Concept and application of ideal
protein in swine nutrition
Outline
Structure and roles of amino acids
Ideal protein
Amino acid requirements
Current areas of research
Conclusions
Lys Gly
Thr Met
Structure of amino acids
Essential Semi-essential Non-essential
Lys Cys (from Met) Arg
Met Tyr (from Phe) Ala
Thr Ser
Trp Gly
Val Pro
Ile Glu
Leu Gln
Phe Asp
His Asn
Structure of amino acids
“Some elements in proteins are essential constituents of the diet”
(William Rose, 1932)
Peptide and protein synthesis
Amino acids and proteins are required and involved in many processes
Structural proteins (e.g., myosin and actin in muscle)
Milk proteins (e.g., casein)
Functional proteins (e.g., enzymes, hormones)
Defense and protective proteins (e.g., glutathione, mucins)
Cell signaling
Nitrogen transport between tissues
Energy transport between tissues
Muscle Hair Endogenous secretions Milk
0 5 10 15 20 25 30 35
Val Trp Thr Cys Met Lys
% o f pr ot ei n
Amino acid composition of proteins
Outline
Structure and roles of amino acids
Ideal protein:
Concept
Expressing requirements
Amino acid requirements
Current areas of research
Conclusions
Law of the minimum (von Liebig, 1850)
Ideal protein (Mitchell et al., 1964)
All essential amino acids are equally limiting for performance:
no deficiency
no excess
Usually expressed relative to Lys:
Lys is typically the first-limiting amino acid in the diet
The Lys requirement (g/kg diet) changes during growth, but the requirements of other amino acids change
proportionally to Lys (assumption)
Simple to use: only 1 value for each amino acid to
remember (e.g., Thr:Lys = 65%)
nutrient intake
nutrient output
nutrient absorption
endogenous secretions
Expressing amino acid values and requirements
0 1 2 3 4 5 6 7 8 9 10 0.0
0.5 1.0 1.5 2.0 2.5 3.0 3.5
Amino acid intake, g/d
Ile al a m in o ac id f lo w , g /d
Basal
endogenous Indigestible
Specific
endogenous
Endogenous losses increase with increasing
amino acid intake
diet ileal indigestible
specific endogenous losses standardized ileal digestible
(SID)
apparent ileal digestible (AID)
basal endogenous losses
Expressing amino acid values and requirements
Basal endogenous losses are:
part of the feed value in an AID system
part of the requirement in an SID system
Lys Thr Content,
g/kg AID,
% SID,
% Content,
g/kg AID,
% SID,
%
Soybean meal 27.8 87 90 17.7 82 87
Corn 2.4 70 80 3.0 74 83
Wheat 3.1 74
81 3.2
75 83
Expressing amino acid values and requirements
Outline
Structure and roles of amino acids
Ideal protein
Amino acid requirements:
Response or requirement?
Factorial method
Model-derived methods
Current areas of research
Conclusions
60 62 64 66 68 70 72 74 76 78 80 200
250 300 350 400 450 500 550
SID Val:Lys, %
D ai ly g ai n, g /d
Requirement vs. response
products
resources
Factorial calculation of amino acid requirements
for growing pigs
diet ileal indigestible
specific endogenous losses standardized ileal digestible
minimum oxidation
(=100% - maximum efficiency)
excess deposition
basal endogenous losses maintenance
available
Factorial calculation of amino acid requirements
for growing pigs
o Growing pigs, gestating and lactating sows
o Factorial approach to determine amino acid requirements o Analysis of nutrient utilization
o Evaluation of nutritional scenarios (what if …?)
The InraPorc and NRC models are conceptually very similar, with slightly different approaches for …
Growing pigs:
basal endogenous losses
efficiency of amino acid use
variation among animals
Gestating and lactating sows:
protein pools
basal endogenous losses
efficiency of amino acid use (i.e., ideal amino acid profiles)
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
