Differences In Specific Growth Rate Research Articles

The Potential Effects of Azolla as a Growth Promoter for Labeo rohita Fingerlings

Non-conventional aqua feeds are crucial for promoting sustainability, reducing costs, and minimizing environmental impact in aquaculture, fostering industry growth and addressing environmental concerns. The 60 days experiment was conducted for the introduction of Azolla into the diet of Labeo rohita fingerlings resulted in significant variations (p<0.05) in several growth parameters, including percentage weight gain, percentage length gain, specific growth rate (SGR), feed conversion ratio (FCR), and survival rate. While no significant difference in FCR was observed among treatments during the initial 0 to 45-day interval, a notable disparity emerged between 45 to 60 days, with the highest FCR recorded in T3 and the lowest in T3. Similarly, although there were no significant differences in SGR among treatments at various intervals, the highest SGR was observed in T3, while the lowest was in T1. Furthermore, percentages of weight increment were significantly different between the intervals of 15-30 days and 30-45 days, with the highest percentage gain observed in T3 and the lowest in T1. Likewise, percentages of length increment showed significant differences between the intervals of 15-30 days, with T1 exhibiting the highest percentage gain and T1 the lowest. The survival rate % of different treatments at the end of the experiment varied, with T3 showing the highest survival rate and T0 the lowest. Statistical analysis confirmed significant differences in percent length gain, percent weight gain, SGR, and FCR among the treatments. These findings underscore the complex interplay between fish species, feed nutrients, additives, and rearing conditions on the growth process of Labeo rohita fingerlings. The observed variations in growth parameters highlight the potential of Azolla as a growth promoter in aquaculture practices. Further research is warranted to elucidate the underlying mechanisms driving these effects and to optimize Azolla supplementation protocols for enhanced growth performance and sustainability in Labeo rohita aquaculture.

Assessment of Full-Fat Tenebrio molitor as Feed Ingredient for Solea senegalensis: Effects on Growth Performance and Lipid Profile.

Tenebrio molitor (TM) is considered as one of the most promising protein sources for replacing fish meal in aquafeeds, among other things because it is rich in protein, a good source of micronutrients and has a low carbon footprint and land use. However, the main drawback of TM is its fatty acid profile, in particular its low content of n-3 PUFA. This study evaluates the effects of partially replacing plant or marine-derived with full-fat TM meal at two different levels on growth performance and lipid profiles of Senegalese sole (Solea senegalensis). For this purpose, a control diet (CTRL) and four experimental isoproteic (53%) and isolipidic (16%) diets were formulated containing 5 and 10% TM meal replacing mostly fish meal (FM5 and FM10), or 10 and 15% TM meal replacing mostly plant meal (PP10 and PP15). Fish (215 g) were fed at 1% of their body weight for 98 days. The final body weight of fish fed the experimental diets containing TM meal was not different from that of fish fed the CTRL diet (289 g). However, the inclusion of TM meal resulted in a gradual improvement in growth rate and feed efficiency in both cases (replacement of fish or plant meals), and significant differences in specific growth rate (SGR) were observed between fish fed the CTRL diet (SGR = 0.30% day-1) and those fed diets with the highest TM meal content (PP15; SGR = 0.35% day-1). The experimental groups did not show any differences in the protein content of the muscle (19.6% w/w). However, significant differences were observed in the total lipid content of the muscle, with the FM10, PP10, and PP15 groups having the lowest muscle lipid contents (2.2% ww). These fish also showed the lowest neutral lipid content in muscle (6.6% dw), but no differences were observed in the total phospholipid content (2.6% dw). Regarding the fatty acid profile, fish fed FM10, PP10 and PP15 had lower levels of linoleic acid (18:2n-6) and higher levels of oleic acid (18:1n-9) in liver and muscle compared to fish fed CTRL. However, no differences were found between fish fed CTRL and TM-based diets for docosahexaenoic acid (22:6n-3) and total n-3 PUFA in liver and muscle. In conclusion, our study demonstrated that full-fat TM inclusion up to 15% in S. senegalensis diets had no negative effects or even some positive effects on fish survival, growth performance, nutrient utilization and flesh quality.

