Ajinomoto Bulletin

R ecent advances in the determination of amino acids (AA) requirements of pigs and the increas-ing availability of feed-grade AA allow a reduc-tion in the crude protein (CP) content of feed, while maintain-ing the supply of essential AA. Such diets markedly reduce N excretion without detrimental effects on nitrogen (N) reten-tion or growth performance. Studies on this subject have shown that lowering CP content in pig feed by 1 percentage point leads to a reduction in the amount of nitrogen excreted by about 10% (Ajinomoto Eurolysine s.a.s. Bulletin 22, 2000; Portejoie et al., 2004).

Low protein diets are also associated with reductions in energy losses. Lowering dietary CP reduces deamination of excess AA and the consequent synthesis and excretion of urea in urine, lowers body protein turnover and heat produc-tion of animals. Reducing dietary CP therefore increases the energy available for tissue deposition. To fully take advan-tage of low CP diets, it is necessary to work with the energy system that accounts for this energy sparing effect i.e. the net energy system.

In addition to better feed efficiency and a reduction of nitrogen output, moving from a formulation based on (mini mum) CP to a formulation based on each essential AA gives much more flexibility in the choice of feedstuffs, a better optimization of the formula and a reduction of the feed cost. This approach also leads to locally-produced feedstuffs (cereals, rapeseed meal, sunflower meal) being preferred in the formulations rather than imported feedstuffs (soybean products). For the successful implementation of this approach, estimates must be made of the minimum requirements of each of the essential AA for pigs and used for feed formulation.

In this bulletin, a meta-analysis of the Trp requirement in growing and finishing pigs is presented together with the review of the available information about Val and Ile require-ments. In a second part, the different steps that should be taken to formulate to each essential AA will be reviewed: the use and practical interest of the net energy system, the determination of the limiting AA in a grower diet, and the degree of protein reduction that is achievable.

Essential Amino Acids Requirements, Energy Systems and Low Protein Diets

Formulating Pig Grower Diets With No Minimum Crude Protein

Information N 37October 2011

G O T O E S S E N T I A L S

2 | Information n 37 | ajinomoto eurolysine s.a.s.

Formulating Pig Grower DietsWith No Minimum Crude Protein

Essential Amino Acids Requirements,Energy Systems and Low Protein Diets

1. Essential amino acid requirementsof growing and finishing pigs ............................................................................................................................................ 5

1.1 The Tryptophan requirement is at least 20% SID Trp:Lysin grower diets ........................................................................................................................................................................................................ 5

1.2 Valine requirement: A minimum of 65% SID Val:Lys ........................................................................................ 10 1.3 The Isoleucine requirement is no higher than 53% SID Ile:Lys ............................................................ 13 1.4 Ideal amino acid profile for growing and finishing pigs .................................................................................. 17

2. Practical aspects of formulatingto each essential amino acid ............................................................................................................................................ 18

2.1 Using Net Energy to take into account the better efficiencyof low protein diets ....................................................................................................................................................................................... 18

2.2 Determining the limiting amino acid in pig grower diets ............................................................................. 26 2.3 Formulating without a minimum constraint on dietary crude protein ...................................... 28

References ......................................................................................................................................................................................................... 33

Conclusions ..................................................................................................................................................................................................... 39

Focus 1: The SID Trp:Lys requirement might be 1 point lower in finisherthan in grower pigs .............................................................................................................................................................................. 8

Focus 2: Avoiding imbalances and AA oversupply to achieve the best performance .............. 16Focus 3: Calculating Net Energy values of ingredients and feeds using EvaPig ........................ 19Focus 4: Reducing the amount of soybean meal and using local feedstuffs ...................................... 24Focus 5: Utilisation of free amino acids in very low crude protein diets ............................................... 32

ajinomoto eurolysine s.a.s. | Information n 37 | 5

1. Essential amino acid requirements of growing and finishing pigs

twenty amino acids (aa) are the building blocks of proteins. nine of them (lysine, threonine, methionine, tryptophan, Valine, isoleucine, leucine, Histidine and Phenylalanine) are either not synthesised or syn-thesised only in small quantities by pigs (Boisen, 2003). they must therefore be supplied through the diet and are referred to as essential aa (eaa). Feeds must provide the eaa in sufficient quantities to cover the requirements of animals, while avoiding an excessive supply. the extent to which dietary crude protein (CP) can be reduced depends on the limiting aa in a diet and therefore on the require-ment level that is set for each of the eaa.

The ideal AA profile is a practical way in which to express EAA requirements. In this concept, the AA pattern (g of AA / 100 g Lys) that maximizes a performance criterion (growth, nitrogen retention) is defined. In the ideal profile, all AA are considered to be equally limiting for performance. In practical nutrition, this offers the advantage that while the Lys requirement varies (per kg of feed or per unit of energy) the ideal AA profile expressed relative to Lys remains the same.

The determination of AA requirements is generally done by dose-response trials but several factors can affect the outcome of a dose-response study, starting with the protocol itself. It is therefore important to review and analyse carefully the avail-able data and how they were generated before making decisions on requirement levels.

The Thr requirement of growing pigs has been reviewed in a recent publication (AEL Bulletin 31, 2008). In the following section the Standardized Ileal Digestible (SID) requirement for Trp, Val and Ile are considered within the framework of the ideal protein concept.

1.1 The Tryptophan requirement is at least 20% SID Trp:Lys in grower diets

The Trp requirement and its specific effect on feed intake and health status in piglets have been extensively studied and reviewed (Le Floch et al., 2007; Simongiovanni et al., 2010). Tryptophan is also known to limit the growth of heavier pigs when its dietary supply is reduced (Russel et al., 1986). In growing pigs, the SID Trp:Lys requirement reported from dose-response trials ranges from 17 to 22% (Kendall et al., 2007; Eder et al., 2003), and a recent trial (Vinyeta et al., 2010) found that a strong response to dietary Trp occurred between 18 and 21% SID Trp:Lys: Feed Conversion Ratio (FCR) was improved by 6% in pigs between 23 to 50 kg live weight (LW).

This variability illustrates that a single study is insufficient to provide a reliable estimate of a requirement. The meta-analysis method (Sauvant et al., 2008) appears to be the best tool to summarise all the available information and to estimate the Trp requirement. In the following section, the SID Trp:Lys requirement to maximise the Average Daily Gain (ADG), Average Daily Feed Intake (ADFI) and gain to feed ratio (G:F) in grower pigs has been determined using the meta-analysis method.

> Selection of trials and statistical method (Figure 1, first flap)

A database with 79 scientific publications or trial reports from research institutes was constructed. The trials, covering up to 2011, studied the Trp requirement of pigs between 25 and 120 kg LW fed ad libitum, using a basal diet supplemented with different levels of L-Tryptophan. The method of reporting nutritional values varies between trials (expected vs. measured value, total vs. apparent or standardized ileal digestible) and the AA profiles were incomplete in some cases. Consequently, to obtain the complete AA profiles and to standardize the values on a SID basis, the EvaPig software (Noblet et al., 2008, using INRA tables, Sauvant et al., 2004) was used based on the feed ingredients used in the respective trials. Because a regression analysis indicated a good agreement between calculated and reported values, only calculated values were used in the meta-analysis.


ADG ADFI G:F

Plateau (A) 821 g/day 2012 g/day 0.421

Slope (U) -0.00412 -0.00274 -0.00212

SID Trp:Lys requirement (%)

20.8 (0.7) 19.8 (1.6) 21.2 (0.9)

Table 2: Meta-analysis of the Trp requirement of growing pigs. Parameter estimates and error of estimates for Average Daily Gain (ADG), Average Daily Feed Intake (ADFI) and Gain to Feed (G:F) as response criteria.

3000

2800

2600

2400

2200

2000

1800

1600

1400

1200

1000

800

ADFI (g/d)

8 2810 12 14 16 18 20 22 24 26

SID Trp:Lys (%)

1000

900

800

700

600

500

400

300

200

ADG (g/d)

8 2810 12 14 16 18 20 22 24 26

SID Trp:Lys (%)

0.55

0.50

0.45

0.40

0.35

0.30

0.25

0.20

Gain to feed

8 2810 12 14 16 18 20 22 24 26

SID Trp:Lys (%)

Bikker and Fledderus (2008) a

Bikker and Fledderus (2008) b

Burgoon et al. (1992)

Eder et al. (2003) a

Eder et al. (2003) b

Eder et al. (2003) c

Henry et Sve (1993)

Quant et al. (2007)

Renaudeau (2010)

Schedle et al. (2011)

Segers and Geers (2006)

Torrallardona (2006)

Figure 2: Selected SID Trp:Lys dose-responses in grow-ing pigs. Effect on Average Daily Feed Intake (ADFI), g/day.

Figure 4: Selected SID Trp:Lys dose-responses in growing pigs. Effect on Gain to Feed ratio (G:F).

Figure 3: Selected SID Trp:Lys dose-responses in grow-ing pigs. Effect on Average Daily Gain (ADG), g/day.

79 experiments (up to 2011) entered in the database

Selection 1: At least four levels of Tryptophan tested

Practical use of the results:

SID Trp:Lys requirement in growing pigs Pigs response to increasing levels of Trp

OBJECTIVE: To estimate the SID Trp:Lys requirement of growing pigs

12 experiments retained 21 experiments eliminated

33 dose-response experiments 46 two/three-level experiments

Selection 2: The Trp:Lys ratio used as the mode of expression

Modelling

ExternalValidation

YES NOYES NO

22 experiments retained 24 experiments eliminated

YES NOYES NO YES NOYES NO

Figure 1: Schematic representation of the main steps involved in the meta-analysis of the Trp requirement of growing pigs.

