The Effects of Different Dietary Fat Sources on General Performance and Carcass Fatty Acid Composition of Broiler Chickens

Two experiments were conducted to estimate the effects of adding poultry grease (PG), beef tallow (BT), and pork lard (PL) singly or in combination with rapeseed oil (RSO) to starter and finisher diets fed to 3000 broiler chickens. Neither male nor female mortality was affected by the different dietary fat sources. Diets supplemented with a combination of BT and PL resulted in reduced female body weights compared with diets supplemented with either BT or PL as single fat sources. These body weight differences were significant (P<.05) at 28 but not 48 days of age. A comparison of animal fats revealed that a combination of PG-BT-PL resulted in the best feed conversion but was not significantly (P<.05) different except when compared with diets supplemented with BT. Combining Tower RSO with each of the animal fats resulted in increased final female body weights, improved feed conversion, and monetary returns. Only small differences were observed in the fatty acid composition of the neutral lipids among dietary treatments (Experiment 2), and in each case the composition of the diet reflected the composition of the fat making up the diet. Total carcass lipids were not significantly affected by dietary treatment, indicating that an array of fat sources and combinations can be used in poultry feed formulations without significantly affecting total carcass fat or its composition. Lipid class analysis of diet and carcass lipids indicated primarily triglycerides with small amounts of polar lipids and free fatty acids and only minor differences among dietary treatments. Carcass moisture content was found to have a high negative correlation (r = —.86) with carcass lipids, suggesting that a simple and rapid estimate of carcass fat of broilers might be made by simply determining carcass moisture.