Protective Effects of Sanyar Prebiotic on Immunity and Tissue Changes of Common Carp (Cyprinus carpio) Exposed to CuSO4 Stress

Prebiotics, as feed additives, can activate the antioxidant and immune systems of fish and significantly improve the survival of aquaculture animals in stressful conditions. The exposure of fish to copper sulfate leads to oxidative stress, suppression of the immune system, and destruction of vital body tissues. This study aimed to investigate the protective effects of Sanyar prebiotic on the immunity and tissue changes of common carp (Cyprinus carpio) exposed to CuSO4 stress. Two hundred common carp fish with an average weight of 12.33 ± 0.93 g were stocked in four treatments (triplicates) for 60 days. The experimental treatments contained Sanyar commercial prebiotics in 100 g of food, which included P1 (1 ml prebiotic liquid), P2 (0.1 g prebiotic powder), P3 (0.5 ml liquid and 0.05 g powder), and treatment C (control treatment without any additives). At the end of the experimental period, the fish were exposed to acute toxicity of Cu (0.1 m/l) for 96 hours. Gill, kidney, and liver tissue samples were collected and evaluated after 96 hours. According to the results obtained, there were significant differences in specific growth rate (SGR) and final weight ( p < 0.05). The lowest feed conversion ratio (FCR) was observed in the Sanyar treatments (1.56 ± 0.37), which had a significant difference from the control treatment (1.85 ± 0.35) ( p < 0.05). The results showed that immunity indices such as lysozyme, cortisol, and ACH50 increased in the experimental treatments compared to the control treatment ( p < 0.05). The highest and lowest lysozyme activities were observed in P2 (16.35 ± 0.57) and control treatments (13.15 ± 1.00), respectively ( p < 0.05). Generally, no significant difference was observed between growth and nutrition indices in Sanyar treatments ( p < 0.05). Symptoms of kidney, liver, and gill tissue damage were reported from mild (hyperemia and infiltration of inflammatory cells) to severe (hemorrhage and necrosis). The lowest severity of tissue damage was observed in the treatments fed with Sanyar food supplement. In general, the results of this study showed that the addition of Sanyar prebiotic to the diet of common carp improves the growth indicators and immune response and can also be beneficial in increasing fish resistance to copper toxicity.

Effects of substituting plant-based protein sources for fish meal in the diet of Nile Tilapia (Oreochromis niloticus)

The purpose of this study was to evaluate the nutritional adequacy and suitability of rice polish and mustard oil cake as protein sources in the diet of Nile Tilapia (Oreochromis niloticus). To assess the growth performance and feed utilization of Nile Tilapia, three diets containing rice polish (0, 8, and 16%) and mustard oil cake (8, 16, and 24%) were formulated and fed to the fish over a period of 60 days. According to the findings, the growth performance tended to decline as the levels of rice polish and mustard oil cake increased. The control diet (30% Fish meal) resulted in the highest weight gain (373.79±49.78%), whereas the diet (20% Fish meal) resulted in the least weight gain (341.24±27.23%). The specific growth rate (SGR) followed the same pattern, and there were no statistically significant differences in SGR between diets (p>0.05). At the end of this trial, the feed intake (FI) of the various diets ranged between 32.37 g and 37.78 g per fish. Although feed conversion ratio (FCR) and protein efficiency ratio (PER) were not significantly different among diets (p>0.05), feed intake decreased as the incorporation of rice polish increased.

Effects of Bacillus halophilus on growth, intestinal flora and metabolism of Larimichthys crocea

