EFFECTS OF DIFFERENT DIETARY-FAT SOURCES ON PERFORMANCE AND CARCASS CHARACTERISTICS OF BROILERS

The effects of four different dietary fat sources on the performance, carcass characteristics, meat quality and fatty acid composition of ab dominal fat of broilers were evaluated. As fat sources, a commercial a nimal/vegetable fat blend (Group 1), soybean oil (Group 2), rapeseed o il (Group 3) and a processed fat product (Group 4) were used. A total of 1300 one-day-old broiler chicks was assigned to 20 litter pens. Eac h dietary treatment consisted of five replicates (5 pens), The chicks were fed corn-soy-based all mash diets which contained 3.5% of the res pective fat source for 43 days. The broilers which were fed the vegeta ble oils (Groups 2 and 3) performed better than those in Groups 1 and 4. Group 4 also excreted a higher amount of fat because of the decreas ed metabolizability of the saturated long-chain fatty-acids. The fatty acid composition of the fat excreted in the droppings confirmed that the saturated long-chain fatty-acids cannot be metabolized by young br oiler chickens. The proportion of legs, breast meat and abdominal fat was not affected by the dietary treatment. There were no significant d ifferences between the groups in dry matter, protein, and fat content of the thigh meat, or in organoleptic traits of the breast meat. The c omposition of the abdominal fat was typically influenced by the dietar y fat source: the content of polyunsaturated fatty acids was significa ntly elevated in Group 2. Group 3 contained more oleic acid than any o f the other groups, and in the abdominal fat of the broilers of Group 4 significantly higher contents of myristic acid, palmitic acid, palmi toleic acid, and behenic acid were found. It was concluded that the gr owth performance of broilers can be improved by incorporation of polyu nsaturated fatty acids at levels higher than generally recommended wit hout negative effects on quantitative carcass characteristics. However , the feeding of fats with a high percentage of saturated long-chain f atty-acids has a significant positive influence on the composition and the consistency of broilers' adipose tissue. (C) 1997 Elsevier Scienc e B.V.