Experimental birds, housing, and management A total of 160 day-old broiler chicks (Cobb 500)was procured from a local hatchery to conduct a 35d feeding trial in battery cages. The chicks were weighed on receipt, equalized, and then randomly assigned into four dietary treatment groups i.e. D0, D1, D2, and D3, where each treatment was replicated 5 times with 8 birds per replicate in a completely randomized design (CRD). Chicks were allotted into 16 pens of equal size that were furnished with a feeder and a drinker. All the birds had free access to the diet, along with adlibitum fresh, clean drinking water during the entire trial period. The birds were exposed to a continuous lighting program. All the birds were vaccinated against Ranikhet (New Castle Disease) and Gumboro diseases. Diet formulation- Four different test diets (D0, D1, D2, and D3) were formulated with locally available plant-sourced ingredients to meet or exceed the requirements of the National Research Council. The control diet (D0) was formulated with all the feedstuffs except for L-Met, whereas D1, D2, and D3 test diets were prepared with the supplementation of L-Met at the rate of 0.30 %, 0.35%, and 0.40%, w/w of the diet, respectively. All the test diets were iso-energetic and iso-nitrogenous and were supplemented with multi-enzymes (Natuzyme®, Bioproton Pty Ltd., Sunnybank, Australia) according to the level stated by the manufacturing company. Chicks were fed starter diet in crumble form up to 2 weeks of age as an adjustment period, after that formulated diets were used in mash form up to 35d of age, Data and sample collection- Mortality of the bird was recorded as it occurred, while body weight and feed intake were recorded weekly for the calculation of body weight gain, and feed conversion ratio (FCR). Livability was calculated from the mortality of birds per replicate cage. Two birds per pen were selected randomly, weighed, and killed humanely on day 35 to record the relative weight of gastro-intestinal organs (liver, pancreas, heart, small intestine, proventriculus, gizzard, spleen) for assessing the gastro-intestinal development of the bird. Meat yield traits were also collected to appraise the proportionate of different meat cuts of the body (dressing %, breast weight, thigh, drumstick, shank, neck, wing, and abdominal fat). Feed samples were also collected prior and posted to supplying to the birds to assess the nutritive value of the feeds. Lastly, all the prices of input supplies say feed cost, chick cost, labour, medication, vaccination, and another cost, etc., were also recorded to assess the profitability of raising broiler chicken. Sample processing and analyses-Feed sample- After collection, the feed samples were processed by grinding with the help of mortar and pestle and then mixed thoroughly for lab analyses. About 500gm of each diet of the finisher, as well as starter diet, were taken and sent to the laboratory for the proximate analysis of dry matter (DM %), moisture %, crude protein (CP %), crude fiber (CF %), ether extract (EE%) and ash using standard laboratory procedure. Dry matter was determined by the oven-dry method. Crude protein was recovered by Kjeldahl process. Ether Extract was quantified by Soxhlet apparatus. Ash was measured by igniting the pre-ashing sample on a Muffle furnace at a temperature of 600°C for four to six hours. Additionally, calcium (Ca %) and phosphorus (P %) were determined by atomic absorption and spectrophotometry, respectively. Statistical analyses- All collected data were subjected to analysis by one-way ANOVA using Minitab software. The significance of differences between means was tested using Duncan’s multiple range test (DMRT). Statistical significance was considered at p≤0.05.