©2007 Poultry Science Association, Inc.
Efficacy of a Litter Amendment to Reduce
Pododermatitis in Broiler Chickens1
M. Nagaraj, C. A. P. Wilson, B. Saenmahayak, J. B. Hess, and S. F. Bilgili2
Department of Poultry Science, Auburn University, AL 36849
Primary Audience: Broiler Production Managers, Nutritionists, Plant Quality Control
SUMMARY
Broiler house environment, especially volatile NH3 content, has a significant effect on
pododermatitis in chickens. The efficacy of NaHSO4 in reducing pododermatitis in broiler chickens
was investigated in this study. A total of 960 straight-run 1-d-old chicks were randomly assigned
to 16 environmental chambers with 4 different levels of NaHSO4 (4 chambers/treatment). The
treatments (TRT) comprised of TRT 1 (control), TRT 2 with NaHSO4 applied at 1× rate (0.22 kg/
m2) on the day of placement of chicks, TRT 3 with NaHSO4 applied at 2× rate on the day of
placement of chicks, and TRT 4 with NaHSO4 applied at 1× rate on the day of placement of chicks
and at 1× rate on 21 d. Birds were raised to 49 d of age on a 4-stage feeding program with diets
formulated to contain high protein levels and all-vegetable ingredients. At 35 d of age, the litter
was moistened artificially to see the effect of NaHSO4 on NH3 volatilization. In addition to assessing
live performance, feet were scored on 42 and 49 d of age for incidence and severity of pododermatitis.
Ammonia concentration (ppm) in the chambers was measured before placement of chicks and on
a weekly basis throughout the experiment. No differences in live performance of the birds were
observed throughout the study (P > 0.05). Sex had significant effects on incidence of pododermatitis
(P < 0.05), with females showing higher incidence of pododermatitis than males. The NaHSO4 had
a significant effect on NH3 volatilization in the chambers (P < 0.05). Ammonia concentration was
significantly reduced in all TRT except the control (TRT 1). Sodium bisulfate had no significant
effect on NH3 levels after 35 d upon addition of moisture to the litter. Although not significant
(P > 0.05), using NaHSO4 as a litter amendment numerically reduced the incidence of pododermatitis
by 10 or more percentage points.
Key words: broiler, chicken feet quality, ammonia, pododermatitis, litter amendment
2007 J. Appl. Poult. Res. 16:255–261
DESCRIPTION OF PROBLEM
The economics of efficient, low-cost broiler
production dictate concentrated and confined
broiler production systems with birds raised in
large environmentally controlled houses under
uniform management practices. The broiler
house environment is a reflection of the overall
1
efficiency of the growout operation. House design [1, 2] and environmental control [1, 3],
ventilation [4, 5], feeder and drinker management [1, 6, 7], flock health [8, 9], stocking density [10, 11, 12], litter quality [7, 13], and husbandry are important factors in the maintenance
of a good production environment. Because
birds spend most of their lifetime in close contact
Mention of trade names or commercial products in this publication does not imply recommendation or endorsement by
the authors.
2
Corresponding author: [email protected]
JAPR: Research Report
256
Table 1. Composition of high-protein and all-vegetable diets1
Feeding stage
Item
CP (%)
ME (kcal/kg)
Ca (%)
Available P (%)
Lys (%)
Met (%)
Met + Cystine (%)
K (%)
Na (%)
Vitamin premix2
Trace mineral premix3
DL-Met
L-Lys
Coccidiostat4
Antibiotic5
Starter
Grower
Finisher
Withdrawal
24.7
3,096
1.08
0.52
1.38
56
0.95
1.1
0.2
0.25
0.25
0.2
0.04
0.08
0.05
22.4
3,117
1.06
0.50
1.18
0.55
0.88
0.97
0.2
0.25
0.25
0.2
—
0.08
0.05
20.2
3,149
0.92
0.47
1
0.57
0.86
0.86
0.2
0.25
0.25
0.25
—
0.08
0.05
19.6
3,186
0.70
0.45
0.9
0.45
0.75
0.86
0.23
0.1
0.1
0.16
0.01
—
—
1
Starter diet placed: 0 to 17 d of age; grower diet placed: 18 to 30 d of age; finisher diet placed: 31 to 41 d of age; withdrawal
diet placed: 42 to 48 d of age.
