01WApplied Pouluy Science, Inr
SODIUM BICARBONATE
AND BROILER
PERFORMANCE
AT HIGHSTOCKING
DENSITIES
IN A TROPICAL
ENVIRONMENT
DIEGO PURON' and RAUL SANTAMARIA
UNNASA S A . de C.K, Avenida Principal x Jost Maria Castro Tejero.,
Apdo. Postal 59, Cd. Industrial, Mkridu, Yucathn, Mkiico C.P. 97288
Phone: (99) 4608-60
FAxr (99) 46-08-27
JOSE C . SEGURA
Facultad de Medicina Veterinariay Zootecnia, UniversidadAutbnoma de Yucatcin,
Mkridu, Yucatan, M&ico 97100
Primary Audience: Broiler Producers, Nutritionists, Veterinarians,
Researchers
of NaHC03, ascorbic acid, or acetylsalicylic
DESCRIPTION
OF PROBLEMacid had no effect on broiler performance.
Some studies carried out under controlled
conditions using high ambient temperatures
(>30°C) have shown an improvement in
weight gain, feed conversion, and/or survival
of broiler chicks when sodium bicarbonate
(NaHCO3) was added to the diet or drinking
water [l, 2, 31. However, the results of other
researchers [4,5] did not reveal the benefits of
NaHC03 on the performance of broilers
under heat-stressed conditions. Under field
conditions Puron et al. [6] found the addition
1
To whom correspondence should be addressed
Whiting et al. [4] and Puron et al. [6] attributed
the lack of response of the birds to the fact that
temperatures in their study produced only
mild heat stress.
In some tropical areas of the world temperatures rarely exceed 41°C for long periods
of time and broiler producers use low stocking
densities in order to reduce the stress caused
by local environmental conditions. Stocking
densities from 8 to 10 broilers/m2are common
in the southeastern tropics of Mexico during
444
the hot months. Furthermore, normal practices such as the use of foggers and ceiling fans
reduce the expected detrimental effect of the
hot environment in those regions. This study
hypothesized that increasing stocking density
would produce a higher stress than in normal
density situations and allow the effect of the
NaHC03 to be expressed under mild tropical
environments. Crowded birds will have less
ventilation and air movement; therefore, their
ability to lose heat will decline. On the other
hand, high stocking densities reduce the fmed
cost of production and increase the profitability up to a certain point [7,8].
The objective of this study was to evaluate
the effect of adding 0.5% NaHC03 to the diet
of broilers at high stocking densities in the
tropics.
MATERIALS
AND METHODS
The climate of the region is tropical (hot
and humid) with an average temperature and
a relative humidity of 26°C and 75%, respectively [9]. During Trial 1and Trial 2, the minimum and maximum temperatures from the
3rd to the 7th wk were 20.1 and 39.6"C, respectively. The relative humidity ranged from 40%
to 90%. Birds were reared in open houses
with insulating sheet roof and cement floors,
divided into 24 pens of 5 m x 4 m.
Trial 1 was conducted in the months
of May to July of 1994 and involved 5760
Peterson x Hubbard 1-day-oldmale broilers.
The treatments consisted of 1) male broilers at
a stocking density of 10.5 birds/m2 without
NaHC03 in the diet, 2) male broilers at a
stocking density of 10.5 birds/m2 with 0.5%
NaHC03 in the diet, 3) male broilers at a
stocking density of 13.5 birds/m2 with 0.5%
NaHC03 in the diet, and 4) male broilers at a
stocking density of 13.5birds/m2without0.5%
NaHC03 in the diet. There were sixreplicates
per treatment. The pens with stocking density
of 10.5 birds/m2 (210 birddpen) had five feeders and three waterers, whereas the pens
with stocking density of 13.5 males/m2
(270 birdstpen) had six feeders and three
waterers.
Trial 2 was conducted in the months of
May to July of 1995 using 4320 male and 4960
female 1-day-old broilers (stocking densities
of 13.5 and 15.5 birds/m2). There were two
sexes and four treatments per sex: 1) Broilers
given 0.5% of NaHCO3 in the diet during the
NaHC03 AND STOCKING DENSITY
last 2,3, and 4 wk of production and 2) a control diet (without NaHC03). Each sex was
allocated in different houses and there were
four replicates per treatment. Each male pen
had six feeders and four waterers and each
female pen had seven feeders and four waterers. The circumference of the waterers and
feeders were 1.06 and 1.22 m, respectively.
