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A 90 days experimental trial was conducted to evaluate the effect of urea treated sugarcane bagasse on the growth, gut microflora and digestive enzymes of grass carp (Ctenopharyngodon idella). Fish were fed to 3% wet body weight per day with experimental diets having 0% (CTRL), 0.7% (T1), 1.4% (T2) and 2.1% (T3) urea, with each group having two replicate tanks. Fish fed on 2.1% urea treated sugarcane bagasse (T3) showed significantly (P<0.05) higher growth as compared to T2, T1 and CTRL. The feed conversion ratio and specific growth rate were also significantly higher in T3 fish group, followed by the T2, T1 and CTRL groups. Proximate analysis of fish showed that the level of crude protein was higher significantly in T2 fish than other groups and crude fat level was significantly higher in T1 fish, followed the T2, CTRL and T3 fish groups. The percentage level of dry matter was significantly higher in T3 fish and ash percentage was significantly higher in T2 fish relative to T3, T1 and CTRL groups. Amylase and Lipase concentration was significantly higher in T2 fish compared with T3, T1 and CTRL groups. Protease concentration was significantly higher in T3 fish, followed by the T1, T2 and CTRL fish groups. Lastly, the presence of Lactobacillus fermentum was confirmed in the T1, T2 and T3 fish groups. Overall, the results showed that urea treated sugarcane bagasse can be used as a feed ingredient for C. idella and has no adverse effect on the nutritional value of fish. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effects of selenium nanoparticle (Se-NP) supplementation on the growth performance, carcass composition, antioxidant status, hepatic enzyme activities, and immunity of Cirrhinus mrigala. For this purpose, fish with an average initial weight of 7.44 ± 0.04 g were fed five experimental diets containing 0 (control), 0.25, 0.5, 1, and 2 mg kg-1 Se-NPs diets for 90 days. The analysed selenium (Se) contents of the diets were 0.35, 0.64, 0.92, 1.43, and 2.39 mg kg-1. Twenty five fish were randomly distributed in each of 5 aquarium (36 × 23.7 × 24.3 inches) in triplicate. The results showed that supplementation with Se up to 0.92 mg/kg significantly increased (p<0.05) weight gain, weight gain% (WG%), and specific growth rate (SGR) by 34%, 33%, and 16%, respectively, compared to the control diet. Dietary Se concentrations up to 0.92 mg/kg significantly increased the crude protein and crude fat and reduced (p<0.05) the moisture content as compared to the control group. Fish fed 0.92 mg kg-1 Se had significantly lower malondialdehyde (MDA) contents and higher activities of catalase, superoxide dismutase, and glutathione peroxidase in liver and serum as compared to other experimental diets. Moreover, a significant increase (p<0.05) in the level of serum immunoglobulin and lysozyme (LYZ) activity was recorded in fish fed 0.92 mg/kg Se diet. Moreover, the highest (p<0.05) values of aspartate transaminase (AST) and alanine transaminase (ALT) were recorded in fish fed 2.39 mg/kg Se level. However, serum alkaline phosphatase (ALP) activity remained unaffected by dietary treatment. Broken-line regression analysis indicated that 0.83 mg/kg Se is required for the optimum growth performance of C. mrigala. [ABSTRACT FROM AUTHOR]