Source Country WeightWeight

CategoryGenetics Sex

Estimated Trp requirement

In the study % NRC (1998)

Bikker and Fledderus (2008)a, Vinyeta et al. (2010)

Published NL23 to 50 kg

Grower GY x (GY x Scandinavian Landrace) Females 20.5% AID Trp:Lys 121%

Burgoon et al. (1992) Published USA22 to 45 kg

GrowerYorkshire-Landrace sowsx Duroc-Hampshire boars

Males0.10% to 0.13% AID

Trp:Lys77 to 100%

Eder et al. (2003)a Published DE25 to 50 kg

Grower(German Edelschwein or Landrace

x Deutsches Edelschwein)x Pietrain

Females140 to 143 mg SID

Trp /MJ ME128%

Quant et al.(2007) Abstract USA25 to 40 kg

Grower Crossbred (non reported) Males15.7 to >18.4% SID

Trp:Lys88 to

>102%

Schedle et al. (2011) Trial report AT30 to 45 kg

Grower (LW x German land race) x Pitrain Females 22% SID Trp:Lys 122%

Torrallardona (2006) Trial report SP22 to 70 kg

Grower Landrace x Pitrain Males 18% SID Trp:Lys 100%

Henry and Sve (1993) Published FR40 to

100 kgGrower/Finisher

Pietrain x LW Males 22% SID Trp:Lys 122%

Renaudeau (2010) Trial report FR40 to

100 kgGrower/Finisher

LWMales + Females

20 to 23% SID Trp:Lys

111 to 128%

Bikker and Fledderus (2008)b

Trial report NL50 to

110 kgFinisher GY x (GY x Scandinavian Landrace) Females 19% AID Trp:Lys 116%

Eder et al. (2003)b Published DE50 to 80 kg

Finisher(German Edelschwein or Landrace

x Deutsches Edelschwein)x Pietrain

Females>127 mg SIDTrp /MJ ME

>144%

Segers and Geers (2006)

Trial report BE45 to 75 kg

Finisher Pietrain x Hypor (ZTC) Males not calculated

Eder et al. (2003)c Published DE80 to

115 kgLate

Finisher

(German Edelschwein or Landracex Deutsches Edelschwein)

x PietrainFemales

62 to 90 mg SIDTrp /MJ ME

90 to 130%

GY Great Yorkshire, LW Large White

Table 1: Key features of the 12 selected dose-response trials used in the meta-analysis for Trp requirement.


To express the Trp requirement as a Trp:Lys ratio, trials were selected on the basis that Lys was the second-limiting AA in the diet after Trp, and the requirements for the other EAA were met or exceeded (Boisen, 2003). The SID Lys and EAA:Lys ratios in the diet were then compared with official recommendations (NRC, 1998 and Whittemore et al., 2003). Trials in which the SID Lys content did not appear to be limiting and/or in which the supply of the EAA other than Lys and Trp was below the recommendations, were removed from the meta-analysis. In addition, only trials in which at least 4 levels of Trp were included were selected for the meta-analysis. Trials that included a lower number of Trp levels were used later in the validation step.

A curvilinear-plateau model is used to describe the pooled response to dietary SID Trp:Lys supply in the selected trials, and to estimate the SID Trp:Lys requirement:

Y = A (1 + U (R - X)2) for X < RY = A for X R

R is the minimum SID Trp:Lys ratio required to reach the plateau (i.e. the SID Trp:Lys requirement) Y is the response criterion (ADG, ADFI or G:F) X is the SID Trp:Lys ratio A is the maximum response of the criterion in each trial (plateau) U is the parameter describing the response to Trp before the plateau

The PROC NLIN procedure of SAS was used to find out the model (SAS, 2008). The residues (residue = observed value in one trial value predicted by the model) were then analyzed and compared to the outcome. In addition, 22 trials testing 2 or 3 levels of Trp were used as external data (not used in the meta-analysis) to validate the model obtained from the selected dose-response trials.

> Analysis of the data and results of the meta-analysis

The selection process resulted in 12 trials fulfilling the criteria for inclusion in the meta-analysis. Twenty-one dose-response trials had to be eliminated because the feeds were either not limiting in Lys (13 trials) or were deficient in Thr (8 trials, with average SID Thr:Lys of 57% 4.5%).

It should be noted that in this work, the trials were selected according to the AA concentration only. It is possible that other factors limited responses to Trp but they were not taken into account. Other factors include nutrients (energy, phosphorus, sodium), feed intake capacity, genetic potential

The key features of the selected trials are summarized in Table 1. As a first analysis and to overcome the problem of dif-ferent modes of expression, the reported Trp requirements were compared to the NRC (1998) recommendations which are themselves expressed in different units (i.e. 0.15% SID Trp or 18% SID Trp:Lys or 2.8 g/day SID Trp, for pigs between 20 to 50 kg).

9 of the 12 trials reported a Trp requirement equal to or higher than the NRC (1998) recommendation (from 100 to >144%).

The average value calculated from all the quoted trials showed the Trp requirement of pigs to be 112% of the NRC recommendations.

The relationship between the Trp levels tested in these 12 trials (expressed as SID Trp ratios to Lys) and performance (ADFI, ADG and G:F) is shown in Figures 2, 3 and 4.

When the SID Trp:Lys ratio increases, feed intake increases, confirming the importance of this nutrient in the control of feed intake.

When the SID Trp:Lys ratio decreases, both ADG and G:F are adversely impacted.

Through the use of the curvilinear-plateau model and taking into account individual trial effect, it was possible to plot the pooled response to Trp of the 12 selected trials and estimate the SID Trp:Lys ratio that maximizes pig growth performance (Table 2).

A minimum of 21% SID Trp:Lys is necessary to achieve the best ADG and G:F for growing pigs. The average estimate calculated from the 3 criteria studied is 20.6% SID Trp:Lys. This value corresponds to 117% of the NRC (1998) recommendation.


The comparison of the residual values to the model (Figure 5) confirms that the curvilinear-plateau model is adapted to this dataset.

900

800

700

600

500

400

300

200

ADG (g/d)

8 2810 12 14 16 18 20 22 24 26

SID Trp:Lys (%)

0.45

0.40

0.35

0.30

0.25

Gain to feed

8 2810 12 14 16 18 20 22 24 26

SID Trp:Lys (%)

Figure 5: Data from each selected trial (residues, in grey) compared to the general model (in red). Average Daily Gain (ADG) and Gain to Feed (G:F) response to dietary SID Trp:Lys.

> Validation and estimation of the response of pig performance to SID Trp:Lys

From the data set of 79 trials, 46 experiments tested less than 4 levels of Trp and were not used in the modelling work. Of these 46 trials, Trp was not the first limiting factor in the basal diets used in 24 of the trials. However, the data from the remaining 22 trials can be used as external data to validate the average response curves estimated by the model (Figure 6).

100

90

80

70

60

50

40

100

90

80

70

60

50

40

ADG (%)

8 2810 12 14 16 18 20 22 24 26

SID Trp:Lys (%)

Gain to feed (%)

8 2810 12 14 16 18 20 22 24 26

SID Trp:Lys (%)

Figure 6: Validation of the response curves obtained for Average Daily Gain (ADG) and Gain to Feed (G:F) using 22 external datasets each with 2 or 3 levels of SID Trp:Lys.

By comparing the external data, the graphical analysis clearly shows that the model is a good predictor of pigs responses to increasing levels of SID Trp:Lys.


Focus1

The SID Trp:Lys requirement might be 1 pointlower in finisher than in grower pigs

Of the 12 selected dose-response trials, 6 relate to the grower phase specifically and 3 to the finisher phase. However, it was not possible to test if the requirement was different for each weight category because there were too few trials in each category. Nevertheless, this effect can be seen in the study of Bikker and Fledderus (2008) where the Trp requirements of growing (25 to 55 kg) and finishing (55 to 110 kg) pigs were investigated simultaneously.The experiment comprised 2 parts, each with 4 dietary treatments (SID Trp:Lys varying from 15 to 24% ) in the grower and finisher phases. The design and results are presented in Table 3. In treatments 1 to 4, the pigs received the experimental feeds during the growing phase and then a diet with a fixed amount of Trp in the finishing phase (20% SID Trp:Lys). In treatments 5 to 8, all the pigs received the same diet in the growing phase (20% SID Trp:Lys) and the experimental feeds in the finishing phase.To ensure that the Trp requirement could be expressed relative to Lys, the dietary Lys was sublimiting during the whole trial by mixing a high Lys grower diet with an increasing proportion of a low Lys finisher diet with a change every two weeks. Animals (gilts) were fed ad libitum. Performance (ADG, ADFI and FCR) were measured and the duration of the experiment was also reported, the pigs being slaughtered at the same weight. Linear-plateau and quadratic models were then used to estimate the SID Trp:Lys requirement in each period.

Trp effects during the grower phase (treatments 1 to 4) Increasing the dietary Trp level had a significant effect on feed intake, ADG and FCR

(+11%, +17% and -6% respectively between 18 and 21% SID Trp:Lys), with the best performance being reached at 21% SID Trp:Lys.

Body weight was 9% heavier (18 vs 21% SID Trp:Lys) at the end of the grower period. In the finisher phase, all the animals were fed the same Trp level (20% SID Trp:Lys).

The FCR was affected by the Trp content in the grower period but the length of time taken to reach the same weight was substantially increased in the group limited in Trp. The difference in duration was 11.5 days between the lowest and the optimal Trp level.

21% SID Trp:Lys optimized growth performance in pigs between 25 and 55 kg.

