Food Conversion Efficiency Research Articles

Suitability of Turkey Oak, European Beech, and Hornbeam to Gypsy Moth Feeding

Pest resistance of trees should be taken into account in future forest strategy planning and predicting risks of defoliation. The gypsy moth (GM) (Lymantria dispar L.) is a serious forest pest with outbreaking population dynamics. To estimate defoliation risk of the most widely distributed tree species in Balkan Peninsula and Europe (Turkey oak Quercus cerris L., European beech Fagus sylvatica L. and hornbeam Carpinus betulus L.), we carried out laboratory feeding trials and investigated their acceptability and suitability for GM development. We determined morphological and chemical attributes of these hosts as well as larval host preference, growth and nutritional indices. Preference, growth, and efficiency of food conversion into biomass were ranked in the order: Turkey oak ˃ European beech ˃ hornbeam. Hornbeam was the most avoided and showed the lowest conversion efficiency although, comparing to optimal oak host, its leaves were less tough, contained more water and exhibited similar values of nitrogen (index of protein content) and C/N ratio (index of investment into carbon based plant defense). We suggest that hornbeam and beech leaf chemical profiles should be further studied to reveal specific compounds that impose high metabolic cost to GM larvae. Moreover, additional research are needed to understand how intermediate hosts in natural populations affect GM outbreaks.

Effect of Metarhizium anisopliae on the nutritional physiology of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

BackgroundThe fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), was recorded for the first time in Pakistan in 2019, and now it has spread in several regions, i.e., Punjab and Sindh, affecting maize production. Farmers are using widely synthetic pesticides to control the pest. Further, the resistance development in insects and the non-target effect of chemicals on the environment and humans pose serious threats of using insecticides. The use of entomopathogenic fungi (EPF) is being considered an important tool in integrated pest management program. The main objective of this study was to check the impact of different conidial concentrations of Metarhizium anisopliae fungus on the nutritional physiology of S. frugiperda.ResultsThe dose-dependent effect of tested EPF was observed, and the highest concentration (1 × 109 conidia/ml) considerably affected nutritional parameters. Reduced relative consumption rate (21.7%), relative growth rate (19.5%), the efficiency of conversion of ingested food (24.2%), and approximate digestibility (16.3%) were observed in treated larvae compared to the untreated by using a higher concentration of EPF. Pupal weight was also found lower (77.9 mg and 84.2 mg, respectively), when larvae were treated by 1 × 109 and 1 × 108 conidia/ml concentrations of EPF. Further, 46.7% of larvae were found dead with this conidial concentration.ConclusionsThis study suggests that the application of a higher concentration of M. anisopliae could be an effective option to control S. frugiperda. The EPF can enhance the integrated pest management programs and could be useful in reducing the environmental impact of synthetic insecticides.

Survival rate, growth and condition index of tank-raised Clarias gariepinus under different salinities

The study evaluated varying levels of salinity on survival, growth and condition index of tank raised Clarias gariepinus for ten weeks. A total of 120 healthy C. gariepinus fingerlings having a bulk weight and average length of 131.73 ± 0.85 g and 5.06 ± 0.24 cm respectively were procured from the hatchery complex of University of Calabar fish farm and used for the study. Sea water was collected from Ibeno Beach and diluted with borehole water to obtain various salinity concentrations of ≤1, ≤5, ≤10 and ≤15 ppt. This represented four treatments(Tanks A to D) and each treatment had three replicates. Evaluation of growth indices and culture water parameters followed standard procedure. Results revealed significant (p < 0.05) differences with regards to food intake in the treatment Tanks A (≤1ppt), B (≤5ppt), C (≤10ppt) and D (≤15ppt). Food conversion efficiency (FCE), ratio (FCR) and protein efficiency ratio (PER) were significantly different (p < 0.05). Body weight gain were observed to be higher in Tank A with a value of 75.83± 0.07g/kg and a total length of 11.13 ±0.38cm and the lowest weight gain was recorded in Tank D with a value of 43.56 ± 0.76g/kg and a mean total length of 6.67± 0.43cm. There were significant differences (p < 0.05) in the final condition factor (K) of the fish. Hence, it could be established that C. gariepinus fingerlings can survive and be reared in 5ppt saline water without any adverse effect on growth. At salinity level above 5ppt, fish growth rate may be slow.
 Keywords: Survival rate, Growth, Clarias gariepinus, Salinity, Physicochemical parameters

Influence of Garlic (Allium sativum) Clove-Based Selenium Nanoparticles on Status of Nutritional, Biochemical, Enzymological, and Gene Expressions in the Freshwater Prawn Macrobrachium rosenbergii (De Man, 1879).

