Protease supplementations of corn-based and wheat-based diets for layer chickens (Gallus gallus domesticus L.) during the second six months of egg production

Two experiments were conducted to determine the effect of protease supplementation of corn-based and wheat-based diets on nutrient digestibility and performance of layers during the second six months of egg production. In each trial, 80 fifty-week-old individually caged layers were randomly distributed to four dietary treatments following a Complete Randomized Design (CRD). Each treatment was replicated 20 times with a caged layer replicate. The treatments consisted of control diet, reduced CP [crude protein] diet, reduced CP diet +0.075% acid protease and reduced CP diet +0.10% acid protease to be fed for five months. In corn-based diets (study 1), the aCOD [coefficient of digestibility] of nutrients except NFE [nitrogen free extract] was not significantly affected by the reduction of CP or supplementation of reduced CP diet with protease relative to the control diet. Reduction in CP of the diet significantly (P 0.05) decreased shell thickness relative to the control diet but had slight effect on egg weight, feed efficiency, feed consumption and body weight loss. Supplementation of reduced CP layer diet with 0.10% acid protease significantly (P 0.05) increased egg production but if minimal effect on egg weight, feed consumption, shell thickness, yolk color index and body weight loss. In wheat-based diets (study 2), the aCOD of nutrients except NFE, was not significantly affected by the reduction of CP or supplementation of reduced CP layer diet with protease. Reduction in CP of diet significantly (P 0.05) depressed egg weight, egg production and feed efficiency. Supplementations of reduced CP diet with 0.075 or 0.10% protease did not significantly (P 0.05) affect egg production, egg weight and yolk color index. For both studies, neither the reduction of CP nor the supplementation of reduced CP corn and wheat-based diets with protease increased IOFC [income over feed cost].