Adaptive Agriculture Resilient Innovations for Sustainable C

9 Abstract Polyhydroxyalkanoates (PHAs) are biodegradable thermoplastic polymers synthesized by microorganisms as intracellular carbon and energy reserves. With their renewable origin and environmental compatibility, PHAs are considered promising candidates for sustainable feed additives in aquaculture. This study investigated the effects of dietary PHA supplementation on growth performance, feed utilization, and immune response in butter catfish (Ompok bimaculatus). Three isonitrogenous diets were formulated: a control diet without PHA and two test diets supplemented with 1% and 2% PHA-enriched microbial cells. Juvenile O. bimaculatus (initial mean weight: 0.87 ± 0.10 to 0.93 ± 0.10 g) were randomly stocked in concrete tanks (1.5 × 3 × 1.2 m) at a density of 100 fish per tank and fed to apparent satiation within a 30-minute period, twice daily, for six months. At the end of the trial, no significant differences (p > 0.05) were observed among treatments in final body weight, daily weight gain, lysozyme activity, or survival rate. However, fish fed PHA-supplemented diets showed significantly better feed utilization. The feed conversion ratio (FCR) was 1.21 ± 0.01 and 1.14 ± 0.02 in fish fed 1% and 2% PHA, respectively, compared to 1.41 ± 0.01 in the control group. Similarly, protein efficiency ratio (PER) was higher in the PHA-fed groups (2.17 ± 0.03 and 2.30 ± 0.04), while the control group recorded 1.89 ± 0.02. These findings suggest that PHA-enriched microbial cells can improve feed efficiency in O. bimaculatus, supporting their potential as functional and environmentally friendly feed additives in aquaculture. Keywords : Polyhydroxyalkanoates, Growth Performance, Feed Utilization, Immune Response, Ompok bimaculatus Effects of Dietary Polyhydroxyalkanoates Supplementation on Growth Performance, Feed Utilization and Immune Response in Butter Catfish ( Ompok bimaculatus ) Jamjun Pechsiri* ¹ , Kanokphorn Sangkharak ² ¹ Program in Modern Agriculture /Faculty of Technology and Community Development, Thaksin University, Thailand ² Program in Modern Agriculture /Faculty of Agricultural Technology, Phuket Rajabhat University, Thailand *Corresponding author’s email: jamjun@tsu.ac.th Webinar Seminar: Adaptive Agriculture: Resilient Innovations for Sustainable Change Date: 7 November 2025 | Time: 09.00 – 12.00 (Thai Time) Hosted: Faculty of Technology and Community Development, Thaksin University, Thailand