Effects of Dietary Phosphorus and Calcium Contents on the Absorption of Phosphorus in the Digestive Tract of Carp

Abstract

The absorption rate of dietary P in the digestive tract of carp was investigated by feeding them with test diets of different P or Ca contents. The dietary P content was varied from 0.64% to 0.35, 0.64, 1.23, 1.83 and 3.14% each for one week, at a fixed Ca content of 0.70%; the absorption rate was in a range of 85–91% and the amount of P absorbed showed a positive and linear relationship with the dietary P content. The dietary Ca content was varied from 0.70% to 0.10, 0.41, 0.70, 1.32 and 2.65% each for one week, at a fixed P content of 0.64%; the highest absorption rate of P (98.1%) was obtained for the 0.10% Ca diet and then the rate decreased with the increase of the dietary Ca content. A negative and linear relationship was observed between the amount of P absorbed and the dietary Ca content. In the series of diets in which the P content was varied, the plasma inorganic P concentration was significantly lowered by feeding of the 0.35% P diet and then recovered with the increase of the dietary P content. © 1982, The Japanese Society of Fisheries Science. All rights reserved.