Energy Expenditure by Broiler Chickens Fed Diets Containing Various Blends of Beef Tallow and Soybean Oil

Abstract

Replacement of dietary saturated fatty acids (SFA) by polyunsaturated fatty acids (PUFA) has been consistently shown to reduce the amount of abdominal fat in broiler chickens, but the metabolic basis for this effect is unknown. It was hypothesized that the feeding of PUFA instead of SFA would induce more heat expenditure, this effect being associated with less deposition of abdominal fat. Broiler chickens were given one of five diets in which the beef tallow component, which is rich in SFA, was replaced by increasing amounts of soybean oil, which is rich in PUFA. The variable fat content of the diets was 3% (w/w). There were neither significant nor systematic effects on weight gain and feed:gain ratio. The amount of body fat was reduced significantly (p<0.05) when about 75% of the tallow was replaced by soybean oil, but there was no further decrease after the incorporation of more soybean oil into the diet. Calculated energy expenditure, either expressed as absolute amount or percentage of intake, trended to enhance but was not significantly affected by the amount of soybean oil in the diet.