Nanayakkara, K.G.M.D.2021-03-192021-03-192012UWU/ANS/08/0050http://www.erepo.lib.uwu.ac.lk/bitstream/handle/123456789/6148/UWULD%20ANS%2008%200050-09042019093534.pdf?sequence=1&isAllowed=yAn experiment was conducted for comparative study on the performance of commercial broiler chickens feed ration with DL — methionine and with herbal methionine. Because methionine is an indispensable amino acid, must be supplied in the diet of the chicken. Methionine deficiency leads to poor Feed Conversion Ratio (FCR), retarded growth, in chickens. However recently the use of synthetic methionine has been questioned and their use is becoming restricted. A day old, 630 Hubbard Flex chicks were randomly divided into three experimental groups, comprising three replicates. Each replicates was consisted of 70 birds. The birds were fed basal diet without methionine supplementation (To), diet with DL- methionine (T1) and diet with herbal methionine(T2). Broiler starter was given from 1st day to 28th day and broiler finisher was given 28th day to 35th day of experiment. Weekly, body weight gain, FCR and feed intake was measured. Superior performance (p<0.05) in body weight gain and lower FCR were found in herbal methionine supplemented group compare to other groups. Feed intake was not shown significance difference among each treatment groups. According to the above results this was evident that for optimum growth and FCR, herbal methionine can be used more efficiently than synthetic methionine in broilers. So it can be concluded that herbal methionine supplied feed can more efficiently replace synthetic DL- methionine supplied feed with sustained and higher level of activity. Key words: Performance, herbal methionine, DL- methionine, broiler, FCR, weight gain and feed intake.enAnimal Science Degree ProgrammeThesis