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Ideal Amino Acid Profile
For Piglets
by
G O TO E S S E N T I A L S ®
October 2013
Ideal Amino Acid Profile
For Piglets
Table of Contents
Preface
...........................................................................................................................
3
Amino Acids in Pig Nutrition ....................................................................... 4
Nutritional Systems ............................................................................................. 5
Methodology ............................................................................................................. 6
Tryptophan .................................................................................................................. 8
Valine ............................................................................................................................. 10
Isoleucine .................................................................................................................. 13
Leucine ........................................................................................................................ 15
Histidine ...................................................................................................................... 16
Phenylalanine and Tyrosine ....................................................................... 17
Ideal Amino Acid Profile ............................................................................... 18
Low Crude Protein Diets ............................................................................. 20
Conclusion
References
...............................................................................................................
...............................................................................................................
22
23
Preface
Recent advances and update of
the amino acids profile for piglets
The increasing availability of crystalline amino acids (AA), as L-Tryptophan and L-Valine, has
definitely changed the piglet feed structure and the way to deal with the nitrogen nutrition
issue for these animals. Recently, the availability of L-Valine has been a breakthrough in
feed formulation since it allows to match the requirement of this strong limiting AA, and to
efficiently move from a formulation based on dietary crude protein (CP) to a formulation
based on each essential AA. This increasing practice all over Europe results in a drastic
decrease of the dietary CP levels and is the insurance to supply a feed in which AA needs
are met with a high degree of precision. This technic enables the improvement of nitrogen
efficiency while maintaining the performance of pigs. In these formulas, 7 AA are co-limiting
and the dietary AA profile reaches an optimal balance to optimize the growth performance
and the economic value of the feed.
Implementing an optimized AA nutrition needs prerequisites on the knowledge of AA
requirements. Getting this information is crucial to answer the animal need but also to
determine what the limiting AA in each particular situation is. The most limiting AA in a diet
represents indeed the axis of progress of the formula and of the overall technico-economic
performance. In the past 5 years, AjInomoTo EuRoLysInE s.A.s. (AEL) has implemented
various research programs to fill the gap of knowledge concerning the next limiting AA for
piglets. A masterpiece of this program has been the work of Gloaguen (2012) about Valine,
Isoleucine, Leucine, Histidine, Phenylalanine, Tyrosine and dietary protein reduction in piglets.
These new outcomes, together with the other works supported by AEL in Europe, are now
integrated in our recommended Ideal Amino Acid Profile for piglets. In the present document,
the focus is made on the recent advances concerning Tryptophan, the branched-chain AA
and the next limiting AA. Data about Lys, met and Thr are based on previous works (van
milgen and Le Bellego 2003, sève 1994).
This document is a synthesis and more detailed information is available in the reference
list. The objective is to make the link between the scientific data and their implementation
in piglets feeds to formulate diets which have to support efficiently the growth of variable
population of animals.
Étienne Corrent, aude simongiovanni,
Éric le Gall and loïc le tutour.
ajinomoto eurolysine s.a.s. | 3
amino acids in Pig nutrition
Determining the indispensable
amino acids requirements and the next
limiting dietary amino acids
Twenty AA are the building blocks of proteins. Each AA is encoded in the DNA as codons,
which enables the protein synthesis. All AA are critical to life and nine of them are either
not synthesized at all or only in small quantities by pigs (Table 1). They must therefore be
supplied through the diet and are called indispensable (or essential by usage) amino acids
(IAA or EAA). In practice, it is of great importance to control that the minimum requirements
of the IAA are met, even more when dietary CP is reduced.
Essential Amino Acids (AA): AA involved in the biological functions that are necessary
for life supplied through the diet or synthesised de novo by animals
Indispensable AA
Semi-dispensable AA
Dispensable AA
AA that cannot be synthesised
de novo or at a sufficient
rate to maintain associated
biological functions
AA that can be synthesised
de novo but could become
indispensable in specific situations
when the synthesis is not
sufficient to cover the requirement
AA that can be synthesised
de novo by the animal
in a sufficient rate
Lysine (Lys)
Glycine (Gly)
Threonine (Thr)
Serine (Ser)
Methionine (Met)
Cysteine (Cys)
Proline (Pro)
Tryptophan (Trp)
Alanine (Ala)
Valine (Val)
Aspartate (Asp)
Isoleucine (Ile)
Asparagine (Asn)
Leucine (Leu)
Glutamate (Glu)
Histidine (His)
Glutamine (Gln)
Phenylalanine (Phe)
Tyrosine (Tyr)
Arginine (Arg)
Table 1: usual classification of the 20 amino acids encoded directly by the genetic code for pigs.