The current study was performed to investigate the impact of different temperatures and protein levels on the growth performance, proximate composition and digestive and hepatic enzyme activities of Labeo rohita fingerlings. For this purpose, healthy fingerlings (average initial weight of 6.40 ± 0.02 g) were acclimatized for 15 days, then reared at three temperatures (25°C, 30°C and 35°C) and fed three levels of crude protein (25%, 30% and 35% crude protein (CP)) twice daily until satiation for 60 days. The results of the study revealed that the highest growth performance was observed in fish fed 35% protein and reared at 30°C. Similarly, fish reared at 35°C and 25°C water temperature showed comparatively better growth performance in fish fed with 35% protein. Furthermore, a significant enhancement in feed intake was observed with increasing culture temperature and increasing CP levels, but at 25°C, increasing CP levels significantly decreased the feed intake. Sligh variations were also observed in proximate composition in terms of moisture, CP, crude fat (CF) and ash contents in fish fed with different CP levels and reared at different temperatures. The hepatosomatic index and viscerosomatic index decreased significantly with increasing levels of protein and temperature. Amylase activities were significantly reduced with increasing culture temperature at each protein level. Increasing culture temperature did not affected the lipase activities. However, lipase activities were enhanced with increasing CP levels at 25°C and activities decreased with increasing CP levels at 30–35°C. Protease activity was enhanced with increasing temperature and CP levels. Significant increases were also observed in serum total proteins and liver functioning enzymes such as alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase in response to increased temperature, and protein had a reciprocal effect. It is concluded that increasing the CP levels increased the growth performance independent of temperature. However, similar growth performance at 30 CP (30°C) and 35 CP (35°C) indicates that L. rohita requires more protein at higher temperature for optimum growth. [ABSTRACT FROM AUTHOR]

Natural herbs are excellent alternatives to synthetic compounds to enhance the growth performance and health status of fish. This study was conducted to evaluate the efficacy of black cardamom (Amomum subulatum) extract (BCE) as an herbal supplement in improving the growth, antioxidant status, haematology, and serum biochemistry of Catla catla. The acclimatized fish (N = 900; average initial weight = 14.44 ± 0.33 g) were allocated into five groups (60 fish/group in triplicate) in hapas (4 × 2 × 2.5 ft) and provided with feed containing 0 (control), 0.5, 1, 2 and 4 g/kg BCE for 90 days before being subjected to 8 days of crowding stress. After 90 days, significantly higher feed utilization and growth were observed in all BCE‐fed treatments compared to the control; however, the maximum values of these parameters were noted in the 2 g/kg BCE‐fed treatment. Moreover, the BCE‐fed groups exhibited a significant increase in antioxidant indices (glutathione peroxidase, superoxide dismutase and catalase), with a significant reduction in malondialdehyde levels, indicating a higher antioxidant capacity compared to the control. Significant improvements in haematological parameters, such as an increase in haematocrit, haemoglobin and red blood cells and a decrease in white blood cells, were observed in BCE‐fed treatments compared to the control. Furthermore, BCE‐fed groups showed a significant decrease in serum glucose, cortisol and triglycerides, while total protein, globulin and albumin levels were significantly higher compared with the control. During the feeding trial of 90 days, no mortality was observed; however, the lowest cumulative mortality was noted in the 2 g/kg BCE group after crowding stress of 8 days. In conclusion, the use of BCE in feed can enhance the growth performance, antioxidant status, haematology, and serum biochemistry of C. catla and improve the resistance against crowding stress. The optimum levels of BCE for C. catla were estimated based on weight gain % (1.78 g/kg; R2 = 0.97), feed conversion ratio (1.65 g/kg; R2 = 0.98), MDA content (1.66 g/kg; R2 = 0.93) and serum lysozyme activity (1.72 g/kg; R2 = 1) using broken‐line regression analysis. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the optimal dietary phosphorus (P) requirement and its effects on growth performance, body composition, mineralization and alkaline phosphate (ALP) activity in silver carp (Hypophthalmichthys molitrix). A total of 360 fish with an average initial weight of 7.0 ± 0.15 g were divided into 18 tanks (70 L capacity each) with a stocking density of 20 fish per tank in triplicate. The fish were fed diets containing six levels of P (3.3, 4.4, 5.5, 6.5, 7.5 and 8.6 g/kg) up to satiation for 90 days twice daily at 09:00 and 16:00. The results showed that fish fed diets containing 6.5 and 7.5 g/kg dietary P had significantly higher (p < 0.05) growth performance in terms of final weight gain, average weight gain (AWG), weight gain% (WG%), protein efficiency ratio (PER) and specific growth rate (SGR) than fish fed other diets. The best value of the feed conversion ratio (FCR) was observed in fish fed the 6.5 g/kg P diet, which was not significantly different from the 7.5 g/kg P diet. Increasing P supplementation above 6.5 g/kg significantly reduced (p < 0.05) the feed intake of silver carp. Whole‐body composition analysis indicated that increasing P levels resulted in a decrease (p < 0.05) in crude fat (CF) and an increase (p < 0.05) in crude ash (CA) content, while crude protein (CP) and moisture content remained unaffected (p > 0.05). Fish fed diets containing ≥6.5 g/kg P had significantly higher (p < 0.05) Ca content in the whole body, bones and scales compared to those fed diets containing ≤5.5 g/kg P. A similar trend was observed for P and Mg contents in the whole body, bones and scales. The Zn content tended to decrease (p < 0.05) with increasing P supplementation in the whole body and bones, but fish fed diets containing ≥6.5 g/kg P had significantly higher (p < 0.05) Zn content compared to fish fed diets containing ≤5.5 g/kg P. The Ca/P ratio was significantly affected by P supplementation. Fish fed diets containing ≥6.5 g/kg P had significantly higher (p < 0.05) Ca and P contents in the serum than fish fed other diets. ALP activity increased (p < 0.05) with increasing P levels up to 6.5 g/kg P and decreased (p < 0.05) thereafter. In conclusion, supplementing P up to 6.35 g/kg is recommended for the optimal growth of silver carp. [ABSTRACT FROM AUTHOR]

