DIETARY CRUDE PROTEIN INCREASES SLIGHTLY THE REQUIREMENT FOR THREONINE IN KITTENS

Previous work indicates that the essential amino acid requirements for kittens are not positively correlated with the concentration of dieta ry nitrogen as they are in other species. In the studies presented her e, the interaction between graded levels of threonine and dietary crud e protein was investigated. Dose-response curves were generated using six 4 x 4 Latin squares. Each square represented one concentration of threonine (4.0, 5.0, 6.0, 7.0, 9.0 or 12.0 g/kg diet) and four concent rations of crude protein (150, 200, 300 and 500 g/kg diet). Food intak e, weight gain, nitrogen retention and plasma amino acids were measure d. There was no strong positive relationship between the threonine req uirement of kittens and dietary crude protein, Increasing crude protei n when threonine was limiting in the diet increased growth and food in take under some conditions, whereas under other conditions food intake and growth were decreased in a manner consistent with an amino acid i mbalance response. An additional experiment was done to verify some of these findings. The requirement for threonine was found to increase f rom 5.0 g/kg diet at 150 and 200 g crude protein/kg diet to 6.0 g/kg d iet when crude protein was 300 or 500 g/kg diet. The requirement for c rude protein in the kitten appears to be between 200 and 300 g/kg diet .