All chicks received a starter diet for 3 wk,
followed by a grower diet for 3 wk, and a
finisher diet for 1 wk. The composition of the
basal diets appears in Table 1. The NaHC03
was added to the basal diets in substitution of
grain. The calculated analysis of the diets
withNaHCO3 increased the Na to 0.27%
compared to 0.18% Na in the diet without
NaHC03. The chicks were fed mashed diets
and had water ad libitum. The amount of feed
offered was recorded daily, and at the end of
the trials the remainder feed was weighed.
All chicks were weighed on arrival at 1day
old as well as at 3 and 7 wk of age. Deaths were
registered daily and the birds weighed in order
to adjust feed conversion. Chicks were vaccinated against Newcastle Disease at 8 days old
(ocular and subcutaneous).
The variables measured included: body
weight, feed intake, and mortality. Feed conversion was calculated weekly as total feed
consumed divided by the weight of live and
dead birds. Kilograms of live broilers per
square meter (kg BW/m2) was calculated as
total body weight of broilers in a pen divided
by 20 m (the size of the pen: 5 m x 4 m).
Data were analyzed as described [lo, 111.
All statements of statistical significance are
based on P c .05.
RESULTS
AND DISCUSSION
The analysis of Trial 1 showed significant
impact of stocking density on body weight and
kg BW/m2 at 3 wk of age and also on feed
consumption at 7 wk of age (Table 2). As expected, higher body weights but lower kg
BW/m2 were obtained at the stocking density
of 10.5 than at 13.5 males/m2. These results
agree with those of other studies [7,8,12,13].
Feed conversion and mortality at 3 and 7 wk of
age were similar (P > .OS) for the two stocking
densities.
No significant differences between the
3-wk-old broiler chicks given 0.0% or 0.5%
of NaHC03 in the diet at stocking densities
of 10.5 and 13.5 males/m2 appeared in Trial 1
Research Report
PURONetal.
445
TABLE 1. Composition of the basal diets for Trials 1 and 2
*Mimet (2-hydroxy-4-(methyltio)butanoic acid) HMB, Nows Intl., St. Louis, MO.
%
. : ’
BProvides per of diet: wtamin A, 10,OOO IU; vitamin D3,2,5Oa IU; vitamin E, 30 mg; vitamin K, 5 mg; vitamin B1,
2.5 mg; tamin in 2,6 mg, vltamin B6 3.5 mg;vitamin BIZ,0.03 mg; niacin, 55 mg; pantothenic acid, 13.5 mg; folic acid,
1 mg; biotin, 0.29 mg.
%rovides per kg of diet: manganese, 70 mg; zinc, 45 mg; iron, 50 mg; copper, 2 mg; iodine, 1.1 mg; selenium, 0.25 mg.
DZinc bacitracin
%n starter 12.5 DDm of nicarbazin. In Dower and finisher 60 DDm of salinomvcin.
(Table 3). However, at 7 wk of age, broilers fed
the diets with NaHC03 had higher body
weight and better feed conversion than did
those birds given the diet without NaHC03
(Table 4).
It might therefore be unnecessary to add
N a H C O 3 to the starter diet, which could reduce the cost of feeding. However, the results
of Trial 2 do not support this conclusion. No
differences between the control (without
N a H C O 3 ) and the treatments given the diets
with N a H C O 3 during the last 2 , 3 , and 4 wk of
production appeared in Trial 2 (Table 5).
The lack of differences in the kg BW/m2
at the stocking density of 10.5for the diets with
or without NaHC03 agrees with previous re-
JAPR
N a H C O 3 AND STOCKING DENSITY
446
TABLE 2. Mean values for some parameters of economic interest in 21- and 49day-old male broilers at two
stockina densities in the months of June to July of 1994 (Trial 1)
I
FEED INTAKE
DENSITY
BODY
WEIGHT
10.5
772a
107Sa
1.390a
1.90”
7.96a
13.5
75Ib
1062a
1.413a
1.92=
956b
0.0256
0.0082
0.168
S.D.B
11.26
CONVERSION
14.84
10.5
233?
4973“
2.153a
4.62a
23.42b
13.5
226Ib
4803b
2.140a
5.25”
28.94a
0.0247
0.0103
S.D.
47.28
63.05
sults by Puron et al. [6] under the same environmental and management conditions, but at
a slightly lower stock density (10 bxds/m2).