4 | Ideal Amino Acid Profile For Piglets
L-Trp
L-Val
0
DL-Met
100
L-Thr
Supply and source of dietary AA in % of the AA requirement
L-Lys
With the feed-use AA available on the market it is possible to formulate diets without
minimum constraint on the
CP level in which at least 7
AA are co-limiting: Lys, Thr,
Trp, Met (and Cys), Val and
the next one which determines the resulting dietary
CP level (Figure 1). Thus,
determining AA requirements
aims also at identifying the
next limiting AA in local situation which then depends
on the local feedstuffs used.
Lys
Thr
Met
+ Cys
Trp
Val
Ile
Leu
His
Phe
+Tyr
■ Amino Acids from feedstuffs ■ Amino Acids from Feed-use AA
Figure 1: Example of the 7 co-limiting AA in a piglet formula in which dietary crude protein is reduced, taking into
account requirement of EAA, and using feed-grade AA.
nutritional systems
Evaluating amino acids supply:
Total vs digestible AA,
Apparent vs Standardized digestibility
The first and only direct way to estimate AA contents in feedstuffs is to analyze samples using
specific methods. Total AA contents can be measured with a good precision using reference
methods. The repeatability and reproducibility levels are at least similar to those of proximal
analyses. Regressions equations based on total Nitrogen (N) are also available and give an
accurate prediction of the total AA contents (Bulletin 32, AEL).
The total AA supplied from feedstuffs cannot be entirely absorbed by the animal’s digestive
tract. The amount of each AA that can be absorbed depends on the type of raw material
used and on the AA under consideration. The most effective way to formulate feeds for pigs
is thus by using the digestible AA values rather than the total ones. This results in a more
accurate supply to meet animal requirements and a better economic solution.
Knowledge of the digestibility of each AA in each raw material is therefore essential for the
adequacy of the dietary supply of AA (Figure 2). The apparent ileal digestibility (AID) is a
first attempt to estimate the AA available for pigs. It represents the difference between the
intake and the ileal outflow (excreta). However the ileal outflow contains also endogenous
losses with large quantities of endogenous protein and AA. This system can be corrected
by considering the basal endogenous losses to give a more accurate value of the feedstuffs
digestibility: The standardized ileal digestibility (SID).
100%
➊
➋
➌
Excreta
{
SID
0
AID
Total
81%
74%
Undig
Undig
EL
EL
➊ Total AA supply
➋ AID: Total - Excreta
➌ SID: Total - (Excreta - EL)
AID: Apparent ileal digestibility
SID: Standardized ileal digestibility
Undig: Undigestible fraction
EL: Endogenous losses
Figure 2: Representation of the digestibility systems used in pigs.
Example based on the Lys digestibility of wheat (InRA, 2004).
For instance, the EvaPig® software proposes coefficients of SID values to apply on total AA
and use directly in the feed formulation (www.evapig.com).
ajinomoto eurolysine s.a.s. | 5
methodology
An usual definition of “the requirement” for practical issues is the minimal
amount of the studied nutrient needed to reach optimal or maximum
performance, assuming that all the other nutrients are provided in adequate
amounts (Hauschild et al., 2010). The practical objective of determining
amino acid requirements is to use these values to supply a feed that must
support the growth of a heterogeneous population of pigs. However,
reported results can be quite variable, and a major part of this variability lies
in the methodological aspects which must be taken into account when a
review is performed with the objective to assess practical recommendations
(Simongiovanni et al., 2012).
Factorial approach vs empirical approach
(Haushild et al., 2010)
➔ the factorial approach: Daily requirements are obtained for an individual animal at a
specific point in time by combining the estimated requirements for maintenance and
production.
➔ the empirical approach: Nutritional requirements are defined as the minimal amount
of nutrients needed to maximize or minimize population responses for one or several
performance criteria during a given period.
Both methods have strengths and limitations but for practical feeds given to growing animals
the definition of the requirement is in the scope of the empirical approach.
In this review, dose-response studies are used to allow estimating AA requirements by
depicting the response of a growing population to increased levels of an AA.
Expressing amino acids requirement
within the ideal protein concept (i.e. ratio to Lys)
In the ideal protein concept, AAs are expressed relatively to Lys. Working with this unit
implies that the protocol of a dose-response trial must follow specific conditions: The first
limiting factor has to be the studied AA, and the second limiting factor has to be Lys. If not,
the AA:Lys requirement estimates will be very variable and undervalued due to unknown
factors limiting the response.
In all the trials reviewed here, attention has been paid to assess if the results can be
extrapolated as AAs ratio to Lys for practical use.
6 | Ideal Amino Acid Profile For Piglets
Digestibility systems and feedstuffs matrix
Obviously any comparison of dose-response studies must be done within the same nutritional system and the result should also be linked to the feedstuffs matrix used in the
dose-response.
➔ Indeed, AA requirement estimates will be varying depending on the nutritional system as
follow:
– Requirement for Total AA > Standardized Ileal Digestible > Apparent Ileal Digestible values,
– The gap between each value per system is different for each AA.
