N.P. Sahu

Dietary high protein and vitamin C mitigates endosulfan toxicity in the spotted murrel, Channa punctatus (Bloch, 1793)

The amelioration effect of dietary high protein and vitamin C against stress was evaluated in spotted murrel, Channa punctatus, exposed to endosulfan. Two hundred and forty fish (average weight: 27.01 g/fish), distributed equally into 4 different groups (control, T(1), T(2), and T(3)), each with 6 replicates were fed with control (40% crude protein, CP and 0.1% vitamin C), T(1) (40% CP and 0.1% vitamin C), T(2) (50% CP and 0.1% vitamin C), and T(3) (50% CP and 0.2% vitamin C) diets for 90 days. Groups fed T(1), T(2), and T(3) diets were exposed to sublethal endosulfan concentration, whereas the control was maintained without endosulfan exposure. Results indicated significant reduction in the growth performance, survival, and activities of lactate dehydrogenase (liver and muscle), malate dehydrogenase (liver and muscle), enzymes of protein metabolism (aspartate amino transferase in liver and alanine amino transferase in liver and muscle), acetyl choline esterase (brain), alkaline phosphatase activity (liver), and ATPase (gill) enzymes of group fed control diet and exposed to endosulfan. However, endosulfan exposed fish fed high CP and vitamin C diet exhibited significant (P<0.05) improvement in their growth performance and metabolic enzyme activities. Further, high CP and vitamin C diet reduced endosulfan accumulation in the muscle. Overall results indicate that vitamin C (0.2%) supplementation in high CP (50%) diet improves growth, metabolism, and reduce endosulfan bioaccumulation in C. punctatus.

Haemato‐immunological and stress responses of Labeo rohita (Hamilton) fingerlings: effect of rearing temperature and dietary gelatinized carbohydrate

A feeding trial of 70-days was carried out to study the haemato-immunological and stress responses of Labeo rohita fingerlings reared at two water temperatures [ambient (Amb) - 27 °C and 32 °C] fed with graded levels of gelatinized corn carbohydrate (GC). Two hundred and sixteen fingerlings were randomly distributed into six treatment groups in triplicate. Three semi-purified diets were prepared containing 30% crude protein with graded levels of GC 40%, 50% and 58%. The six treatment groups were T(1) (40% GC × Amb), T(2) (40% GC × 32 °C), T(3) (50% GC × Amb), T(4) (50% GC× 32 °C), T(5) (58% GC × Amb) and T(6) (58% GC × 32 °C). The blood glucose level was significantly (p < 0.05) lowered in groups fed with 58% GC level. Neither dietary GC levels nor temperature had a significant (p > 0.05) effect on serum cortisol and superoxide dismutase activity. Lysozyme activity was significantly higher (p < 0.05) in T(1) during pre- and post-challenge period while temperature alone had a significant (p < 0.05) effect on post-challenge Nitroblue Tetrazolium and found higher at 32 °C. A significant effect of GC levels and rearing temperature was recorded on WBC in the pre- and post-challenge period. Highest pre-challenge WBC was observed in T(4) group and in the post-challenge period T(1) group recorded maximum. Water temperature had significant effect on pre-challenge haemoglobin content, highest being at 32 °C (T(2) ). A significant (p < 0.05) effect of rearing temperature and dietary GC level on total serum protein and albumin was also observed. Highest total serum protein and albumin was recorded in T(1) and globulin in T(2) . Percentage survival after challenging with Aeromonas hydrophila was highest in T(1) followed by T(3) group and lowest in T(6) . The results obtained in the present study suggest that L. rohita fingerlings may utilize higher levels of dietary GC at higher temperature (32 °C) but may affect its immunity status.