Grower Study Finisher Study SID Trp:Lys requirement (%)

Treatments 1 2 3 4 5 6 7 8Linear

-Plateau Model

Quadratic model

Average

SID Trp:Lysfrom 25 to 55 kg

15% 18% 21% 24% 20% Grower Phase

BW at start (kg) 23.0 23.1 23.0 23.1 25.8 25.8 25.8 25.8

ADFI (g/d) 1186a 1429b 1590c 1582bc 1591 1568 1601 1579 19.6 22.4 21.0

ADG (g/d) 509a 645b 752c 753c 794 792 794 778 20.0 22.8 21.4

FCR 2.49b 2.29ab 2.15a 2.15a 2.02 2.00 2.04 2.05 19.7 22.5 21.1

BW at the end (kg) 44.2a 50.1b 54.5c 54.6c 53.7 53.6 53.7 53.1

Duration (days) 41.8 41.8 41.8 41.8 35.2 35.2 35.2 35.2

SID Trp:Lysfrom 55 to 110 kg

20% 15% 18% 21% 24% Finisher phase

ADFI (g/d) 2311a 2421ab 2486b 2431ab 2145a 2420b 2533c 2427b 18.8 20.8 19.8

ADG (g/d) 939 951 957 935 675a 838b 898c 853b 18.8 21 19.9

FCR 2.49a 2.56ab 2.61b 2.64b 3.34a 2.93b 2.87b 2.89b 18.5 21.2 19.9

BW at the end (kg) 110.6 110.6 110.7 110.7 107.9a 110.4b 110.5b 110.4b

Duration (days) 71.5c 64.0b 59.0a 60.9ab 83.1c 68.9b 63.8a 68.3aba,b,c : Within a row, different letters indicate signifi cantly different values at p


16.0 22.017.0 18.0 19.0 20.0 21.0

SID Trp:Lys (%)

107

106

105

103

104

101

102

99

100

97

98

96

Response of ADG and FCR (%)

Average Daily Gain (ADG) Feed Conversion Ratio (FCR)

- 3.5% FCR

+ 6% ADG

Figure 7: Average response to SID Trp:Lys (base 100 = perfor-mance obtained at 17% SID Trp:Lys).

The average of the responses based on the meta-analysis shows that increasing SID Trp:Lys from a defi-ciency level to the requirement improves performance (Figure 7). It is calculated that:

Increasing the SID Trp:Lys from 17% to 20% SID Trp:Lys, results in an improvement in ADG of 6% and FCR of 3.5%.

Based on the plateau-values determined in the meta-analysis, this means an increase of 50 g/d in daily gain and a reduction of 0.08 points in FCR.

Twelve dose-response trials were selected for a meta-analysis and an average requirement of 20.6% SID Trp:Lys was demonstrated to maximize ADFI, ADG and G:F (FCR) of growing pigs.

A minimum recommendation of 20% SID Trp:Lys is therefore proposedto optimize the performance of pigs between 25 and 65 kg pigs. A minimum of 19% SID Trp:Lys is proposed for heavier pigs.

According to this meta-analysis, when dietary Trp is increased from 17 to 20% SID Trp:Lys, ADG is improved by 6% and the FCR by 3.5%, on average.

Trp effects during the finisher phase (treatments 5 to 8)

In the grower phase, all pigs received the same level of Trp and, as expected, no dif-ferences in growth performance were observed.

In the finisher phase, the pigs received different Trp diets resulting in a significant improvement in feed intake, ADG and FCR : +5%, +7% and -2% respectively between 18 and 21% SID Trp:Lys

The time to reach finishing weight was also reduced with increasing levels of Trp. The treatment with the lowest Trp (15% Trp:Lys) failed to rear animals to the target weight of 110 kg.

The average requirement was calculated to be 20% SID Trp:Lys for pigs between 55 to 110 kg.

This study confirms the importance of supplying the correct level of dietary Trp in growing and finishing pigs. The estimated Trp requirements (21 and 20% SID Trp:Lys resp.), whatever the model used, are in the range of the outcome of the meta-analysis and suggest that the SID Trp:Lys requirement is probably lower (1 percentage point less) in finisher pigs than in grower pigs.


1.2 Valine requirement: A minimum of 65% SID Val:Lys

Valine is a limiting EAA in current piglet diets (Barea et al., 2009, AEL Bulletin 35) and potentially limiting in grower pig diets containing very low levels of CP. In Figueroa et al. (2003), Val was considered limiting before Ile and His in an 11% CP corn-based diet fed to pigs between 20 and 45 kg LW. In comparison to piglets, the Val requirement of growing pigs has not been extensively studied. In this section, the 4 dose-response trials available in the literature are reported, and1 trial report from the experimental program of AJINOMOTO EUROLYSINE S.A.S. is described. The objective is to provide a recommendation for the minimum dietary SID Val level expressed as a ratio to Lys.

> Is there a response to Valine in growing and finishing pigs ?

Very little information is available concerning the Val requirement of growing pigs and a meta-analysis of the data (as was done for Trp) is not feasible. In Figure 8, the published information (4 datasets) and 1 trial report in which at least 3 levels of Val were tested are presented. Because trials were performed with various pig types and experimental designs, the tested Val levels could not be compared directly. Valine levels were therefore expressed as a percentage of dietary Lys. Since at this stage of the analysis the trials have not been selected according to the method employed by the authors to report the Val requirements, these graphs remain descriptive.

1100

950

950

1000

900

850

800

750

700

ADG (g/d)

40 10045 50 55 60 65 70 75 80 85 90 95

SID Val:Lys (%)

3.50

2.75

3.00

3.25

2.50

2.25

2.00

1.75

1.50

FCR

40 10045 50 55 60 65 70 75 80 85 90 95

SID Val:Lys (%)

Liu (2000) 60 to 85 kg Lewis and Nishimura (1995) 67 to 80 kg Waguespack et al. (2011) 20 to 50 kg

Gaines et al. (2011) 21 to 33 kg Ajinomoto Eurolysine (2009) 33 to 70 kg

Figure 8: Dose-response to dietary SID Val. Effect on Average Daily Gain (ADG) and Feed Conversion Ratio (FCR).

When the dietary Val level was reduced, ADG and FCR were affected.

As there was an impact of dietary Val on pig performance in these trials, it is clear that there is a need to monitor this AA in feeds.


> Estimation of the Valine requirement in growing and finishing pigs

The variability in the experimental results is mainly due to the experimental design itself which has to be chosen in accor-dance to the targeted unit of expression of the requirement. A precise analysis of the trials has been performed and is presented in Table 4. In the following analysis, all the results were recalculated on SID values using the INRA database of literature (J. van Milgen, Pers. Comm.) or the EvaPig software.

Live Weight

Sex

Estimated Val requirement

(in the published unit)

Dietary Lys SID

(%)

Lyslimiting ?1

Doubts on the fi rst limiting

AA2

Estimate of the Val requirement in SID

values and choice of the mode of expression

Val requirement (% of NRC,

1998)

Gaines et al. (2011)

21 to33 kg

Males 65% SID Val:Lys 1.10% No Trp 0.73% SID Val 106%

Waguespacket al. (2011)

20 to50 kg

na0.56% SID Val & 67% SID Val:Lys

0.83% Partially 67% SID Val:Lys 98%

Ajinomoto Eurolysine (2009) Trial report

33 to45 & 70 kg

Males & Females

No more than 65% SID Val:Lys or 0.53% SID Val

0.82%Partially

(from 30 to 45 kg)

No more than

65% SID Val:Lys96%

Liu (2000)60 to85 kg

Males11.4 g SID Val

per day for pigs gaining 1 kg/day

0.69% No 0.42% SID Val 93%

Lewis and Nishimura (1995)

67 to85 kg

Males & Females

0.38% AID Val, 0.45% Total Val

0.61% Yes Trp, His 0.41% SID Val 91%

1: Comparison to NRC (1998) and Whittemore et al. (2003) reference 2: The named AA is likely limiting in the basal diet

Table 4: Key features, results and analysis of the dose-response studies on the Val requirement in pigs.

Dose-response trials from literature

Gaines et al. (2011) studied the Val requirement in pigs from 21 to 33 kg LW. Two dose-response trials were con-ducted but only one of them is reported here due to an unknown limiting factor mentioned by the authors in their second experiment. The trial tested a negative control (16.2% CP, 1.10% SID Lys) deficient in Val (0.60% SID). Five levels of Val were obtained by the addition of L-Valine to the basal diet. As a result of the higher Val levels, performance was significantly improved up to 0.73% SID Val. In this trial, the SID Lys was not limiting (130% of NRC, 1998, and 118% of BSAS, 2003 recommendations). In addition, the low dietary Trp:Lys level (16% SID) would have limited the pigs response. The interpretation of the results by expressing Val as a ratio to Lys is not appropriate because of the non-limiting level of Lys. However, it can be stated that a minimum of 0.73% SID Val in the feed was necessary to achieve the best performance.

Waguespack et al. (2011) performed a Val dose-response trial in growing pigs from 20 to 50 kg LW. The animals were fed a corn soybean meal based diet containing 0.83% SID Lys, which is 100% of NRC (1998) and 86% of BSAS (2003) recommendations, so probably limiting during the first weeks of the trial. It appears that no dietary AA were limiting (based on the abstract information), other than Val in the basal formula (0.51% SID Val). A response to Val was observed up to a plateau at 0.56% SID Val, which corresponds to 67% SID Val:Lys.

Liu (2000) studied the effect of increasing dietary levels of Val in finishing pigs (60 to 85 kg LW). Based on the results of a previous Lys dose response trial, the Lys level was chosen by the author not to be limiting, and so Val was supposed to be the only limiting factor. However no effect of dietary treatment was shown. It is speculated in the discussion that the high feed intake had influenced the results and so the basal diet was probably not deficient. The level of 0.42% SID Val was sufficient to maximize the performance.

Lewis and Nishimura (1995) studied the effect of dietary Val in pigs from 67 to 85 kg LW. Valine was supposed to be the only limiting factor but SID Trp:Lys (14%) and SID His:Lys (29%) were probably also limiting. In this trial, performance was increased by increasing SID Val in the feed up to 0.41%. Additional measurements (nitrogen excretion and plasma urea concentration) confirmed these findings.

The range in weight categories studied in dose-response trials has a large impact on the result when requirements are expressed per unit of feed, due to the increase of feed intake with age. Consequently, when expressed as % of the feed, the level of SID Val that optimizes performance decreases from 0.73% SID Val (at 27 kg LW) to 0.41% SID (at 75 kg LW). However, expressing the Val requirement in this way has its limitations when it is applied to pigs other than those studied (i.e. with different feed intakes or fed with different Lys levels).


