Assessment of the Direct, Precipitated and Friedewald Methods for Quantifying LDL and HDL Cholesterol in Broilers

Abstract

The objective was to evaluate the direct and precipitated methods for cholesterol from highdensity lipoprotein, and the direct, precipitated and Friedewald methods for cholesterol from low-density lipoprotein in broilers. Serum was obtained from thirty 36-day old fasting broilers from the Cobb 500 line; triglyceride and total cholesterol levels were determined using an enzymatic-colorimetric kit. Cholesterol, both of high and low density lipoprotein, was measured by the precipitation method and the direct method, and the estimation of the low density lipoprotein cholesterol was determined using the Friedewald formula. The mean ± standard deviation for cholesterol levels of high density lipoprotein by the direct and precipitated methods in mg/dl, were: 92.8 ± 16.7, 92.2 ± 16.3, respectively. The f-test p-value is higher than 0.05, and therefore there is no statistically significant difference, with a confidence index of 95 % between methods, and for the cholesterol levels of low density lipoprotein by the direct, precipitated and Friedewald methods, in mg/dl, they were: 51.8 ± 9.4; 21.9 ± 12.6 and 26.1 ± 12.9 respectively. The f-test p-value is less than 0.05, demonstrating a statistically significant difference, with a confidence index of 95 % between methods. It is concluded that, in broilers, high-density lipoprotein cholesterol can be quantified by means of both of the evaluated methods (direct and precipitated); however, only the direct method is recommended to calculate low density lipoprotein cholesterol, as the precipitated and Friedewald methods gave much lower results in that species.