Growth Performance and Duodenal Morphometry of 1-6 Week Old Kampung Chickens Supplemented With L-Leucine

This study evaluated the effects of dietary L-leucine supplementation on growth performance and duodenal morphometry of Kampung chickens during the starter phase (1–6 weeks). A total of 600 one-week-old Kampung chickens were randomly assigned to five dietary treatments with six replicates of 20 birds each in a completely randomized design. The treatments consisted of a basal diet without L-leucine (T0) and diets supplemented with 0.50% (T1), 0.75% (T2), 1.00% (T3), and 1.25% (T4) L-leucine, selected to evaluate a graded range of leucine supplementation in relation to growth performance and intestinal development. Growth parameters (body weight, body weight gain, feed intake, and feed conversion ratio), carcass traits, and duodenal morphometry (villus height, villus width, and crypt depth) were measured. Data were analyzed using analysis of variance followed by Duncan’s multiple range test. Dietary L-leucine supplementation significantly affected body weight, body weight gain, feed conversion ratio, carcass traits, and duodenal morphometry (P<0.01). Chickens receiving 1.00% L-leucine showed the best growth performance, characterized by higher body weight and weight gain, improved feed conversion ratio, and greater carcass yield compared with other treatments. This treatment also resulted in the highest villus height, villus width, and crypt depth in the duodenum, indicating enhanced intestinal development. These findings suggest that dietary supplementation with 1.00% L-leucine may improve growth performance and intestinal development of Kampung chickens during the starter phase and may provide useful information for optimizing feed formulation strategies in local chicken production systems.