The incorporation of probiotics into the diet of large yellow croaker has been demonstrated by several studies to confer partial disease resistance. Bacillus halophilic isolated from the intestinal flora was used to study its effects on performance growth indicators, intestinal tissue structure, intestinal flora and the metabolism of Larimichthys crocea. A total of 180 fishes with an initial body weight of (164.00 ± 54.00) g were fed diets with three different concentrations of Bacillus halophilic: 0 cfu/mL (FC0, control group), 108 cfu/mL (FC8, treatment group), and 1012 cfu/mL (FC12, treatment group). The results showed that there were no significant differences in specific growth rate among all groups (P > 0.05). Compared to the FC0 group, the final body weight and Weight gain rate were significantly higher in FC8 and FC12 groups (P < 0.05). The Survival of the FC12 group significantly improved (P < 0.05). Compared to the FC0 group, crude protein content in muscle of the FC8 group significantly increased (P < 0.05), crude fat content significantly increased in the FC12 group (P < 0.05), crude protein content in whole fish experimental groups significantly increased (P < 0.05), and ash content significantly increased in the FC8 group (P < 0.05). In terms of antioxidant ability, the content of LZM in blood increased significantly in the FC8 group (P < 0.05), GSH content in liver of the FC12 group increased significantly (P < 0.05), while the content of MDA and AKP in blood and liver had no significant difference (P > 0.05). At the level of intestinal structure, there were no significant differences in villus height, crypt depth and goblet cell number between control group and treatment groups (P > 0.05). At the phylum level, Firmicutes was the dominant phylum, and the genus level, Lactobacillus and Bacteroides were the dominant bacteria in FC8 and FC12. A total of 1070 metabolites were identified, among which lipid metabolites accounted for 46.7%. Metabolites were involved in six main ways, mainly related to the metabolism of amino acids and lipids. The correlation analysis between microbes and metabolites showed that the intestinal flora of Larimichthys crocea could promote the synthesis of metabolites, among which Bacteroides and Megamonas could promote the synthesis of beneficial metabolites such as amino acids and vitamins. Through this study, we found that Bacillus halophilic can significantly improve growth, the antioxidant immunity ability and promote the expression of growth related metabolites, with the FC12 group being the better successful.

No adaptation to warming after selection for 800 generations in the coccolithophore Emiliania huxleyi BOF 92

Ocean warming is suggested to exert profound effects on phytoplankton physiology and growth. Here, we investigated how the coccolithophore Emiliania huxleyi (BOF 92, a non-calcifying strain) responded to changes in temperature in short- and long-term thermal treatments. The specific growth rate after 10 days of acclimation increased gradually with increasing temperatures (14, 17, 21, 24, 28°C) and peaked at ~23°C, followed by a significant decrease to 28°C. Chlorophyll a content, cell size, photosynthetic rate, and respiratory rate increased significantly from 14°C to 24°C, but the cellular particulate organic carbon (POC) and nitrogen (PON) showed the lowest values at the optimal temperature. In contrast, during long-term thermal treatments at 17°C and 21°C for 656 days (~790 generations for 17°C treatment; ~830 generations for 21°C treatment), the warming significantly stimulated the growth in the first 34 days and the last 162 days, but there was no significant difference in specific growth rate from Day 35 to Day 493. Chlorophyll a content, cell size, cellular POC/PON, and the ratio of POC to PON, showed no significant difference between the warming and control for most of the duration of the long-term exposure. The warming-selected population did not acquire persistent traits in terms of growth and cell quotas of POC and PON, which resumed to the levels in the control temperature treatment after about 9 generations in the shift test. In summary, our results indicate that warming by 4°C (17°C and 21°C) enhanced the growth, but did not result in adaptative changes in E. huxleyi (BOF 92) over a growth period of about 800 generations, reflecting that mild or non-stressful warming treatment to E. huxleyi isolated from cold seas does not alter its phenotypic plasticity.

Effects of fish meal replaced by methanotroph bacteria meal (Methylococcus capsulatus) on growth, body composition, antioxidant capacity, amino acids transporters and protein metabolism of turbot juveniles (Scophthalmus maximus L.)

