Dietary propylene glycol mitigates cold stress and improves physio-metabolic responses in Pangasianodon hypophthalmus (Sauvage, 1878) fingerlings reared at low temperature.

A 60-day feeding trial was carried out to determine the effect of propylene glycol (PG) on feed intake and growth in Pangasianodon hypophthalmus (striped catfish) reared at low temperature (18.0 ± 1.0 °C) re-circulatory aquaculture system (RAS) with a flow rate of 1.6 L min. Six isonitrogenous (370.0 g kg) and isocaloric (17.22 MJ kg dietary energy) practical diets were designed and prepared with varying levels of PG, viz., control (0 ml kg PG), T (2.5 ml kg PG), T (5.0 ml kg PG), T (7.5 ml kg PG), T (10.0 ml kg PG), and T (12.5 ml kg PG) diet. Fish were fed twice daily till satiation. The result showed that dietary supplementation of propylene glycol showed significantly higher feed intake in the treatment groups than in control (p < 0.05). The highest feed intake, growth rate, and feed conversion were observed in T group (p < 0.05). However, these did not vary within T, T, and T fed groups (p < 0.05). The highest protease and amylase activities were found in fish fed with 10.0 and 10.0-12.5 ml kg PG fed group (p < 0.05). However, lipase activity showed an increasing trend with the PG supplementation (p < 0.05). Metabolic enzymes and oxidative stress enzymes activities were highest in T group fed with 10.0 ml kg PG. Serum total protein and albumin were also increased with PG supplementation and exhibited maximum values at 10.0 ml kg PG supplementation. These findings suggest that dietary supplementation with propylene glycol at a dose of 7.5-10.0 ml kg can improve feed intake, growth, feed conversion, and metabolic activities in P. hypophthalmus fingerlings raised at low temperature.