Week 1

Nutrients

Proteins

Text Transcript

Time: 7.42

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• Chemical composition: amino acids (AA)
• Figure 2.6 – Chemical structure of amino acid
• Hydrogen, amine, carboxyl, and R group



• All proteins contain nitrogen
• AA and linkages determine protein properties
• Figure 2.7 – Structure of protein



• Functions
• Structure
• Movement
• Digestion
• Metabolism
• Growth
• Defense
• Synthesis
• Regulated by deoxyribonucleic acid (DNA)
• Requires specific AA
• Limiting amino acid
• Twenty AA
• Table 2.1 – Dietary essential and nonessential AA

 

Table 2.1 - Amino Acids

Essential AA	Nonessential AA
Arginine	Alanine
Histidine	Aspartic acid
Isoleucine	Citrulline
Leucine	Cystine
Lysine	Glutamic acid*
Methionine	Glycine*
Phenylalanine	Hydroxyproline
Threonine	Proline*
Tryptophan	Serine
Valine	Tyrosine
Taurine	*Additional amino acids required by chicks

 

 

 

 

 

 

 

 

 

 

 

• Essential
• Animal cannot synthesize adequate amounts; required in diet
• Nonessential
• Animal can synthesize adequate amounts; not required in diet
• Monogastrics
• Digestion – stomach and small intestine
• Mammalian enzymes and other compounds
• Absorption – small intestine
• Amino acids
• Similar AA profile consumed and absorbed
• Ruminants
• Figure 2.8 – Protein nutrition in ruminant



• Dietary protein
• Rumen inert or rumen undegradable protein (RUP) or undegradable intake protein (UIP)
• Not changed in rumen
• Digested to AA and AA absorbed in small intestine
• Rumen degradable protein (RDP) or degradable intake protein (DIP)
• Digested in rumen – microbes
• Microbial proteins
• Digested to AA and AA absorbed in small intestine
• Nonprotein nitrogen (NPN) compounds
• Metabolized in rumen – microbes
• Microbial proteins
• Digested to AA and AA absorbed in small intestine
• Microbial protein synthesis
• Substrates – nitrogen and energy
• N recycling
• Requirements
• Monogastrics
• Total protein – true protein
• Limiting amino acids – lysine, methionine, and tryptophan
• Ruminants
• Total protein – True protein and NPN compounds
• Relative amounts
• Limiting amino acids – lysine and methionine