Measurement of lipids in chicken carcass dry matter

Three procedures were used to measure the lipid fraction of chicken carcass dry matter. The resulting data were evaluated by calculating carcass residuals (carcass dry matter-protein-ash-lipid) and by application of multiple linear regression to estimate the energy values of carcass fat and protein. Petroleum ether extraction led to carcass residuals of about 5% and an estimated energy value of protein that was larger than previous estimates. Chloroform:methanol (2:1) extraction gave a negative residual (-6.5%) and a very low predicted energy value for protein. However, when the chloroform:methanol extract was corrected for crude protein content, the residual was approximately 1.0% of the dry matter, and the energy estimates were similar to those obtained previously. The importance of conducting analytical analyses in duplicate is illustrated.