A chick growth test for the evaluation of protein quality in cereal‐based diets

Abstract

A chick growth test of the protein efficiency ratio (PER) type has been developed in which chicks previously fed a normal starting diet containing 21 per cent protein are given, from 14 to 28 days of age, diets containing 18.5 per cent protein of which 12 per cent is provided by the test supplement and the remainder by cereals with the inclusion of a small quantity of yeast. The total protein efficiency (TPE) of the test supplement is calculated as the weight gain of the chicks divided by the total weight of the protein (supplement, cereals and yeast) eaten by the chicks. The method is flexible and the diets used allow the testing of supplements varying in crude protein content from 20 to 100 per cent. Reproducibility of results and discrimination between samples is good. The method is particularly adapted to examining the supplementary values of proteins whose inability to support satisfactory growth unaided precludes their evaluation by a normal PER procedure. Exploratory experiments to study the influence of various factors upon performance are described.