➔ AA requirement estimates are also very dependent on the reference system (i.e. INRA
2004, NRC 2012, or analyzed values). Direct comparisons should take into account the
variability induced by the reference system.
In this review, all values are expressed in SID and were recalculated based on INRA
tables (Sauvant et al., 2004).
Models used to interpret the dose-response
A dose-response study must be analyzed with an adequate model to depict the response
and estimate the value that maximizes a chosen criteria.
➔ The linear-plateau model will always give lower AA requirement values than a curvilinear-plateau model, and has a very poor description of experimental data,
➔ The curvilinear-plateau model is superior to determine requirement values to be applied
in practical situation and allows to estimate the marginal efficiency of the response.
In this document, responses and AA requirements are determined based on dose-response studies using curvilinear-plateau models. They are issued from meta-analysis
works when meaningful or review and synthesis of dose-response trials.
ajinomoto eurolysine s.a.s. | 7
tryptophan
Tryptophan is generally the 4th limiting amino acid in a European cereals
based diet. Besides being a constituent of body protein, Trp also plays other
important roles in metabolism. It is involved in feed intake regulation,
in the immune response and in the animal’s defence system. Increasing
the Trp content in the diet has also been shown to limit the impact
of an unfavourable health environment on performance in piglets
(Bulletin 30, AEL). Being an indispensable AA for pigs, Trp has to be supplied
by the diet in sufficient quantities to cover the animal’s requirement for both
growth and health challenged situations.
22% SID Trp:Lys to take advantage of the
numerous effects of Trp on piglets’ performance
More than 130 studies about the effect of Trp on piglets’ performance have been listed by
Simongiovanni et al. (2012) who performed a meta-analysis concerning the piglet response
to Trp. This AA has been extensively studied due to a practical interest linked to its numerous biological functions and its importance for piglet nutrition. Among the 130 studies, 37
have been selected by Simongiovanni et al. (2012) to assess a Trp requirement as a ratio
to Lys. Using a curvilinear-plateau model, and based on INRA tables (Sauvant et al., 2004),
requirement estimates for ADG, ADFI and G:F have been determined varying from 20 to
22% depending on the criteria to maximize. This level of 22% SID Trp:Lys is the basis of
the Trp recommendation proposed by AEL and again confirmed by new dose-responses.
Indeed, these new results are in line with the model estimated in the meta-analysis (Figure 3).
ADG (% of the best performance)
100
90
Simongiovanni et al., 2012
Naatjes et al., 2010a
Naatjes et al., 2010b
Ma et al., 2010
Petersen, 2011a
Petersen, 2011b
Kluge et al., 2010
Wessels et al., 2011
80
70
60
50
40
30
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
SID Trp:Lys (%)
Figure 3: Effect of Trp on the average daily gain (ADG) of piglets. Comparison of the model
determined by simongiovanni et al. (2012) with external Trp dose-reponses (not used in
the meta-anlaysis work).
8 | Ideal Amino Acid Profile For Piglets
Tryptophan: An amino acid to face efficiently
the challenges of the piglet life
During the whole piglet period, diets must enhance feed intake, ensure a maximum growth,
support a good health status and avoid stress. The various Trp functions are related to each
of these challenges (Figure 4). It is therefore of primary importance to assess an adequate
level of Trp in piglet diets.
Animal Behavior
Feed intake
Ghrelin
Dietary
tryptophan
Melatonin
Serotonin
Gastrointestinal
tract
mood, stress response,
ans sleep regulation
Brain
Trp : LNAA (% CP)
4 limiting
amino acids
th
Plasma
Tryptophan
Protein
synthesis
Growth
performance
TDO
IFN
gamma
IDO
Acute phase
protein
Immune response and
health maintenance
Kynurenine
Metabolites
Trp : LNAA (Tryptophan : Large Neutral Amino Acids ratio)
CP (Crude Protein)
IDO (Indoleamine 2,3 dioxygenase)
TDO (Tryptophan dioxygenase)
Increase
Regulate
Figure 4: Global pattern of biological roles of Trp and their implications for piglet growth
(Bulletin 30, AEL).
The versatile effects of Trp due to its numerous biological functions and its importance for
protein deposition lead to recommend a level of 22% SID Trp:Lys for practical piglet diets.
ajinomoto eurolysine s.a.s. | 9
Valine
Valine is the fifth limiting amino acid after Trp in European diets for piglets.
Valine is an indispensable amino acid for body protein deposition and
growth, and a dietary deficiency in valine affects the utilization of previous
limiting amino acids and consequently animal growth. Valine is a branchedchain amino acid (BCAA), together with isoleucine and leucine. Due to their
common catabolic pathway, some interactions exist between them. It is
therefore very important to well know their requirements and to ensure that
the feed supplies a balanced BCAA profile.
