Biophysical Models for Poultry Production Systems
by P.C. Harrison, K.W. Koelkebeck, G.L. Riskowski
UNIVERSITY OF ILLINOIS EXPERIMENT
NORTHEAST REGIONAL PROJECT, NE-127
Biophysical Models for Poultry Production
1. Project: NE 127
2. Cooperating Agencies and Personnel
- P.C. Harrison - Project Leader
- K.W. Koelkebeck - Project Leader
- G.L. Riskowski - Project Leader
3. Progress of Work and Principle Accomplishments
Studies have been initiated and completed in the following areas:
- Influence of application frequency of a topically applied manure ammonia
inhibitor solution (Al+Clear®) on mass ammonia
- Evaluation of non-feed removal methods for molting laying hens
3.1Influence of Application Frequency of a Topically Applied Manure
Ammonia Inhibitor Solution (Al+Clear®)
 on Mass Ammonia Generation Rate (Report by P.C. Harrison and
During the past four years we have developed three emission calorimeters (EC)
that can be used to evaluate mass generation and utilization of gasses. We
have tested various treatments that could influence ammonia generation by laying
hen manure. One of the most effective treatments that we have evaluated was
a sprayed solution of an Aluminum Sulfate-based substance that is generally
applied in a dry form.
This experiment was conducted to determine if frequency of application of the
Aluminum Sulfate (standard liquid [48% A12(SO4)3-14
H2O]) based commercial product (Al+Clear®)
to laying hen manure would influence ammonia generation rate. We have found
that liquid application of Al+Clear® made from a
dry product (5 lb./gallon) and applied at the rate of .033 pounds per square
foot of hen manure, was effective in reducing mass ammonia generation rate.
In another experiment we evaluated the relationship between concentration of
Al+Clear® and ammonia generation with the following
treatments: 1) Control - manure was sprayed daily with 40 ml of deionized-distilled
water. 2) Standard - manure was spayed daily with 40 ml of Aluminum Sulfate
standard liquid (48%). 3) Reduced - manure was sprayed daily with 40 ml of
the solution used for the Standard treatment but diluted 50 percent, by volume,
with deionized-distilled water. Regardless of Al+Clear®
concentration all treatments were sprayed daily with 40 ml of water, or aqueous
solution, over the approximately 1.6 ft2 manure collection area.
In all our Al+Clear® studies, manure samples were
sprayed at the start of each analysis day and we noted that mass generation
rate of ammonia per unit of manure increased during the analysis day. Therefore,
to determine if frequency of Al+Clear® application
over time influenced NH3 production we designed the experiment reported
The manure collection area utilized 81 hens located in a commercial type laying
hen facility at the University of Illinois Poultry Research farm. Three SCWL
birds were housed per 12" x 18" raised wire cage. Treatments were randomly
blocked over three replications of nine hens per each treatment. Manure was
collected into side-by-side tubs (5'H x 7'W x 11'L) that were on stainless
steel trays (18' x 36') supported beneath each cage. Three collection tubs
(surface area = 1.6 ft2) were sprayed for each treatment replication
and each treatment was replicated three times. Treatments consisted of: 1)
Control - manure was sprayed on alternate days with 25 ml/ft2 of
deionized-distilled water. 2) Two-day - manure was sprayed on alternate days
with 25 ml/ft2 of 48% Al2SO4
 (Standard Solution). 3) Four-day - manure was sprayed every
fourth day with 50 ml/ft2 of 48% Al2SO4 (Standard
All treatments were initiated on day one of the experiment and rate of mass
ammonia generation (MAG) was determined on Day-1, Day-7, and Day-14 following
the start of treatment. On MAG days the collection tubs were transported to
the emissions calorimeters (EC), located in the Environmental Research Laboratory
at the University of Illinois. Ammonia emission from all replications of all
treatments were determined for a one hour period in each of the three EC over
approximately six hours of each emissions evaluation day. During the ammonia
generation evaluation day, feces was collected into separate tubs (clean) and
then dumped into the respective treatment collection tub when returned to the
poultry farm, at the end of that day.
