01999Applied PoulIq Science, Inc
ACIDSUPPLEMENTATION
OF
LOW=PROTEIN
BROILER
DIETS:
1. GLUTAMIC
ACIDAND INDISPENSABLE
AMINO ACIDSUPPLEMENTATION
AMINO
B. J. KERR' and M.T.KIDD
Nuti-Quest, Inc., 1400 Elbridge Payne R o d Suite 110, Chestefleld MO 63017
Phone: (636)537-4057
F M : (636)532-1710
E-mail: [email protected]
Primarv Audience: Nutritionists. Researchers
I
formulation on a dgestible amino acid basis,
DESCRIPTION
OF PROBLEMand applicationof an ideal amino acid concept
The most limiting dietary amino acids are
available to the poultry industry as dietary
supplements, allowing the opportunity to
accurately meet the amino acid needs of the
1
To whom correspondence should be addressed
[l] m& result in crude protein (CP) levels
much lower than those listed by the NRC [2].
Animals cannot convert excess amino acids
into body protein, in fact, an oversupply of
Research Report
KERR and KIDD
and has been shown to depress performance,
leading to inefficient and uneconomical
meat production [3,4]. In addition, excessive
protein or amino acid consumption leads
to increased nitrogen excretion [5, 61. The
purpose of the following experiment was
to feed broilers reduced CP, amino acidsupplemented diets and evaluate the impact of
dispensable and indispensable amino acid
(IDAA) supplementation on bird performance and carcass characteristics.
299
(0.29%/1000 kcal kg-'). Withdrawal diets also
contained 3245 kcal ME kgl, but digestible
Lys content was lowered t o 0.84%
(0.259%/1000kcal kg-l). The positive control
finisher diet contained 19%CP, while the positive control withdrawal diet contained 18%
CP.All other diets had CP levels reduced from
these initial levels. In addition to meeting the
estimated digestible amino acid requirement,
all diets were formulated to meet a digestible
Cys ratio [l].Treatment 1 was formulated to
reflect typical diets utilized in industry, while
Treatments 2,3, and 4 were reduced in CP by
2,4, and 6%, respectively. Treatments 5 6 , and
7 were similar to Treatments 2,3, and 4 except
that 1% Glu was added as a dispensable amino
acid nitrogen source. Treatments 8,9, and 10
were similar to Treatments 5,6, and 7 except
that IDAA were supplemented according to
an ideal amino acid pattern. All amino acids
were added at the expense of corn.
Pen BW were obtained on Days 28 and 52
to determine BW gain and feed conversion for
the interim time period. Mortality was monitored throughout the experiment. On Day 52,
nine birds/pen that were close to the pen average and had no visible signs of abnormalities
were randomly chosen for processing. Feed
was withdrawn for 12 hr prior to the birds
being processed at a pilot processing laboratory. Buds were weighed at the poultry farm
on Day 53, transported in coops (less than
1 km) to the processing plant, stunned with an
electric knife, bled for 90 sec via severing of
the jugular vein, scalded for 2 min, and
defeathered in a rotary picker. Eviscera and
abdominal fat were removed manually. The
abdominal fat was weighed and birds were
placed in an ice bath for 12 hr. Carcass parameters measured were live weight, chill weight,
Pectoralis major and minor weq$t, thigh meat
weight (skinned and deboned), drumstick
meat weight (skinned and deboned), and wing
weight. Data were analyzed using GeneraI
Linear Models of SAS [8], using the pen as
the experimental unit for all analysis. All percentage data were subjected to square root
transformation prior to analysis. This transformation did not alter statistical interpretation;
therefore data are presented as actual percentages. Statements of statistical si@icance
are based on P 4.05.
MATERIALS
AND METHODS
One-day-old male Ross x Ross broilers
were allocated to 50 floor pens layered with
new pine shavings. Each pen consisted of 120
broilers with three tube feeders and two bell
waterers in pens that measured 3.66 x 3.05 m
(0.093m2 floor space per bird). All broilers
consumed feed and water ad libitum and were
reared on continuous incandescent lighting.
From Day 1 to 14 all birds were fed a diet
containing corn, soybean meal, and meat and
bone meal consisting of 3140 kcal ME/kg,
21.5% CP, 0.93% TSAA, and 1.22%total Lys.
From Day 14 to 28 all birds were fed a similarly
composed diet consisting of 3160 kcal ME/kg,
19%CP, 0.91% TSAA, and 1.08%Lys.
Corn, soybean meal, meat and bone
meal, and rice bran were analyzed for CP and
amino acid content prior to diet formulation
to assure accurate amino acid content. Dietary
treatments were also analyzed for amino
acids and Cl? Crude protein was calculated as
nitrogen (N) X 6.25, amino acid concentrations determined following acid hydrolysis,
B p concentration following alkaline hydrolysis, and Met and C y s following performic
acid oxidation [q.True digestibility coefficients obtained from published tables [2]
were applied to the analyzed amino acid
levels in each ingredient to formulate diets on
a true digestible amino acid basis. The Illinois
Digestible Ideal Amino Acid profile was
applied in diet formulation to ensure IDAA
adequacy [l].