Microbial levan in the diet of Labeo rohita Hamilton juveniles: effect on non-specific immunity and histopathological changes after challenge with Aeromonas hydrophila

A 60-day feeding trial was conducted to study the immuno-protective effect of microbial levan on Labeo rohita juveniles challenged with Aeromonas hydrophila. Six purified diets were prepared with different levels of microbial levan: control (no levan), T1 (Basal + 0.25%), T2 (Basal + 0.50%), T3 (Basal + 0.75%), T4 (Basal + 1%) and T5 (Basal + 1.25%), fed to six groups of fish in triplicate. Among the treatment groups the haemoglobin content and total leucocyte count were increased with a dietary supplementation of levan at 1% or more. An increasing trend for total erythrocyte count was observed with increasing level of dietary levan. Lower levan-supplemented groups showed a higher albumin/globulin ratio. As the levan supplementation was increased, there was a gradual increase in serum lysozyme activity and respiratory burst activity [nitroblue tetrazolium (NBT) assay] reduction values. The highest lysozyme activity and NBT were observed in the T5 group although this was similar to the T4 group (P > 0.05). No significant histo-architectural changes were associated with dietary levan levels. After challenge with A. hydrophila, moderately degenerated hepatocytes, oedema and leucocytic infiltration in parenchymatous tissues, and extensive haemorrhage and haemosiderosis in the kidney were observed in the control group. However, the T5 group supplemented with 1.25% levan showed infiltrating leucocytes in the liver while the kidney showed only moderate degeneration of renal tubules. The relative survival per cent of juveniles after challenge with A. hydrophila was the highest in the T5 group followed by T4. This suggests that microbial levan at 1.25% can be used as dietary immunostimulant for L. rohita juveniles.

Yeast extract, brewer’s yeast and spirulina in diets for Labeo rohita fingerlings affect haemato-immunological responses and survival following Aeromonas hydrophila challenge

A feeding trial was conducted for 60 days to study the immunomodulatory role of three different immunostimulants yeast extract (YE), brewers yeast (BY) and spirulina (SP) in Labeo rohita fingerlings. Four hundred and fifty fingerlings (avg. wt 3.35±0.15 g) were randomly distributed in ten treatments and fed with either of ten iso-nitrogenous and iso-caloric semi-purified diets, prepared with three incremental levels (1%, 2% and 4%) of different immunostimulants except the control. Growth parameters did not vary significantly (p>0.05) among the experimental groups. Haematology and serum parameters was performed before Aeromonas hydrophila challenge whereas respiratory burst activity was analysed following challenge. The respiratory burst activity, total leucocyte count, serum total protein and globulin was significantly higher (p<0.05) in YE 1% supplemented group. The survival (%) after challenging with A. hydrophila was also highest in the YE fed groups. The results indicate that among the different sources and levels of immunostimulants, YE at lower inclusion level is more effective in promoting the immune status of L. rohita fingerlings.

Higher water temperature enhances dietary carbohydrate utilization and growth performance in Labeo rohita (Hamilton) fingerlings.

A 60-day experiment was conducted to delineate the effect of three dietary levels of gelatinized carbohydrate (GC) on growth, nutrient-utilization and body composition of Labeo rohita fingerlings (avg. wt 6.5 ± 0.3 g) reared at two water temperatures (ambient-AT (26 ± 0.8 °C) and 32 °C). Two hundred and sixteen fingerlings were randomly distributed into six treatments in triplicates. Three semi-purified isonitrogenous diets were prepared with graded levels of GC viz. D(1) : 40%, D(2) : 50% and D(3) : 58%. Growth rate, feed efficiency and protein efficiency ratio were significantly (p < 0.05) higher in 50% GC and 32 °C reared groups than their AT counterparts. Hepato Somatic Index was higher in AT reared groups compared to 32 °C reared counterparts. Apparent digestibility co-efficient of carbohydrate was significantly (p < 0.05) higher at 32 °C reared groups but decreased with increasing carbohydrate (GC) levels. Fish reared at 32 °C showed significantly (p < 0.05) higher amylase, protease and hexokinase activities while glucose-6-phosphate dehydrogenase and glucose-6-phosphatse were significantly (p < 0.05) higher at ambient temperatures. The results obtained in present study indicated that L. rohita could utilize higher level (50%) of dietary carbohydrate at 32 °C.

