A. Ashayerizadeh, M. Chaji, M. Mamouei, M. Baghaei, M. Eslami, Effects of Avilamycin, FormycinGold and FYTO-MIX on Serum Lipid Concentrations of Young Broilers, Journal of Animal and Veterinary Advances, Volume 9,Issue 1, 2010, Pages 108-111, ISSN 1680-5593, javaa.2010.108.111, (https://makhillpublications.co/view-article.php?doi=javaa.2010.108.111) Abstract: This experiment was conducted for comparison the effect of some feed growth promoter additives on serum lipid concentrations of 21 days old broiler chickens. Based a randomized completely design, 300 days old Ross 308 broilers were distributed into 20 floor pens and reared for 21 days. A basal diet was formulated according to NRC recommendations for starter (1-21 days) period. The basal diet was also supplemented with antibiotic (Avilamycin), a commercial composition (FormycinGold), herbal additive (FYTO-MIX) and mixture of FormycinGold plus FYTO-MIX, resulting 5 dietary treatments were prepared including control group. Each dietary treatment was fed ad-libitum to 4 replicates group of 15 birds at the beginning of rearing period. Serum cholesterol and Low Density Lipoprotein (LDL) levels of broiler were fed FYTO-MIX and FormycinGold plus FYTO-MIX was significantly lower than control group (p<0.05). The higher High Density Lipoprotein (HDL) concentration was recorded for birds fed diet supplemented with FormycinGold, FYTO-MIX and FormycinGold plus FYTO-MIX. None of the treatments had significant effect on triglycerides and Very Low Density Lipoprotein (VLDL) levels. Keywords: HDL;cholesterol;herbal additive;avilamycin;Broiler;LDL