Rachitogenic Activity of Isolated Soy Protein for Chicks

Abstract

Influence of isolated soybean protein on bone calcification in chicks and the modifying effect of certain dietary substitutions were investigated. Chicks fed a diet containing 40% isolated soybean protein and levels of calcium, phosphorus and vitamin D3 higher than National Research Council recommendations had reduced bone ash. Supplementation with soybean meal, autoclaving the isolated soybean protein or reducing the level of soy protein improved bone ash. Tibia uptake of 45Ca or 32P was generally increased by soybean meal supplementation but individual variation in uptake was great. A water extract of soybean meal significantly stimulated growth but did not change bone ash. Absorption of 45Ca by intestinal loops of fasted chicks previously fed isolated soy protein was no less than that of chicks previously fed casein-gelatin diets.