In addition to accumulated manure mass and ammonia generation from the mass/surface
area, samples were taken from each of the nine collection tubs for moisture
and pH determination. For moisture determination, approximately 10 g of manure
was obtained from each of the three treatment replicate samples, weighed, then
placed into a 70 C oven and weighed daily until weight no longer changed. Manure
samples (approximately 1.5 g) were diluted with deionized-distilled water for
Results and Discussion
Spraying laying hen manure with Al2SO4, as it collected
under cages, reduced ammonia release. Ammonia emission from the control treatment
had its peak level when the manure samples had been collected for one week.
This same time course pattern of ammonia loss has been observed in our previous
studies. Al2SO4 treatments were effective regardless
of frequency of spraying or even a two-day interval between applications. Increased
frequency of Al2SO4 spraying did not show a significant
difference because it was confounded by manure age, which increased NH3
production, and time from last treatment (Table 1, Figure 1).
Effects of time interval (lag) between treatment application to the manure
surface and NH3 emission analysis was indicated by between treatment
differences during the first week and the four-day treatment differences at
week one and week two. At the first week analysis period, both the two-day
and four-day spray frequency treatments had received 180 ml of the 48% Al2SO4
spray. However the two-day treatment had received 40 ml of spray on the day
of emissions analysis, while the four-day treatment had received 80 ml two days
prior to the analysis; and NH3 emission was 1.7 and 10.8 mg/h/kg
of manure, respectively. Also, the four-day treatment had been treated two
days prior to analysis when the manure was one week of age, and one day prior
to analysis at two weeks of age and the NH3 emission level was 10.8
and 2.3 mg/h/kg of manure, respectively.
Manure pH followed the same response pattern and inference level (P
< . 05) as NH3 emissions (Table 2). Effects of lag time between
treatment and pH analysis also followed the same response and inference pattern
as NH3 emission. When manure treated on the same day as the analysis
was compared to manure treated either one or two days prior to analysis the
mean pH was 7.7, 7.6, and 8.2, respectively. The relationship of NH3
emission and pH of the manure (Figure 2) reflect the acid-base nature and pKa
(9.37) of ammonium. The relationship between NH3 release from manure
and manure pH needs to be investigated independent of Al2SO4.
Mean manure moisture was 73.39 ± 0.54 and was not affected by
age of manure or treatments. Manure mass increased over the entire collection
period and was independent of moisture and treatments (Table 3).
Mass generation rate of gaseous NH3 from laying hen manure was reduced
by liquid spray application of Al2SO4. Magnitude of NH3
emission reduction was less as time between spray application and emission analysis
(lag time) increased. Regardless of Al2SO4 spray application
frequency or volume, there was a lag time influence.
3.2 Evaluation of Non-Feed Removal Methods for Molting Laying Hens (Report
by K.W. Koelkebeck)
In recent years, concern for the well being of hens during a molt (feed withdrawal)
has been questioned mainly by animal rights groups. These concerns have generated
the need to develop molting programs that do not utilize feed withdrawal to
initiate a molt. The past several years we have conducted two experiments that
have evaluated several non-feed removal molting methods in comparison to a conventional
feed removal program. These studies have been financially supported by the
California Egg Commission, Ridley Feed Ingredients, Inc., and the United Egg
Producers, from whom a majority of the funding was received.
In the first study, we wanted to evaluate the effect of several non-feed removal
methods in comparison to a short feed removal period and a conventional feed
removal period on long-term postmolt laying hen performance. For the second
study, we evaluated eight treatments including the use of wheat middlings, corn,
wheat middlings and corn combination, corn gluten feed, and distillers grain
with solubles in comparison to a conventional 10-day feed withdrawal program.
Thus, the purpose of both studies was to evaluate the effects of non-feed removal
molting alternatives on long-term postmolt performance of laying hens.
In this experiment, Single Comb White Leghorn hens of
the DeKalb White Strain (60 wk of age) were housed in a cage layer house of
commercial design with water and feed provided for ad libitum consumption
and exposed to a 17-h daily photoperiod. Prior to starting the experiment,
all hens were weighed and allocated to each treatment group according to equal
body weights. Seven replicate groups of 12 hens each (4 adjacent raised wire
cages, 30 x 46 cm, containing 3 hens per cage, i.e., 72 sq in per hen) were
randomly assigned to each treatment.
