Fundamentals of Small Animal Nutrition

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Fundamentals of Small Animal Nutrition

• Dr. Randy Ackman
• Protein and Amino Acid Metabolism

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Proteins and Amino Acids

• Proteins (Amino acids)
• Protein synthesis
• Supply nitrogen
• Protein is 16 N
• Animals
• Essential amino acid requirement more so than
  protein

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Proteins and Amino Acids

• Adult animals
• Protein required to replace loss from
• Hair
• Skin
• Mucosal cells
• Digestive enzymes
• Amino acids lost in catabolism

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Proteins and Amino Acids

• Young dogs
• Same protein loss as in adults
• Plus
• Growth of new tissue

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Proteins and Amino Acids

• Protein requirement
• Minimum intake of dietary protein that promotes
  optimal performance
• Nitrogen balance
• Growth rate

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Nitrogen Content

• Kjeldahl method
• Standard for nitrogen analysis
• Digestion
• Distillation
• Titration
• Used to determine nitrogen in food and excreted
  matter

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Nitrogen Content

• Nitrogen Balance
• Nitrogen balance nitrogen intake nitrogen
  excretion
• Excretion
• Urine
• Urea-end product of protein catabolism
• Feces
• Unabsorbed dietary protein
• Endogenous nitrogen

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Proteins and Amino Acids

• Zero nitrogen balance
• Normal state of healthy adult
• Daily loss is equal to intake
• No net gain or loss of total body protein
• May not be adequate to promote optimal
• Health
• Performance
• Represents minimum requirement
• Feed slightly higher for optimal health

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Proteins and Amino Acids

• Positive Protein Balance
• N intake gt N excretion
• During periods of
• Gestation
• Growth
• Recovery from illness or disease

• Negative Protein Balance
• N intake lt N excretion
• Losing nitrogen from tissue more rapidly than
  replaced
• During periods
• Severe illness
• Renal failure
• GI disease
• Decreased consumption

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Proteins and Amino Acids

• Factors affecting nitrogen balance
• Dietary factors
• Protein quality
• Amino acid composition
• Protein digestibility
• Energy density of diet
• Physiological factors
• Activity level
• Physiological state
• Nutritional status

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Proteins and Amino Acids

• Protein requirement
• Inversely related to digestibility and essential
  amino acids that are available (quality)
• Increase digestibility and quality ? decrease in
  protein requirement
• Commercial dog foods
• 80-90 premium diets
• lt70 low end diets

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Proteins and Amino Acids

• Protein Requirement
• Protein quality
• Higher biological value Less amount needed
• Commercial diets
• Mix protein sources
• Allows source for all essential amino acids

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Proteins and Amino Acids

• Protein requirements
• Presence of non-protein calories
• Either fat or CHOs
• Spares protein from being used for energy
• Diet meet energy needs first
• Weight loss and lean body tissue decrease
• Protein utilized for energy

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Protein and Amino Acids

• Protein requirement
• As energy increases
• Higher total concentration of protein needed
• Why?
• For example
• Diet One
• 25 crude protein
• 20 fat
• Diet Two
• 30 fat
• 29 crude protein

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Protein and Amino Acids

• Protein requirement
• Animals prior nutritional status
• Protein depletion
• Requires less protein to achieve nitrogen balance

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Protein and Amino Acids

• Protein requirements
• 4-7 of ME as protein
• Very high quality pet food
• Commercial diets
• Lower quality protein
• Adult
• 18 on Dry matter basis (DMB)
• Growth and reproduction
• 22 on Dry matter basis (DMB)

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Protein and Amino Acids

• Cat
• Growth and reproduction
• 30 protein on a dry matter basis
• Adult maintenance
• 26 protein on a dry matter basis

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Protein and Amino Acids

• Cat
• High protein requirement due to
• Increased needs for the maintenance of normal
  body tissue, rather that increase needs for
  growth

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Protein and Amino Acids

• Cats
• No change in gluconeogenic enzymatic activity
• Cats maintain a constant level
• No change with high protein diet
• No change with low protein diet

