SILOAM E. CRUZ, SILVINO V. REYES Hl, CARLYN N. RAMOS July 2022. PERFORMANCE OF COBB BROILER CHICKEN TREATED WITH VARYING LEVELS OF THYME AND PEPPERMINT EXTRACTS SUPPLEMENTED IN DRINKING WATER. Bachelor of Science in Agriculture major in Animal Science Pampanga State Agricultural University, PAC, Magalang, Pampanga. Adviser: JULIET L. ACOSTA, Ph.D. The objective of the study was to determine the effects of varying levels of thyme and peppermint extract supplemented in drinking water. Specifically, it aimed to determine the following: average initial weight, average final weight, average gain in weight, average daily gain (ADG), average feed consumption, average water consumption and average feed conversion ratio (FCR). The study was conducted for 35 days from May 23, 2022 to June 26, 2022 at Sitio Cabayung Sarul Maragul, San. Ildefonso, Magalang, Pampanga. A total of one hundred eighty (180) day old of Cobb broilers were used in the study which was arranged in a two (2) factorial experiment Complete Randomized Design (CRD). The birds were divided into six (6) treatments and were replicated three times with ten (10) birds per treatment. The experiment has two (2) independent variables which include Factor A is the types of Phytobiotics that were added into 1 liter of water. These extracts were Al-thyme and A2-peppermint extract. On the other hand, Factor B was the level of inclusion of the extracts: Bl-Control, B210ML, and B3-20ML, respectively. Based on the results gathered, the treatment A2B2 recorded the highest gain in weight, and A1B2 had the best Feed Conversion Ratio (FCR) among the other treatment. The group in A2B2 had an average gain in weight of 1,119.33 grams, and A1B2 the lowest FCR with an average of 1.86 to produce lkg of meat. But statistical analysis showed the supplementation of Thyme Extract and Peppermint Extract did not significantly affect all the parameters. It can be concluded that birds supplemented with varying levels of thyme and peppermint extract statistically had no significant effect on the growth performance of broilers. However, relevant to the main goal of the study is to determine the growth performance of cobb broiler chicken. The experiment revealed that at least 10ml of peppermint and thyme added to Iliter of drinking water can help the broilers during the growing to finishing stage. Based on the results it is recommended to use thyme and peppermint extract to add on drinking water during the growing and finishing stage of the roilers.