The effects of dietary fat on growth performance, carcass composition, and feed efficiency in the broiler chick

In two experiments broiler chicks were fed nonisocaloric diets with either 0, 3, or 7% added lard. Megacaloric percentages of all major nutrients were the same in all diets. In Experiment 1 (broiler chicks 0 to 5 d of age), added dietary lard did not affect body, heart, spleen, or pancreas weight. Liver weight was suppressed by the inclusion of lard in the diet, yet liver composition changed, becoming higher in protein and lower in fat. Yolk sac weight decreased during the first 5 d posthatch, with the decrease being most pronounced by 3 d of age. There were no differences in feed consumption due to treatment in Experiment 1. In Experiment 2 (broiler chicks 6 to 11 d of age), added dietary fat resulted in differences in liver, body, and fecal excreta composition. Chicks given 7% added lard had lower liver fat throughout the trial than chicks fed no added lard. Additionally, these chicks had a higher body protein content at 6 and 7 d of age. However, body fat only increased in chicks fed 7% added lard by 11 d of age. Furthermore, chicks receiving 7% added lard had elevated fecal fat at Day 6, but did not consume more feed than chicks receiving 0 or 3% added lard. Additionally, chicks fed lard had lower liver weights than those fed 0% added lard.