Dietary inosine monophosphate improved growth, feed utilization, blood biochemical characteristics, and intestinal histo-morphology of slow growing golden mahseer (Tor putitora)

A 10-week long feeding trial was run to determine the effects of inosine monophosphate (IMP) as functional nutrient on growth, feed utilization, haemato-immunological characteristics, and intestinal morphology of juvenile T. putitora. Casein and fishmeal based semi-purified basal diet (control) was formulated to contain 40 % protein and 10 % lipid. Four levels of IMP nucleotide viz., 0.05 %, 0.1 %, 0.2 % and 0.4 % were added to the basal diet for diet groups IMP-0.05, IMP-0.1, IMP-0.2 and IMP-0.4, respectively. Each diet was assigned randomly to triplicate groups of fish occupying an initial average weight of 9.1 ± 0.02 g. The results indicated that dietary IMP significantly enhanced the growth performance of fish and fish fed IMP-0.05 and IMP-0.1 diets showed significantly highest values. Compared to the control, IMP-0.05 diet group showed significantly lower feed conversion ratio, while protein efficiency ratio (PER) was significantly higher in fish fed IMP-0.05 and IMP-0.1 diet groups followed by IMP-0.2 diet group. Control and IMP-0.4 groups showed significantly lower PER. Higher IMP included group (IMP-0.4) showed significantly lower feed intake value. Again, the whole-body lipid content was significantly influenced by dietary IMP inclusion among major whole-body nutrients. Significantly reduced plasma glucose, bilirubin, and alanine aminotransferase level accounted for in IMP supplemented units compared to the control. IMP supplementation also significantly improved total immunoglobulin and hematocrit content. Supplementation of IMP significantly increased and decreased peroxidase and catalase activity, respectively. Fish fed 0.05–0.15 % IMP supplemented diets showed significant improvement in fold height (hF), enterocyte height (hE) and microvillus height (hMV) of anterior intestine compared to the control. In posterior intestine, similar supplementation level of IMP (0.05–0.15 %) showed significant improvement in hE and hMV, while hF showed numerically higher values except in fish fed IMP-0.05 diet group. Based on the current experimental conditions, a dietary IMP of 0.05 % resulted in improved outcomes in the majority of the fish growth and health performance indicators. However, quadratic regression analysis of all the significantly influenced fish performance parameters disclosed that the optimal level of dietary IMP was 0.17 % and this is also consistent with the majority of fish growth and health performance measures.