Selenium (Se) is one of the essential micronutrients for performing vital body functions. This study aims at examining the influence of dietary supplementation of garlic clove-based green-synthesized selenium nanoparticles (GBGS-SeNPs, 48-87nm) on carcass minerals and trace elements, and growth, biochemical, enzymological, and gene expression analyses in the freshwater prawn, Macrobrachium rosenbergii post larvae (PL). The 96h LC50 of this GBGS-SeNPs to M. rosenbergii PL was 52.23mgL-1. Five different artificial diets without supplementation of GBGS-SeNPs (control, 0.0mgkg-1) and with supplementations of GBGS-SeNPs starting from 100 times lower than the LC50 value (0.5, 1.0, 1.5, and 2.0mgkg-1) were prepared and fed to M. rosenbergii PL for 90days. A dose-dependent accumulation of Se was observed in the carcass of experimental prawns. GBGS-SeNPs, up to 1.5mgkg-1 significantly influenced the absorption of other trace elements (Ca, Cu, and Fe) and mineral salts (K, Mg, Na, and Zn). GBGS-SeNPs-supplemented diets showed efficient food conversion ratio (FCR) of 1.32g against 2.71g, and therefore enhanced the survival rate (85.6% against 78.8% in control) and weight gain (WG) of 1.41g against 0.46g of control prawn. GBGS-SeNPs significantly elevated the activities of protease, amylase, and lipase, and the contents of total protein, essential amino acids (EAA), total carbohydrate, total lipid, monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and ash. These indicate the growth promoting potential of GBGS-SeNPs in prawn. The insignificantly altered activities of glutamic oxaloacetate transaminase (GOT), glutamic pyruvate transaminase (GPT), superoxide dismutase (SOD), and catalase, and the content of malondialdehyde (MDA) up to 1.5mgkg-1 suggest its acceptability in prawn. Moreover, a respective down- and upregulated myostatin (MSTN) and crustacean hyperglycemic hormone (CHH) genes confirmed the influence of GBGS-SeNPs on the growth of prawn. In contrast, 2.0mgkg-1 GBGS-SeNPs supplementation starts to produce negative effects on prawn (FCR, 1.76g; survival rate, 82.2%; WG, 0.84g against respective values of 1.32g, 85.6%; and 1.41g observed in 1.5mgkg-1 of GBGS-SeNPs-supplemented diet fed prawn). This study recommends a maximum of 1.5mgkg-1 GBGS-SeNPs as dietary supplement to attain sustainable growth of M. rosenbergii. This was confirmed through polynomial and linear regression analyses.

Comparison the Effect of Bromelain and Papain Enzymes on Fish Food which Prepared from Poultry Waste Powder on Common Carp (Cyprinus Carpio L.) Growth Performance

The study was conducted in the Fish Laboratory / College of Agriculture / University of Tikrit to study the effect of poultry waste powder supplemented with the Bromelain and Papain enzymes at rates of 2% and 3% on growth rates, 60 fish were randomly distributed with two replicates for each treatment, 6 fish for each replicate into 10 aquaria. The fish feed containing poultry droppings powder were prepared and chemical analyzes were conducted and they were used to feed common carp fish Cyprinus Carpio L. Treatment T3 recorded the highest weight gain of 91.49 g, while it decreased in treatment T2 to 69.85 g. The relative growth rate of treatment T3: 54.62% increased, and the specific growth of 0.30 g / day, and the efficiency of food conversion decreased in treatment T4: 28.30% compared with the other treatments. Significant differences were recorded at the level (P≤0.05) between the different experimental treatments, and most of the treatments covered the common carp requirements of essential amino acids.

