Abstract
The present study aimed to evaluate the effects of differently dietary concentrations of Lactoferrin on growth performance, specific and relative growth rates, and condition factor the common carp. The present study conducted from November 2025 to January 2026. A total 120 palm-sized common carp fish (55.18±0.45 g weight) were collected from the ponds of fish hatchery in Salah Al-Deen city. Fish were randomly to four treatments: T1 was fed a commercial pellet diet only, while T2, T3, and T4 were fed the same diet supplemented with Lactoferrin 400, 800, and 1200 mg kg⁻¹ diet, respectively. Fish were fed daily at 3% of body weight in two equal meals for 56 days. The result of this study indicated that dietary Lactoferrin can improve growth performance of the common carp, especially at LF 800, resulting in the highest final weight, weight gain, specific growth rate, and relative growth rate, while a weak improvement in performance was observed at LF 1200, suggesting a dose-dependent response. The condition factor of common carp fed diets including Lactoferrin significantly differed at end of experimental: highest value was recorded for group of fish from the groups fed with Lactoferrin at the level of 800 mg kg⁻¹ diet. Fish in this group exhibited enhances physique conditions and physiological status when compared with other treatments, whilst very low and higher levels exhibited only reasonable improvements. In conclusion, supplementation of Lactoferrin at 800 mg kg⁻¹ diet was the most effective level for enhancing growth performance and physiological condition of common carp under the conditions of this study.

Key words: Common carp, Condition factor, Feed additives, Growth performance, Lactoferrin.