Lactoferrin (LF) is a multi-functional glycoprotein with molecular weight of 80 KD. In this research, Pangasius sanitwongsei , with initial weight of 16 g were fed for 8 weeks with diet containing Lactoferrin at a rate of 0, 100, 200 and 400 mg per kg of food. The experiment was conducted in a completely randomized design with three replications. At endop the experiment, growth, hematology, some blood biochemical characteristics, iron levels in muscle and liver, intestinal histology, bacterial population of the gastrointestinal tract and the stress of anesthesia with propofol were evaluated. The results of growth indices showed no significant difference in different treatments (p 0.05), Only condition factor showed significant differences by increasing lactoferrin in the diet (p 0.05). Also, viscera index in treatments containing lactoferrin significantly reduced compared to the control treatment (p 0.05). Blood hemoglobin level increased by increasing the amount of lactoferrin in the diet but did not show any significant difference with the control group (p 0.05). Likewise, the total red blood cell counts, hematocrit and white blood cells counts showed no significant differences (p 0.05). Some of secondary hematological indices sach as ratio of white blood cells to red blood cells and Mean Corpuscular Hemoglobin concentration, did not show any significant difference compared to control treatment (p 0.05) But Mean Corpuscular Volume was significantly decreased compared to the control treatment and the mean cell hemoglobin concentration, showed a significant increase compared in control group than 400 treatment (p 0.05). Total protein, albumin, globulin levels showed no significant difference among treatments (p 0.05).The lowest Plasma iron levels were observed in 100 and 200 treatments has significant differences to the control group (p 0. 05).In treatments recieving Lactoferin, total iron-binding capacity showed a significant increase compared to control (p 0. 05). Iron levels in the liver and muscle tissues showed no significant differences among treatments (p 0.05). Total bacteria and lactobacilli populations, showed significant differences among the groups in according to lactoferrin concentrations (p 0. 05), while the lowest total bacterial counts and the highest level of lactobacillus bacteria were found in the fish fed on the diet contain 100 and 400 mg/kg LF respectively. Maximum Intestinal folding was observed at 100 treatments which has a significant difference with other treatments (p 0.05).The induction time for anesthesia was in creased in a dose dependent manner of lactoferrin. The recovery time showed significant difference among the groups in according to lactoferrin concentration (p 0. 05). The results indicated that the level of 200 and 400 mg lactoferrin had positive impacts on some physiological indices and it could recommended as a feeding additive in the catfish diets. Keywords : Growth, Hematology, Iron, Microbial flora, Stress, Lactoferrin