2
Vitamin premix supplied the following per kilogram of diet: vitamin A, 16,183 IU; vitamin D3, 4,851 IU; vitamin E, 16.6
IU; vitamin B12, 0.04 mg; riboflavin, 12 mg; biotin, 0.05 mg; niacin, 80 mg; pantothenic acid, 29 mg; choline, 1,102 mg;
menadione, 4.8 mg; folic acid, 1.1 mg; pyridoxine, 4.4 mg; and thiamine, 2.2 mg.
3
Trace mineral premix supplied the following per kilogram of diet: Mn, 143 mg; Zn, 121 mg; Fe, 13 mg; Cu, 13 mg; I, 2.2
mg; and Se, 0.7 mg.
4
Monensin Na premix, Coban 60 (Elanco Animal Health, Indianapolis, IN).
5
Starter and grower periods: bacitracin methyl salicylate, BMD-50 (Alpharma Inc., Fort Lee, NJ); finisher period: virginiamycin,
Stafac-20 (Phibro Animal Health, Fairfield, NJ).
with the bedding material, litter quality has a
major effect on health and performance of a bird.
It is a common practice to raise multiple flocks
on used litter in the United States. However,
wet and sticky litter conditions resulting from
intestinal disorders such as diarrhea or feed-passage, high pH, and excessive NH3 production
negatively affect litter quality. Poor drinker management practices, low air temperature, and high
RH result in many cases of wet litter [6, 14, 15].
Moisture levels in litter exceeding 35% have
negative effects on bird health, often resulting
in conditions such as pododermatitis [16, 17, 18,
19, 20], folliculitis, and necrotic enteritis [21].
Moisture also increases the rate of production of NH3 and potentially other irritant substances [17, 22]. Ammonia is produced as a
result of microbial activity on uric acid. Wet
litter conditions and high pH act like a catalyst
in this process. The formed NH3 remains at an
equilibrium between the uncharged NH3 and the
charged ammonium ion (NH4+) at neutral pH.
But as the litter pH increases (above 8), there
is a shift in this equilibrium, resulting in production of higher levels of NH3 [23]. Levels of NH3
as low as 10 ppm can impair performance [24]
and immunity of a bird and increase susceptibility to respiratory infections [24, 25, 26, 27].
Higher levels of NH3 released from litter cause
severe irritation to the respiratory tract and skin
of birds, resulting in pododermatitis, hock burns,
and breast blisters [28].
Hence, litter amendments are suggested to
improve litter conditions and keep NH3 levels
in check [23, 29, 30, 31]. Many litter additives
such as propionic acid [32], monobasic Ca phosphate and H3PO4 [33], FeSO4 [34, 35], AlCl3
[35], KMnO4 [35], alum [35, 36], clay [37], and
NaHSO4 (poultry litter treatment) [31, 38] have
been used successfully to reduce litter pH, reduce NH3 volatilization, and inhibit microbial
activity.
Sodium bisulfate, a dry anhydrous crystalline acidifier, is used widely by the broiler industry to control NH3 [38]. It is readily soluble in
water, and a 5% aqueous solution has a pH <1.
Sodium bisulfate reduces NH3 volatilization
through lowering the litter pH, interacting with
uric acid, and by limiting the growth of microbial
populations that generate NH3 gas [39]. Sodium
NAGARAJ ET AL.: LITTER AMENDMENT TO REDUCE PODODERMATITIS
257
Table 2. Influence of NaHSO4 as a litter amendment on broiler performance
42 d of age
49 d of age
Item
Weight
(g)
FC1
Mortality
(%)
Weight
(g)
FC1
Mortality
(%)
Treatment2
1
2
3
4
SEM
NS
2,260
2,310
2,270
2,280
26.9
NS
1.713
1.708
1.705
1.723
0.026
NS
3.03
3.90
3.51
3.51
1.14
NS
2,640
2,670
2,630
2,630
40.6
NS
1.872
1.867
1.869
1.881
0.026
NS
2.68
1.34
0.46
2.71
0.96
FC = feed conversion adjusted for mortality.
