Effect of Dietary Energy, Environmental Temperature, and Sex of Market Broilers on Lipoprotein Composition

Broiler chicks were fed starter diets (days 1 to 28) containing 3.09, 3.20, or 3.31 kcal ME/g, grower diets (days 29 to 43) containing 3.14, 3.25, or 3.36 kcal ME/g, and then finisher diets (days 44 to 49) containing 3.20, 3.31, or 3.42 kcal ME/g, respectively. For each dietary treatment there were two replicate floor pens containing 78 male and 78 female chicks in a cool environment and two replicate pens in a warmer environment. Blood samples were obtained from one male per pen on days 42 and 44 and from one female per pen on days 43 and 45. Plasma lipoproteins were separated into d<1.006 and d>1.006 fractions by ultracentrifugation. Total lipids extract (TLE), neutral lipids (NL), phospholipids (PL), free fatty acids (FFA), and triglycerides (TG) were determined. Females had higher TLE, NL, PL, and TG and lower FFA levels in the d<1.006 fraction. In the d>1.006 fraction females had higher TLE, PL, and TG and lower FFA levels. Both males and females had lower FFA levels in the d>1.006 fraction in the warmer environment TLE and TG levels were significantly elevated in females fed the highest energy level. No other dietary effects were observed.