Ten dietary treatments were replicated
five times (600 birddtreatment) in a randomized complete block design. Diet compositions
for the finisher (Day 28 to 42) and withdrawal
(Day 42 to 52) time periods are presented in
Tables 1 and 2, respectively. Finisher diets
were formulated to contain 3245 kcal ME kg-',
with the digestible Lys calculated to be 0.94%
300
AMINO ACID-FORTIFIED DIETS
Supplementation of IDAA to the diets
RESULTS
AND DISCUSSIONalready containing Glu and reduced in CP
Analysis of the mixed diets yielded results
in close agreement to the calculated composition (Tables 1 and 2). Performance and processing results of individual treatments are
presented in Table 3. Initial BW at Day 28 did
not differ due to dietary treatment. Reduction
of CP by two percentage units without Glu or
IDAA + Glu supplementation (Treatment 2)
had no impact on daily BW gain or feed conversion compared to birds fed the positive
control diet. However, further reductions in
CP (Treatments3 and 4) caused a reduction in
BW gain and feed conversion. Reduced CP
diets without amino acid supplementationhad
little effect on feed intake, although birds fed
Treatment 4 exhibited lower feed intake than
birds fed Treatments 1,2, or 3. It was not surprisiig that buds fed the treatment reduced in
CP by two percentage units had BW similar to
birds fed the high protein treatment, since this
level of CP reduction results in amino acid
levels being relatively close to current recommendations [2] (Tables 1 and 2). That small
reductions in dietary CP have little effect on
performance has been shown by others [9,10,
111. As dietary levels of CP are further reduced, other IDAA may become limiting and
result in reduced performance [9,10,12].
Addition of 1% Glu to the low CP treatments numerically reduced daily BW gains
compared to buds fed the unsupplemented
diets, possibly due to minor reductions in feed
intake. Feed intake was reduced, however, in
birds fed the lowest CP treatment with Glu
supplementation (Treatment 7). Although
Glu is an excellent source of nonspecific N
[13], and IDAA are poor sources of nonspecific N [141, the response of broilers to diets
containing supplemental Glu varies. Supplementation of Glu to reduced-CP diets has
yielded improvements in gain [15] and feed
conversion [15, 16, 1 7 . In contrast, Leclercq
et al. [18] and Deschepper and de Groote [5]
have reported little effect of Glu supplementation on chick performance. The impact of
supplemental Glu on feed intake is also unclear. Leclercq et al. [18] showed no effect of
Glu on feed consumption, while negative effects of Glu on feed intake have been reported
by others [5, 191. Ando et al. [20]noted negative effects of Glu on feed intake, but only
when Glu supplementationwas 6% of the diet.
by four or six percentage units improved
BW gain, but failed to improve gains to the
level achieved by birds fed the positive control diet. Supplementation of IDAA alleviated
the reduction in feed intake due to Glu supplementation in the diet reduced in CP by
six percentage units. The reduced feed
conversion noted in diets reduced in CP by
four percentage units (Treatments 3 and 6)
was improved by IDAA + Glu supplementation (Treatment 9) to a level similar to that
of birds fed the positive control diet. Even
though daily BW gain and feed conversion
improved in birds fed the treatment reduced
in CP by six percentage units with IDAA +
Glu supplementation compared to birds fed
the unsupplemented or Glu-supplemented
treatments (Treatments4 and 7, respectively),
their performance was not equivalent to that
of birds fed the positive control diet. Several
studies indicate that birds do not perform as
well on low-CP, amino acid-supplemented
diets as on higher CP diets [9, 10, 11, 21,221;
while other studies suggest that similar performance can be achieved [5, 15, 16, 23, 24,
25, 261. A limitation of this experiment was
that IDAA were not tested in the absence of
Glu so that IDAA supplementation could be
evaluated independently. Dietary treatment
had no effect on chick livability.
The effects of dietary treatments on processing live weight reflect the results obtained
on BW. Percentage chilled carcass weight was
reduced due to a reduction in dietary CP by
four or six percentage units when no amino
acids were supplemented. Supplementation
of Glu to the reduced CP treatments did not
affect carcass yield. Supplementation of
IDAA + Glu to the low-CP treatments, either
with or without Glu, improved carcass yield to
a level similar to that of birds fed the positive
control diet.
Percentage abdominal fat was unaffected
when dietary CP levels were reduced by two
percentage units, regardless of amino acid
supplementation (Treatments 2, 5, and 8).
This might be expectedbecause dietary amino
acid levels were near recommended levels [2].