Treatment (TRT) 1 = control with no litter amendment; TRT 2 = litter amendment applied at a rate of 0.02 kg/ft2 at the
day of placement of chicks; TRT 3 = litter amendment applied at a rate of 0.04 kg/ft2 at the day of placement of chicks;
TRT 4 = litter amendment applied at a rate of 0.02 kg/ft2 at the day of placement of chicks and again at 21 d of age.
1
2
bisulfate is hygroscopic and binds N to form
stable ammonium sulfate. Research on the use
of NaHSO4 as litter amendment has shown better
broiler performance [40], reduced pH and NH3
levels [39, 40] in the house, and decreased microbial load in the litter [39, 41].
Previous research in our laboratory has
shown that high-protein and all-vegetable diets
increase the incidence and severity of pododermatitis in broilers. This could be due to excessive
N excretion and NH3 formation in the litter [42].
The objective of this current study was to evaluate the effect of NaHSO4 as a litter amendment
on the incidence and severity of pododermatitis
in market-age broilers fed a high-protein and an
all-vegetable diet.
MATERIALS AND METHODS
The experiment was conducted in 16 environmentally controlled chambers [43]. Sixty
straight-run 1-d-old chicks were placed in each
of 16 chambers (10 birds/m2). Each chamber
was equipped with 8 cm of used pine shavings
as litter, a tube feeder, and 14 nipple drinkers.
Ventilation was controlled separately by chamber with exhaust fans running 1 min on and 10
min off to 2 wk and 2 min on and 8 min off
thereafter. From 2 to 3 wk of age, exhaust fans
overrode the timer when chamber temperature
reached 84°F. After 3 wk of age, temperature
overrode the timed ventilation at 75°F. Before
the placement of chicks, the NH3 levels in each
chamber were measured using Dräger NH3 meters [44, 45]. There were 4 litter amendment
treatments (TRT): TRT 1 was the control, with
no litter amendment added; TRT 2 comprised
of chambers hand-sprinkled with NaHSO4 at a
recommended rate of 0.22 kg/m2 at the day of
placement of chicks; TRT 3 NaHSO4 consisted
of 2× recommended rate or 0.44 kg/m2 at the
Table 3. Moisture levels of litter from different treatments
Moisture (%)
Item
Treatment1
1
2
3
4
SEM
Before
placement
of chicks
35 d of age
42 d of age
49 d of age
NS
10
9
8
10
1.4
NS
11
10
12
11
1.5
NS
18
16
17
14
1.8
NS
14
13
13
12
1.7
1
Treatment (TRT) 1 = control with no litter amendment; TRT 2 = litter amendment applied at a rate of 0.02 kg/ft2 at the
day of placement of chicks; TRT 3 = litter amendment applied at a rate of 0.04 kg/ft2 at the day of placement of chicks;
TRT 4 = litter amendment applied at a rate of 0.02 kg/ft2 at the day of placement of chicks and again at 21 d of age.
JAPR: Research Report
258
day of placement of chicks; TRT 4 consisted of
NaHSO4 applied at a rate of 0.22 kg/m2 at the
day of placement of chicks and then again on
21 d.
Birds were raised for a period of 49 d on a
4-stage feeding program of high-protein and allvegetable diets (Table 1), which have been previously shown to induce high incidence of pododermatitis [42]. Feed and water were provided
for ad libitum consumption through the whole
growing period. Ammonia concentration (ppm)
in each chamber was measured on a weekly
basis using Dräger NH3 meters throughout the
experiment [44, 45]. The litter used in this experiment was used for 2 flocks previously and was
dry and flaky at the time of chick placement. To
facilitate the solubility of NaHSO4, at 35 d, the
litter was artificially dampened to dissolve the
NaHSO4 and to increase NH3 generation [46].