Methanotroph bacteria meal (MBM) is produced by the fermentation of Methylococcus capsulatus, which use methane as carbon source. To evaluate the potential of replacing dietary fish meal (FM) with MBM, an eight-week growth trial was conducted on turbot juveniles (Scophthalmus maximus L.) with initial average weight of 9.13 ± 0.02 g. Seven isonitrogenous (crude protein, 51.00%) and isolipidic (crude lipid, 11.50%) diets were formulated by substituting FM protein with 0% (MBM0, the control diet), 15% (MBM15), 30% (MBM30), 45% (MBM45), 60% (MBM60), 80% (MBM80) and 100% (MBM100) MBM. Each diet was randomly assigned to triplicate fibreglass tanks (600 L). The survival rate (over 98%) was not significantly different among dietary treatments (P > 0.05). Also, no significant differences in specific growth rate (SGR), feed efficiency ratio (FER) and flesh yield (FY) were observed among fish fed with diets MBM0, MBM15 and MBM30, whereas these parameters were significantly reduced by further increase of dietary MBM (P < 0.05). Apparent digestibility coefficient (ADC) of nutrients was significantly liner reduced with increasing dietary MBM (P < 0.05). The body composition was altered by dietary MBM, as evidenced by an increase in carcass ash and muscle palmitic acid (C16:0) proportion, along with a decrease in n-3 polyunsaturated fatty acids (PUFA) proportion in muscle. The antioxidant capacity was not compromised until the replacement level reached 80%, characterized by a significant decrease in serum total antioxidant capacity (T-AOC), superoxide dismutase (SOD) activity and an increase in malondialdehyde (MDA) content. The liver health also tended to be compromised in fish fed with diets MBM80 and MBM100, evidenced by significantly increased glutamic oxalacetic transaminase (GOT) in serum and severe vacuolation of liver. The gene expression of intestinal amino acids transporters and hepatic general control nonderepressible 2 (gcn2) was first up-regulated and then down-regulated with significantly quadratic pattern (P < 0.05). Also, the expression of genes related to protein degradation in muscle, such as calpain small subunit 1-like (capns1-like), autophagy related 4B cysteine peptidase (atg4b) and cathepsin-d, exhibited a similar trend. While the gene expression of myogenic regulatory factors in muscle, such as follistatin, myogenin and myosin light chain (mlc), was significantly reduced in groups MBM80 and MBM100 as compared with the control (P < 0.05), which resembled the expression of mammalian target of rapamycin (mtor) in liver. Overall, MBM can replace up to 30% dietary FM without significantly adverse effects on growth performance and health of turbot juveniles, but excessive substitution levels (80% and 100%) would compromise antioxidant capacity, liver health and protein metabolism.

Thermal plasticity of growth and chain formation of the dinoflagellates Alexandrium affine and Alexandrium pacificum with respect to ocean acidification

The amount of CO2 absorbed by the oceans continues to rise, resulting in further acidification, altering some functional traits of phytoplankton. To understand the effect of elevated partial pressures of CO2 (pCO2) on functional traits of dinoflagellates Alexandrium affine and A. pacificum, the cardinal temperatures and chain formation extent were examined under two pCO2 (400 and 1,000 μatm) over the range of temperature expected to be associated with growth. The growth rate and chain formation extent of A. affine increased with higher pCO2, showing significant changes in cardinal temperatures and a substantial increase in middle chain-length (4‒8 cells) fractionation under elevated pCO2 condition. By contrast, there were no significant differences in specific growth rate and any chain-length fractionation of A. pacificum between ambient and elevated pCO2 conditions. The observed interspecies variation in the functional traits may reflect differences in ability of species to respond to environmental change with plasticity. Moreover, it allows us to understand the shifting biogeography of marine phytoplankton and predict their phenology in the Korea Strait.

A mesocosm study on bacteria-kelp interactions: Importance of nitrogen availability and kelp genetics.

Macroalgal holobiont studies involve understanding interactions between the host, its microbiota, and theenvironment. We analyzed the effect of bacteria-kelp interactions on phenotypic responses of two genetically distinct populations of giant kelp, Macrocystis pyrifera (north and south), exposed to different nitrogen (N) concentrations. In co-culture experiments with different N concentration treatments, we evaluated kelp growth responses and changes in three specific molecular markers associated with the N cycle, both in epiphytic bacteria (relative abundance of nrfA-gene: cytochrome c nitrite reductase) and macroalgae (expression of NR-gene: nitrate reductase; GluSyn-gene: glutamate synthase). Both kelp populations responded differently to N limitation, with M. pyrifera-south sporophytes having a lower specific growth rate (SGR) under N-limiting conditions than the northern population; M. pyrifera-north sporophytes showed no significant differences in SGR when exposed to low-N and high-N concentrations. This corresponded to a higher GluSyn-gene expression in the M. pyrifera-north sporophytes and the co-occurrence of specific nrfA bacterial taxa. These bacteria may increase ammonium availability under low-N concentrations, allowing M. pyrifera-north to optimize nutrient assimilation by increasing the expression of GluSyn. We conclude that bacteria-kelp interactions are important in enhancing kelp growth rates under low N availability, although this effect may be regulated by the genetic background of kelp populations.