Further reductions in CP, without supplemental Glu or IDAA + Glu (lkeatments 3 and 4),
resulted in increased abdominal fat. Supplementation of Glu to the diets reduced in CP by
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KERR and KIDD
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AMINO ACID-FORTIFIED DIETS
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AMINO ACID-FORTIFIED DIETS
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six percentage units, supplementation of
IDAA + Glu improved the yield of I! majclr,
but failed to improve it to the level achieved
by birds fed the positive control diet. Suppkmentation of IDAA + Glu to the diet reduced
in CP by six percentage units improved the
yield of R minor to a level equivalent to birth
fed the positive control. Except for the yield of
Rmajor of birds fed Treatment 10, supplementation of IDAA + Glu to all the reduct:d
CP diets resulted in R major and R mimr
yields similar to those of birds fed the positive
control diet. Research indicates that dietary
CP level has no impact on breast meat yield
when crystalline amino acids are supplemented to the low-CP diet [19, 24, 251. [n
addition, Summers et ai. [28] and Leclercq
er al. [18] reported that total carcass protein
content was equivalent between birds fcd
high-CP or low-CP, amino acid-supplemented
diets. In contrast, Fancher and Jensen [9] and
Moran et al. [12] reported that broilers fed
low-CP, amino acid-supplemented diets hiid
reduced breast meat yields.
Yields of deboned thigh meat, deboncd
drumstick meat, and whole wings were unaffected by dietary treatment. Similar results
have been reported by Kidd et ai. [24], while
Moran et al. [12] noted slight differences in
thigh yields due to dietary protein level.
four and six percentage units had no effect on
percentage abdominal fat. Supplementation
of IDAA + Glu to birds fed the diets reduced
in CP by six percentage units resulted in abdominal fat levels similar to those of birds fed
the positive control. It has been shown that
Glu may [9, 10, 19, 271 or may not [15]affect
body fat, depending upon the type of diet (51
or broiler genetics used [18]. Increased abdominal fat in broilers fed low-CP, amino
acid-supplemented diets has been reported
[lo, 12, 21, 241. Inconsistency in amount of
body fat may be attributable to the dietary Thr
level as recent research suggests that adequate
levels of dietary Thr may minimize carcass
fatness [23].
Lowering dietary CP by two percentage
units (Treatments 2, 5, and 8) did not affect
R major or R minor yields. Further reductions
in CP (Treatments 3 and 4) reduced R major
and f? minor yields. Supplementation of Glu
had no effect on R major or R minor yields.
This is in agreement with past research [5,15,
18,191 demonstratingno effect of dispensable
amino acids on carcass protein deposition.
Supplementation of IDAA + Glu to the diet
reduced in CP by four percentage units produced only numerical improvements in
Rmajor and Rminor yields, each of which
were similar to birds fed the positive control
diet. In the treatment reduced in CP by
CONCLUSIONS
AND APPLICATIONS
1. Feeding reduced CP diets without amino acid supplementation severely reduced broiler
performance and carcass meat yield.
2. Supplementation of 1% Glu exerted no positive effects on bird performance or carcass
characteristics and appeared to reduce feed intake, resulting in reduced weight gains.
3. Supplementation of indispensable amino acids according to an ideal amino acid pattern
improved broiler performance and carcass meat yield compared to birds fed unsupplemented or Glu-supplemented diets, but failed to completely alleviate some of tht:
depressed performance and carcass parameters at the lowest level of dietary CP.
REFERENCES
AND NOTES
1. Baker, D.H., 1994. Ideal amino acid profile for
maximal protein accretion and minimal nitrogen excretion in m n e a n d poultry. Pages 134-139 in: Proc. Cornel1
Nutr. Conf., Rochester, NY.
2. National Research Council, 1994. Nutrient Reuirements of Poult 9th Rev. Edition. Natl. Acad.
$ r e s , Washington, D??
3. Waldroup, P.W., RJ.Mitchell, J.R Payne, and
KR Haze%1976.Performance of chicks fed diets formu-
I
lated to minimize excess levels of essential amino acids.
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4. Baker, D.H. and RA. Easter, 1976. Soy prot8:in
as a source of amino acids for nonruminant animals.
Pages %9-976 in: World Soybean Research. L.E. Hill, ed.
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5. Deschepper, K. and G. de Groote, 1995. Effecl of
dietary protein, essential and nonessential amino acids
on the performance and carcass compositian of male
broiler chickens. Br. Poultry Sci. W229-245.
Research Report
KERR and KIDD
6. Kerr, BJ., 1995. Nutritional Strategies for Waste
Reduction-Management:Nitrogen. Pages 47-68 in: New
Horizons in Animal Nutrition and Health (November),
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24. Kidd, M.T., BJ. Kerr, J.D. Firman, and S.D.
B o k g , 1996. Growth and carcass characteristics of
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25. Holsheimer, J.P., P.F.G. Vereuken, and J.B.
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