A total of 336 hens were assigned to four treatments, which consisted of birds
fed a high corn molt diet or high wheat middlings molt diet and birds deprived
of feed for 4 or 10 days. At the start of the experiment (Day 1), feed was
withdrawn from the groups designated to be deprived of feed for 4 or 10 days.
The birds in the other two treatments were fed their respective diets which
consisted of a 95% corn diet and a 95% wheat middlings diet (Table 4). These
diets were fed for 28 days, then all hens were fed the 16% protein layer diet
(Table 4 ). On Day 5, the 4-day feed withdrawn hens were given ad libitum
access to the corn molt diet (Table 4). On Day 11, the 10-day feed withdrawn
hens were fed the corn molt diet. The hens deprived of feed for 4 or 10 days
were fed the corn molt diet until Day 28, and then were fed a 16% protein layer
diet (Table 4). The total length of the experiment was 44 weeks (four weeks
for the molt period and 40 weeks for the postmolt lay period).
On Day 1 (the initiation of feed withdrawal or feeding molt diets), the daily
photoperiod was decreased to 10 h. On Day 24 and 31, the daily photoperiod
was increased to 12 and 13 h, respectively, then increased 15 min per week for
the next four weeks. For the next six weeks, the photoperiod was increased
30 min per week until a photoperiod of 17 h was reached.
experiment 636 Single Comb White Leghorn hens of the DeKalb White Strain (69
weeks of age) were used. They were housed in the same facility as Experiment
1 and exposed to a 17-h daily photoperiod prior to the start of the experiment.
Six replicate groups of 12 hens each (4 adjacent raised wire cages, 30 x 46
cm, containing 3 hens per cage, 72 sq. in. per hen) were randomly assigned to
each treatment. Prior to the initiation of the experiment, all hens were weighed
and allocated to each treatment group according to equal body weights.
On Day 1, feed was withdrawn from the groups designated to be deprived of feed
for 10 days. The birds in the other six treatments were fed their respective
diets immediately (corn, wheat middlings, corn gluten feed, corn distillers
grains with solubles (Table 5). On Day 11, the 10-day feed withdrawn hens were
fed a 16% protein corn-soybean meal molt or a 94% corn diet for 18 days (Table
5). The hens that were not deprived of feed (Treatments 3-8) were fed ad
libitum their diets for 28 days. Hens on all treatments were fed a 16%
protein layer diet as shown in Table 4 for Experiment 1 after Day 28. Photoperiod
reduction was the same for this experiment as previously described for Experiment
1. The total length of the experiment lasted for 44 weeks.
Thus, the eight dietary
molt treatments were as follows:
- Fed a 94% corn diet continuously for 28 days
- Fed a 94% wheat middlings diet continuously for 28 days
- Fed a 47.0% wheat middlings:47.0% corn diet continuously for 28 days (50:50)
- Fed a 71% wheat middlings:23% corn diet continuously for 28 days (75:25)
- Fed a 95% corn gluten feed diet continuously for 28 days
- Fed a 95% corn distillers grain with solubles diet continuously for 28 days
- Feed withdrawn for 10 days, then fed a 16% protein corn-soybean meal molt
diet for 18 days
- Feed withdrawn for 10 days, then fed a 94% corn diet for 18 days
It was of interest to determine the degree of ovarian regression among treatments,
particularly for the hens not deprived of feed compared to the 10-day feed withdrawn
hens. Therefore, an additional group of 12 hens (four adjacent cages containing
hens hens per cage) were allocated to Treatments 1, 3, 4, 7, and 8 (n=60).
To determine the regression in ovary and oviduct weights, three hens from each
group were euthanized on Day 1, 10, 21 and 28. Ovary and oviduct weights were
recorded and the data is presented as a percentage of body weight. In addition,
general physiological stress was determined by counting blood leukocytes and
calculating the heterophil:lymphocyte ratio. Blood samples were obtained from
the wing vein from one hen per replicate on Day 1, 10, and 28. All data were
analyzed by analysis of variance procedures appropriate for a one-way completely
randomized design with the Fisher's least significant difference test used to
determine significant differences among treatment means.
