Plasma lipoprotein concentration as an indicator of fatness in broilers: effect of age and diet

1. The relationships between plasma very low density lipoprotein (VLDL) plus low density lipoprotein (LDL) triglyceride concentrations at 3 and 7 weeks of age and body fat content at 7 weeks were studied in male and female broiler grandparent stock fed on diets containing about 25 or 90 g fat/kg. 2. Plasma VLDL plus LDL triglyceride concentrations were similar in males and females and only slightly higher in birds fed on the high-fat diet. Concentrations at 3 weeks were similar to those at 7 weeks. 3. Body fat content was correlated more closely with plasma VLDL plus LDL triglyceride measured at 7 weeks than at 3 weeks. 4. Phenotypic correlations between body fat content and plasma VLDL plus LDL triglyceride concentrations at 7 weeks were 0.47 and 0.43 for males and females respectively fed on the high-fat diet and 0.70 and 0.60 for males and females fed on the low-fat diet. 5. Phenotypic correlations between body fat content and measurements with an abdominal caliper were 0.35 and 0.49 in birds fed on the high- and low-fat diets respectively. 6. A possible procedure for selecting for leanness in broiler breeding programmes on the basis of measurements of plasma VLDL plus LDL triglycerides is discussed.