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Proteins and Amino Acids

• Cats
• Cat will catabolize a substantial amount of
  protein after each meal, regardless of protein
  content
• Cats are obligated to consume high protein diets
• Inability to conserve nitrogen from body
• Adhering to high protein diet, less evolutionary
  pressure

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Protein and Amino Acid

• Cats
• Do not have substantially higher essential amino
  acid requirement
• Unique amino acid requirements
• Inability to synthesize arginine for normal
  functioning of the urea cycle
• Dietary requirement of taurine

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Protein and Amino Acid

• Cat
• Arginine
• Component or urea cycle
• Ornithine precursor
• Allows large amounts of ammonia generated from
  consumption of a high protein diet to be
  converted to urea for excretion
• Low-arginine diet
• Hyperammonemia within several hours of
  consumption
• Vomiting, tetanic spasms, ataxia

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Protein and Amino Acid

• Cat
• Arginine sensitivity due to
• Inability to synthesize ornithine
• Other mammals can utilize glutamate and proline
  as precursors for ornithine
• Cats have low levels of pyrroline-5-carboxylate
  synthase and low activity of ornithine
  aminotransferase
• Inability to synthesize arginine from ornithine
  for extrahepatic tissue.

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Protein and Amino Acids

• Cats
• Require taurine
• A free amino acid
• Most animals synthesized from methionine and
  cysteine
• Important to myocardium and retina
• Ability to concentrate taurine
• 100-400X
• Dilated cardiomyopathy
• Central retinal degeneration
• Important for conjugation of bile acids

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Protein and Amino Acid

• Cats
• Taurine deficiency
• Contributing factors
• Heat processing produces Malliard products
• Reducing sugars and proteins
• Increase microbial taurine degradation and fecal
  taurine loss
• Cat diets must have higher levels of taurine in
  diet
• Taurine only present in animal tissue
• Shellfish rich in taurine

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Protein and Amino Acid

• Other amino acids
• Lysine
• Requirement increases as protein level increases
• Susceptible to processing
• Heat
• Cause cross linking of amino acids
• Malliard products
• Resistant to digestion
• Reduces availability of protein / lysine

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Protein and Amino Acids

• Methionine and cysteine
• Sulfur containing amino acids (SAA)
• Methionine is essential
• Cysteine can be synthesized from methionine
• Cats have higher SAA requirement
• Produces compound called felinine
• Synthesized from cysteine
• Excreted in urine
• Highest intact male cats
• Urine marking

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Protein and Amino Acids

• Methionine and cysteine
• High requirements in cat
• Thick hair coat
• Increased methylation reactions for the synthesis
  of phospholipids
• Breeds of dogs may differ in methionine
  requirements
• One study showed
• Labs needed higher percentage for growth

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Protein and Amino Acids

• Lysine
• Is the first limiting amino acid in cereal based
  dog foods
• Methionine
• Is the first limiting amino acid in commercial
  foods with animal tissues and plant protein
  sources

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Protein and Amino Acids

• Niacin
• Derived from tryptophan
• Cats unable to synthesize niacin from tryptophan
• Piconlinc acid carboxylase activity 30-50 times
  more than that dirves to nicotinic acid
• Figure 12-2

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Protein and Amino Acids

• Protein deficiency
• Retarded growth
• Weight loss
• Impaired reproductive and work performance
• Usually occurs with energy deficiency
• Protein/calorie malnutrition (PCM)
• Lethargy
• Decreased digestive efficiency
• Reduced resistance to infection

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Protein and Amino Acids

• Protein deficiency
• Low blood protein
• Ascites
• Edema
• Usually occurs
• Cats fed cereal based diets
• Low quality protein diets during periods of high
  protein needs

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Protein and Amino Acid

• Protein Excess dog
• Excess protein in body
• Energy source
• During zero energy balance
• Stored as fat
• Positive energy balance
• Excess protein is not stored in body as protein

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Protein and Amino Acid

• Protein excess
• No conclusive study that high protein diet leads
  nephropathy
• No need to systematically decrease protein
• Signs of renal disease
• Avoid excess protein
• High quality protein

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