Expressing the outcome of each trial relative to the corresponding NRC (1998) recommendation (for instance, 68% SID Val:Lys or 0.45% SID Val for pigs between 50 to 80 kg LW) gives the advantage of a common point of comparison.

Three of the 4 publications report a lower requirement than NRC (1998). The average of all the quoted references sets the Val requirement of pigs at 96% of the NRC recommendations. According to this analysis, a minimum of 65% SID Val:Lys should be recommended for growing and finishing pigs.

Trial report: Effect of low dietary CP diet and Val levels fed to growing pigs(AJINOMOTO EUROLYSINE S.A.S., 2009)

To test the hypothesis that the optimum SID Val:Lys value could be higher than 65%, a trial was performed by AJINOMOTO EUROLYSINE S.A.S. to estimate the effect of increasing levels of SID Val:Lys above 65% in a low CP (14%) diet (wheat, barley and soybean meal: formula detailed in Table 14, final flap) in growing pigs (30 to 70 kg LW).

The secondary EAA levels (Ile, Leu, Phe and His) were adjusted so that they were not below current recommendations and net energy was maintained constant at 9.8 MJ/kg. A positive control was formulated to contain at least 16% CP (Table 5). The Lys level (0.82% SID) was limiting during the first part (30 to 45 kg) of the trial but not for the entire experimental period (to 70 kg). This means that expressing the Val requirement as a ratio to Lys is meaningful only during the first part of the experiment which is reported in Table 5.

Positive control (high CP diet) Low Protein diets

Expected SID Val:Lys (%) 75 65 70 75

Analysed values

Crude Protein (%) 16.4 14.3

SID Lys (%) 0.82 0.82

SID Thr:Lys (%) 73 69

SID M+C:Lys (%) 62 62

SID Trp:Lys (%) 24 20

SID Ile:Lys (%) 67 53

SID Leu:Lys (%) 125 102

SID P+T (%) 139 115

SID His:Lys (%) 39 33

SID Val:Lys (%) 79 64 72 78

Starting weight (kg) 33 33 33 33

ADFI (g/d) 1502 1520 1492 1509

ADG (g/d) 715 734 691 700

FCR 2.11 2.08 2.17 2.17

Intermediate weight (kg) 44 44 43 43

No signifi cant effects on growth performance were found.

Table 5: Effect of low protein diets and dietary SID Val:Lys levels in growing pigs, Ajinomoto Eurolysine s.a.s. (2009).

The reduction of dietary CP from 16.4 to 14.3% did not impair the performance of the pigs, provided that the minimum EAA ratios to Lys were maintained.

Dietary SID Val, Ile, Leu and His ratios to Lys can be reduced at least to 65, 53, 102 and 33%, respectively. Increasing the SID Val:Lys ratio above 65% did not improve the performance of pigs between 30 and 45 kg. This also applied to pigs up to 70 kg (Figure 8, p 10) with average ADG of 900 g/d and FCR of 2.22.

This more practical trial demonstrated that 65% SID Val:Lys was adequate for pigs between 30 and 70 kg.

This trial also confirmed that feeds can be formulated without a minimum protein constraint as long as the ideal AA profile is observed.

The information about the Val requirement in growing pigs is scarce, but Val is a potentially limiting AA for pigs between 25 and 110 kg.

A minimum of 65% SID Val:Lys is recommended in diets for growing pigs.


1.3 The Isoleucine requirement is no higher than 53% SID Ile:Lys

Spray dried blood cells

Soybean meal

0

3

5

8

10

13

15Lys:CP

Ile:CP

Leu:CP

Val:CP

His:CP

Phe:CP

Figure 9: Amino acid profile of spray dried blood cells vs soybean meal, as % of crude protein (AEL Bulletins 32 and 35).

Isoleucine, together with Val and Leu, belongs to the group of Branched-Chain AA (BCAA). This group of AA shares the same catabolic pathways (see AEL Bulletin 35). Experimental data must be interpreted with care when AA imbalances exist within this specific group. For instance, an excess of Leu will enhance the catabolism of Val and Ile even if these EAA are defi-cient in the diet resulting in depressed performance (Wiltafsky et al., 2010).

In addition to being in the BCAA group, Ile belongs to the group of Large Neutral AA (LNAA) together with Val, Leu, Trp, Phe, Tyr, Met and His. The latter group of AA shares a common L-type saturatable transporter at the blood brain barrier level (Smith and Stoll, 1998).

An analysis of literature about the Ile requirement in pigs must take into account these factors. One key finding in an analysis of the literature is that the design of Ile-deficient diets used to conduct dose-response studies with Ile have generally involved the use of specific feedstuffs (blood by-products) that are very deficient in Ile but also very rich in Val, Leu, Phe and His (Figure 9 and Focus 2).

> Dose-response to Isoleucine reported in the literature and feedstuffs effect

It has been reported that the source of feedstuff influences the Ile response and requirement in piglets (Wiltafsky et al., 2009). In a previous review (AEL Bulletin 35), it was concluded that the dietary Ile requirement did not exceed 53% SID Ile:Lys for piglets when there was no use of blood by-products, but a minimum of 63% was advised when blood meal or blood cells were present.

This apparent source effect might exist in growing and finishing pigs too. Recently, van Milgen et al. (2010) reviewed dose-response trials performed in pigs, and illustrated the lack of an Ile response when there was no use of blood by-products. In Figures 10 and 11 (next page), the outcome of dose-response trials performed in growing pigs is presented. As a descriptive approach and in order to account for the variability in the Ile levels tested, in the figures, the Ile levels have been expressed relative to dietary Lys (SID basis).

When the diets did not contain blood by-products, no response to increasing level of Ile was observed. On the contrary, when blood by-products were used, very low levels of dietary Ile were reached and a response

to increasing amounts of Ile was noted. When blood by-products are used, the response to Ile remains variable (moderate to substantial).

On one hand, in the case of the Ile dose-response trials performed without blood by-products, basal diets containing 50% SID Ile:Lys were not deficient enough to show a response to Ile and this makes it impossible to establish a requirement. It also suggests that Ile is probably not a limiting AA in practical pig diets.

On the other hand, when blood by-products were used, very low levels of Ile were reached (around 40 to 45% SID Ile:Lys) but the response to higher levels of Ile was probably increased by the excessive dietary supply of other AA like Leu. However, some trials do not show such large responses when using blood by-products. This raises the question of the amount and quality of the blood-products used; these factors could have influenced the final results.

The reasons for this specific effect were demonstrated in piglets by focusing on BCAA interactions (Wiltafsky et al., 2010). The excessive supply of Leu enhanced the common catabolism of all three BCAA, creating an Ile deficiency. Other work shows that this effect exists in heavier pigs and helps to explain the specific effect of blood by-products (Focus 2, p 16).


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ADG (g/d)

30 8035 40 45 50 55 60 65 70 75SID Ile:Lys (%)

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ADG (g/d)

30 8035 40 45 50 55 60 65 70 75SID Ile:Lys (%)

Without Blood Products With Blood Products

Figure 10: Dose-response to dietary SID Ile, with or without the use of blood products. Effect on Average Daily Gain (ADG).

Figure 11: Dose-response to dietary SID Ile, with or without the use of blood products. Effect on Feed Conversion Ratio (FCR).

4.5

4.0

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FCR

30 8035 40 45 50 55 60 65 70 75SID Ile:Lys (%)

4.5

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FCR

30 8035 40 45 50 55 60 65 70 75SID Ile:Lys (%)

Without Blood Products With Blood Products

Fu (2005) Chap. 3, 58-77 kg

Fu (2005) Chap. 3, 58-78 kg

Htoo et al. (2010) 25-40 kg

Kendall (2004) Chap. 5, Exp. 1, 92-116 kg


Dean et al. (2005) Exp. 3, 85-123 kg

Dean et al. (2005) Exp. 5, 81-115 kg

Fu (2005) Chap. 2, Exp. 2&3, 88-112 kg

Fu (2005) Chap. 2, Exp. 1, 97-122 kg

Fu (2005) Chap. 2, Exp. 2&3, 88-113 kg


Lenis and van Diepen (1997) 18-38 kg

Parr et al. (2003) 27-42 kg

Parr et al. (2004) 87-99 kg

Waguespack et al. (2011) 20-50 kg


> Estimation of the Isoleucine requirement of growing and finishing pigs

In Table 6, the dose-response studies on the Ile requirement of growing pigs are presented and analysed, according to the presence or absence of blood by-products. There is more information available than for the Val requirement. However, there is still a lot of variability in the way in which the requirement is expressed and a further analysis was needed to homogenize the data.

Live Weight

Estimated Ile requirement

(in the published unit)

Amount of blood meal or

cells

Dietary Lys SID

(%)

Lys limiting ?1

Doubts on the fi rst

limiting AA2

Re-estimation of the Ile

requirement in SID values and choice of the mode of expression

Ile require-ment (% of NRC,

1998)

Waguespack et al. (2011) 20 to 50 kg 0.43% SID Ile 0% 0.83% Partially 52% SID Ile:Lys 96%

Fu (2005) Chap. 3 58 to 77 kg 55% SID Ile:Lys 0% 0.78% No Trp 0.38% SID Ile 103%

Dean et al. (2005) Exp. 5 81 to 115 kg


Focus2

Avoiding imbalances and AA oversupplyto achieve the best performance

By definition, the ideal AA profile provides the ratios of EAA to Lys that optimize animal perfor-mance. The ratios are generally considered as minima and the AA profile does not take into account per se the interactions between the AA.

However, the increasing knowledge about AA interactions and their practical impact confirms that this profile has to be considered also as an ideal balance between all the EAA, and the nutritionist should be careful to avoid an excessive supply of any of the AA by correctly selecting feedstuffs or by decreasing the dietary crude protein content. Effects of imbalances between AA of the BCAA group have been described in piglets (Gloaguen et al., 2011 and Wiltafsky et al., 2010) and also in heavier pigs.