Valine requirement in piglets is confirmed
to be 70% SID Val:Lys
With about 20 publications mostly in piglets, the number of Val dose-response studies is
lower than for Trp but is increasing since L-Valine has been made available for feed-use
in 2009 by AEL. Using most of the Val dose-responses studies available, van Milgen et al.
(2013) determined by a meta-analysis work that there is a response of +5% for the ADG
when SID Val:Lys is increased from 64 to 69%. A data set of 10 trials is presented in Figure
5. These trials were selected to allow to express the performance according to dietary
Val:Lys levels. It shows that on average, a value of 70% SID Val:Lys enables to obtain the
optimal performance.
ADG (g/day)
600
500
Mavromichalis et al. (2001) - Exp. 5 Barea et al. (2009)a - Exp. 4 Barea et al. (2009)b - Exp. 4 Dusel et al. (2008)
Paulicks et al. (2008)
Torrallardona et al. (2008)
Vinyeta et al. (2010)
Millet et al. (2010)
Gloaguen et al. (2012)
Soumeh et al. (2013)
400
300
200
100
0
45
50
55
60
65
70
75
SID Val:Lys ratio (%)
80
85
Figure 5: sID Val:Lys dose-responses in piglets. Effect on average daily gain (ADG).
10 | Ideal Amino Acid Profile For Piglets
Impact of the branched-chain AA metabolism
on performance
gut flow
ILE
LEU
nt
all i
sm
KIV
le
musc
in
e
VAL
e st
liver
A-CoA1
BCKDH
KMV
A-CoA2
KIC
A-CoA3
Glucogenic
Ketogenic
VAL ILE LEU
PROTEIN SYNTHESIS
CATABOLISM
LYS
VAL
TRP
BCAA
LEU
THR
ILE
VAL
ALA
BCKA
KIV
BCAT
ILE
KMV
LEU
KIC
GLU
NH3
GLN
Figure 6: Global pattern of the branched-chain amino acids metabolism.
Since AA cannot be stored, any excess of AA is catabolized. The group of the BCAA shares
in common the two first steps of their catabolism (Figure 6). The second step is under the
influence of Leu which activates the BCKDH enzyme complex leading to the catabolism
of Val and Ile when Leu is in excess. The Val and Ile catabolism is enhanced even if these
AA are deficient in the diet (Bulletin 35, AEL). Indeed, it has been shown that when dietary
ajinomoto eurolysine s.a.s. | 11
Leu supply is high, the requirement per se of Val is not affected by the Leu content but the
response to Val is even more increased (Gloaguen et al., 2012, Figure 7). In addition, piglets
avoid (decrease) to eat BCAA imbalanced diet (i.e. Val deficient). Indeed, Gloaguen et al.
(2012) shown that a piglet is able to detect within 1 hour after meal the dietary Val deficiency
and consequently reduces its feed intake. The combination of the decreased feed intake
and feed efficiency results in a drastic decrease of the ADG.
ADG, % of the best performance
FCR, % of the best performance
100
95
90
85
80
75
70
65
60
55
50
115.0
55
112.5
110.0
107.5
105.0
102.5
60
65 70 75 80
SID Val:Lys ratio (%)
Barea et al. (2009) Low Leu
85
100
55
60
65
70
75
80
SID Val:Lys ratio (%)
Glaoguen et al. (2012) High Leu
85
Area of the requirement
Figure 7: Effect of sID Val:Lys on piglets performance with (Gloaguen et al., 2012) or
without (Barea et al., 2009) large supply of Leucine.
Among the BCAA,Val is the limiting AA in the piglet diets when no L-Valine is added. It is
therefore crucial to control the minimum levels of dietary Val. The use of 70% SID Val:Lys
allows to counter act any imbalance in BCAA supply and to maximize feed intake, growth
and feed efficiency of piglets.
12 | Ideal Amino Acid Profile For Piglets
isoleucine
Isoleucine is a potential limiting AA after Val and its dietary level could
determine the dietary protein level in a formula using the complete range of
available feed-use AA. It is therefore necessary to consider this AA in the
formulation and to assess a safe requirement level. The literature is
important concerning Ile but controversial results were published on the
requirement estimates. However, the factor of variation has been described
and today robust recommendations on Ile levels can be established for
commercial diets.
53% SID Ile:Lys is recommended for piglets
Isoleucine belongs to the group of the branched-chain AA together with Val and Leu, but
also to the Large Neutral AA group (LNAA) which includes BCAA, Trp, His, Phe and Tyr.
This group of AA shares a common saturable transporter at the blood brain barrier level. An
analysis of literature about the Ile requirement in piglets must take into account these factors.
