Week 10

Swine

Protein

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• Protein makes up 15% of total body mass
• Pig carcasses contain 45 to 55% muscle, approx 22% is protein
• 7 to 9% of the whole body (10 to 12% of the carcass) is in the form of edible protein
• No specific need for protein but pigs have specific requirements for amino acids
• There are 10 essential amino acids that must be provided in the swine diet
  • The other 12 a.a. can be synthesized by the pig provided sufficient nitrogen is present

Ideal Protein Concept

• The NRC expresses the dietary requirements for the 10 essential a.a. on the basis of the “ideal amino acid balance”
  • An ideal balance is one in which the 10 essential a.a. are provided in proportions necessary to support growth in the pig
    • i.e. reflects tissue composition of pig
• Amino acids are required for:
1. Maintenance of protein in body
2. Protein accretion in the carcass and other body tissues

Amino Acids

• Lysine is generally the 1st limiting AA
  • High concentration of Lys in muscle (7%)
  • Lys content of most feedsuffs is low
• Requirements of other amino acids are often expressed in relationship to Lys
  • Ratio of each AA to Lys approximates the ratios in whole body protein
• Excess amino acids are degraded and secreted in urine as nitrogen
• This is both a cost and an environmental concern….
• Synthetic amino acids can be fed to prevent an excess of other amino acids
  • Usually only cost-effective to supplement lysine and methionine

Amino Acids

• Traditionally, diets have been formulated based on CP
  • CP levels are established for various weights of pigs so that Lys is present in adequate amounts
• System works well for corn and SBM diets
• Formulate on Lys basis when other ingredients are used

Protein

• When expressed on a daily basis, CP and AA requirements increase with BW
• When expressed as a percent of diet, requirements decrease with increasing pig weight
  • Feed consumption increases with increasing weight

Ideal Amino Acid Pattern

Energy (calorie) : protein (lysine) ratio

• energy density = feed consumption
• Thus its important to maintain energy:protein ration to ensure amino acid deficiencies do not occur

Protein Sources

• SBM - accounts for 85% of protein
  • Especially high in Lys, Trp, & Thr
• Other plant sources - Lys content and/or palatability limit inclusion
• Animal sources
  • Excellent AA profile
  • Drying process important (ring or flash dried)
  • Spray dried porcine plasma