Lancaster farming. (Lancaster, Pa., etc.) 1955-current, September 25, 1993, Image 200

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    Page 14—Poultry Notes Supplement to Lancaster Farming, Saturday, Sept. 25,1993
\ Lancaster Fanning I V I U
Benchmarks in Layer
Paul H. Patterson
It is easy to document prog
ress in the layer industry with
the excellent records that are
kept on commercial white egg
strains today. In his “Egg Eco
nomics Update” Don Bell,
poultry specialist at Riverside,
Calif, looked back on 18 years
of summarizing performance
records of table egg flocks and
the progress that has been
made (Table 1).
During the period from 1973
to 1991, eggs pet hen housed
has improved 45.4 eggs, or 2.5
eggs per hen per year. The
average rate of egg production
has increased by 13.4 percent
Table 1.
Mortality %
HH eggs HD % Weekly Total
172.0 663 .33 10.6
183.3 6.94 .26 9.9
184.6 70.9 .27 10.1
186.4 70.8 .29 11.0
185.5 70.8 .30 11.3
190.0 71.8 .28 10.5
205.4 76.0 >, .20 8.0
205.4 76.4 .22 8.8
204.2 75.4 .22 8.8
207.1 76.1 .22 8.6
210.5 76.5 .20 7.9
212.5 76.6 .20 8.1
214.6 78.6 .71 6.8
217.4 79.7 .15 6.0
Table 2
1991 HH eggs Hen-Day HD peak Mortality Feed Feed Undcr
flocks to 60 wk ave % 28-31 wk % lb/100 hd Ib/doz grade %
Best 25% 229.1 83.4 92.7 2.6 19.2 2.92 _ 2.2
204.3 75.3 85.2 10.6 23.0 3.45 5.7
Grilless Pan
or .74 percent per year. Mortal
ity percentages have gone
down weekly from .33 to .15
percent, while total figures
have dropped from 10.6 to 6.0
percent (.26 percent per year).
Birds today tend to weigh less
than they did 20 years ago, and
with this trend feed consump
tion has been reduced from
.234 pound per hen per day to
only .212 pound. This repre
sents an annual improvement
of .12 pound per 100 hens per
day during the 18-year period.
Feed conversion (pounds of
feed per dozen eggs) has
improved from 3.86 to 3.19
pound in 18 years, with an
annual drop of .04 pound per
dozen per year.
Feed Feed Under
lb/100 hd. Ib/doz. grade %
(from 25 to 60 wks)
23.4 3.86
24.3 3.81
23.6 3.71
23.4 3.60
22.9 3.56
23.6 3.62
(from 21 to 60 wks)
22.4 3.54
22.1 3.48 5.50
22.0 3.50 5.51
21.9 3.45 5.61
21.7 3.41 5.33
21.7 3.38 4.86
21.3 3.26 4.97
21.2 3.19 4.02
World Cla
wfm mw
_ V _“Zir -wyi;-"
HILo Pan
While these numbers are not
the most that can be expected
from today’s laying hens, they
represent an “average” and
demonstrate the progress that
has been made over 18 years of
keeping records. Ranges in
performance are shown for
1991 in Table 2. These arc the
corresponding “best 25 per
cent” and “poorest 25 percent”
records of 360 flocks
Compared to the 1991 aver
age flock, there is the oppor
tunity to get an additional 11.7
eggs to 60 weeks. Don’t be
satisfied with an average 79.7
percent hen day egg production
when the best 25 percent are
getting 83.4 percent and peaks
of 92.7 percent. Furthermore,
better flocks have less mortali
ty, fewer undergrades, and do it
all with less feed.
As a target, you can compare
your flocks with this range of
performance, and ask the hard
questions: why is my flock not
performing as well in certain
categories listed below? With
out good records, and the time
to really look them over and
evaluage flocks performance,
it’s difficult to get to the bot
tom of a bird health, equip
ment, or performance problem.
Dietary Treatment For
Laying Hens With
Kidney Damage
Paul H. PAtterson
Assistant Professor,
Poultry Science, Penn State
Researchers at Penn State
Adult Turkey Feeder
Wednesday, September 29
Thursday, September 30,
Lancaster Host Resort
University have shown that
when Leghorn pullets are fed
laying hen diets during the
growout period (6 to 18
weeks), formation of kidney
stones or uroliths are induced
in the ureters and urine collect
ing ducts of the kidney.
Compared with the young
pullets requirements, layer
rations contain high levels of
calcium (3.5 to 4.0 percent)
and relatively low levels of
available phosphorus (.4 to .5
percent). Pullets fed these
rations will exhibit, in addition
to stones, kidney atrophy, fiber
formation, tissue mineraliza
tion, asymmetry and a reduc
tion in die number of urine fil
tering units.
These symptoms are similar
to the degenerative renal dis
ease “urolithiasis”. In addition,
infectious bronchitis virus
(IBV) has been suspected as a
cause of urolithiasis, based on
the evidence that some strains
of IBV cause kidney damage
similar to field outbreaks of
In experimental work com
bining the effects of the “Gray”
strain of IBV and layer rations,
urolithiasis incidence has been
observed at between 8.6 and 25
percent, and kidney damage
between 25.8 and 58 percent.
Unfortunately, the degree of
kidney damage may not be
realized until later in the adult
life of the hen when accumu
lated kidney calcium deposits
and loss of functional tissue
results in a drop in egg produc
tion and increase in hen mortal
Poultry Leader
ity! What is a egg-producer to
do if these circumstances hap
pen to your birds?
Prevention is the best cure,
by closely monitoring the cal
cium levels fed to your pullets
and ensuring adequate IBV
protection with a polyvalent
vaccination program. If you
still are faced with kidney
damaged hens, there are some
remedial treatments that can be
applied in preventing further
growth of the kidney stsones.
These calcium deposits are
caused in laige part because of
a metabolic alkalosis brought
on by an increase in the
cation;anion ratio of the ration.
This leads to an increase in
urine calcium concentration, a
decrease in the H+ ion concent
ration, and providing an excel
lent medium for precipitation
of calcium-urate, the primary
mineral in avion uroliths.
Treatment lies with the
strategy of increasing dietary
H+ ion concentration (more
acid) in hopes of reducing
urine pH and dissolving urin
ary calcium. Calcium solubil
ized by urine acidification can
then be excreted without preci
pitation in the kidney. These
are several means of modifying
dietary pH or H+ ion concent
ration to prevent kidney stone
enlargement and dissolve pre
formed deposits. Ammonium
chloride added to the diet at the
O.S percent level has been suc
cessful in reducing calcium
induced kidney damage and
stone formation, however, it
(Turn to P»go 15)
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