Therefore, the effect of NaHC03 appears
to be more important at high stocking densities as hypothesized. At the stocking density
of 13.5 males/m2 the broilers fed the diet
withNaHC03 were heavier by 3.1%, had a
2.1% better feed conversion, and produced
2.6% more kg BW/m2 than did the birds given
the diet without N a H C O 3 (Table 4). These
results could come from Na+ more than from
HC03-. Other authors [14, 151 have found
that Na+ induces greater water consumption,
allowing better heat dissipation from the sur-
NaHC03
BODY
WEIGHT
FEED INTAKE
g
g
I
0.536
face of the lungs. Teeter and Belay [15]found
a positive correlation between water consumption and body growth rate (R>.98);
however, they mentioned that the acid-base
status of the bird becomes rate limiting for
both growth and survival when water consumption is equalized. Probably the broilers
consuming diets with increased Na+ from
NaHCO3 may have consumed more water.
However, improvements in body weight do
not appear to be associated with increased
body water retention [15]. Better planned
designs are needed in order to determine if
the effect of the sodium bicarbonate was due
to the sodium or to the bicarbonate.
FEED
CONVERSION
MORTALITY
kg BW/mU
70
Without
76ga
107T
1.403a
2.00a
7.92a
With
777a
1073a
1.37fia
1.81a
8.01a
Without
752a
106?
1.418”
1.48”
10.02a
With
750a
1056”
1.408a
2.3?
9.90a
0.0256
0.0082
0.168
S.D.B
I
11.26
14.84
a’bColumnswith different letters are significantly different (P< .OS).
Research Report
447
PURON et al.
TABLE 4. Mean values for some parameters of economic interest in 49day-old male broilers at two stocking
densities, with or without the addition of 0.5%NaHC03 in the diet in the months of June to July of 1994 (Trial 1)
NaHC03
BODY
WEIGHT
FEED INTAKE
g
g
FEED
CONVERSION
MORTALITY
kg BW/mM
%
Without
2301b
4959a
2.174'
4.3?
23xa
With
2372a
498?
2.132b
4.86a
23.70a
Without
2227b
47fBa
2.162a
5.03a
2a.57b
2.1Bb
5.4Sa
29.32a
0.0247
0.0103
0.536
With
2296a
S.D.B
47.28
48Ba
63.05
BS.D. = Standard deviation
a,bColumnswith different letters are significantly different (P < .OS).
Mortality was slightly higher in broilers
given the diet with NaHCO3 at the stocking
density of 10.5;no differences under the stocking density of 13.5 males/m2 appeared. As
mentioned before, the environmentaltemperatures reached during the study were not high
enough to cause mortality from heat stress.
Shane [16] indicated that it is necessary to
consider both temperature and humidity in
order to determine stress. He pointed out that
I when the apparent temperature exceeds 36"C,
egg production and growth rate decline,
whereas losses by mortality occur only above
47°C.
Profit margins in Trial 1 calculated as
monetary return/m2 minus cost of food/m2
andchicks/m2 were $10.38/m2 for the birds
given the diets without and $10.90/m2 with
sodium bicarbonate and kept at a stocking
density of 10.5 males/m2. For the males
TABLE 5. Mean values for some parametersof economic interest in 49day-old male and female broilers given
diets with NaHCO2 fed for different times iTrial2)
WEEKS FED
NaHCO3
BODY
WEIGHT
FEED INTAKE
FEED
CONVERSION
MORTALITY
kg/mM
4
191Sa
4179a
2.14a
6.69a
27.73a
3
1897
424ga
2.1Sa
6.59a
27.S4a
2
1914a
41na
2.13a
5.4ga
28.0ga
0
1rn3~
418T
27.72a
S.D.B
42.66
76.18
2.17a
6.12a
0.0437
0.0184
0.986
4
2174a
4571a
2.11a
8.59a
26.91a
3
2223a
4wa
2.07
6.93a
27.99a
2
22Wa
4609a
2.10a
8.50a
27.Ma
0
21sa
4630a
2.13a
8.7ga
26.97
0.0477
0.0236
S.D.
64.34
40.19
1.193
JAPR
N a H C 0 3 AND
448
under the stocking density of 13.5 males/m2
fed diets without NaHC03 the profit margin
was $12.70/m2, but for those fed diets with
NaHC03 the margin was $13.34/m2. For example, in a broiler house of 1500 m2 (the size
commody used in the southeast of Mexico),
STOCKING DENSITY
there would be a profit of $960 per house.
Profit margins were calculated on the basis
of $0.24 per kg of feed, $1.15 per kg of live
weight, and $0.45 per chick. A higher price of
market broilers or a reduction in feed cost will
increase the profit margins.
