Farm-scale evaluation of a fermented probiotic–rice bran formulation on pond conditions, gut bacteria, immunity, and production performance of Penaeus monodon in semi-intensive shrimp ponds

Abstract

Sustainable shrimp production depended on maintaining suitable pond environments, microbial balance, and efficient production practices. However, the effectiveness of microbial management strategies during complete production cycles under farm conditions has remained insufficiently documented because previous studies have mainly focused on laboratory experiments or short-term trials. This study investigated probiotic supplementation and a fermented probiotic–rice bran formulation in semi-intensive Penaeus monodon culture systems in coastal Bangladesh. The influence of these treatments on pond characteristics, gut bacterial populations, immune responses, growth performance, and economic returns was evaluated. The 152-day trial was conducted in nine ponds assigned to control, probiotic, and fermented probiotic–rice bran formulation groups, with three replicate ponds per treatment. The fermented formulation treatment resulted in lower sediment organic matter accumulation, higher dissolved oxygen and alkalinity, and reduced diurnal pH fluctuations compared with the other treatments. At harvest, shrimp receiving the fermented formulation showed higher presumptive Bacillus spp. and lower presumptive Vibrio spp. bacterial abundance in the gut, along with higher haemocyte count, lysozyme activity, prophenoloxidase activity, and superoxide dismutase activity. The treatment also resulted in the lowest feed conversion ratio, greatest final body weight, and highest production (6111.67 kg ha-1). Despite higher production costs, the fermented formulation generated the highest net profit and benefit–cost ratio (1.87). Overall, the fermented formulation enhanced pond conditions, gut bacterial abundance patterns, physiological responses, feed efficiency, production performance, and profitability. The findings indicated that this approach improved measured physiological responses, production performance, and farm profitability under semi-intensive coastal farming conditions.