The effect of carbohydrate source and energy‐to‐amino acid ratio on the growth of chicks given diets containing crystalline amino acids

Synopsis

In each of two experiments chicks aged 7 d were housed individually and given purified diets containing crystalline amino acids for a period of 13 or 14 d.

In the first experiment a comparison was made of four amino acid mixtures and of starch plus sucrose as a carbohydrate source. It was found that an amino acid mixture formulated on the basis of current recommendations for overall amino acid balance and for the high ME value of purified diets (diet G), gave superior growth and efficiency of food conversion. The amount of food eaten was greater with diets containing starch plus sucrose than with starch alone and as a result growth was improved. Carbohydrate source had no significant influence on the efficiency of food conversion.

In the second experiment diet G was modified by reducing the level of ME with a concomitant reduction in the level of all amino acids. The effect of modifying a comparable diet developed at the University of Illinois by lowering the ME level while keeping the level of all amino acids constant was also tested. It was found that diet G modified by the incorporation of 10% extracted sawdust gave the best growth performance and it is suggested as an amino acid reference diet. The growth rate achieved with it was 16 g/d from 7 to 14 d which surpassed that obtained with a practical broiler diet. Modification of the Illinois diet did not improve the growth performance.