CONCLUSIONS
AND APPLICATIONS
1. Male broilers raised at a stocking density of 13.5 males/m2 and fed on diets with 0.5% of
N a H C 0 3 during 7 wk had in general a better performance than those given the diets
without N a H C 0 3 .
2. The addition of 0.5% N a H C 0 3 to the diets and fed during 7 wk increased the profit margin
by $0.64/m2.
3. The results of this study suggest that N a H C 0 3 should be added to the broiler diets for at
least the last 5 wk of production. However, further studies are recommended on the effect
of N a H C 0 3 at high densities in the tropics.
REFERENCES
AND NOTES
1. Mariinez, k k , J. Salazar, and G . Vela, 1993.
Estudio controlado del efecto del bicarbonato de sodio
en pollos bajo estrts calbrico. Pages 138-141 in: Proc. 18th
Convencibn Nacional ANECA, Cancun Q.Roo, Mexico.
2. Teeter, RG., M.O. Smith, F.N. Owens, S.C. Arp, S.
Sangiah, and J.E. Breazile, 1985. Chronic heat stress and
respirato alkalosis: Occurrence and treatment in broiler
chickens.youltry Sci. 64:106&1064.
3. Teeter, RG. and M.O. Smith, 1986. High chronic
ambient temperature stress effects on broiler acid-base
balance and their response to supplemental ammonium
chloride, potassium chloride, and potassium carbonate.
Poultry Sci. 65:1777-1781.
9. Garcia, E, 1988. Modificaciones al Sistema de
Clasificacibn Climatica de Koppen. Universidad
Autbnoma de M6xic0, Mexico, D.F.
10. In Trial 1, data was analyzed usin three preplanned comparisons (orthogonal contrasts?: Contrast 1
compared stocking densities (10.5 vs. 13.5 males/m2, the
mean ofTreatments 1and 2vs. the mean of Treatments 3
and 4); Contrast 2 compared Treatments 1 and 2;
Contrast 3 compared Treatments 3 and 4. In Trial 2,
differences between treatments were established by a
two-way analysis of variance; mean comparisons were
made by Tukey's test. Data on mortality were converted
to arc-sine before statistical analysis was carried out. The
general linear model procedure of SAS [ l l ] was used.
4. Whiting, T.S., LD. Andrews, and L Stamps, 1991.
Effects of sodium bicarbonate and potassium chloride
drinking water supplementation. 1. Performance and
exterior carcass quality of broilers grown under thermoneutral or cyclic heat-stress conditions. Poultry Sci. 705359.
11. SAS Institute, 1989. SAS/SI'AT User's Guide.
Version 6. 4th Edition, Volume 2. SAS Institute, Inc.,
Cary, NC.
5. Boltje, W.G. and P.C. Harrison, 1985. Effects of
carbonated water on growth performance of cockerels
subjected to constant and cyclic heat stress temperatures.
Poultry Sci. M1285-1292.
13. %ares, P.R, J.B. Fonseca, M. de A. Silva, A S .
Gracas, H.S. Rostagno, and k C A Silva, 1991. Performance of broilers of four commercial strains, housed at
different densities. Revista da Sociedade Brasileira de
Zootecnia 2074-79.
6. Puron,D., R Santamaria, and J.C. Segura, 1994.
Effects of sodium bicarbonate, acetylsalicylic, and ascorbic acid on broiler performance in a tropical environment.
J. Appl. Poultry Res. 3(2):141-145.
7. Shanawany, M.M., 1988. Broiler performance
under high stocking densities. Br. Poultry Sci. 29:43-52.
8. Puron, D., R Santamaria, J.C. Segura, and J.L
Alamilla, 1994. Broiler performance at different stocking
densities in an environmentally controlled house in the
tropics. J. Appl. Poultry Res. 4:55-60.
12. Bolton, N., N.A. Dewar, R.M. Jones, and R
Thompson, 1972. Effect of stocking density on performance of broiler chicks. Br. Poultry Sci. 13:157-162.
14. Balnave, D. and L Gorman, 1993. A role for
sodium bicarbonate supplements for growing broilers at
high temperatures. World's Poultxy Sci. J. 49:23&241.
15. Teeter, RG. and T. Belay, 1996. Broiler management during acute heat stress. Anim. Feed Sci. Tech.
58127-142.
16. Shane, S.M., 1994. The relationship of temperature and relative humidity on performance of flocks.
Zootecnica Intemacional 17(10):92-95.