Ideal Amino Acid Profile For Piglets

Transcription

1 Ideal Amino Acid Profile For Piglets by GO TO ESSENTIALS October 2013

2 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 Isoleucine Leucine Histidine Phenylalanine and Tyrosine Ideal Amino Acid Profile Low Crude Protein Diets Conclusion References... 23

3 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

4 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 suffi cient rate to maintain associated biological functions AA that can be synthesised de novo but could become indispensable in specifi c situations when the synthesis is not suffi cient to cover the requirement AA that can be synthesised de novo by the animal in a suffi cient 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. 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. Supply and source of dietary AA in % of the AA requirement L-Lys L-Thr DL-Met Lys Thr Met + Cys L-Trp 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. L-Val 4 Ideal Amino Acid Profile For Piglets

5 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: ty: The standardized ileal digestibility (SID). 100% ➊ ➋ ➌ 81% 74% Total AID SID ➊ Total AA supply ➋ AID: Total - Excreta ➌ SID: Total - (Excreta - EL) 0 Excreta{ Undig EL Undig 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 ( ajinomoto eurolysine s.a.s. 5

6 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

7 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

8 tryptophan Tryptophan is generally the 4 th 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) 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., 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

9 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. Feed intake Animal Behavior Ghrelin Melatonin Serotonin mood, stress response, ans sleep regulation Dietary tryptophan Gastrointestinal tract Brain Trp : LNAA (% CP) 4 th limiting amino acids Plasma Tryptophan Protein synthesis TDO IDO IFN gamma Acute phase protein Growth performance Kynurenine Immune response and health maintenance 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

10 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) 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) SID Val:Lys ratio (%) Figure 5: sid Val:Lys dose-responses in piglets. Effect on average daily gain (ADG). 10 Ideal Amino Acid Profile For Piglets

11 Impact of the branched-chain AA metabolism on performance gut flow VAL ILE LEU small intestine liver KIV KMV KIC BCKDH A-CoA 1 A-CoA 2 A-CoA 3 Glucogenic Ketogenic muscle VAL ILE LEU PROTEIN SYNTHESIS LYS VAL TRP BCAA CATABOLISM BCKA LEU THR ILE VAL KIV BCAT ILE KMV LEU KIC ALA GLN GLU NH3 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

12 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 SID Val:Lys ratio (%) FCR, % of the best performance SID Val:Lys ratio (%) Barea et al. (2009) Low Leu Glaoguen et al. (2012) High Leu 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

13 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 Spray dried blood cells Soybean meal Ile:CP His:CP Leu:CP Val:CP Figure 8: Amino acids profile of sdbc vs soybean meal; as % of crude protein (CP). ajinomoto eurolysine s.a.s. 13

14 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) 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) 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

15 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) 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 Gain to Feed SID Leu:Lys requirement estimates (%) % defi ciency 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

16 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 Gloaguen et al. (2013), 1 Gloaguen et al. (2013), SID His:Lys (%) Figure 11: sid His:Lys doseresponses in piglets. Effect on average daily gain (ADG) and feed conversion ratio (FCR). Criteria to maximize ADFI ADG Gain to Feed SID His:Lys requirement estimates (%) % defi ciency affects the response by -1.6% -2.6% -1.5% 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 Requirement estimates Izquierdo et al., kg ADFI, ADG, G:F 0.36% total His Li et al., kg ADFI, ADG, G:F 30% AID His:Lys Gloaguen et al., 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

17 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 (%) % Phe defi ciency affects the response by SID Tyr:Lys requirement estimates (%) % Tyr defi ciency affects the response by 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

18 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. SID Values BSAS (2003) UK NRC (2012) VSP (2013) USA (1) DK INRA (2013) (2) FR Ajinomoto Eurolysine (2013) Lys:Lys Thr:Lys Met:Lys (Met+Cys):Lys Trp:Lys Val:Lys Ile:Lys (3) 53 (3) Leu:Lys His:Lys Phe:Lys (Phe+Tyr):Lys Tyr:Lys Indicatives recommended SID Lys levels: From 1.35 to 1.15% for 6-12 and kg piglet live weight respectively. 1) AA profi le 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

19 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 Experimental data Reference feedstuffs matrix of the trials Interactions between AA Use of Low Protein Diets Ideal AA profile for practice Statistical models Factorial vs empirical approach Accuracy of the user feed matrix Variability of the pig population to feed Risk management Response to the AA Figure 12: Example of factors to consider to assess an amino acid profile for piglet commercial diets. ajinomoto eurolysine s.a.s. 19

20 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). Lordelo et al. (2008) Jansman et al. (2008) Norgaard and Fernandez (2009) Vinyeta et al. (2010) Gloaguen et al. (2013) Jansman et al. (2013) Body weight (kg) Dietary CP (%) SID Lys (%) ADFI (g/d) ADG (g/d) FCR 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

21 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 Feedstuffs used CEREALS - SBM - L-AA CEREALS & L-AA Cereals (%) Soybean Meal (%) L-Lys HCL (%) DL-Met, L-Thr, L-Trp L-Val Others L-EAA Others L-NEAA SID Lys (%) Ideal AA profi le Crude Protein (%) P BWi, kg BWf, kg 22.2a 22.2a 21.9a 20.1b 21.8a 22.3a <0.01 ADFI, g/d 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 % 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

22 Conclusions Ideal Amino Acid profile for piglets (up to 25 kg live weight) expressed in standardized ileal digestible (SID) values. SID Values Ajinomoto Eurolysine (2013) Lys:Lys 100 Thr:Lys 65 Met:Lys 30 (Met+Cys):Lys 60 Trp:Lys 22 Val:Lys 70 Ile:Lys 53* Leu:Lys 100 His:Lys 32 Phe:Lys 55 (Phe+Tyr):Lys 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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26 n Van Milgen J., M. Gloaguen, N. Le Floc h, L. Brossard, Y. Primot, and E. Corrent Meta-analysis of the response of growing pigs to the isoleucine concentration in the diet. Animal, 6, n Van Milgen J., M. Gloaguen, N. Le Floc h, L. Brossard, Y. Primot, and E. Corrent. Meta-analysis of the response of growing pigs to valine content of the diet. 134, Sacramento, CA, USA. EAAP. Energy and protein metabolism and nutrition in sustainable animal production. Wageningen Academic Publishers, Wageningen, the Netherlands. n Vinyeta, E. and J. van de Klis. Pilot study on valine requirements of weaned piglets. Schothorst Feed Research. 09NL02 Trial Report n Vinyeta, E., R. Gerritsen, M. Rovers and E. Corrent. Le besoin en valine des porcelets (Valine requirements of weaned piglets) Journées Recherche Porcine, Paris, France n VSP. P. Tybirk, N. M. Sloth and L. Jørgensen. Nutrient requirement standards. 18 th edition of nutrient Danish standards n Wiltafsky, M. K., J. Bartelt, C. Relandeau, and F. X. Roth Estimation of the optimum ratio standardized ileal digestible isoleucine to lysine for 8- to 25-kilogram pigs in diets containing spray-dried blood cells or corn gluten feed as a protein source. J. Anim. Sci. 87: n Wessels, A., H. Kluge, and G. Stang Effect of Trp on piglet performance. Trial report. Martin-Luther-Universität Halle-Wittenberg Germany. AEL 10DE02. n Wessels, A., H. Kluge, and G. Stang. Leucine requirement in piglet. Trial report. Martin-Luther-Universität Halle- Wittenberg Germany. 26 Ideal Amino Acid Profile For Piglets

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