Noi broiler chicks (one-day-old; n=256) were allotted to 4 treatments replicated four times with 16 birds in each replicate in a completely randomized design. The control treatment contained lysine at 1.0, 0.9, and 0.8% of the diet for three periods 1-28, 29-56, and 57-84 days of age respectively. The three experimental diets had additional lysine at levels of 0.1%, 0.2%, and 0.3% in each period. One male and one female bird were taken from each replicate to estimate the apparent digestibility (AND) on the last 7 days of the experiment. Ferric oxide (Fe2O3) was used as a digestibility marker based on the different concentration of Fe2 O3 in diets and feces. The birds were vaccinated against Newcastle disease and infectious bursa. They had access to fresh water and were fed ad libitum throughout the experiment. The increase in dietary lysine did not affect feed consumption, but improved bodyweight gain and feed conversion ratio. AND was increased when additional lysine was increased from 0.1% to 0.3%. The concentration of glucose, total protein, globulin, creatinine, and uric acid in blood serum samples did not differ, but albumin was increased. These findings imply that lysine in addition to recommended requirement may have beneficial effects for broilers.

Keywords: albumin, digestibility, feed conversion