The influence of type and level of dietary fat upon fatty acid composition in the adipose tissue of broiler chickens

Abstract

This investigation studied the effects of different levels and types of commercially available dietary fat supplements upon fatty acid composition in the adipose tissue of broiler chickens. Dietary fat supplements are used in the broiler chicken industry as an economical means of improving performance (Griffiths et al., 1977). Equal numbers of male and female Ross 1 broiler chickens were fed from birth on one of four alternative fat additives of widely differing fatty acid composition which were incorporated at 5% or 2.5% levels (diets A-D and E-H respectively) into the same approximately isocaloric diets. Details of dietary supplements, carcass processing, lipid extraction procedures and statistical procedures are given in an earlier report (Khan et al., 1986). After a modified Folch et al. (1957) extraction upon 0.4 g of adipose tissue, the lipid samples collected were used to prepare FAMES for gas chromatographic analysis by refluxing for 45 min at 70°C with methanolic sulphuric acid. After washing with NaCl and then NaHCO, solutions, the methyl esters were extracted with hexane, which was then removed at 50°C under a nitrogen stream. Analysis was performed with a Pye-Unicam PU 4500 gas chromatograph using a 2 m glass column filled with EGSS-X. FAMES were identified from retention times in comparison with standards (Sigma Co.) and quantified using a Pye-Unicam CDP1 integrator. The results show that dietary treatments (tested mutually by Kruskal-Wallis analysis of variance) significantly affected most adipose tissue fatty acids. These differences substantially reflect dietary supplement fatty acid composition which will be detailed elsewhere. In contrast, sex had no statistically significant effect upon fatty acid composition. The data presented here provide evidence that by feeding broiler chickens with suitable commercially available dietary fat supplements it is feasible to substantially influence the ratio of polyunsaturated to saturated fatty acids in chicken meat consumed by human beings.