Results and Discussion
in daily hen-day egg production during the 28-day molt period is graphically
shown in Figure 3. Hens that were deprived of feed for 4 or 10 days went out
of production by Day 5, and those fed the wheat middlings molt diet ceased egg
production by Day 8. In contrast, hens which were fed the corn molt diet never
went completely out of production, and were producing at a rate of 2.7% by Day
28 of the molt period. From Day 5 through 13, hens fed the corn molt diet produced
significantly more eggs than those on the other three treatments. By Day 15,
12, and 23, hens fed the wheat middlings molt diet, deprived of feed for 4 or
10 days returned to egg production, respectively.
The return to egg production after the initiation of feeding the layer diet
is graphically shown in Figure 4 and summarized in Table 6 Postmolt egg production
was generally higher for those hens fed the wheat middlings molt diet and 10-day
feed removal treatments than for the corn and 4-day feed removal treatments.
Hens fed the wheat middlings molt diet reached 50% egg production the soonest
with peak egg production being 89.6 and 90.7% for the 10-day feed removal treatment.
Postmolt hen-day egg production was significantly greater for hens deprived
of feed for 10 days compared to those fed the corn molt diet and deprived of
feed for 4 days during Weeks 5 to 44 (Table 6). In addition, egg production
was not significantly different for hens fed the wheat middlings molt diet and
those deprived of feed for 10-days. There were no differences in postmolt mortality
between any of the treatments during Weeks 5 to 44 (data not shown).
Figure 5 shows the cumulative hen-housed eggs per hen for Weeks 5 to 44. This
shows that hens that were deprived of feed for 10 days produced the most hen-housed
eggs per hen up to 44 weeks (207), followed by 202 eggs per hen for hens fed
the wheat middlings molt diet. Hens that were deprived of feed for 4 days and
those fed the corn diet produced 180 and 171 eggs per hen, respectively. Table
7 depicts the results for postmolt egg specific gravity. These data show that
there were no significant effects of molt treatment on egg specific gravity
towards the end of the postmolt production period.
Finally, Table 8 depicts the effect of the molt treatments on postmolt egg
income minus feed costs for Weeks 1 to 44. Egg income minus feed costs were
compared using the total number of eggs produced and total feed (molt plus layer)
consumed for all hens in each treatment. The cost of each molt and the layer
diets were calculated using appropriate feedstuff prices. As noted in Table
8, the hens which were deprived of feed for 10 days had the highest egg income
minus feed costs, with hens fed the wheat middlings molt diet producing the
second highest profit.
6 depicts the decrease in daily egg production during the 28-day molt period.
Hens that were deprived of feed for 10 days reached 0% production by Day 6.
Those hens that were fed the 16% protein molt diet returned to production by
Day 23 of the molt period, while those fed the corn diet after the 10-day feed
withdrawal period came back into production by Day 24 (1.4%). None of the other
six treatments produced total cessation of lay, however, those hens fed the
high wheat middlings molt diet reached a low of 2.8% on Day 12 and was at a
6.9% production by Day 28. Similar egg production trends were seen for hens
fed the 71:23% wheat middlings/corn diet and those fed the corn gluten feed
Body weight loss and mortality during the molt period is depicted in Table
9. Hens that were deprived of feed for 10 days and fed the 16% protein molt
diet or 8% protein corn diet lost 24.9 and 27.1% body weight, respectively.