Body weight, feed conversion, and mortality
were determined on 42 and 49 d of age. Feet
were scored for pododermatitis on 42 and 49 d
of age, and the severity was recorded [47]. Litter
samples were collected (5 sites, 4 corners and
1 central sample) before placement of chicks
and on 35, 42, and 49 d of age to assess moisture
content [48]. Data were analyzed using the GLM
procedure of SAS [49, 50].
RESULTS AND DISCUSSION
No differences in live performance of the
birds were observed throughout the study (P >
0.05; Table 2). This was not consistent with
the findings of other investigators who observed
better live weight gain at 23 and 49 d of age
with the use of NaHSO4 [40, 50, 51]. The use
of high nutrient density diets in this study may
have masked the beneficial effects of NaHSO4
on live performance. Table 3 summarizes the
data on litter moisture for the study period. There
were no significant (P > 0.05) differences in
litter moisture content among the different TRT.
Further, the low stocking density followed in this
study, the use of nipple drinkers, and effective
ventilation for aeration of the chambers may
have helped to maintain a drier litter, preventing
the development of wet litter conditions.
At the beginning of the experiment, the NH3
levels in the chambers were fairly low (3 to 5
ppm) on used litter (Figure 1) and remained low
through 35 d of age, with all 3 NaHSO4 TRT
Figure 1. Influence of NaHSO4 on NH3 levels (ppm) in
chambers on a weekly basis. Treatment (TRT) 1 =
control with no litter amendment; TRT 2 = litter
amendment applied at a rate of 0.02 kg/ft2 at the day
of placement of chicks; TRT 3 = litter amendment
applied at a rate of 0.04 kg/ft2 at the day of placement
of chicks; TRT 4 = litter amendment applied at a rate of
0.02 kg/ft2 at the day of placement of chicks and again
at 21 d of age. *P < 0.05.
showing significantly (P < 0.05) lower NH3 levels than the control. Addition of moisture to the
litter at 35 d of age caused NH3 levels to increase
significantly (20 to 28 ppm). There were no differences in NH3 levels within different rates of
NaHSO4 application after 35 d of age. The depression in NH3 volatilization by NaHSO4 depends on age and moisture of the litter material
used. It is surmised that low levels of litter moisture also suppressed the hygroscopic effect of
NaHSO4. Further, variability in ventilation rates
could also have affected NH3 levels in the chambers. It is clear from this study that wet litter
conditions hasten the process of NH3 release
from litter. Further investigation is required
about the solubility of NaHSO4 and the amount
of moisture needed for its dissolution to be effective in trapping volatile NH3.
Table 4 summarizes the pododermatitis incidence at 42 and 49 d of age. There were no
significant (P > 0.05) effects due to the NaHSO4
TRT. However, there was a numerical trend of
decreasing incidence and severity of pododermatitis with the use of NaHSO4. This finding
suggests that other factors in the litter may also
play a role in the etiology of pododermatitis
apart from NH3. Mayne et al. [20] also reported
no direct correlation between NH3 concentration
in houses and the incidence of pododermatitis
in turkeys and further suggested research into the
role of unknown compounds in different litter
materials in the causation of pododermatitis in
broilers and turkeys. It is also possible that low
NAGARAJ ET AL.: LITTER AMENDMENT TO REDUCE PODODERMATITIS
259
Table 4. Influence of NaHSO4 on footpad lesions1 (%)
42 d of age
Item
Treatment
1
2
3
4
SEM
Sex
Female
Male
SEM
2
49 d of age
None
Mild
Severe
None
Mild
Severe
NS
33
41
47
50
6.9
NS
42
40
36
36
3.6
NS
24
19
18
14
3.8
NS
50
57
60
60
7.2
NS
35
28
33
31
3.9
NS
15
15
8
10
4.0
*
40
46
2.1
**
43
34
2.0
NS
18
20
1.4
*
52
61
2.3
**
37
26
2.0
NS
10
13
1.6
No interactions were significant (P > 0.05).
