Lysine requirements of the immature dog

These studies examined the lysine requirement of the immature Beagle dog fed a purified L-amino acid diet. The immature female dog was found to require between 0.461 and 0.577% dietary lysine for optimum growth and nitrogen balance. Plasma and urinary urea were significantly increased in female dogs fed 0.461% or less dietary lysine. Maximum growth and nitrogen balance occurred in immature male dogs fed 0.577% or more lysine. Consumption of diets containing excess dietary lysine (1.73%) significantly reduced growth in both immature male and female dogs. Varying dietary lipid from 5 to 20% did not appear to alter the lysine requirement of the immature male dog. Increasing the nitrogen content of the diet from approximately 14% crude protein to 28% accentuated the symptoms of low lysine intakes. The lysine requirement of the immature dog appears to be lower than that reported for the growing pig or rat.