Van Milgen et al. (2012) ran a meta-analysis work on the response of growing pigs to Ile and
concluded that the requirement is influenced by the presence of spray-dried blood-cells
(SDBC) in the diet. Indeed, in these products the AA pattern is very imbalanced (Figure 8),
and their use increases the Ile requirement level. Due to their poor Ile contents, SDBC have
been extensively used in Ile dose-response studies but the requirement estimates used to
be very variable and very high in comparison to requirement estimates based on blood-free
diets (Bulletin 35, AEL).
Phe:CP
Lys:CP
15
Spray dried blood cells
13
Soybean meal
10
8
5
Ile:CP
3
0
Leu:CP
His:CP
Val:CP
Figure 8: Amino acids profile of sDBC vs
soybean meal; as % of crude protein (CP).
ajinomoto eurolysine s.a.s. | 13
A review of the Ile dose-responses in piglets is proposed in Figure 9; only the trials in which
blood-free diets were used were selected. Van Milgen et al. (2013) proposed a minimum
requirement of 50% SID Ile:Lys when blood-free diets are used. For practical purpose we
recommend the use of 53% SID Ile:Lys. When using blood-cells attention must be paid to
the dietary level of Ile with an increased requirement.
ADG (g/d)
600
500
400
300
200
Wiltafsky et al. (2009) Exp3.
Gloaguen et al.
Gloaguen et al. (2012)
Trautwein et al. (2010)
Millet et al. (2010)
Noorgard et al. (2012)
Soumeh et al. (2013)
100
0
30 35 40 45 50 55 60 65 70 75 80
SID Ile:Lys ratio (%)
Figure 9: sID Ile:Lys dose-responses in piglets, blood-free diets. Effect on average
daily gain (ADG).
14 | Ideal Amino Acid Profile For Piglets
leucine
Leucine is a BCAA, generally in excess supply in current piglet’s diets.
Leucine plays a key role in the catabolism of the BCAA. A Leu excess
together with Val and/or Ile deficiencies is described in the literature to be
detrimental for piglet performance (Bulletin 35, AEL). Indeed, any imbalance
within BCAA dietary supply must be avoided. However, a recommendation
of a leucine maximum is not meaningfull since the issue lies in the balance
with the others BCAA. The most efficient way is to formulate closer to the
leucine requirement and to control the minimum Val and Ile levels. It is
therefore necessary to assess the animal response to Leu and the
requirement of Leu to determine to what extent Leu levels can be reduced.
Leucine levels can be reduced
to 100% SID Leu:Lys in piglet diets
Literature about Leu requirement in
piglets is scarce but recent trials have
been performed in Europe and are
reported in Figure 10. For instance,
Gloaguen et al. (2013) published a
study about the Leu requirement in
piglets and concluded that 102%
SID Leu:Lys was necessary on average to maximize the piglet performance. However, as shown in Table
2, a 10% deficiency slightly affects
the response, which is confirmed by
recent trials conducted in cooperation
with AEL and shown in Figure 10.
ADG (g/d)
600
500
400
300
200
100
60
70
80
90 100 110 120 130 140
SID Leu:Lys (%)
Augspurger and Baker (2004), 1
Augspurger and Baker (2004), 2
Gloaguen et al. (2012), 1
Gloaguen et al. (2012), 2
Soumeh et al. (2013)
Wessels et al. (2013)
Figure 10: sID Leu:Lys dose-responses in piglets. Effect on average daily gain (ADG).
Criteria to maximize
ADFI
ADG
SID Leu:Lys requirement estimates (%)
102.4
101.9
Gain to Feed
97.2
-10% deficiency affects the response by
-1.9%
-3.3%
-2.0%
Table 2: Results of Gloaguen et al. (2013). sID Leu:Lys requirement estimates and effect of a 10%
deficiency on performance, based on a curvilinear-plateau model.
Based on these data a level of 100% SID Leu:Lys is recommended for piglet diets.
ajinomoto eurolysine s.a.s. | 15
Histidine
Histidine is considered as an essential AA for piglets but its requirement has
not been extensively studied. The current dietary levels in piglets’ diets are
not limiting and His could be limiting after the BCAA group depending on
the structure of the formula (i.e. feedstuffs AA contents). To be complete, an
ideal AA profile must account for His level.
Overview of the Histidine dose-response
studies in piglets
In order to express the His requirement within the ideal protein concept, Gloaguen et al.
(2013) performed two His dose-responses in piglets (10 to 22 kg LW) in which Lys was
sublimiting (1.00% SID). The results of this study are presented in Figure 11 and Table 3,
and an average requirement of 32% SID His:Lys has been assessed.
ADG (g/d)
FCR
500
2.25
400
2.00
300
1.75
200
1.50
100
1.25
16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46
SID His:Lys (%)
Gloaguen et al. (2013), 1
Gloaguen et al. (2013), 2
Figure 11: sID His:Lys doseresponses in piglets. Effect on
average daily gain (ADG) and feed
conversion ratio (FCR).