For instance, Fu (2005) designed a series of experiments to study the reason for the Ile require-ment to be higher when spray-dried blood cells (SDBC) were used. The SDBC have a limited supply of Ile but are very rich in Lys, Val, Leu, His and Phe (Figure 9, p 13). Due to the imbalanced BCAA profile, the higher Ile requirement in pigs fed diets with SDBC is readily attributable to BCAA interactions. However, Phe and His both of which are LNAA along with the BCAA, share the same transporter as Ile at the brain blood barrier level, and this must also be taken into account.

In one experiment, barrows (from 92 to 114 kg LW) were fed 6 corn-based diets (Table 7) to test the combined effects of BCAA, Phe and His on performance. A positive control diet containing 4% of SDBC was also formulated.

Diet 1 Diet 2 Diet 3 Diet 4 Diet 5 Diet 6

Corn + SBM Diet 1+ Val + Leu Diet 2 + Val + Leu Diet 3 + Val + Leu Diet 3 + His + Phe Corn + SDBCSID AA (%)

Ile 0.30

Val 0.38 0.53 0.67 0.81 0.67 0.68

Leu 0.96 1.16 1.37 1.58 1.37 1.38

His 0.23 0.48 0.49

Phe 0.40 0.60 0.60

ADFI (g/d)3962ab 4056a 3765abc 3645bc 3581c 3625c

100% 102% 95% 92% 90% 91%

ADG (g/d)1104ab 1158a 1047abc 996bc 945c 931c

100% 105% 95% 90% 86% 84%

Gain to Feed0.279ab 0.284a 0.279ab 0.272ab 0.263ab 0.256b

100% 102% 100% 97% 94% 92%

The diets provided the same Lys (0.51% SID), and net energy (11.2 MJ/kg) levels a,b,c: Within a row, different letters indicate signifi cantly different values at p


1.4 Ideal amino acid profile for growing and finishing pigs

This review allows the recommended ideal AA profile to be updated (Table 8). This new AA profile provides the basis for maximizing the growth performance of pigs from 25 to 110 kg (grower and finisher diets). Choices of the minimum ratios of EAA to Lys have been made based on this review of the available data (literature and trial reports).

in SID ratio to Lys (%)Grower Finisher

25 to 65 kg 65 to 110 kg

Lys 100 100

Thr 67 68

Met+Cys 60 60

Trp 20 19

Val 65 65

Ile* 53 53

Leu 100 100

His 32 32

Phe+Tyr 95 95

*SID Ile:Lys is increased if blood by products are used in a diet.

Table 8: Ideal amino acid profile for growing and finishing pigs (AJINOMOTO EUROLYSINE S.A.S., 2011).

It has been demonstrated that the Thr requirement increases with the weight of a pig due to the particular func-tions of this AA in maintenance requirements (AEL Bulletin 31).

As in piglets, Trp has a strong effect on growing pig performance. It is of primary importance to monitor carefully this AA since a limited supply significantly lowers the gain and feed efficiency. The meta-analysis shows a minimum requirement of 20% SID Trp:Lys for growing pigs.

The Val and Ile requirements have been updated on the basis of the available information; recommendations for Met+Cys, Leu, Phe+Tyr and His are based on recommendations made by Henry (1993) and Sve (1994).

A further analysis of trials using low protein diets can assist in the practical use and validation of this AA profile (see Section 2.3, p 30).

This ideal AA profile ensures that the nutritional needs of the animal are metand should be used as a practical tool to design diets that allow the full expression of the growth potential of pigs fed and reared in variable conditions.

The use of this AA profile allows feed to be formulated on each EAA insteadof dietary CP. This precise method of formulating provides a way to avoidan excessive supply (above the requirement) of some EAA and reduces dietaryCP safely.


2. Practical aspects of formulatingto each essential amino acid

By placing minimum constraints on each of the eaa, it is possible to optimize a formulation without controlling protein per se. the limiting eaa will determine the protein level and the dietary CP can be reduced with confidence. to take full advantage of low protein diets, the energy supply must also be taken into account. With high protein diets, excess absorbed amino acids are converted into nitrog-enous waste which is excreted through urine and faeces into the environment. this process uses up valuable energy consequently, when the protein level is reduced, less energy is required in the feed. However, the more efficient utilization of dietary energy with low protein diets is not taken into account in all energy systems.

These nutritional aspects (energy and AA requirements) are the factors that determine the level to which CP can be reduced. They are also key levers that can be used to save formulation costs and increase feed efficiency.

With this background, the different steps that should be taken to implement low protein diets in practice will be reviewed: the use of the Net Energy system the determination of the limiting AA in pigs diets the formulation without a minimum dietary CP constraint

2.1 Using Net Energy to take into account the better efficiencyof low protein diets

> Different energy systems (Noblet, 2005)

The total amount of energy supplied by a feedstuff or a feed, called Gross Energy (GE), is not completely available to an animal. An important fraction of the GE is lost in faeces, urine, methane and heat. Evaluation of the energy content of a feed or an ingredient can be done through different energy systems (Figure 12).

Faeces Urine & Gases Heat

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60

70

80

90

100Starch (Wheat) Lipid (Oil) Protein (Soybean meal) Fiber (Wheat Straw)

0Gross Energy Digestible Energy Metabolizable Energy Net Energy

% of the Gross Energy

Figure 12: Energy utilization of nutrients in growing pigs. Illustration based on feedstuff values from EvaPig software. Within a nutrient category, energy values are expressed as a percentage of gross energy.


Digestible Energy (DE) is the first level of energy utilization and takes into account the energy lost in the faeces. Most of the variation in the DE coefficient is associated with the presence of fibre which is less digestible than other nutrients, as illustrated in Figure 12 with the example of the DE value of wheat straw.

However, DE is not entirely available and Metabolizable Energy (ME) is the DE less the energy lost in urine and gases. Gas production results from bacterial fermentation in the large intestine while energy losses in urine are mainly dependent on the urinary nitrogen excretion. The quantity of energy excreted in urine is therefore directly dependent on the dietary crude protein content and how accurately it meets an animals requirement. That is why the ME:DE ratios are linearly related to dietary CP content. In Figure 12, only the protein source impacts the ME evaluation in comparison to the DE value.

Metabolizable Energy is needed to cover the energy requirements of the pig, but there are associated heat losses due to the metabolism of this ME and the energy cost of ingestion and digestion. Thus ME is still not the best estimate of the energy available for anabolic processes. Only the Net Energy (NE) system, in contrast to the other energy systems, takes into account the impact of the heat losses on the utilisation of all nutrients as illustrated in Figure 12. The heat increment associated with the metabolism of digested crude protein is significantly higher than for starch or lipid and, as a result, the impact on its NE value is greater.

After reviewing the different energy systems, it appears that net energy represents the closest estimate of the true energy of a feed.

In practice, each energy system has its own predictive equation to estimate the energy value of ingredients, based on proximal analyses (protein, starch, fibre). The free EvaPig software (INRA, AFZ and AJINOMOTO EUROLYSINE S.A.S.) gathers all this information and simplifies the implementation and practical use of the net energy system (Focus 3).

Focus3

Calculating Net Energy values of ingredientsand feeds using EvaPig

The EvaPig software was developed by INRA, AFZ and AJINOMOTO EUROLYSINE S.A.S. to calculate energy, amino acid (total and digestible) and phosphorus values of ingredients and

diets for growing and adult pigs.

EvaPig includes the chemical composition and nutritive values for the pig of about 100 reference ingredients, mostly derived from the INRA-AFZ Tables (Sauvant et al., 2004).

New ingredients can be created either by copying and modifying the reference ingre-dients or from a users own data. Complete diets can also be created either by mixing ingredients or by providing a chemical composition. Specific and generic equations calculate energy, amino acid and phosphorus values.

This free software is available in more than 10 languages on www.evapig.com. Many documents relating to energy evaluation are also downloadable from this website (concepts, equations).

al.

Free download on www.evapig.com


> Taking account of the energy sparing effect of low protein diets

- 1 g protein

+ 1 g starch

+ 4.1KJ NE

+ 20.5KJ NE

+ 1 g lipid

Figure 13: Effect of the substitution of 1 g of proteinby 1 g of starch or lipid on the net energy content (Noblet, 1996; Le Bellego et al., 2001).

When low protein diets are implemented, a part of the protein is replaced by starch or lipid resulting in higher NE contents (Figure 13). If these diets are optimized using the ME rather than the NE system, the final feed will underestimate the utilisable energy content.

This underestimate of the utilisable energy in low-CP feeds has an impact on performance and carcass adi-posity. Figure 14 presents the effect on carcass fatness of a protein reduction in diets formulated using either ME or NE measured in independent trials.

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Adiposity criteria(% of positive treat.)

8 2010 12 14 16 18

Dietary Crude Protein (%)

Using the ME system

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Adiposity criteria(% of positive treat.)

8 2010 12 14 16 18


Using the NE system

Nonn and Jeroch (2000)Castrates

Nonn and Jeroch (2000)Gilts

OConnell et al. (2006)

Shriver et al. (2003)

Bourdon et al. (1995)

Cromwell et al. (1996)

Dourmad et al. (1993)

Galassi et al. (2010)

Tuitoek et al. (1997)

Valaja et al. (1993)

Jondreville et al. (1995)

Kerr et al. (1995)

Kerr et al. (2003)

Liu (2000) Chap. 2, Exp. 2

Figure 14: Effect of dietary crude protein (CP) reduction on carcass adiposity (% of the level on the high CP diet) measured in pigs given feeds formulated using the ME or NE system.

When feeds were formulated using the ME system, as dietary CP decreased, the carcass fatness increased up to 115% of the control treatments.

When the diets were formulated using the NE system, the decrease in CP did not affect carcass fatness. The 2.5% variability was either not significant or was attributed by the authors to small deficiencies in some of the EAA.