Chemical composition and bioactivities of Melaleuca alternufolia essential oil and its main constituents against Spodoptera littoralis (Boisaduval, 1833)

BackgroundSpodoptera littoralis is mostly controlled by the use of synthetic insecticides. Nonetheless, the use of these insecticides causes a slew of issues. On this pest, the antifeedant activity of Melaleuca alternifolia essential oil (EO) and its two principal components was investigated.ResultsThe gas chromatography–mass spectrometry (GC/MS) analysis revealed that the M. alternifolia EO was composed of eleven compounds. Terpinen-4-ol (40.1%) and γ-terpinene (21.9%) were chosen as the major constituents. In terms of antifeedant efficacy, treatment with M. alternifolia EO and these components reduced leaf consumption and the efficiency of food conversion in larvae in a concentration-dependent manner. When compared to untreated larvae, weight, growth, and pupation percentage were all significantly lower.ConclusionsThe findings show that M. alternifolia EO and its components, terpinen-4-ol and γ-terpinene can be effectively combined for cotton leafworm management.

Cry3Aa Toxin Is Not Suitable to Control Lepidopteran Pest Spodoptera littoralis (Boisd.).

The toxicity of the Bacillus thuringiensis (Bt) toxin Cry3Aa—originally used against the main potato pest, the Colorado potato beetle, Leptinotarsa decemlineata—was verified on this species and then evaluated against the Egyptian armyworm, Spodoptera littoralis, which is a pest of several economically important plants. Larvae of S. littoralis were fed a semi-artificial diet supplemented either with a recombinant or with a natural Bt toxin Cry3Aa and with the genetically engineered (GE) potato of variety Superior NewLeaf (SNL) expressing Cry3Aa. Cry3Aa concentration in the diet and the content in the leaves were verified via ELISA (enzyme-linked immunosorbent assay) and HPLC (high-performance liquid chromatography) during and at the end of the experiments. The biological effectiveness of the coleopteran-specific Cry3Aa with previous reports of activity against S. littoralis was tested on five different populations of S. littoralis larvae by monitoring 13 parameters involving development from penultimate instar, weight, the efficiency of food conversion to biomass, ability to reproduce, and mortality. Although some occasional differences occurred between the Cry3Aa treatments and control, any key deleterious effects on S. littoralis in this study were not confirmed. We concluded that the Cry3Aa toxin appears to be non-toxic to S. littoralis, and its practical application against this pest is unsuitable.

In vitro hemocyte phagocytosis activation after experimental infection of common octopus, Octopus vulgaris (Cuvier, 1797) with Photobacterium damselae subsp. piscicida or Vibrio alginolyticus at different temperatures and infection routes

Due to the fast growth rate, the short life cycle, the high market price and the high food conversion efficiency, O. vulgaris is considered as a good candidate for aquaculture. One of the prerequisites for the successful integration of new species, such as octopi, into industrial-scale production, is the knowledge of the pathological conditions that may arise, with emphasis on infectious diseases caused by microorganisms and para-sites transmitted through wild populations, especially for the farmed organisms cul-tured in cages in proximity to teleost fish. The main objectives of this study were to investigate the sensitivity of common octopus to experimental infection with pathogenic bacteria, to assess the activation of hemocytes and more specifically their phagocytic activity after infection and to associate sensitivity of the species and phagocytic activity of hemocytes to temperature changes, route of infection and pathogen. Common octopus individuals were intramuscularly and intravenously infected with either Photobacterium damselae subsp. piscicida or Vibrio alginolyticus. The hemocyte phagocytosis activation in vitro at two temperatures (21 ± 0.5 °C and 24 ± 0.5 °C) was studied, in an effort to relate these aspects to climate change. Hemolymph was withdrawn on days 0, 3 and 7 post infections/injections. Number of circulating hemocytes/ml hemolymph, phagocytosis ability and Phagocytosis Particle Binding Intensity index were determined. Correlations between hemocytes and bodyweight and between hemocytes and phagocytosis ability were also determined.No mortalities were recorded irrespective of pathogen, route of infection and temperature employed. Circulating hemocytes in control specimens ranged between 1.60x105 hemocytes ml−1 hemolymph to 20.02x105 hemocytes/ml hemolymph at both experiments and temperatures. The interrelation between octopi weight and circulating hemocytes showed that natural fluctuations, age, maturity stage and temperature may affect this relationship.Rise of temperature influenced phagocytosis which seemed to be route of infection, time-point and pathogen related. Specimens infected with Photobacterium damselae subsp. piscicida showed decreased phagocytosis with rise of temperature while when Vibrio alginolyticus was used, phagocytosis activity increased, in most cases. Temperature also played an important role in the correlation between the circulating hemocytes and phagocytosis activity, as at lower temperatures a negative strong correlation was observed. The results prompted us to calculate the activation index. This index showed that temperature is an important factor in hemocyte activation since for Photobacterium damselae subsp. piscicida infected specimens, hemocytes were more activated at 21 ± 0.5℃ instead of 24 ± 0.5℃, and the opposite observed for Vibrio alginolyticus samples and only later post-infection.Comparing the phagocytosis ability results with those obtained from Particle Binding Intensity index important differences concerned mainly confidence levels. The use of phagocytosis ability instead of PBI index provides more accurate results.