Gelatinized to non-gelatinized starch ratio in the diet of Labeo rohita: effect on digestive and metabolic response and on growth

A 60-days experiment was conducted to study the optimum gelatinized (G) to non-gelatinized (NG) starch ratio in the diet of Labeo rohita juveniles with respect to digestive and metabolic response and on growth. Two-hundred and thirty-four juveniles (avg. wt 2.53 +/- 0.04 g) were randomly distributed in six treatment groups with each of three replicates. Six semipurified diets either containing NG and/or G corn starch viz., T(1) (100% NG, 0% G starch), T(2) (80% NG, 20% G starch), T(3) (60% NG, 40% G starch), T(4) (40% NG, 60% G starch), T(5) (20% NG, 80% G starch) and T(6) (0% NG, 100% G starch) were prepared. The dry matter digestibility and carbohydrate digestibility were highest (p < 0.05) in T(6) group and lowest in T(3) and T(4) groups. The amylase activity in intestine increased as G:NG level increased in the diet. Protease activity in intestine was highest in T(6) group and lowest in T(1) group. Similar trend was recorded for specific growth rate, protein efficiency ratio and apparent net protein utilization. Liver glycogen, hepatosomatic index and blood glucose level increased linearly with the increasing level of G starch in the experimental diet. The results indicate that higher nutrient digestibility and growth was recorded either at low (20% G starch, T(2)) or high (100% G starch, T(6)) G starch fed group. But high G starch fed group (T(6)) exhibits higher liver glycogen and blood glucose level, which may lead to stress due to long-term feeding. Hence, it is suggested that 20% G and 80% NG starch is optimum for better nutrient digestibility and growth in L. rohita juveniles.

Efffect of Feeding Probiotic (Lactobacillus cremoris) on Growth and Survival of Macrobrachium rosenbergii Post Larvae

Abstract Suralikar, V. and Sahu, N. P. 2001. Efffect of feeding probiotic (Lactobacillus cremoris) on growth and survival of Macrobrachium rosenbergii post larvae. J. Appl. Anim. Res., 20: 117–124. To study the viability of probiotic (Lactobacillus cremoris) and optimum concentration in the diet, its impact on growth and survival of Macrobrachium rosenbergii post larvae (PL), three hundred PL (140–170 mg) were equally divided in five experimental groups having four replicates each. Five experimental diets prepared by adding different concentrations of L. cremoris (T1, 2.8 × 10 11 cfu/100g; T2, 5.7x 1011 cfu/100g; T3, 8.5 × 10 11 cfu/100g; T4, 11.4 × 10 11 cfu/100g; T5, control) with similar all other ingredients were fed for 60 days. Although insignificant (P<0.05) but growth promoting effect was elucidated at a minimum concentration of 8.5 × 10 11 cfu/100g (L. cremoris) diet. But maximum concentration of inclusion remained inconclusive and needs further investigation. Maximum viability of L. cremoris in the pelleted diet was found to be 18 days at 4 C. Survival was not affected due to feeding of L. cremoris in the diet of Macrobrachium rosenbergii PL.

Effect of dietary supplementation of l-tryptophan on thermal tolerance and oxygen consumption rate in Cirrhinus mrigala fingerlings under varied stocking density

