The effect of dietary energy level and broiler body weight on abdominal fat

Utilizing a moderate rearing temperature regimen, two trials were conducted to determine the effect of dietary energy level on the amount of abdominal fat deposited when broilers are grown to equal body weight by varying growth time. The most abdominal fat (2.29% average of live weight for male and females) was produced by broilers offered a diet calculated to contain 3325 ME kcal/kg. The least amount of abdominal fat (1.92% average of live weight for male and females) was produced by broilers offered diets calculated to contain 3100 and 3175 metabolizable energy (ME) kcal/kg. In one additional day (48 vs. 47 days) the growth of the broilers offered diets calculated to contain 3100 and 3175 ME kcal/kg equalled that of broilers offered diets calculated to contain 3250 and 3325 ME kcal/kg. Feed conversion (g feed/g live weight) significantly decreased as dietary energy level increased. Three additional trials were conducted to determine when abdominal fat is deposited in relation to age and weight. It was found that male broilers offered diets calculated to contain 3325 ME kcal/kg had as much abdominal fat when expressed as a percent of body weight at 40 days of age as they did at 53 days of age.