The explanation lies in the better utilization of energy in low protein diets. When dietary protein is reduced, urea excretion in urine and the metabolism associated with urea synthesis both decrease. As a result, there is a reduction in energy excretion in urine (-3.5 KJ/g of protein) and in heat loss (-7 KJ/g of protein) as calculated by Le Bellego et al. (2001). When a formulation is based on ME, the large decrease in heat loss is not taken into account. This leads to a surplus of retained energy which is deposited as fat in the carcass. Only the net energy system takes account of this energy-sparing effect of low protein diets.


> The Net Energy system predicts performance more accurately

Experiments using feed with a constant dietary Lys/NE ratio but varying levels of NE, have demonstrated that pigs regulate their feed intake based on its NE content (Le Bellego et al., 2001, in AEL Bulletin 24) and maintain their performance.

Recently, Quiniou and Noblet (2011) tested the effect of a wide range of dietary NE levels on pigs performance. In the tested diets, the Lys/NE concentrations were kept the same (0.90% SID Lys/NE). Animals were individually penned and had ad libitum access to the feed.

The results are presented in Figure 15 and are expressed as a percentage of the performance obtained with the diet containing10.5 MJ NE/kg. Due to increasing carcass yield with dietary energy content, to make the data comparable, performance were adjusted by the authors by using carcass parameters as covariable.

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% of the results obtained with the 10.5 NE MJ/kg feed

8.1 8.7 9.3 9.9 10.5 11.1

Dietary Net Energy (MJ/kg)

ADG (g/d)

Ingested NE

ADFI (g/d)

Figure 15: Effect of dietary net energy on pig performance, using a constant SID Lys/NE ratio (Quiniou and Noblet, 2011).

When dietary NE increases, feed intake decreases but ingested NE and ADG remain constant unless the NE concentration is so low that pigs cannot consume enough feed to compensate for the reduction in energy density.

A pig is able to regulate its feed intake according to the NE supply with feeds between 8.7 to 10.5 MJ NE/kg. According to the authors, below 8.7 MJ/kg animals ability to respond to decreases in the NE content of their feed is limited by their intake capacity.

The FCR values based on DE or NE ingestion are presented in Table 9. It appears that the FCR based on NE remains constant, while the FCR based on DE is linearly decreased. But this decrease is related to the increasing proportion of NE in the highest DE feeds and confirms that the animals regulated their intake according to the NE provided by the feed and not the DE. This trial indicates superiority of the NE system over the DE system for predicting pig performance.

Treatments 1 2 3 4 5 6

Dietary DE content (MJ/kg) 11.5 12.2 13 13.7 14.4 15.1

Dietary NE content (MJ/kg) 8.1 8.7 9.3 9.9 10.5 11.1

Calculated NE/DE 0.70 0.71 0.72 0.72 0.73 0.74

SID Lys/ NE (g/MJ) 0.90 0.90 0.90 0.90 0.90 0.90

FCR MJ DE/kg weight gain 36.2a 35.2ab 36a 33.9b 33.6ab 34.2ab Linear effect, p


> The Net Energy system gives flexibility and reduces formulation costs

Metabolizable Energy System Net Energy System

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Relative ME or NE (% dietary ME or NE content)

Ranking in the different energy systems

WheatCorn

Barley

Sunower Meal

Soybean Meal

Rapeseed Meal

Figure 16: Relative metabolizable and net energy values of ingredients for growing pigs. Within each system, values are expressed as percentages of the energy values of a pig grower feed of 12.8 MJ/kg of ME or 9.7 MJ/kg of NE (Low protein feed in Quinou et al., 2011).

The use of the NE system instead of the DE or ME systems changes the nutritional ranking of ingredients as illustrated in Figure 16.

Compared to the NE system, the ME and DE systems over-estimate the utilisable energy in protein and fibrous feeds while fat and starch sources are underestimated.

In the ME system, soybean meal and wheat have almost the same energy value but in the NE system, cereals are more valuable than protein feedstuffs.

To estimate the impact of the energy system used in the feed formulation, a growing pig feed was optimized using either the ME or NE system, with no minimum or maximum on dietary protein, but with the same minimum levels of EAA in all formulations. Lysine was 0.90% SID and other EAA were set using the ideal AA profile presented in Table 8. The diet was optimized with either 13.5 MJ/kg of ME or 10 MJ/kg of NE (NE/ME = 74%, Noblet et al. 1994).In addition, different prices of soybean meal were used (from 260 to 370 /T), while the cereal price was kept constant (wheat at 230 /T), the resulting spread between SBM and Wheat varies from 30 to 140 /T. The results are presented in Figures 17 (CP levels), 18 (AA levels) and 19 (changes in the cost of the feed).

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Soybean Meal Price (/T)

360

21

20

19

17

18

16

15

Dietary Crude Protein (%)Formulation using the ME systemFormulation using the NE system

Figure 17: Effect of the energy system (ME or NE) on the level of dietary protein in pig grower feed optimized at different prices of soybean meal (wheat kept at 230 /T).

Formulating using the ME system resulted in the highest dietary protein levels while for-mulating with the NE system allowed the dietary CP to be reduced by 1.5 points in this example.


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% of the requirement

Formulation using the ME system Formulation using the NE system

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107105

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100 100 100

M+C THR TRP VAL ILE LEU HIS P+T

Figure 18: Effect of the energy system (ME or NE) on the dietary amino acid content relative to their requirement (dietary crude protein is 17% with ME and 15.4% with NE).

The ME system led to an excessive supply of AA in comparison to their require-ment which would lead to increased nitrogen excretion.

Soybean Meal price (/T)

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Relative cost of the formula (%)

Using the ME system Using the NE system

260 280 300 320 340 360 380

Figure 19: Effect of the energy system (ME or NE) on the cost of the feed at different prices of soybean meal (Wheat kept at 230 /T).

The cost of the diet and the effect of increases in the SBM price are much lower when formulating with the NE system.

Due to the high ME value of protein feedstuffs, the ME sys-tem leads to formulations with a high protein content. When nutritionists apply a maximum constraint to CP in formulations (because of environmental concerns for instance), the ME system leads to formulations that push against this constraint but this is not the case with the NE system. This is one reason why the NE system gives much more flexibility in formulations and allows cost-savings.

The Net Energy system is the only one that takes account of the lower efficiency of energy utilisation of dietary protein.

The Net Energy system is the best predictor of pig performance (growth and carcass parameters).

The ranking of feedstuffs is different between the NE and ME systems.

The Net Energy system gives more flexibility in formulations and leads to reductions in dietary costs.

The Net Energy system facilitates the formulation of low protein diets.


Focus4

Reducing the amount of soybean mealand using local feedstuffs

The implementation of reduced protein diets combined with the use of feed-grade AA provides a way to take advantage of locally produced feedstuffs such as cereals and protein sources other than soybean meal (SBM). In theory, it should be possible to formulate diets for pigs without using SBM. With correct supplementation of AA, rapeseed meal (RSM) appears to be a good candidate.

Rapeseed meal is becoming more commonly used in pig diets with the increasing availability of this co-product generated by the biofuel industry. The nutritional characteristics of RSM are well known and genetic selection has largely removed its antinutritional factors. Incorporation of RSM in pig diets at levels up to 18% have been successfully tested (Maupertuis et al., 2011).

Use of RSM and the decrease of dietary CP that is achievable has been recently studied by Quiniou et al. (2011) in 144 pigs (27 to 110 kg LW, ad libitum feeding). Increasing amounts of RSM were tested in 3 treatments (Table 10). This was achieved at the expense of SBM and feed-grade AA were added to maintain the correct balance of EAA. In this trial, soybean meal was completely excluded from the diets in the finishing period. All the formulations contained the same level of Net Energy. The dietary CP was reduced from 16% to 14.5% in the grower phase and from 15% to 13% in the finisher phase. Performance data (gain and feed intake) were collected every 2 to 3 weeks and it was therefore possible to use the InraPorc software to estimate the nitrogen output per pig. The results are presented in Table 11.

Growing diets Finishing diets

Treatments 1 2 3 1 2 3

Barley (%) 52 26 28 63 30 47

Wheat (%) 29 56 55 20 54 40

Soybean meal (%) 16 5 3 14

Rapeseed meal (%) 9.5 10.3 - 13.2 10.4

Rapeseed oil (%) 0.5 0.5 0.5 0.5 0.5 0.5

L-Lysine (%) 0.27 0.45 0.50 0.19 0.41 0.45

L-Threonine (%) 0.08 0.14 0.16 0.05 0.10 0.13

DL-Methionine (%) 0.04 0.04 0.04 0.02 0.02 0.03

L-Tryptophan (%) 0.02 0.03 0.02 0.02

L-Valine (%) 0.03 0.03

Net energy, MJ/kg 9.7 9.7 9.7 9.7 9.7 9.7

Crude protein (%) 16.0 15.0 14.5 15.0 14.0 13.0

SID Lys (%) 0.83 0.83 0.83 0.73 0.73 0.73

SID Thr:Lys (%) 65 66 66 66 65 65

SID M+C:Lys (%) 62 65 64 62 71 66

SID Trp:Lys (%) 20 20 21 21 22 20

SID Val:Lys (%) 78 70 70 84 74 73

SID Ile:Lys (%) 67 68 55 71 59 54

SID Leu:Lys (%) 116 105 100 125 110 101

SID His:Lys (%) 40 37 35 43 39 35

Table 10: Composition of the grower and finisher diets used in Quiniou et al. (2011).


Treatments 1 2 3 Treatment effect

ADG, g/d 801 801 818 ns

FCR 2.94 2.97 2.87 ns

Lean content, % 61.3 60.9 61.8 ns

Nitrogen utilization

N Ingested, kg/pig 6.06 (100%) 5.65 (93%) 5.40 (89%)

N Excreted, kg/pig 4.03 (100%) 3.63 (90%) 3.37 (84%)

Table 11: Effect of decreasing levels of dietary crude protein in pig feeds and substitution of soybean meal by rapeseed meal (Quiniou et al., 2011).

