Modeling nutrient utilization in pigs
Symposium on Inheritance, History, and Innovation in Animal Nutrition and Feed Science Sichuan Agricultural University, June 26-28, 2016
Outline
Variation in energy utilization and energy values
Mechanistic (nutritional) modeling of growth
Concepts
Efficiency of nutrient utilization
Model-derived amino acid requirements
Dealing with variation among animals
Conclusions
Sauvant et al., 2004
0 5 10 15 20 25 3035 40
GE (kJ/g DM) 45
GE values of feed ingredients
0 5 10 15 20 25 30 35
Energy value (kJ/g) 40
GE values of nutrients
Lys Met Cys Thr Trp Ile Leu Val Phe Tyr His Arg Ser Gly Ala Glu Gln Pro Asp Asn
0 5 10 15 20 25 30 35
Energy value (kJ/g)
GE values of amino acids
10 15 20 25 30 35 40 60
70 80 90 100
NDF (%)
Energy digestibility (%)
growing pigs: 0.90
Le Goff and Noblet, 2001
Effect of fiber on energy digestibility
10 15 20 25 30 35 40 60
70 80 90 100
NDF (%)
Energy digestibility (%)
growing pigs: 0.90
sows: 0.64
Effect of fiber on energy digestibility
Le Goff and Noblet, 2001
0 10 20 30 40 50 60 70 80 90 100 0.80
0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00
crude protein (% in DM)
ME/DE
Sauvant et al., 2004
The ME value of protein depends on its utilization
deposited protein digestible
protein
excess protein
carbon chain urea
2 NH3 + CO2 + 4 ATP → urea (22.6 kJ/g N)
The ME value of protein depends on its utilization
Lys Met Cys Thr Trp Ile Leu Val Phe Tyr His Arg Ser Gly Ala Glu Gln Pro Asp Asn
0 5 10 15 20 25 30
35 urea carbon chain
Energy value (kJ/g)
The ME value of protein depends on its utilization
nutrient intake nutient deposition
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
protein lipid carbohydrate fiber ash
Rate, kg DM/d
The transformation of dry matter into a pig
Nutritional modeling of growth
protein deposition
water deposition ash
deposition lipid
deposition
body weight gain
nutrient intake
Concepts used in nutritional growth models
0 50 100 150 200 250 300 350 400 450 500 0
20 40 60 80 100 120
Protein intake, g/d
Protein deposition, g/d
Whittemore and Fawcett, 1974
upper limit to protein deposition
(PDmax)
gross efficiency of protein utilization
Protein deposition depends on protein intake
0 5 10 15 20 25 30 35 40 45 50 0
20 40 60 80 100 120
DE intake, MJ/d
Protein deposition, g/d
Whittemore and Fawcett, 1974
Protein deposition also depends on energy intake
upper limit to protein deposition
(PDmax)
~ minimum LD/PD ratio
Key concepts
Growth is mainly determined by PD and LD
Upper limit to PD
Energy partitioning rule (between PD and LD)
Protein quality affects PD
These (can) change during growth
lipid
protein starch sugars fiber
intermediary metabolism
deposited
lipid ATP
deposited protein
heat
The transformation of organic matter into a pig
theoretical experimental
starch lipid 0.84 0.84
lipid lipid 0.97 0.88
protein lipid 0.67* 0.52
protein protein 0.87* 0.60
*no protein turnover
The energy efficiency of nutrient transformation
van Milgen, 2002
van Milgen, 2002
60 70 80 90 100 110 120
kJ ME / ATP
Energy cost of ATP synthesis
glucose
intermediary metabolism
ATP
lipid glycogen
non-essential amino acids
~74.2 kJ/ATP
Energy cost of ATP synthesis
direct 74.2 kJ/ATP = 100%
via glycogen (muscle) 97%
via glycogen (liver) 95%
via glutamate (amino acid) 95%
via glutamate (protein) 82%
via lipid 80%
Energy cost of ATP synthesis
(essential) amino acids
protein synthesis
5 ATP degradation
0 ATP glucose or
acetylCoA
energy cost
amino acid “loss”
Energy cost of protein deposition
protein turnover
cycles* energy efficiency
0 0.87
1 0.78
2 0.70
3 0.64
*5 ATP/cycle
glucose as energy source (74 kJ/ATP)
Energy cost of protein deposition
Halas et al., 2004
Towards a more mechanistic approach
Creating simplicity in complexity
www.rennes.inra.fr/inraporc/
diet ileal indigestible
specific endogenous losses standardized ileal digestible
minimum catabolism
(=100% - maximum efficiency)
excess deposition
basal endogenous losses maintenance
available
Factorial calculation of amino acid requirements
for growing pigs
Item Value
Body weight, kg 50
DM intake, kg/d 2
Protein deposition, g/d 150 Lys content in body protein, % 6.96 Minimum catabolism of Lys, % 28 Maintenance Lys requirement,
mg/(kg BW0.75)/d 28.4
Basal endogenous losses,
mg/kg DM intake 313
0 2 4 6 8 10 12 14 16 18
deposition
minimum oxidation maintenance
basal endogenous losses
SID Lys requirement, g/d
Factorial calculation of amino acid requirements
for growing pigs
Protein deposition and feed intake vary differently during growth
0 20 40 60 80 100 120 140 160
0 500 1000 1500 2000 2500 3000 3500
0 20 40 60 80 100 120 140 160
Body weight, kg
Feed intake, g/d Protein deposition, g/d
Amino acid requirement ~ protein deposition feed intake
The bottom line:
We have to construct these curves!
Lysine utilization according to InraPorc
The InraPorc and NRC models for growing pigs
Conceptually very similar, but different approaches towards:
basal endogenous losses
efficiency of amino acid use
variation among animals
Does it matter?
Model-derived Lys requirements for growing pigs
20 40 60 80 100 120 140
0 1 2 3 4 5 6 7 8 9 10
InraPorc NRC
Body weight, kg
SID Lys requirement, g/kg diet
Model-derived SID Thr:Lys requirements for growing pigs
20 40 60 80 100 120 140
56 58 60 62 64 66 68 70
InraPorc NRC
Body weight, kg
SID Thr:Lys requirement, %
Amino acid InraPorc NRC
Met 30 29
Met + Cys 60 58
Thr 65 (64-65) 64 (61-68)
Trp 18 18
Val 70 66 (65-68)
Ile 55 53
Leu 100 101
Phe 50 61
Phe + Tyr 95 95
His 32 34
Arg 42 46
Average ideal amino acid profile for growing pigs
70 80 90 100 110 120 130 140 0.3
0.5 0.7 0.9 1.1 1.3
Age, d
Lys requirement, %
Dealing with variation among pigs:
which pig in the population do you want to feed?
1850 1980
real-time monitoring
precision livestock farming?
2010
nutrition as “art”
modeling &
computing characterization
nutrient discoveries
1950
The future?
Acknowledgements:
Ludovic BROSSARD1 Jean-Yves DOURMAD1
Kees DE LANGE2 Serge DUBOIS1 Michel ÉTIENNE1
Jean NOBLET1 Bernard SÈVE1 Alain VALANCOGNE1
1INRA-Agrocampus Ouest
2University of Guelph