Effect of inoculant density on the growth of glagah consortium culture

The inoculant is an important factor in microalgae cultivation. The right initial density will be more efficient and minimise production costs. The Glagah consortium culture is a mixture of microalgae and bacteria isolated from the Glagah coast in Yogyakarta, Indonesia. This study aimed to determine the initial density to produce optimal growth for the Glagah consortium culture. The study used 3 initial densities: 100,000 cells ml−1, 500,000 cells ml−1 and 1,000,000 cells ml−1, with 3 replicates of each treatment. Parameters observed included specific growth rate, doubling time, biomass and productivity. The results showed significant differences in specific growth rate and doubling time between inoculant treatments. The highest growth rate and fastest doubling time were reached with 100,000 cells ml−1 although the highest cell density was reached with 1,000,000 cells ml−1. Biomass and productivity were not significantly different between treatments. The inoculant density of 100,000 cells ml−1 is considered the most efficient treatment, as compared to the other treatments it can produce similar biomass with less inoculant; it is therefore recommended for use in the cultivation of the Glagah consortium isolate.

High lipid and high carbohydrate diets affect muscle growth of blunt snout bream (Megalobrama amblycephala) through different signaling pathways

The study was carried out to explore the effect of high lipid/carbohydrate diet on muscle growth of Megalobrama amblycephala. In vivo, three experimental diets, a control diet (6% lipid and 28.13% carbohydrate, CD), a high lipid diet (11%lipid，HLD) and a high carbohydrate diet (39.6% carbohydrate, HCD), were formulated and randomly fed to Megalobrama amblycephala (average initial weight 19.80 ± 0.15 g) for 12 weeks. The results showed that there was no significant difference in specific growth rate (SGR) and weight gain rate (WGR) between the control diet group and the high energy diets group (P > 0.05). The springiness, gumminess, chewiness and muscle fiber density were significantly up-regulated in the high energy diets group than control diet group (P < 0.05). HLD, compared with HCD, significantly increased the muscle fiber cross-sectional area (CSA) and muscle fiber diameter in the white muscle (P < 0.05). High energy diets significantly elevate the transcriptional levels of Myf5, Myog and Mrf4, and reduce the transcriptional levels of MSTNa and MSTNb (P < 0.05). The transcriptional levels and protein expressions of AMPK and Sirt1 were significantly elevated in the HLD group (P < 0.05). The CAMK and CAN protein levels were significantly increased in the HCD group (P < 0.05). In vitro, the isolated primary hepatocytes from Megalobrama amblycephala were coincubated with 0.4 mM oleic acid (OA) and 40 mM d-glucose respectively. The results clearly state that 0.4 mM OA significantly increased the transcriptional levels of AMPKα1, AMPKα2 and Sirt1, the protein level of AMPK, p-AMPK, p-AMPK/AMPK and Sirt1 (P < 0.05). The protein expression of CAMK and CAN in hepatocytes treated with 40 mM d-glucose were significantly higher than that in the other two treatments (P < 0.05). In summary, high energy diets promoted the muscle fiber hyperplasia in Megalobrama amblycephala while high lipid and high carbohydrate diets may affect muscle growth through AMPK/Sirt1 pathway and Ca2+-dependent pathway, respectively.

The optimum level of dietary protein and feeding for improving the growth performance and feed efficiency of juveniles Hybrid tilapia (Oreochromis niloticus× Oreochromis aurea) reared in brackish water

A 6-weeks factorial trial (2 × 2) was conducted to determine the optimum level of dietary protein and the optimum feeding rate for the best growth and feed efficiency of hybrid tilapia, Oreochromis niloticus × Oreochromis aurea. Two dietary protein levels were examined; 27% and 34% CP with 5% and 7% of the biomass, and each treatment was performed in triplicate. Twelve plastic tanks (54 × 38 × 28 cm: L × W × H) were used to accomplish this work. The average initial weight was determined (7.5 ± 0.16 g), and fish samples were stocked (12 juveniles/tank). Fishes were fed three times daily and 6 days weekly. The water was daily exchanged at a rate of about 20% of water volume/tank. Results showed that dietary protein levels (from 27% to 34%) did not significantly affect either growth or feed usage parameters. However, 7% feeding rate had significantly higher growth parameters than 5%. Statistical analysis of the interaction between dietary protein and feeding levels showed that fishes fed at 7% as the feeding level with dietary protein at 27% or 34% was significantly higher in growth than those fed at 5% with the same diets. Additionally, results confirmed the significant difference in specific growth rate and survival rate of fishes fed at 7% as feeding rate with any diet protein level. Thus, this study suggests that 27% CP with 7% as feeding rate is more for the best growth of hybrid tilapia juvenile under the same conditions of this trial.