Treatment (TRT) 1 = control with no litter amendment; TRT 2 = litter amendment applied at a rate of 0.02 kg/ft2 at the
day of placement of chicks; TRT 3 = litter amendment applied at a rate of 0.04 kg/ft2 at the day of placement of chicks;
TRT 4 = litter amendment applied at a rate of 0.02 kg/ft2 at the day of placement of chicks and again at 21 d of age.
*P < 0.05; **P < 0.01.
1
2
levels of NH3 as observed in this study in contrast to commercial growout operations may not
cause irritability to skin and cause lesions in the
footpad. Although not severe, other effects of
volatile NH3, like respiratory discomfort and labored breathing, were observed in some birds
by 42 d of age.
Sex had a significant effect on incidence of
pododermatitis (P < 0.05), with females showing
higher incidence of pododermatitis than males.
This finding is in contrast to earlier research,
which indicated higher incidence of pododermatitis in males [42, 52, 53]. Higher incidence
of lesions in female birds indicates that both the
sexes are susceptible to pododermatitis and that
it is not just a problem in males. Female broiler
skin, having less skin protein and collagen matrix than male broilers, has also been reported
as a predisposing factor to skin injury and ulceration. However, males had a higher proportion
of severe lesions compared with females.
The reduction in NH3 levels in our study
was comparable with the findings of other researchers bearing the effectiveness of NaHSO4
as a litter additive [39, 49]. Although not sig-
nificant (P > 0.05), using NaHSO4 as a litter
amendment appeared to reduce the incidence
and severity of pododermatitis. A small number
of sampling units (i.e., 4 chambers/TRT) and
possible influence of variable ventilation rates
between chambers and the use of nipple drinkers
may have reduced the sensitivity of the study.
Previous studies suggest a relationship between
litter NH3-N and the incidence of pododermatitis
[42, 54]. Hence, additional studies with many
flocks may be warranted to assess the relationship of litter NH3-N, volatile NH3, and litter
moisture in reference to pododermatitis incidence and severity.
The extent of pododermatitis prevalence is
used to assess the animal welfare conditions and
may be used as an indicator of the overall litter
quality as well [2, 55, 56, 57]. The above findings
suggest that the incidence and severity of pododermatitis may be affected by factors other than
feed ingredients, litter moisture, and volatile
NH3. Further research is necessary to understand
the interactions among those factors for the development of an effective control program for
pododermatitis in broiler flocks.
CONCLUSIONS AND APPLICATIONS
1. Sodium bisulfate as a litter amendment had no significant effect on live performance and
mortality of birds.
2. Wet litter conditions increased volatilization of NH3 from the litter.
JAPR: Research Report
260
3. Use of NaHSO4 as a litter amendment significantly reduced volatile NH3 levels in the chambers
through 35 d of age.
4. The incidence of pododermatitis appeared to improve numerically (although not statistically)
with the use of NaHSO4.
5. Litter amendments, such as NaHSO4, may be a component of a litter management program to
control pododermatitis in broiler chickens.
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45. The direct-reading Dräger chip measurement system uses
chemical-specific chips and an electronic analyzer for precise measurements of NH3 gas and vapors, and the reading appears on a
liquid crystal display screen. The chips used in this experiment ranged
from 0.2 to 5, 2 to 50, and 10 to 150 ppm, depending upon the NH3
concentrations in the chambers. The NH3 meter was hand-held at
about 1 ft from the litter in the center of the chamber for measuring NH3.
46. Water (3.75 L) was evenly sprayed on the litter in each
chamber at d 35.
47. The scoring system followed was a 3-point score in which
the footpad lesions were assigned to 1 of 3 values: 0 = footpads with
no lesions, dermal ridges intact within a central, with or without
discoloration; 1 = footpads with mild lesions, dermal ridges not intact
within a central, round to oval ulcer on the central plantar footpad
surface, roughened lesion surface with small tag of crust <1.5 cm in
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