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A 2 × 2 × 2 factorial experiment was designed to study the main effect of dietary microbial phytase, citric acid, crude protein (CP) level and their interactions on growth performance, nutrient digestibility and body composition of Labeo rohita juveniles. Two basal diets were formulated using plant-based ingredients containing either sub-optimum (25%) or normal (35%) CP levels. Both the diets were supplemented with microbial phytase (U kg−1) and citric acid (%) at the level of 0, 0; 500, 0; 0, 3; and 500, 3 respectively. One hundred and twenty L. rohita juveniles (average weight 12.61–13.72 g) were randomly distributed in eight treatments, each with three replicates. Dietary microbial phytase alone had no significant effect on whole-body ash content but addition of citric acid (3%) in the diet activated the phytase as evidenced by their significant interaction. A significant interaction between citric acid and microbial phytase was also found on weight gain%, specific growth rate, protein efficiency ratio. Increasing the dietary CP level from 25% to 35% significantly ( P<0.01) decreased phosphorus and dry matter digestibility. Thus, these results showed that the growth-promoting effect was higher in groups fed a sub-optimum protein (25%) diet containing both 3% citric acid and 500 U kg−1 of microbial phytase than those fed 35% CP diets. This suggests that microbial phytase and citric acid in sub-optimum CP diet had a synergistic effect on nutrient digestibility and growth performance of L. rohita juveniles. [ABSTRACT FROM AUTHOR]

A feeding trial was conducted for 60 days to study the effect of dietary protein, microbial phytase and citric acid on intestinal digesta pH, bone ash and bone mineral contents inLabeo rohitajuveniles. Eight experimental diets were prepared in 2× 2× 2 factorial arrangement with crude protein levels (25% and 35%), microbial phytase (0 and 500 U kg−1), and citric acid (0 and 3%). The 25% crude protein level feed was supplemented with phytase (U kg−1) and citric acid (%) at the level of 0,0 (C25); 500,0 (T1); 0,3 (T2); 500,3 (T3), and 35% crude protein level feed at 0.0 (C35); 500,0 (T4); 0,3 (T5) and 500,3(T6) respectively. One hundred and twenty juveniles ofL. rohita(av. wt. 12.61–13.72 g) were distributed randomly in eight treatments, each of with three replicates. Addition of citric acid in the 25% crude protein feed significantly decreased (P<0.001) feed pH with concurrent decrease in intestinal digesta pH (P<0.001) and increased the bone ash content (P<0.05) by 4.6%. An interaction between citric acid and phytase (P<0.05) was also observed for bone ash content. Increasing the dietary protein content from 25% to 35% significantly decreased (P<0.01) bone Zn content by 14.9%, which was more prominent with the addition of citric acid, resulting in significant interaction between protein and citric acid (P<0.05), but the bone Cu content was significantly increased (P<0.01) with increasing dietary protein content. Dietary supplementation of microbial phytase (500 U kg−1) significantly increased (P<0.05) bone Na, Ca, K, P and Fe contents by 15%, 12.1%, 17.4%, 9.2% and 40.7%, respectively, whereas bone P and Mn content was significantly increased (P<0.05) by addition of citric acid (3%). Addition of phytase to plant-based diets increased the bioavailability of minerals, thereby increasing bone mineralization. The effect of phytase was increased because of addition of citric acid (3%). [ABSTRACT FROM AUTHOR]

A 60-day feeding trial was conducted to quantify the effects of microbial phytase supplementation on apparent absorption, whole body and bone contents of minerals inPangasius pangasiusfingerlings. Seven isoprotein (35.67%) and isocaloric (3870 kcal kg−1) diets were prepared with graded levels of supplemental phytase at 0 (T1), 150 (T2), 250 (T3), 350 (T4), 500 (T5), 1000 (T6) and 2000 (T7) FTU (Phytase Units) kg−1. Three hundred and fifteen fingerlings ofP. pangasius(1.97–2.05 g) were randomly distributed in seven treatments with three replicates each. There was significant increase (P<0.05) in tissue protein content in phytase-supplemented groups compared with the control. Apparent absorptions of calcium (Ca), phosphorus (P), magnesium (Mg), manganese (Mn), zinc (Zn), iron (Fe), potassium (K), copper (Cu) and cobalt (Co) were significantly (P<0.05) higher in the phytase-supplemented groups than the control group. Faecal ash and P contents were significantly (P<0.05) higher in the control (T1) than the phytase-supplemented groups. Whole-body contents of Ca, P, Zn, Fe, Cu and Co were significantly (P<0.05) improved by the dietary supplementation of phytase-barring Mg and Mn. Concentrations of bone Ca, P, K, Cu and Co were significantly (P<0.05) higher in phytase-supplemented groups. Bone ash contents (40.77–44.85%) were increased concomitantly with the increased level of phytase inclusion upto 500 FTU kg−1 diet. It was observed that a minimum dose of 250 FTU phytase kg−1 diet improved the mineral absorption and utilization inP. pangasiusfingerlings. [ABSTRACT FROM AUTHOR]

A feeding trial was conducted for 60 days to study the effects of exogenous microbial phytase supplementation on the growth and nutrient digestibility ofPangasius pangasiusfingerlings. Eight isocaloric and isoprotein experimental diets (35.67% crude protein and 3870 kcal kg−1) were prepared with graded levels of phytase, e.g., 0 (T1), 150 (T2), 250 (T3), 350 (T4), 500 (T5), 1000 (T6) and 2000 (T7) FTU (phytase units) kg−1. Three hundred and fifteen fingerlings ofP. pangasius(1.97–2.05 g) were randomly distributed in seven treatments with three replicates each. Maximum weight gain (350.72%), specific growth rate (2.51%), protein efficiency ratio (2.1), apparent net protein utilization (27.85%), energy retention value (88.47%) and feed conversion efficiency were observed in T5 group supplemented with 500 FTU phytase kg−1 diet. Apparent dry matter and protein digestibility in phytase-supplemented groups were significantly (P<0.01) higher at a minimum supplement of 500 FTU kg−1 or higher. Liver alkaline phosphatase activity increased significantly in treatment groups. Supplementation at 500 FTU kg−1 of phytase is optimum in the diet ofP. pangasiusfingerlings. [ABSTRACT FROM AUTHOR]