Growth rates were the same across all treatments, with no detrimental effect from the crude protein reduction.

Carcass parameters were not affected by the decrease in crude protein.

On average, the reduction of crude protein by 1 percentage point decreased nitrogen excretion by 10% (treatments 1 vs 2 and 3).

Use of RSM and the elimination of SBM in the finisher period had no detrimental effect on performance.

This trial illustrates the possibility to take advantage of local feedstuffs such as RSM. Other raw materials can be also of interest like Sunflower Meal or Peas.


2.2 Determining the limiting amino acid in pig grower diets

The limiting AA in a diet determines the extent to which the dietary CP level can be reduced. The protein level is determined by both the AA specification set for the diet and by the available ingredients. In a practical formulation, the availability of feed-grade AA also determines the level of reduction of dietary crude protein.

Therefore, the so called next limiting AA can be different depending of the local situation. However, a study can be done to determine the global trend and to reveal which AA must be controlled and particularly focused.

> A theoretical approach: Ranking the limiting AA

In order to assess the ranking of limiting AA under typical European conditions, a grower diet was formulated based on French (IFIP) recommendations (0.85% SID Lys and 9.5 NE, MJ/kg), using the ideal AA profile presented in Table 8, page17. The feeds contained fixed amounts of corn (10%) and rapeseed meal (12%). By progressive substitution of soybean meal by wheat and feed-grade AA, it was possible to determine the extent of protein reduction and the order in which the EAA became limiting. The outcome of this exercise is presented in Figure 20.

22

16

18

20

14

12

10

Crude Protein level (%)

20.4

18.9

17.0

15.6

14.9 14.5 14.3

13.7

Lys Thr Trp M+C Val Ile Leu His

+L-Lys

+L-Thr

+L-Trp

+L-Val +DL-Met

Figure 20: Changes in the dietary crude protein (CP) level in a standard European grower pig diet when soybean meal is gradually replaced by wheat. Ranking of limiting amino acids (from left to right) and lowest CP achievable without supplementation with the corresponding AA.

In this example, Trp was a limiting AA after Lys and Thr. Without L-Trp supplementation, it was not possible to decrease CP below 17%. The use of all the available feed-grade AA allowed protein to fall to 14.5%. The BCAA became colimiting when protein was further reduced.

> A practical approach: The next limiting AA in pig diets (feed survey)

A survey was conducted in 2008 by AJINOMOTO EUROLYSINE S.A.S. on commercial early-grower/grower feeds (145 samples collected in 15 countries throughout Europe). The crude protein content was analysed using nitrogen determination by Dumas, and the total AA were determined by ion exchange chromatography (AEL Bulletin 32). In Figure 21, the total Trp content (% of Lys) has been plotted against the total Lys/CP ratio. When this ratio increases, Lys is more concentrated in the crude protein and reflects a strategy of protein reduction.


27

21

23

25

19

17

15

Total Trp:Lys (%)

Total Lys:CP (%)

4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5

Figure 21: Total Trp:Lys levels in growing pigs diets (early grower and grower). Source: AJINOMOTO EUROLYSINE S.A.S. feed survey 2008.

When Total Lys/CP increases, the Total Trp:Lys decreases. 33% of the samples were deficient in Trp (i.e. below 21% total Trp:Lys which corresponds to a requirement of

20% SID Trp:Lys). 67% of the samples were above the Trp requirement, meaning that in these samples a further dietary CP reduc-

tion would be possible and a better balance of EAA could be achieved.

80 16010090 120110 140130 150

For each AA, % of its requirement

Trp

Ile

Val

His

Leu

P+T

Figure 22: Total EAA dietary content in growing pigs diets. AJINOMOTO EUROLYSINE S.A.S. feed survey 2008. For each AA, the dietary AA content was calculated as a percentage of its requirement for the growing pig; 100% corresponds to the requirement. In a box, the vertical line corresponds to the median.

In Figure 22, information is given about the other EAA in these samples. For each AA, the dietary AA content was calculated as a percentage of their requirement for the growing pig; 100% corresponds to the requirement (Table 8, p 17).

The median value for Trp was 102% and more than 110% for the other AA

Tryptophan was the most limiting AA in these diets, before the BCAA group.

A substantial reduction in the CP content in grower pig diets is possibledue to the commercial availability of feed-grade AA (from 17.0% to 14.5% in this example).

Tryptophan is limiting before the BCAA group in grower pig diets. The useof L-Tryptophan is necessary to achieve a dietary CP reduction with the minimum constraint of 20% SID Trp:Lys.


2.3 Formulating without a minimum constrainton dietary crude protein

Taking account of the use of the energy of nutrients, and knowing the EAA requirements and the response to the supply of the most limiting AA in a diet, are a prerequisite for a formulation based on each EAA. The advances made in animal nutrition provide all the tools to implement this method. The decision to be made on the level of EAA (ideal AA profile) must be done based on the scientific knowledge of the requirement and its practical consequence. These objectives are integrated into the ideal AA profile proposed by AJJINOMOTO EUROLYSINE S.A.S. presented in Table 8 (page 17) which will be also validated in the following section.

The energy system, the availability of feed-used amino acids and the family of feedstuffs used in a factory determine the reduction of dietary CP which is achievable. In grower pig diets, it appears that the L-Tryptophan is a very effective lever for this reduction because of the level of the Trp requirement when compared to the Trp content in feedstuffs, and because of the associated animal response to this nutrient. With the availability of 5 feed grade AA, implementing the formulation on each EAA has never been more relevant and beside its effect on the environment, it helps to reduce feed cost.

> Diets with very low CP contents do not depress performance

A review of trials testing dietary CP reduction is presented in Table 12. In all these trials, the diets were formulated on the NE system, using digestible AA, and the digestible Lys was adjusted to the NE content. To homogenize the data and get the complete AA profile, all the diets were re-evaluated using the EvaPig software (Table 14, final flap).

In some trials (Bourdon et al., 1995 and Jondreville et al., 1995) some of the EAA like Val and Leu were below recom-mended levels which explains why some of the performance criteria were affected.

Weight Feeding SID Lys/MJ NE Dietary NECrude Protein levels tested

Limiting factorsEffect of CP

reduction

Dourmad et al. (1993)

29 to 103 kg ad libitum 0.73% 9.9 MJ/kg17.6 vs 15.0 vs

12.5no ns

Jondreville et al. (1995)

24 to 101 kg ad libitum 0.90% 10.0 MJ/kg 16.4 vs 13.8AA defi ciencies

(Thr & Val 57%, Leu 90% of SID Lys)

FCR is increased

Bourdon et al. (1995) Exp. 1

30 to 100 kgrestricted / multiphase

feeding0.74% 22 MJ NE/day

17.0 vs 16.0 > 13.3 > 11.6

AA defi ciencies in the last treatment (Val 58% & Leu 93% of SID Lys)

Adiposity is increased in the last treatment

Bourdon et al. (1995) Exp. 2

30 to 100 kgrestricted / multiphase

feeding0.74% 22 MJ NE/day

17.0 vs 16.0 > 13.3

no ns

Canh et al. (1998)

55 to 105 kg0.9 MJ NE / Kg BW.75 in 2 meals per day

0.74% 9.6 MJ/kg15.5 vs 13.9 vs

12.3no ns

Nonn and Jeroch (2000)

25 to 110 kg ad libitum0.87 - 0.72 -

0.70%10.3 MJ/kg

17.0 > 15.0 > 13.6 vs 13.0 > 11.0 >

10.5no ns

Le Bellego et al. (2002)

27 to 100 kg ad libitum 0.85 - 0.70%variable (10.3

to 11.2 MJ/kg)19.0 > 17.0 vs

17.0 > 13.0no ns

Kerr et al. (2003) Exp 2

25 to 110 kg (fi nisher not presented)

ad libitum 0.78% 10 MJ/kg 18.0 vs 15.0Strong difference in analyzed values in the fi nisher diets

ns

Ajinomoto Eurolysine (2009)

33 to 70 kg

Femalesad libitum

Males27MJ/d NE

0.87% 9.8 MJ/kg 16.0 vs 14.0 no ns

Quiniou et al. (2011)

27 to 111 kg ad libitum 0.85 - 0.75% 9.7 MJ/kg 15.5 vs 14.0 no ns

Table 12: Literature review of trials testing different levels of dietary CP and using the net energy system.

The growth performance in the trials that used balanced AA profiles are presented in Figure 23. The effect of the dietary CP reduction on nitrogen excretion is reported for all the trials in Figure 24.


1150

1100

1000

950

800

700

ADG (g/d)

20 1019 18 17 16 15 14 13 12 11

Dietary Crude Protein levels (%)

900

750

850

3.5

2.6

2.7

2.8

2.9

3.0

3.1

3.2

3.3

3.4

3.6

2.5

2.2

2.0

FCR

20 1019 18 17 16 15 14 13 12 11


2.4

2.1

2.3

Dourmad et al. (1993) 29 to 103 kg

Le Bellego et al. (2002) 27 to 100 kg Low T

Le Bellego et al. (2002) 27 to 100 kg High T

Ajinomoto (2009) 33 to 70 kg

Nonn and Jeroch (2000) 85 to 110 kg

Bourdon et al. (1995) 30 to 100 kg


Kerr et al. (2003) 25 to 83 kg Medium Energy


Kerr et al. (2003) 25 to 83 kg High Energy

Canh et al. (1998) 55 to 105 kg


Quiniou et al. (2011) 27 to 111 kg


Kerr et al. (2003) 25 to 83 kg Low Energy

Figure 23: Effect of dietary crude protein reduction on Average Daily Gain (ADG) and Feed Conversion Ratio (FCR). The X axes are inversed (from high to low protein content).