Criteria to maximize
ADFI
ADG
SID His:Lys requirement estimates (%)
32.7
31.6
28.8
-1.6%
-2.6%
-1.5%
-10% deficiency affects the response by
Gain to Feed
Table 3: Results of Gloaguen et al. (2013). sID His:Lys requirement estimates and effect of a 10%
deficiency on performance, based on a curvilinear-plateau model.
Two other studies had been performed in the past (Table 4) but the requirement estimates
are expressed in different units which makes difficult the synthesis. However, considering
the response when His is deficient, the estimate of 32% SID His:Lys is safe to be used in
low protein diets.
Body weight
Response criteria
Izquierdo et al., 1988
10-20 kg
ADFI, ADG, G:F
0.36% total His
Li et al., 2002
10-20 kg
ADFI, ADG, G:F
30% AID His:Lys
Gloaguen et al., 2012
10-22 kg
ADFI, ADG, G:F
32% SID His:Lys
Table 4: Literature available about the His requirement in piglets.
16 | Ideal Amino Acid Profile For Piglets
Requirement estimates
Phenylalanine and tyrosine
Phenylalanine and Tyrosine are aromatic AA also classified as indispensable
AA and semi-dispensable AA, respectively. The current piglet diets still
provide large amount of Phe and Tyr, even after the dietary crude protein
reduction which is currently achievable using the available feed-use AA.
The requirement of these AA had therefore not been studied.
Pioneer works supported by AEL are presented here.
First work to refine a Phenylalanine
and Tyrosine requirement in piglet
Phenylalanine can be converted to Tyr by irreversible hydroxylation through an enzyme which
is activated by Phe itself. Tyrosine is considered as a semi-dispensable AA because a Tyr
deficiency could occur when the dietary Phe supply is insufficient to supply Tyr. Because
Phe can be used for Tyr synthesis, the requirement for the latter had not been explicitly
quantified and the requirement had been usually expressed in recommended AA profile as
the sum of Phe + Tyr.
Recommended requirements vary from 54 to 57% SID Phe:Lys and 93 to 111% SID
(Phe+Tyr):Lys. Gloaguen et al. (2014) worked on dose-responses to Phe and Tyr and on
the possibility to substitute Tyr by Phe. It is shown that the minimum SID Phe:Lys requirement
is about 54% and the maximum SID Tyr:Lys requirement is about 43% (Table 5).
Criteria to maximize
ADFI
ADG
Gain to Feed
SID Phe:Lys requirement estimates (%)
54.8
54.2
52.6
-10% Phe deficiency affects the response by
-1.8
-3.0
-1.7
SID Tyr:Lys requirement estimates (%)
42.8
39.7
-
-10% Tyr deficiency affects the response by
-0.6
-0.7
-
Table 5: Results of Gloaguen et al. (2014). sID Phe and Tyr to Lys requirement estimates and
effect of a 10% deficiency on performance, based on a curvilinear-plateau model.
Nevertheless, it seems that considering the sum of Phe+Tyr to assess the requirement is not
relevant since the substitution of Tyr by Phe was not successful in this work (data not shown
here). This could be linked to the particular usage (oxidation) of the Tyr obtained from Phe in
comparison to the dietary Tyr. More research is needed on this issue, and for practical feeds
we still recommend a minimum of 95% SID (Phe+Tyr):Lys with minimum SID Phe:Lys of 55%.
ajinomoto eurolysine s.a.s. | 17
ideal amino acid Profile
The review of the available amino acids dose-responses and the very new
trials concerning the less studied AA are a basis to refine recommendation
of an ideal AA profile for practical piglets diets. However, in addition to the
scientific data available, making a decision on which dietary AA levels have
to be used must take into account others parameters inherent in feed
formulation. AEL’s nutritionists work in close collaborations with institutes
all over Europe to be able to recommend a robust amino acid profile that
ensures the best performance of piglets raised in variable commercial
conditions in Europe.
Update of the Ideal Amino Acid Profile
for Piglets
In growing animals, the concept of “ideal protein” or ideal AA profile is a concept where AA
pattern (defined as a percentage of lysine) maximizes growth, nitrogen retention or another
response criterion of interest. In this profile, all indispensable amino acids are equally limiting
for performance, just covering the requirements for all physiological functions. Lysine has
traditionally been used as a reference because it is the first limiting AA for growth in pigs. It is
frequently assumed that the ideal protein profile does not change for a given growing stage.
In practical nutrition, this offers the advantage that the lysine requirement will vary (per kg of
feed or per MJ of energy), but not the ideal amino acid profile expressed relative to lysine.
Each of these ratios can thus be directly introduced as a constraint in feed formulation.