The replacement of fishmeal (FM) with economical and nutritious FM alternatives including plant- and animal-based protein ingredients has become a global research priority. However, the presence of several anti-nutritional factors (ANFs) in these alternatives may impair nutrient utilization in fish. The supplementation of exogenous protease as feed additives could be an effective approach to improve the nutrient digestibility of these alternative proteins. Proteases are protein-digesting enzymes that catalyze the hydrolysis of complex protein macromolecules into simpler amino acids. Exogenous protease supplementation stimulates the activities of endogenous proteolytic enzymes for better nutrient digestion and absorption in fish. This review article summarizes the optimum protease supplementation levels in various fish species and its beneficial effects on growth performance, nutrient digestibility, intestinal morphology, digestive enzyme activities, whole-body composition, physiochemical parameters, immunity, and gene expression of fish. Moreover, the interactive effects of exogenous protease with organic acids and probiotics are also discussed. Overall, the supplementation of exogenous protease in fish feed is a viable solution for poor nutrient utilization of FM alternatives. Important gaps, however, exist in the current knowledge, particularly with regard to the effect of protease supplementation in animal-based proteins as most of the studies have focused on the effect of protease supplementation on plant-based proteins as FM alternatives. Moreover, additional studies focused on the effect of protease supplementation on the digestive enzyme activities, immunity, gut microbes and antioxidant parameters of fish will provide the basis for a better understanding of the mode of action of protease. The scarce knowledge in these areas limits the scope of protease supplementation as a feed additive in the aquaculture sector. [ABSTRACT FROM AUTHOR]

