In some cases, the Sept. 23
freeze in northwest Ohio was
irrelevant given that much of the
com had prematurely died under
the combined stresses of late
scason drought and leaf diseases,
namely gray leaf spot, said Peter
Thomison.
‘The plants just shut down and
died with kernels prematurely
forming the black layer stage,” he
said.
Producers will see the com- that corn was in the late dent
bined effects of the season’s sites- stage, which would result in a 4
ses as they begin to combine their percent to 8 percent yield loss
fields, requiring extra manage-' because of the freeze.
SCS Approved Manure Storage Facility
Finally, a layer of pigment fol
lowed by an impervious material,
the cuticle, is laid down on the
eggshell surface. The cuticle is
microscopically thin and contri
butes very little to overall eggshell
strength, but it is important for pre
venting dehydration.
The total time spent in the shell
gland is 20 hours. The combina
tion of shape and the integration of
the several different layers of
which the eggshell is comprised
contribute to its strength.
It is interesting that reptiles such
as turtles and snakes form eggs by
a similar process. However, their
eggs are not calcified. Instead, the
shell membranes are thicker and
have a leather-like composition.
It might be possible to select, by
genetic manipulation, hens that
make substantially thicker shell
membranes so that the thickness of
the calcified portion would be a
less critical factor in overall eggs
hell strength.
ment to handle the damaged and
high-moisture com.
Yield losses from freeze dam
age depend on how much stalk
tissue was killed as related to the
stage of kernel development.
Stalks that are green after a frost
can mobilize sugars from the stalk
to the car for continued kernel
development. However, some
Helds didn’t have that chance
because stresses damaged stalks,
which depleted the green color.
Thomison said in the worst
cases of freeze damage, fields in
the fully dented stage could have
had up to 31 percent yield loss,
although those cases were probab
ly rare. The likelihood was greater
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