20 1018 16 14 1219 17 15 13 11


100

95

90

80

85

70

75

60

65

50

55

Relative change in nitrogen excretion (%)

Nonn and Jeroch (2000) Castrates 25 to 60 kg

Nonn and Jeroch (2000) Gilts 25 to 60 kg

Canh et al. (1998) 55 to 105 kg

Dourmad et al. (1993) 29 to 103 kg






Quiniou et al. (2011) 27 to 111 kg

Jondreville et al. (1995) 24 to 101 kg


Figure 24: Effect of dietary crude protein reduction on nitrogen excretion. the X axe is inversed.

Regardless of the experimental conditions or performance level, dietary CP can be reduced without affecting growth performance or carcass parameters (already shown in Figure 14, page 20). In these trials dietary CP was reduced to 14% in grower pigs and 11% in finisher pigs.

The large decrease in nitrogen excretion with lower protein levels was confirmed: -10% in N output for each percentage point reduction in dietary CP.


> Validation of the ideal AA profile

The ideal AA profiles of the feeds used in the low CP trials where performance was maintained were calculated and compared with the AJINOMOTO EUROLYSINE S.A.S. recommendation in Figure 25. This information helps to clarify the requirement of the secondary essential AA: Leu, His and P+T. In this figure, the trial using corn based diets are not reported because high amount of the secondary AA are supplied resulting in a comparison which would not be informative.

30

40

50

60

70

80

90

100

110

120

130

20

10

0

Ratio to Lys (%, SID)

Thr:Lys M+C:Lys Trp:Lys Val:Lys Ile:Lys Leu:Lys His:Lys P+T:Lys

67

60

20

65

53

100101 103

32

95

6763

21

64

56

35

118

65 66

20

70

62

110

38

128

69 68

23

65

53

32

112

6764

19

64

59

30

102

6664

21

70

55

100

35

112

70

62

20

66

54

103

33

117

103

Ajinomoto Eurolysine's prole Dourmad et al. (1993) Bourdon et al. (1995) Canh et al. (1998)

Nonn & Jeroch (2000) Quiniou et al. (2011) Ajinomoto Eurolysine (2009)

Figure 25: Ideal AA profiles of the low CP diets that maintained performance in comparison with Ajinomoto Eurolysines AA profile. Expressed as ratios to Lys (%, SID). The corn based diets are not presented.

For Thr, M+C, Trp, Val and Ile, the average dietary levels in these trials were consistent with the AEL recommendations.

The proposed recommendations for Leu:Lys (100% SID) and His:Lys (32% SID) were confirmed.

It remains difficult to draw conclusions on Phe and Tyr requirements because low levels of these AA were not tested. However, these AA are unlikely to be limiting in pig diets.

> The relationship between EAA and NEAA

A feed provides EAA and Non-essential AA. Non EAA can be synthesised by an animal from EAA so their dietary supply can be decreased as happens in low protein diets. Studies have shown that an optimal balance exists between Nitrogen (N) supplied by the EAA (EAAN) and total N (TotalN). The optimum lies between 43 and 50% (Gotterbarm et al., 1998; Lenis et al., 1999). It is important to notice that in these calculations, Arg was considered by the authors to be an EAA. Also, the calculations were based on total AA rather than digestible AA.

The relationship between the ratio of EAAN and TotalN and dietary CP or Lys/CP concentration from the low CP trials selected in Table 12 is presented in Figure 26.


49%

48%

47%

44%

EAAN / TotalN

10 2111 12 13 14 15 16 17 18 19 20


46%

42%

41%

45%

49%

48%

47%

44%

EAAN / TotalN

4.0 8.04.5 5.0 5.5 6.0 6.5 7.0 7.5

Total Lys / CP

46%

42%

41%

45%

Dourmad et al. (1993) Bourdon et al. (1995) Canh et al. (1998) Nonn and Jeroch (2000)

Le Bellego et al. (2002) Kerr et al. (2003) Ajinomoto Eurolysine (2009) Quiniou et al. (2011)

Figure 26: Effect of dietary CP and total Lys/CP on the ratio between nitrogen supplied by the EAA and the total nitrogen (EAAN/TotalN). Diets from the trials presented in Figure 23.

Within trials, when dietary CP was reduced, the ratio EAAN/TotalN did not move outside of the recommended range of 43 to 50%,

The increased Lys concentration in CP did not affect the ratio EAAN/TotalN as long as the ideal AA profile was maintained.

These observations are explained by the fact that when dietary CP is decreased, the amount of both non EAA and non limiting EAA (i.e Leu, Ile, Phe, Tyr, His) is decreased.Based on this balance, it is possible to estimate the minimum amount of total N (and thus CP) needed in a grower or finisher diet (Table 13). On average, the balance can be maintained down to a dietary CP level as low as 12%. These calculations are in line with the lowest protein levels tested in the trials presented in Table 12.

Total Lys (%) Nitrogen from EAA basedon AEL ideal AA profi le

EAAN/TotalN Total Nitrogen needed MinimumDietary CP (N x 6.25)

Grower diet 1.00 0.90 43 to 50 1.80 to 2.10% 11 to 13%

Finisher diet 0.90 0.81 43 to 50 1.62 to 1.89% 10 to 12%

Table 13: Estimation of the lowest amount of nitrogen (N) needed to maintain the balance between N from EAA and Total N (EAAN/TotalN).

Dietary crude protein levels can be substantially reduced and minimum constraints can be removed from CP provided that minimum EAA values are maintained.

The ideal AA profile proposed by AJINOMOTO EUROLYSINE S.A.S. has been validated and can be used in formulations to allow total nitrogen levels (CP)to be reduced and N excretion to be minimised without risk to performance.


Focus5

Utilisation of free amino acids in very low crude protein diets

The data reported by Quiniou et al. (2011) and presented in Focus 4, demonstrate that the dietary level of free AA in comparison to the protein bound AA has no impact on the performance as long as the ideal AA profile is maintained. In this trial, feed grade AA supplementation was increased in the grower feed from 4.0 kg/T to 7.6 kg/T. The free Lys represented 48% of the total SID Lys content of the grower diet with the lowest CP level. As shown before, this level of supplementation had no effect on the performance of the pigs and was consistent with the provision of a balanced amino acid profile in the feed. This observation is the same for all the trials presented in Figure 23 with amount of L-Lys representing up to 60% of the dietary SID Lys content (formula and nutritional values in Table 14, final flap). Other studies have demonstrated the efficient use of free AA supplementation:

Cook et al. (1983) showed that the utilisation of free AA vs protein bound AA was not different in pigs fed three times a day.

Le Bellego et al. (2001) reported no impact of the multi-supplementation of free AA in a diet fed twice a day (vs 7 times) to growing pigs of 60 kg. The continuous flow of feed and amino acids in the gut, even with a low feeding frequency of twice per day, maintained N and energy utilization and did not affect protein gain.

Provided EAAs are controlled in a diet by minimum constraints in the formulations, there is no detrimental effect on performance of dietary protein reductions and the use of free AA.

References


n Ajinomoto Eurolysine s.a.s. 09 FR 09 Valine et reduction du taux protique chez le porc en croissance. 2009.

n Barea, R., L. Brossard, N. Le Floch, Y. Primot, D. Melchior, and J. van Milgen. 2009. The standardized ileal digestible valine-to-lysine requirement ratio is at least seventy per-cent in postweaned piglets. J. Anim. Sci. 87:935-947.

n Bikker, P. and J. Fledderus. 06 NL 01 tryptophan require-ment of growing finishing pigs: a dose response study. Schothorst Feed Research. 2008.

n Boisen, S. 2003. Ideal dietary amino acid pofiles for pigs. In: J. P. F. DMello (Ed.) Amino Acids in Animal Nutrition. pp. 157-168. CABI.

n Bourdon, D., J. Y. Dourmad, and H. Henry. Rduction des rejets azots chez le porc en croissance par la mise en oeuvre de lalimentation multiphase, associe labaissement du taux azot. Journes de la Recherche Porcine 27, 269-278. 1995.

n Burgoon, K. G., D. A. Knabe, and E. J. Gregg. 1992. Digestible tryptophan requirements of starting, growing, and finishing pigs. J. Anim. Sci.2493-2500.

n Canh, T. T., A. J. A. Aarnink, J. B. Schutte, J. D. Sutton, D. J. Langhout, and M. W. A. Verstegen. 1998. Dietary protein affects nitrogen excretion and ammonia emission from slur-ry of growing-finishing pigs. Livest. Prod. Sci. 56:181-191.

n Cook, H., G. R. Frank, D. W. Giesting, and R. A. Easter. The influence of meal frequency and lysine supplementation of a low protein diet on nitrogen retention of growing pigs. Journal of Animal Science 57 (Suppl.1), 240-241. 1983.

n Corrent, E., A. Simongiovanni, and Y. Primot. Branched-Chain amino acids nutrition in piglets. Ajinomoto Eurolysine s.a.s. Bulletin 35. 2010.

n Cromwell, G. L., M. D. Lindemann, G. R. Parker, K. M. Laurent, R. D. Coffey, H. J. Monegue, and J. R. Randolph. Low protein amino acid supplemented diets for growing-finishing pigs. Journal of Animal Science 74 [suppl.1], 174. 1996.

n Dean, D. W., L. L. Southern, B. J. Kerr, and T. D. Bidner. 2005. Isoleucine requirement of 80- to 120-kilogram barrows fed corn-soybean meal or corn-blood cell diets. J. Anim. Sci. 83:2543-2553.

n Dourmad, J. Y., Y. Henry, D. Bourdon, N. Quiniou, and D. Guillou. Effect of growth potential and dietary protein input on growth performance, carcass characteristics and nitrogen output in growing-finishing pigs. Verstegen, M. W. A., den Hartog, L. A., Kempen, G. J. M., and Metz, J. H. M. 69, 206-211. 93 A.D. Centre for Agricultural Publishing and Documentation (PUDOC), Wageningen, Netherlands. Nitrogen flow in pig production and envi-ronmental consequences: Proceedings of the First International Symposium,

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