Loss of dietary amino acids during mastication by carp.

Abstract

Three experiments were conducted to examine dissolving (loss) of crystalline amino acids from diets into water during mastication by carp. Experiment l: The amino acid diets using agar-gel (diet 1) and CMC (diet 2) as a binder, and the casein diet with agar-gel (diet 3), containing either chromium oxide or norleucine were fed to carp. All fish were sampled 15 min after feeding. Total amount of chromium oxide or nor-leucine remaining in the digestive tract was analyzed and the rate of chromium oxide or norleucine remaining was calculated. Diet 2 group showed lower rates of chromium oxide and norleucine remaining than in diet 1 and 3 groups. Experiment 2: Feeding trial with these diets and the casein diet with CMC (diet 4) was cazried out for 6 weeks. The casein diets (diets 3 and 4) produced higher feed efficiency than diets 1 and 2. The diet 2 group showed lowest feed efficiency. Experiment 3: Diet 1 containing chromium oxide and norleucine was fed to carp, and the con-tents of the digestive tract were sampled 15 min after feeding. The samples were analyzed for the contents of chromium oxide and amino acids, and the % loss of amino acid into water was calculated. The considerable amount of amino acids ingested (except cystine and tyrosine) were dissolved from the diets into water.