BSAS (2003)
UK
NRC (2012)
USA(1)
VSP (2013)
DK
INRA
(2013)(2) FR
Ajinomoto
Eurolysine (2013)
Lys:Lys
100
100
100
100
100
Thr:Lys
65
59
61
65
65
Met:Lys
30
29
32
30
30
(Met+Cys):Lys
59
55
54
60
60
Trp:Lys
19
16
20-22
22
22
Val:Lys
70
63
67
70
70
Ile:Lys
58
51
53
52(3)
53(3)
Leu:Lys
100
100
102
101
100
His:Lys
34
34
32
31
32
Phe:Lys
57
58
57
54
55
(Phe+Tyr):Lys
100
93
111
-
95
-
-
-
40
-
SID Values
Tyr:Lys
Indicatives recommended SID Lys levels: From 1.35 to 1.15% for 6-12 and 12-25 kg piglet live weight respectively.
1) AA profile recalculated from the factorial approach used by NRC (2012)
2) Gloaguen et al. (2013)
3) Requirement is given for blood-free diet
Table 6: AjInomoTo EuRoLysInE s.A.s. Amino Acids profile for piglets and comparison to
other profiles.
18 | Ideal Amino Acid Profile For Piglets
A comparison of the different AA profiles (Table 6) shows that there is still variability between
the different institutes. This is due for instance to different methodological approaches, as
already discussed. As an example, an important difference between NRC (2012) and INRA
(2013) can be explained by the factorial method used by NRC and the empirical approach
used by INRA. The AA levels calculated by NRC maximize nitrogen retention, while the AA
profile given by INRA maximizes growth performance (dose-response studies).
Others factors that lead to recommend an AA profile are listed in Figure 12. Apart from the
methodological aspects, the difference between recommended AA profiles lies in the global
risk management of the feed formulation. In a context of general usage of low protein diets as
it is in Europe, the risk is taken on each AA instead of crude protein, which is more relevant
since crude protein is not a predictor of the piglet’s performance. Then, by using AEL AA
profile, the feed formulation can be done safely without minimum on dietary crude protein.
Criteria
to optimize
Interactions
between AA
Use of Low
Protein Diets
Experimental
data
Reference
feedstuffs
matrix of the
trials
Ideal AA
profile
for practice
Accuracy
of the user
feed matrix
Statistical
models
Factorial vs
empirical approach
Response
to the AA
Variability
of the
pig population
to feed
Risk
management
Figure 12: Example of factors to consider to assess an amino acid profile for
piglet commercial diets.
ajinomoto eurolysine s.a.s. | 19
low Crude Protein Diets
Knowing the amino acid contents of feedstuffs, their digestibility, using net
energy values, and implementing the AEL ideal AA profile, allow to
implement efficiently low protein diets in piglets. The use of low CP levels
in piglets’ diets is increasing in Europe for health, economic and
environmental reasons. This technic is already known and furthermore
implemented since the range of available feed-use AA has increased
(i.e. L-Valine). There is still room for further dietary CP reduction in practical
feeds without compromising growth performance.
Using low protein diets in piglets: Efficient and safe
➔ A lower supply of dietary CP reduces the global amount of undigested protein supplied
in the distal intestine of piglets and results in a better acidification (and digestion) of the
bolus. This ends by a lower proliferation of the pathogenic bacteria and significantly
reduces the occurrence of diarrhea (Lordelo et al., 2008).
➔ By formulating on each EAA instead of minimum dietary CP, the most balanced AA
profile is supplied to the animal avoiding lack and excess of AA, the amount of protein
rich feedstuffs is reduced in the formula and substantive cost savings are achievable.
By applying a precise AA profile, risk management can be implemented and the best
opportunities of using local feedstuffs and co-products can be taken.
➔ Reducing dietary CP is one of the best available technics to reduce nitrogen output into
the environment: -1 point of dietary CP results in -10% of nitrogen excretion.
Using the ideal AA profile recommended by AEL and the available feed-use AA, dietary CP
can be reduced safely and efficiently as shown in the following trials presented (Table 7).
Body
weight
(kg)
Lordelo et al.
(2008)
Jansman et al.
(2008)
Norgaard and
Fernandez (2009)
Vinyeta et al.
(2010)
Gloaguen et al.
(2013)
Jansman et al.
(2013)
7-23
10-25
9-21
8-25
12-23
8-25
Dietary
CP (%)
SID Lys
(%)
ADFI
(g/d)
ADG
(g/d)
FCR
20.5
1.12
932
583
1.60
17.0
1.12
941
571
1.65
19.0
1.03
869
567
1.54
16.0
1.03
866
568
1.52
19.0
1.10
627
445
1.40
17.0
1.10
635
449
1.41
17.5
0.94
857
564
1.52
15.5
0.94
873
567
1.54
17.6
1.00
766
450
1.70
15.6
1.00
775
454
1.71
16.8
1.00
835
548
1.49
15.4
1.00
816
564
1.48
P
AEL
Ideal AA
profile
ns
ns
ns
ns
ns
ns
Table 7: Effect of lowering dietary crude protein (CP) on piglet performance (diets using only
available feed-use AA).
