The optimum performance of birds is obtained in thermoneutral zone, and high and low environmental temperatures depress bird productivity and also affect the quality of products in laying hens exposed to high ambient temperature (35-37 °C 8h and 20-22 °C 16h). The relative albumen weight and height were significantly increased by supplementary L-carnitine (50 mg /kg) in drinking water [23]. However, L carnitine did not affect the growth performance (body weight gain, feed consumption), the laying performance (egg mass and egg weight) the shell quality (weight, thickness, and egg shape index) and the yolk quality (weight and colour score).