Hens that were continuously fed the corn, wheat middlings, corn-wheat middlings
combinations, or corn gluten feed lost body weight in the range of 18.4 to 13.8%,
with no significant weight loss between treatments at Day 28. Mortality during
the molt period was highest for hens fed the 47:47% wheat middlings/corn diet,
however, mortality for this treatment was not different (P > .05)
for hens fed the 71:23% wheat middlings/corn diet or those fed the corn gluten
In Table 10, the days to 50% production, peak and overall egg production is
shown. Hens that were fed the distillers grains with solubles reached 50% production
in the least number of days because their egg production only dropped to around
30% during the molt period. Peak egg production was the greatest for hens fed
the 71% wheat middlings:23% corn diet. Overall hen-day egg production (Weeks
1 to 44) was the best for this treatment as well. Weekly egg production depicted
in Figure 7, showed that hens deprived of feed for 10 days, then fed the 16%
corn-soybean diet was the greatest from Weeks 32 to 44, with those fed the 71:23%
wheat middlings/corn diet being slightly lower. Table 11 depicts subsequent
egg specific gravity and showed that there were no differences between treatments
during Weeks 41 to 44. The economic analysis depicted in Table 12 indicated
that the greatest profit per hen-housed occurred for those hens deprived of
feed for 10 days, then fed the 16% corn-soybean molt diet ($6.08/hen), followed
by the hen fed the 71:23% wheat middlings/corn molt diet produced a return of
$6.07 per hen housed. The effect of selected molt treatments on ovary and oviduct
weights and heterophil:lymphocyte ratio is depicted in Table 13. No significant
effects were noted between treatment for either of these physiological stress
The results of this study indicate that feeding a wheat middlings diet, wheat
middlings and corn combination diets, or corn gluten feed molt diet to initiate
a molt in commercial layers may be effective alternative feeding programs compared
to traditional feed removal methods. The feeding of a wheat middlings molt
diet particularly in the first study, and the feeding of this diet in combination
with corn (71:23%) seemed to provide comparable or slightly less postmolt production
performance compared to a conventional feed withdrawal method. In addition,
these diets did not negatively affect egg shell quality as measured by egg specific
gravity in the latter stage of the postmolt egg production period in the first
experiment. Although economic comparisons are subject to many variables, the
molting programs utilizing the feeding of a wheat middlings or wheat middlings/corn
combination diets may be an economically viable alternative to conventional
feed withdrawal molt programs.
4. Usefulness of Findings
Liquid spray application of 48% standard liquid aluminum sulfate (Al2SO4)
on the surface of accumulating laying hen manure at two and four-day intervals
reduced mass emissions of gaseous NH3. As time interval increased
between application of the Al2SO4, effectiveness in reducing
NH3 emission decreased.
Manure pH was directly related to NH3 emission and followed the
same treatment pattern as mass generation rate. These data indicate that manure
pH may be cause effect related to NH3 production and release from
manure and could possibly be used to not only reduce gas production but also
influence the usefulness of the manure as a soil fertilizer.
If the commercial egg industry is forced by animal
rights/welfare pressures to move towards using molting programs which utilize
a non-feed removal method, then feeding a wheat middlings, corn-wheat middlings
combination, corn gluten feed, or possibly other types of low energy diets to
induce a molt might be considered.
5. Work Planned for Next Year
Ammonia generation rate from laying hen manure will be determined in relation
to manure pH that has been altered with acid-base pairs other than Al2SO4.
Other non-feed removal molt diets, such as raw soy hulls, pelleted soy hulls,
alfalfa meal, and soy and rice hulls combinations will be compared to a conventional
feed removal program for molting laying hens.
Biggs, P.E., M.W. Douglas, K.W. Koelkebeck, and C.M. Parsons, 2001. Evaluation
of non-feed removal versus feed removal methods for molting programs. Poultry
Sci. 80(Suppl. 1):91.
Biggs, P.E., M.E. Persia, K.W. Koelkebeck, and C.M. Parsons, 2002. Evaluation
of several non-feed removal methods for molting programs. Poultry Sci. 81(Suppl.
Koelkebeck, K.W., and P.C. Harrison, 2002. Evaluation of aluminum sulfate
manure treatment application on ammonia generation rate and manure properties
of laying hen manure. Poultry Sci. 81(Suppl. 1):31.
For tables and figures see PDF version.
 Liquid Aluminum Sulfate (Al+Clear®,
Poultry Grade Alum, Product of General Chemical, Parsippany, NJ.
 48% Al2(SO4)3·14H2O.