L-carnitine (?- OH- ?- N trimethyl amino- butyrate) plays an important role in fatty acids oxidation. It's indispensable for the traort of long chain fatty acids from the cytosol into the matrix mitochondria where the ?-oxidation of these fatty acids occurs. Poultry rations contain a high amount of cereals, which have very low l-carnitine levels. The aims of this study were survey of supplemental of l-carnitine and vegetable oil on yolk cholesterol content, albumen quality and performance of laying hens. Three - hundred 24-week-old white leghorn hens Hy-Line W-36 strain were randomly divided into 12 experimental groups of 25 birds each (5 replicates of 5 birds per treatment). Experiment was carried out in a completely randomized design in factorial arrangement (3×4) of treatments, two levels of fat (0, 3%), and four levels of l-carnitine (0, 50,100,150 mg/kg diet) supplementation. A basal layer diets were formulated to be adequate in all nutrients by National Research Council (1994). During the 12 weeks of experiment (24-36 weeks-old) hens had free access to feed and water. Feed consumption was recorded at the end of each two weeks of the experimental period. Egg production, egg weight, egg mass, albumen height and haugh unit score were measured at the end of each two weeks period and egg production were recorded daily. At the end of the trial, three hens were randomly sacrificed from each treatment and killed for measuring abdominal fat content and crud fat of liver. Result of this experiment indicate that l-carnitine and fat had no significant effect on egg production (p 0.05). L-carnitine did not affect egg weight, egg mass and feed conversion (p 0.05). Three percent of fat addition increased significantly egg weight and egg mass (p 0.05) also this level of fat improved feed conversion (p 0.05). Interaction effect of l-carnitine and fat was significant and this effect indicate that 3 percent of fat and 50 ppm l-carnitine improved feed conversion (p 0.01). 50 ppm of l-carnitine and 3 percent of fat increased shell hardness (p 0.05). Albumen height and haugh unit increased by increasing levels of l-carnitine and fat (p 0.05). L-carnitine did not affect cholesterol content of egg but level of 1.5 percent of fat decreased it. Cholesterol content of yolk was decreased by increasing levels of l-carnitine (mg/kg yolk). Content of triglyceride of yolk and egg was affected by levels of l-carnitine and fat (p 0.05). Increasing levels of l-carnitine declined triglyceride of egg (p 0.05) also 3 percent level of fat caused lowest triglyceride content of the yolk and egg (p 0.05). Blood metabolites (serum triglyceride, cholesterol and HDL) were not affected by fat and l-carnitine levels. Crud fat of Liver was not affected by levels of l-carnitine but 3 percent of fat was lo