Comparative analysis of Hermetia illucens L. mixed chicken feed and commercial chicken feed to growth performance, carcass weight, and meat proximate content of Gallus domesticus L.

The development of the broiler farming industry to meet the needs of chicken meat in Indonesia has problems including the availability and high prices of commercial feed. This is due to the use of high-priced protein sources from a fish meal as a commercial feed composition. One option that can replace a fish meal as a composition of broiler feed is Hermetia illucens L. larvae flour. This study aims to determine the difference between H. illucens mixed chicken feed (HiMCF) and commercial chicken feed (CCF) on growth performance of Gallus domesticus L. with parameters Final Body Weight (FBW), Daily Feed Intake (DFI), Daily Weight Gain (DWG), Feed Conversion Ratio (FCR), Approximate Digestibility (AD), Efficiency of Conversion Digestibility (ECD), carcass weight with 3-joint wings, forequarter, and leg quarter, and the meat proximate content. In this study, G. domesticus were cultivated for 33 days with HiMCF and CCF treatment. The complete proximate content of feed and meat was analyzed descriptively, while growth and carcass weight were analyzed by statistical SPSS T-test (T-test, = 0.05). The feeding of HiMCF and CCF treatment on the growth of broiler chickens to DFI, DWG, FCR, AD, and ECD was the same except for FBW. While the feeding of HiMCF and CCF treatment to the carcass weight was not the same except for 3-joint wings. The feeding of HiMCF and CCF treatment gave the same proximate content of broiler chicken meat. Based on this research, the HiMCF can be an alternative feed for broiler chickens.

Growth of black molly Poecilia sphenops (Poecilidae: Pisces) Reared in closed recirculating water system

The experiment was conducted study the effect of temperature and food composition on growth, food conversion efficiency, food conversion rate and quantity of food intake by larvae of black molly Poecilia sphenops in closed recirculating water system Three types of food were employed. The first (I) was live food, brine shrimp Artemia, the second (II) was experimental artificial diet and the third (III) was commercial diet. The three diets were served under two temperature: (28±1°C and 22±1°C). Results showed that under temperature 28±1°C, the total weight increment and relative growth rate were 2.98-5.87 g and 1865.62- 3671.87 respectively. In the temperature 22±1°C these values were significantly lower (p<0.05). The I and II higher values than treatments III with significant difference (p<0.05) in both thermal degrees. In the temperature (22±1°C) the food conversion rate and efficiency rate attained 2.052 and 48.746 respectively in treatment II which were higher than that of treatment III (2.686 and 37.220 respectively), the two items were greater in temperature 28±1°C, and at treatment II (1.662 and 60.177 respectively) in comparison with the treatment III (2.220 and 45.064 respectively), the treatment II higher values than III with significant difference(p<0.05) in both degrees. The food intake larger in the 28±1°C than degree 22±1°C with significant difference for both treatments II and III, food intake in treatment II was larger significantly (p<0.05) than III at degree 22±1°C and non significantly (p>0.05) at degree 28±1°C.