An experiment of 90-days was performed to investigate the effects of dietary calcium (Ca), phosphorus (P) and their interaction on growth, whole-body composition, nutrient digestibility and mineralization of silver carp, Hypophthalmichthys molitrix (average initial weight 13.7 ± 0.05 g). Nine isonitrogenous, isocaloric and isolipidic diets with three Ca levels (0, 1 and 2%) combined with three P levels (0, 1 and 2% P) were prepared. Results showed that silver carp fed the diet supplemented with 1% Ca and 1% P level yielded the similar (p > 0.05) growth performance as was recorded for that fed diet containing 2% Ca and 2% P. No significant difference in survival rate was recorded except for the diet containing 1% Ca with 2% P supplement. The feed intake (FI) of juvenile remained unaffected (p > 0.05) by mineral supplementation. Whole body protein content increased (p < 0.05) slightly with Ca and P supplementation. However, moisture, fat and ash contents remained unaffected (p > 0.05). Dietary Ca and P supplementation improved (p < 0.05) the protein and fat digestibility in silver carp. Ca and P contents showed significant increase (p < 0.05) with increasing Ca and P levels in the whole body, bones and scales, achieving the highest (p < 0.05) values at 2% Ca supplemented with 2% P. Whereas, Mg and Zn contents decreased (p < 0.05) with increasing Ca and P supplementation. Fish fed the diet containing 2% Ca level without P supplement had higher (p < 0.05) Ca/P ratio in whole body and bones. However, it decreased (p < 0.05) at 2% Ca level in scales. Further, increase in P supplementation significantly reduced (p < 0.05) Ca/P ratio regardless of Ca level. Conclusively, supplementation of 1% Ca in the presence of 1% P (1:1 ratio) is required for optimum performance of silver carp. [ABSTRACT FROM AUTHOR]

The dietary effect of vitamin E supplementation on fingerlings of Labeo rohita during refrigerated storage was investigated. Six graded levels of vitamin E, between 0-125 mg/kg vitamin E, were fed to fish. After 60-day feeding trial, fish were sacrificed, fillets were stored in refrigerator at -20°C and analyzed on 0, 15 and 30th day of storage. Upon refrigeration the vitamin E fed fish showed reduced level of Thiobarbituric acid reactive substances (TBARS) at all storage days. The enzyme activities were improved by elevating the levels of vitamin E in diet as well as by storage period (P < 0.05) for all treatments. Fatty acid profile indicated that n-3, n-6 fatty acids and the ratios of ARA/EPA and n-3/n-6 were increased by increasing vitamin E supplementation and decreased with an increase in the storage period. Conclusively, the dietary vitamin E reduced lipid peroxidation and improved the fillet quality of stored fish. [ABSTRACT FROM AUTHOR]

An 8-weeks feeding experiment was performed to study the requirement of vitamin E for rohu fingerlings. Six practical diets were fed to fingerlings including one control diet (E0) and five test diets (E25, E50, E75, E100 and E125) supplemented with graded vitamin E levels including 0, 25, 50, 75, 100 and 125 mg/kg. After the completion of trial, fish growth, vitamin E, antioxidant enzymes activities and fatty acids profile was determined. From the results it was concluded that the graded supplemental vitamin E levels improve the utilization of feed and fish growth. The antioxidant enzymes activities also showed significant results by increasing vitamin E level in the diet. However, an inverse relation was recorded between the contents of liver thiobarbituric acid reactive substances (TBARS) and vitamin E level in the diet. Moreover, analysis of fatty acids profile showed decrease in saturated and monounsaturated fatty acids (MUFAs). While, polyunsaturated fatty acids (PUFAs) were increased in all vitamin E supplemented diets compared to control group. Furthermore, vitamin E level of 80.62 mg/kg was found optimum for maximum growth performance in L. rohita fingerlings, beyond which no increase in growth was observed. [ABSTRACT FROM AUTHOR]

