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Purina Veterinary Diets® Technical Bulletin
Discrepancy between use of lean body mass or
nitrogen balance to determine protein requirements
for adult cats
Dorothy P. LaFlamme, Steven S Hannah
Journal of Feline Medicine and Surgery, January 2013
Inadequate Protein in Cats
Inadequate protein intake can result in a loss of lean body mass (LBM) and leave the cat in a
compromised state.1,2 Traditionally, minimum protein requirements have been set by measuring
the minimum amount of protein needed to maintain nitrogen balance. Nitrogen balance is
defined as having nitrogen intake equal nitrogen losses (mainly in urine and feces). The question
has arisen whether nitrogen balance is an adequate measurement of protein requirements or
whether measurement of lean body mass is a better option.
Protein turnover refers to the continual
catabolism and synthesis of endogenous
protein.3 This process adapts to the
availability of amino acids from the diet
as well as from the LBM including muscle,
skin and other tissues.2 The amount of amino
acids involved daily in protein turnover is
5 – 10 X the amount consumed in the diet.4
Protein turnover allows the body to create
proteins as they are needed to help support
the immune system and metabolism.
Protein Turnover
Catabolism
Dietary Protein
Amino Acid Pool
Body Protein
Energy
LEAN BODY
MASS
Enzymes
Insulin
Immunoglobulins
Etc.
Synthesis
Study Design
•20 MN (male neutered) adult cats (4-8 years) were randomly assigned one of three different diets.
•Initially, all cats were fed a baseline (34% Protein) diet for 1 month, followed by either a 20%
(5.7g/100kcal ME), 26% (7.3g/100kcal ME) or 34% (9.5g/100kcal ME) protein diet for 2 months.
•The attending veterinarian and veterinary technicians assigned to the study were blinded to the specific dietary treatments.
At the beginning and end of the study:
i) Urine and feces were collected over a 96 hour period for each cat for a nitrogen balance assessment.
ii)DEXA (Dual Energy X-ray absorptiometry) scans were performed on all cats to assess LBM.
Results
>All
cats completing the study were able to maintain nitrogen balance.
analysis of the data shows that a daily protein intake of 1.5 g protein/kg of body weight
should be sufficient to maintain nitrogen balance.
>A mean intake of 5.2g protein/kg of body weight was needed to maintain LBM.
>Regression
Conclusion
Nitrogen Balance Studies have significant limitations when determining protein requirements.
Cats on low protein diets can maintain nitrogen balance despite losing LBM.
n A typical healthy adult cat, that consumes 50 – 60 kcal/kg body weight per day, should have
30 – 40% of the calories in its diet coming from protein.
n
n
All Purina Veterinary Diets® essential care feline products have been designed with high protein
levels to meet the unique dietary needs of cats.
TM
References:
1 Wolfe RR. The underappreciated role of muscle in health and disease. Am J Clin Nutr. 2006;84:475-482
2 Wolfe RR. The role of dietary protein in optimizing muscle mass, function and health outcome in older individuals. Brit J Nutr. 2012; 108:S88-S93
3 Waterlow JC. Protein Turnover. CAB International Publishing, Oxfordshire, UK, 2006
4 Swick RW, Benevenga NJ. Labile protein reserves and protein turnover. J Dairy Sci. 1976; 60:505-15
To learn more, ask your Territory Manager about the “Benefits of Protein in Feline Nutrition – Question &
Answer Sheet”, visit www.PurinaVeterinaryDiets.ca or call 1-866-884-VETS(8387), 8:30 am to 4:30 pm EST.
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