Effects of two dietary fish meal levels on growth performance and feed utilization of 9 &amp;lt;italic&amp;gt;Penaeus monodon&amp;lt;/italic&amp;gt; families

Effects of dietary fish meal levels (30%, 20%) on growth performance and feed utilization of <italic>Penaeus monodon</italic> from 9 families were conducted under laboratory conditions. Results showed that there was no significant difference in specific growth rate (SGR), survival rate(SR), feed conversion ratio (FCR) and apparent feed dry matter digestibility between 9 <italic>Penaeus monodon</italic> families fed with two dietary fish meal levels. Survival rates of families No. 1, No. 3, No. 5 and No. 9 in 20% fish meal level diet group were (58.89±4.84)%,(55.56±10.94)%,(73.34±8.82)%,(64.44±5.88)%, respectively, which were significantly higher than those of other families. Two-way ANOVA analysis showed that there was no significant interaction between dietary fish meal levels and <italic>P</italic>. <italic>monodon</italic> famiies. The growth performance and feed utilization of <italic>P</italic>. <italic>monodon</italic> families were not related to dietary fish meal levels, but to genetic factors of <italic>P</italic>. <italic>monodon</italic>, when the diet protein level was high, the phenotypic difference reduced, and when the diet protein level was low, the significant difference of the genetic effect of growth was obvious. The results provide a theoretical basis and data reference for screening fine strains adapted to low dietary fish meal level through family breeding.

Replacing fishmeal with cottonseed protein concentrate in feed for pearl gentian groupers (Epinephelus fuscoguttatus♀ × E. lanceolatus♂): Effects on growth and expressions of key genes involved in appetite and hepatic glucose and lipid metabolism

This study investigated the effects of replacing the fish meal (FM) in a 55 % FM fish feed with cottonseed protein concentrate (CPC) in pearl gentian groupers (Epinephelus fuscoguttatus♀ × E. lanceolatus♂). Effects on growth and the expression of key genes involved in appetite and hepatic glucose and lipid metabolism Four isoproteic and isolipidic diets were formulated containing 0 %, 6.06 %, 18.18 %, or 30.30 % CPC by replacing 0 % (FM, control), 10 % (CPC10), 30 % (CPC30), and 50 % (CPC50) of the FM in the feed, respectively. Each diet was fed to fish raised in triplicate groups for 56 days. No significant differences in specific growth rate, feed conversion ratio, or survival rate were found among dietary treatments. The weight gain in CPC groups was no different than in controls (P < 0.05). Fish fed the CPC50 diet had higher body lipid contents than others (P < 0.05) and the highest activity of hepatic fatty acid synthase, which was significantly higher than in group CPC10 (P < 0.05). The livers of CPC50 fish had significantly higher mRNA expression levels of apolipoprotein B-100, carnitine palmitoyltransferase 1, peroxisome proliferator-activated receptor α (PPARα), and PPARγ genes compared to other groups except CPC30 (P < 0.05). In conclusion, up to 50 % of the FM in fish feed can be replaced with CPC without adversely affecting the growth and feed utilization of pearl gentian groupers. However, 50 % replacement increased body lipid contents via modulation of hepatic lipid metabolism-related genes and enzyme activity.

Use Of The African Locust Bean, Parkia biglobosa Waste Slurry As Energy Feedstuff In Practical Diets For Tilapia, Oreochromis niloticus L

An assessment of the nutritive value of the waste slurry of the African locust bean, Parkia biglobosa as an energy source in practical diets for tilapia was carried out in glass aquaria. Five diets (35% crude protein) were formulated in which yellow maize was replaced at varying level with parkia slurry waste as follows: Diet 1, (100% slurry), diet 2, (100% yellow maize); diet 3 (75% slurry, 25% yellow maize), diet 4 (50% slurry, 50% yellow maize), diet 5 (25% slurry, 75% yellow maize). Growth performance and nutrient utilization of the fish were based on average daily weight gain (ADG), specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER). Good growth and feed utilization efficiencies were obtained in all diets, however diet 5 had significantly better growth and food utilization with the highest average daily weight gain (ADG) of 0.60, SGR (2.32) and PER (3.05% per day). Difference in SGR were not significantly different between all diets. The result showed that parkia slurry was better utilized by tilapia fish in diets 3 and 5 where their replacements were neither wholly nor equal. Keywords: Parkia slurry, energy, feedstuff, Tilapia