A 13‐week feeding trial was conducted to determine the optimum dietary calcium (Ca) requirement of juvenile silver carp, Hypophthalmichthys molitrix (3.20 ± 0.02 g). For this, five isonitrogenous semipurified diets containing 2.3, 5.3, 8.3, 11.1 and 14.2 g/kg Ca levels were formulated. The growth performance of juveniles was significantly affected by Ca supplementation with the maximum increase recorded at 8.3 g/kg Ca and stabilized thereafter (p < 0.05). Whole‐body protein and ash contents were increased (p < 0.05) with increased dietary Ca up to 8.3 g/kg and then levelled off (p < 0.05). However, the moisture and fat contents in whole body were decreased (p < 0.05) with the increased Ca supplementation up to 8.3 g/kg and plateaued thereafter. Calcium and P concentration showed an increasing trend (p < 0.05) with the increasing Ca level up to 11.1 g/kg in whole body and 8.3 g/kg in bones and scales. However, Mg and Zn concentrations were decreased (p < 0.05) with increasing dietary Ca levels. The highest alkaline phosphatase (ALP) activity (p < 0.05) was recorded in the fish‐fed diet containing 11.1 g/kg Ca diet; however, serum Ca, P and Ca/P ratio remained unaffected (p > 0.05). Broken line regression showed that 8.45 g/kg Ca is the optimal requirement for the growth of silver carp. Conclusively, an increase in Ca supplementation up to 8.3 g/kg significantly improved the overall performance of silver carp without urging the negative effects. [ABSTRACT FROM AUTHOR]

This study was planned to determine intestinal digestive enzymes activity and bone mineralization of Ctenopharyngodon idella. Four type food were prepared by using formic acid (%) and vitamin D3 (IU/Kg) in experiment viz, FD1, FD2, FD3 and FD4, respectively. Fish fed with formic acid showed considerable increase in calcium, magnesium potassium, however vitamin D3considerably increase iron and manganese contents (µg/g) in the bones of C. idella. Amylase and protease activity was maximum in fish intestine fed with formic acid followed by fornic acid × vitamin D3, vitamin D3 = control diet. Activity of lipase enzyme was reduced by formic acid supplementation as well as vitamin D3. The observed formic acid and vitamin D3 (interactions) were synergistically bone mineralization of phosphorus, sodium, copper and also showed positive result for the activity of amylase, protease and lipase. Finally, formic acid and vitamin D3improves bone mineralization and digestive enzymes activity in the C. idella. [ABSTRACT FROM AUTHOR]

Proteases are the enzymes responsible for the hydrolysis of complex proteins into simpler units for better digestion and absorption of nutrients. This study was conducted to determine the optimum supplementation level and effects of dietary protease addition in poultry by‐product meal‐based diet (PBM) on growth performance, nutrient digestibility, digestive enzyme activities and physiochemical parameters of juvenile rohu, Labeo rohita (initial weight: 11.33 ± 0.02 g). For this purpose, seven iso‐nitrogenous and iso‐lipidic experimental diets were formulated to contain a positive control (PC) diet (containing fishmeal and no protease), a negative control (NC) diet (containing PBM and no protease) and five other PBM‐based diets supplemented with exogenous protease at the levels of 150, 300, 450, 600 and 750 mg/kg diet. Results indicated that growth performance and body indices of fish fed protease supplemented diets were higher (p < 0.05) compared with those fed the NC diet, while maximum increase was recorded at 450 mg/kg protease supplementation level, which was similar to the PC diet (p > 0.05). Protease supplementation up to 450 mg/kg level linearly improved (p < 0.05) the whole‐body proximate composition and digestibility of dry matter (DM), crude protein (CP), crude lipid (CL) and crude ash (CA) in rohu juveniles. A similar trend (p < 0.05) was observed in the activities of amylases, lipases and proteases in intestinal and hepatopancreatic tissues, peaking at 450 mg/kg which was also similar (p > 0.05) to the PC diet. Protease supplementation significantly improved (p < 0.05) haemoglobin (Hb), haematocrit (Htc) and red blood cells (RBCs) of juveniles while, white blood cells (WBCs) and serum indices remained unaffected (p > 0.05). Based on quadratic regression analysis, the optimal dietary protease supplementation in PBM‐based diet for rohu was 433 mg/kg. Conclusively, increase in protease supplementation from 0 to 450 mg/kg levels improved the fish performance and decreased thereafter with further increase in protease levels (600–750 mg/kg). [ABSTRACT FROM AUTHOR]