Effect of Diet on Growth and the Incidence of Tibial Dyschondroplasia in Broilers

Abstract

Two experiments were conducted to study dietary factors affecting growth rate and the incidence of tibial dyschondroplasia (TD) in broiler cockerels grown to 3 wk of age. Chicks were fed corn-soy-bean meal-based diets containing one of the following: 3,145kcal ME/kg, 24% protein, and .50% available phosphorus (aP) (Diet 1); 2,900kcal ME/kg, 20% protein, and .35% aP (Diet 2); or 2,900 kcal ME/kg, 24% protein, and .50 aP (Diet 3). In experiment 1 chicks were fed Diets 1, 2, and 3ad libitum. During weeks 1 and 2, chicks fed Diet 1 were heavier and had better feed efficiency (g feed/g gain) than those fed Diets 2 and 3. Chicks fed Diets 2 and 3 had a lower incidence of TD (P<.05) than those fed Diet 1.In experiment 2 feed intake of Diet 1 was on an ad libitum and restricted basis (Diet 1-R) and Diet 2 was on an ad libitum basis. Beginning on day 2, chicks fed Diet 1-R were offered 90% of the amount of feed consumed the previous day by chicks fed Diet 1 free choice. Chicks fed Diet 1 were heavier than those fed Diet 1-R at 1 wk, and Diets 1-R and 2 at 2 and 3 wk. Chicks fed Diet 1 had higher incidence (P<.05) of TD lesions at 3 wk than those fed Diets 1-R and 2. No differences occurred (P>.05) in the incidence of TD lesions between chicks fed Diets 1-R and 2. The incidence of leg problems appeared to be related to rate of growth, rather than being a direct effect of dietary aP or calcium:aP ratio.