Use of the African locust bean, Parkia biglobosa waste slurry as energy feedstuff in practical diets for Tilapia, Oreochromis niloticus L

An assessment of the nutritive value of the waste slurry of the African locust bean, Parkia biglobosa as an energy source in practical diets for tilapia was carried out in glass aquaria. Five diets (35% crude protein) were formulated in which yellow maize was replaced at varying level with parkia slurry waste as follows: Diet 1, (100% slurry), diet 2, (100% yellow maize); diet 3 (75% slurry, 25% yellow maize), diet 4 (50% slurry, 50% yellow maize), diet 5 (25% slurry, 75% yellow maize). Growth performance and nutrient utilization of the fish were based on average daily weight gain (ADG), specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER). Good growth and feed utilization efficiencies were obtained in all diets, however diet 5 had significantly better growth and food utilization with the highest average daily weight gain (ADG) of 0.60, SGR (2.32) and PER (3.05% per day). Difference in SGR were not significantly different between all diets. The result showed that parkia slurry was better utilized by tilapia fish in diets 3 and 5 where their replacements were neither wholly nor equal.

Use of solid state fermented bambara nut meal as substitute of fishmeal in the diets of African catfishClarias gariepinus

The use of plant proteins in substituting fishmeal (FM) is mitigated by several anti nutritional factors (ANF) like phytic acid, non starch polysaccharides and protease inhibitors. Fermentation of the plant ingredients can reduce the ANF and improve feed utilization and growth rate of fish. We produced five isonitrogenous and isocaloric diets using solid state fermented bambaranut meal (BNM). Fermented BNM substituted FM in diets of African catfish Clarias gariepinus. The FM: BNM inclusion percentages of the diets were, F1, 50:5; F2, 35:20; F3, 20:35; F4, 5:50 and F5, 0:56. There was a control feed labelled as F6. Feed F6 was a variant of F1 but with non fermented BNM. Fingerling African catfish C. gariepinus with average weight 5.14±0.05 g were fed with the diets for 56 days. Specific growth rate (SGR) was best for the catfish fed with F1, 7.82±0.25 % day-1, followed by those fed with F6, 7.35±0.24 % day-1. There were, however, no differences in SGR of F2, 7.26±0.18 % day-1 and F6. The food conversion ratio was lowest and best for the catfish fed with F1, 1.24±0.19 and F2 1.34±0.06. The growth and nutritional performance of fish fed with F2 were as good as F1 and cost-effective. Feeds made from fermented BNM had better FCR than those from raw BNM. Fermentation increased the protein and amino acid content of the BNM and the catfish gained more weight than from raw BNM. The effects of ANF seem to be highly reduced in solid-state fermented BNM thereby enhancing catfish growth.

Culture of the seaweed, Gracilaria tenuistipitata in brackishwater pond as well as lagoon of Muttukadu, Chennai, Tamil Nadu

In this study, an attempt was made to standardise the method of culture of the seaweed Gracilaria tenuistipitata in brackishwater ecosystems. The species was selected as it is available in abundance due to its tolerance for a wide range of salinity, as seaweed culture in brackishwater ecosystem requires a suitable species which is adaptable and proliferating, An experiment was conducted to estimate the proliferation capacity of G. tenuistipitata with different methods of propagation viz., rope culture and net bag culture with different initial biomass intensity (50, 100 and 200 g m-1 in rope and 50, 100 and 200 g m-2 in net bag) in different ecosystems viz., lagoon and pond. The results showed that G. tenuistipitata proliferates in both lagoon and in pond ecosystem, with high SGR in rope culture compared to net bag method. With respect to different initial biomass intensity in rope method, there was no significant difference in specific growth rate (SGR) between 50 g m-1 (12.86±0.35%) and 100 g m-1 (10.94±0.34%) but it was significantly higher when compared to 200 g m-1 (6.14±1.1%) during 20 days of culture in lagoon ecosystem. It was also observed that SGR was significantly higher with 50 g m-2 (7.23±0.46%) when compared with 100 g m-2 (5.86±0.03%) and 200 g m-2 (5.64±0.02%) in net bag culture in pond ecosystem. Moreover, 20 days of culture showed significantly higher SGR with 50 and 100 g m-1 than 40 and 60 days of culture period in lagoon ecosystem. It can be concluded that rope cultivation of G. tenuistipitata with 50-100 g m-1 of initial biomass intensity was ideal in lagoon for 20 days of culture at brackishwater salinity regime of 19-25 ppt.