20 | Ideal Amino Acid Profile For Piglets
✓
✓
✓
✓
✓
✓
A pioneer work: Formulating diets
for piglets without soybean meal
After a complete review and work on AA requirements, Gloaguen et al. (2013) proposed to
test to what extent the CP content of piglets diets can be reduced by substituting soybean
meal by wheat, barley, corn and free AA, without affecting performance. The study is based
on the AEL AA profile. In the first 4 diets, soybean meal was still used and CP decreased
from 17.6 to 11.8%. In additional 2 diets, only cereals and free AA were used to test the
effect of nitrogen addition (13 vs 14% CP by L-Glu addition in treatment 6). The formulas
and results are summarized in Table 8.
Treatments
1
Feedstuffs used
2
3
4
CEREALS - SBM - L-AA
5
6
CEREALS & L-AA
Cereals (%)
50
60
80
85
80
Soybean Meal (%)
25
20
10
2
0
0
0.28
0.46
0.70
0.92
1.00
1.00
L-Lys HCL (%)
80
DL-Met, L-Thr, L-Trp
+
++
+++
++++
++++
++++
L-Val
-
+
++
+++
++++
+++
Others L-EAA
-
-
+
++
+++
+++
Others L-NEAA
-
-
-
-
+
++
1.00
1.00
1.00
1.00
1.00
1.00
SID Lys (%)
Ideal AA profile
Crude Protein (%)
✓
✓
✓
✓
✓
✓
17.6
15.6
13.5
11.8
13.0
14.0
P
BWi, kg
12.7
12.7
12.6
12.6
13.0
12.8
0.60
BWf, kg
22.2a
22.2a
21.9a
20.1b
21.8a
22.3a
<0.01
ADFI, g/d
766
775
779
734
810
782
0.55
ADG, g/d
450a
454a
442a
358b
450a
451a
<0.01
G:F, g/g
0.59a
0.59a
0.57a
0.49b
0.52b
0.58a
<0.01
Table 8: Effect of reducing dietary crude protein content on performance of piglets
(Gloaguen et al., 2013).
➔ The feed intake is not influenced whatever is the protein level,
➔ Growth performance are maintained till the level of 13.5 – 14.0% CP (treatments 1, 2,
3 & 6)
➔ Comparing diets 5 and 6 shows that at 13% CP, nitrogen was limiting: Adding a N source
up to 14% CP allows to recover performance as in treatment 1,
➔ This trial indicates that efficiency of utilizing AA is not lower for free AA compared with
protein bound AA in pigs offered feed ad-libitum,
➔ In the successful treatment 6, 78% of the SID Lys was supplied by L-Lys-HCL.
This trial shows that there might be a minimum of N between 13 and 14% CP (for 1.00%
SID Lys). However, it confirms that tremendous dietary protein reduction is achievable in
current piglet feeds. It indicates also that when using the AEL ideal AA profile, dietary CP
can be reduced efficiently in piglet diets by using feed-use AA.
AJINOMOTO EUROLYSINE S.A.S. | 21
Conclusions
Ideal Amino Acid profile for piglets
(up to 25 kg live weight) expressed in
standardized ileal digestible (SID) values.
SID Values
Lys:Lys
Thr:Lys
Met:Lys
(Met+Cys):Lys
Trp:Lys
Val:Lys
Ile:Lys
Leu:Lys
His:Lys
Phe:Lys
(Phe+Tyr):Lys
Ajinomoto
Eurolysine (2013)
100
65
30
60
22
70
53*
100
32
55
95
*Ile requirement for diets free of blood-meal or blood-cells
☛ indispensable amino acids, as essential nutrients, must be
supplied in the diets for piglets. as they predict performance
they represent factors of variability of the growth and must be
monitored with care to get the best performance in variable
conditions. as a first step, amino acid contents in feedstuffs
have to be estimated and digestible values used as predictors.
Beside chemical analyses, table values, regressions equations
based on nitrogen, and coefficients of digestibility contribute
to estimate the supply and quality of amino acids in feedstuffs.
☛ the increasing knowledge about amino acid nutrition allows
to recommend a robust ideal amino acid profile that supports
feed intake, growth, nutrients efficiency and health challenges
of the piglets.
☛ the proposed amino acid profile by ael is based on a strong
scientific background, taking also into consideration the
practical issues of animal production and particularly feed
production. this profile provides a tool to optimize feed
on each essential amino acid instead of crude protein.
this technic enables to reach the best solution regarding the
ingredients used in the formula. last but not least, this profile is
a tool to reduce safely and efficiently the crude protein content
in piglets diets by using the available feed-use amino acids in
combination with the local feedstuffs which makes possible
substantial feed costs reduction.
22 | Ideal Amino Acid Profile For Piglets
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