ABSTRACT Lacsina Niel John G. April 2023 REDUCTION OF COLIFORM BACTERIAL GROWTH N COMPOSTED COW MANURE USING ACTIVATED LACTOBA CILLUIS BULGARICUS. Pampanga State Agricultural University. Adviser: Ruth T. Libag The use of animal manure in farm management endangers food safety and may result to foodborme illness. Farmers should adhere to post-harvest protocols, such as washing vegetables before delivery, to reduce contamination. To ensure food safety, a pre- harvest program can be used. In this study, composted animal (cow) manure commonly used in organic tarming has been treated with lactobacillus bacteria to investigate their efticacy as a re-harvest food safety risk reduction method. The number of coliform bacteria was determined in both treated with Lactobacillus bulgaricus bacteria and untreated composted cow manure. Hence, this experimental research evaluated the Lactobacillus bulgaricus against the coliform bacteria in composted cow manure. The study used Two- Group Randomized Design (TGRD) with three replications for each treatment. After composting cow manure was tested for the presence of coliform bacteria, the activated Lactobacillus bulgaricus was sprayed to the manure every week for two weeks. Then, the composted cow manure was tested for the reduction of coliform bacteria. The findings revealed that the bacterial loads in the untreated composted cow manure (Tl) are higher than the treated composted cow manure (T2). The application of Lactobacillus bulgaricus lowered bacterial loads of treated composted cow manure (T2). Further, a significant difference was observed in terms of reduction of coliform bacterial load in the treated and untreated samples. Statistical analysis shows that the efficacy of Lactobacillus bulgaricus to composted cow manure. Hence, the study could help with the proper management of animal manure in organic farming or simply composting. Keywords: Cow manure, Lactobacillus bulgaricus, Coliform bacteria, Foodborne illness.