A 60 day feeding trial was conducted to study the effect of dietary l-tryptophan on thermal tolerance and oxygen consumption rate of freshwater fish, mrigala, Cirrhinus mrigala reared under ambient temperature at low and high stocking density. Four hundred eighty fingerlings were distributed into eight experimental groups. Four groups each of low density group (10 fishes/75L water) and higher density group (30 fishes/75L water) were fed a diet containing 0, 0.68, 1.36 or 2.72% l-tryptophan in the diet, thus forming eight experimental groups namely, Low density control (LC) (basal feed +0% l-tryptophan); LT1 (basal feed+0.68% l-tryptophan); LT2 (basal feed+1.36% l-tryptophan); LT3 (basal feed+2.72% l-tryptophan); high density control (HC) (basal feed+0% l-tryptophan); HT1 (basal feed+0.68% l-tryptophan); HT2 (basal feed+1.36% l-tryptophan); and HT3 (basal feed+2.72% l-tryptophan) were fed at 3% of the body weight. The test diets having crude protein 34.33±0.23 to 35.81±0.18% and lipid 423.49±1.76 to 425.85±0.31KCal/100g were prepared using purified ingredients. The possible role of dietary l-tryptophan on thermal tolerance and oxygen consumption rate was assessed in terms of critical thermal maxima (CTMax), critical thermal minima (CTMin), lethal thermal maxima (LTMax) and lethal thermal minima (LTMin). The CTMax, CTMin, LTMax and LTMin values were found to be significantly higher (p<0.05) in the treatment groups with CTMax 42.94±0.037 (LT2); LT Max 43.18±0.070 (LT2); CTMin 10.47±0.088 (LT2) and LTMin 9.42±0.062 (LT3), whereas the control group showed a lower tolerance level. The same trend was observed in the high density group (CTMax 42.09±0.066 (LT3); LTMax 43 23±0.067 (HT3); CTMin 10.98±0.040 (HT3) and LTMin 9.74±0.037 (HT3). However, gradual supplementation of dietary l-tryptophan in the diet significantly reduced the oxygen consumption rate in both the low density group (Y=-26.74x+222.4, r²=0.915) and the high density group (Y=-32.96x+296.5, r²=0.8923). Dietary supplementation of l-tryptophan at a level of 1.36% improved the thermal tolerance level and reduced the oxygen consumption rate in C. mrigala fingerlings.

Biochemical and stress responses of rohu Labeo rohita and mrigal Cirrhinus mrigala in relation to acclimation temperatures.

The biochemical and stress responses of two Indian major carps, rohu Labeo rohita and mrigal Cirrhinus mrigala were studied after acclimating them to four preset temperatures (26, 31, 33 and 36 degrees C) for 30 days. The blood glucose and liver glycogen levels showed an inverse trend in both the species and were significantly different in L. rohita at higher temperatures. The decrease in the liver glycogen level of C. mrigala, however, was not significant. Plasma cortisol levels increased significantly whereas the ascorbic acid content in the brain and kidney of both the species decreased significantly with increasing temperatures. Total lipid content in the liver of both the species decreased significantly with increasing acclimation temperatures. The phospholipid concentration decreased in L. rohita with increasing acclimation temperatures, and in C. mrigala the values decreased up to 33 degrees C and increased at 36 degrees C. In C. mrigala, the cholesterol level decreased up to 33 degrees C and then increased at 36 degrees C, but the absolute value was lower in comparison to L. rohita. The cholesterol levels, however, were not significantly different in L. rohita. Triglycerides and free fatty acids concentrations decreased significantly with increasing acclimation temperatures in both the species. The present study indicates species-specific metabolic responses of L. rohita and C. mrigala to thermal acclimation.

Non‐gelatinized starch influences the deposition of n‐3 fatty acids in the muscle of a tropical freshwater fish, Labeo rohita

A 60-day feeding trial was conducted to study the influence of gelatinized (G) to non-gelatinized (NG) starch ratio in the diet on fatty acids profiles and oxidative status in Labeo rohita fingerlings. Two hundred and thirty-four fingerlings (average weight: 2.53 g) were distributed in six treatment groups with each of three replicates. Six semi-purified diets either containing NG and/or G corn starch (42.43%) viz., T(1) (100% NG and 0% G starch), T(2) (80% NG and 20% G starch), T(3) (60% NG and 40% G starch), T(4) (40% NG and 60% G starch), T(5) (20% NG and 80% G starch) and T(6) (0% NG and 100% G starch) was fed to respective groups. Catalase, superoxide dismutase and malic enzyme activities decreased linearly with the increasing level of G starch, whereas reverse trend was found for glucose-6-phosphate dehydrogenase. Total saturated fatty acids in muscle increased with the increasing level of G starch in the diet. Total n-3 fatty acids decreased linearly with the increasing level of G starch in the diet. Among the n-3 fatty acids, linolenic acids content was more in NG starch fed group. Similarly, eicosapentaenoic acid contents gradually decreased with increasing level of G starch content. The n-6/n-3 ratio was higher in G starch fed group. This suggests that dietary starch type may be manipulated for quality improvement of fish flesh.