Analysis of the growth performances, muscle quality, blood biochemistry and antioxidant status of Micropterus salmoides farmed in in-pond raceway systems versus usual-pond systems

In-pond raceway system (IPRS) was introduced to China as a sustainable pond farming approach since 2012 that effectively reduces pollution and facilitates management. To assess how IPRS affect the growth and quality of the farmed fish Micropterus salmoides, various rearing parameters were compared to the usual-pond system (UPS). The growth performances, muscle nutritional quality, serum biochemical indexes, antioxidant enzymatic activities and genes expression were analyzed in Micropterus salmoides with body weight of (8.25 ± 0.51) g reared in IPRS versus usual-pond system(UPS) at stocking densities of 37,500 ind./ha with triplication for 240 days. The final body weight of M. salmoides reared in IPRS and UPS was 482.52 ± 22.53 g and 539.51 ± 34.91 g. Survival rates were higher, despite lower weight gain, in IPRS compared to UPS, with no significant differences in specific growth rate or the food conversion ratio. The hepatosomatic index, viscerosomatic index, and lipid content in liver was lower in IPTS compared to URS. Crude fat and crude protein content significantly differed in muscle. EAA/TAA and EAA/NEAA in the muscle was higher in fish reared in IPRS compared to UPS. Saturated fatty acids in the muscle was lower in fish reared in IPRS compared to UPS. IPRS fish had lower percentages of monounsaturated fatty acids and polyunsaturated fatty acids, including EPA and DHA, than in IPRS.Total protein content was higher in the serum of IPRS fish. Total cholesterol and triglyceride content were lower in IPRS fish. Total bilirubin content and alanine aminotransferase activity was lower in IPRS fish. Glutathione peroxidase activity was higher, while malondialdehyde content was lower, in the liver of IPRS fish. Superoxide dismutase and catalase activity did not differ between the two conditions. mRNA expression of gpx and hsp70 was significantly up-regulated in IPRS compared to UPS. The result show, compared to UPS, IPRS can improve the survival rates, nutritional quality of fish muscle, and liver biological functioning and antioxidant ability of the target fish.

Temperature‐dependent competition between juvenile salmonids in small streams

Abstract Biotic interactions affect species distributions, and environmental factors that influence these interactions can play a key role when range shifts in response to environmental change are modelled. In a field experiment using enclosures, we studied the effects of the thermal habitat on intra‐ versus inter‐specific competition of juvenile Dolly Varden Salvelinus malma and white‐spotted charr Salvelinus leucomaenis, as measured by differences in specific growth rates during summer in allopatric and sympatric treatments. Previous laboratory experiments have shown mixed results regarding the importance of temperature‐dependent competitive abilities as a main driver for spatial segregation in stream fishes, and no study so far has confirmed its existence in natural streams. Under natural conditions in areas where the two species occur in sympatry, Dolly Varden dominate spring‐fed tributaries (cold, stable thermal regime), whereas both species often coexist in non‐spring‐fed tributaries (warm, unstable thermal regime). Enclosures (charr density = 6 per m2) were placed in non‐spring‐fed (10–14°C) and spring‐fed (7–8°C) tributaries. In enclosures placed in non‐spring‐fed tributaries, Dolly Varden grew 0.81% per day in allopatry and had negative growth (−0.33% per day) in sympatry, whereas growth rates were similar in allopatry and sympatry in spring‐fed tributaries (0.68 and 0.58% per day). White‐spotted charr grew better in sympatry than in allopatry in both thermal habitats. In non‐spring‐fed tributaries, they grew 0.17 and 0.79% per day and in spring‐fed tributaries 0.46 and 0.75% per day in allopatry and sympatry, respectively. The negative effect of inter‐specific competition from white‐spotted charr on Dolly Varden thus depended on the thermal habitat. However, there was no strong evidence of a temperature‐dependent effect of intra‐ and inter‐specific competition on white‐spotted charr growth. Multiple factors may shape species distribution patterns, and we show that temperature may mediate competitive outcomes and thus coexistence in stream fish. These effects of temperature will be important to incorporate into mechanistic and dynamic species distribution models.