PROCESSING OF FISH PROTEIN CONCENTRATE FROM DRIED FISH BY ACETIC ACID DIGESTION

This investigation is aimed at processing fish protein concentrate from dried fish that subjected to digestion with acetic acid at pH 4. The dried fish contained 46.26% protein, 19.65% fat and 23.89% ash. The processed protein product comprised of 69.84% protein, 8.43% fat and 15.58% ash. The yield was 70.15% of raw materials. The processed product characterized with dark brown colour, acceptable fishy smell and revealed high storage stability when stored at room temperature (28°C) for 60 days without noticeable changes. The stored product had low bacterial count that valued 1200 CFU/gm. Coliform bacteria were not existed. Total volatile Nitrogen Bases (TNVB) was low and valued 9.8 mgN/100 gm. Rancidity hadn’t developed as TBA rated 0.24 mg malonaldehyde/kg. The processed product and a commercial protein concentrate were employed separately in formulating experimental diets R1 and R2 respectively. Each ration was used in feeding trials on carp fingerlings for 60 days. The results for R1 and R2 were respectively as follows: 0.77 and 0.51 for specific growth rate (SGR); 4.04 and 5.79 for food conversion ration (FCR); 24.71% and 17.26% for Food conversion efficiency (FCE); 16.56 and 12.23% protein deposit (PD). It can be concluded that the proposed method employed in this project was successful in processing fish protein concentrate with good storage stability and acceptable sensory properties.

The biological and physiological responses of Leptinotarsa decemlineata Say (Col. Chrysomelidae) to different potato cultivars.

The use of pest-resistant or less susceptible plant varieties is of great importance for integrated pest management programs. This study was conducted to evaluate the resistance of seven potato cultivars to a major pest, namely the Colorado potato beetle (CPB), by measuring its bio-physiological aspects. The longest developmental time and the lowest survival rate of CPB were detected on cultivar 'Manitou.' Although the larvae fed voraciously, the food conversion efficiency was the lowest on this cultivar leading to the lowest relative growth rate. Furthermore, larvae reared on Manitou had the lowest total protease activity and specific activity values of cathepsin B compared to the larvae reared on other cultivars. Additionally, the cluster analysis showed that the Manitou cultivar was the least suitable (partially resistant) CPB. Moreover, the results indicated that the protein content was the lowest in the Manitou cultivar; conversely, this cultivar was rich in polyphenol and flavonoid compared to Agria and Santae cultivars. The overall results in this study indicated that the Manitou cultivar might be a good candidate to be incorporated into integrated pest management programs. © 2022 Society of Chemical Industry.

Dietary Strategies for Better Utilization of Aquafeeds in Tilapia Farming

Feed management practices significantly impact the production performance of tilapia (Oreochromis species) culture economically; hence, adopting appropriate feed management strategies is vital to maximize returns. The advancement in aquaculture has also allowed an advancement in the development formulated feeds to supplement or replace natural feeds. Farmers are now able to prepare their own fish feeds from locally available ingredients. Hence, feed ingredient evaluation is crucial for better development of appropriate diets for different aquaculture species as well as nutritional research. Therefore, this review used secondary data to evaluate the different strategies employed for better utilization of nutrients in feed by providing a discussion of functional feed additives used in aquafeeds such as the addition of enzymes, pre/probiotics, feeding stimulants, and use of hormones. Supplementation of diet with xynalase and phytase enzymes ( P < 0.001 ) and probiotics ( P < 0.05 ) improved growth (g/d) and FCR when applied individually. The combination of enzymes and probiotics showed an interaction effect ( P < 0.05 ) on growth and FCR. A detailed discussion of feed ingredient processing strategies like fermentation, heat treatment, germination, and other biological methods meant to improve the nutritional quality of the feed and minimize antinutritional factors is provided. Furthermore, information on how genetic selection is being used to enhance feed utilization in tilapia fish is provided. The food conversion efficiency was found to be significantly higher ( P < 0.05 ) in transgenic tilapia compared to the nontransgenic red tilapia fish with average weight ± SD of 384 ± 158 g and 314 ± 101 for transgenic fish and red tilapia, respectively, after 275 days of culture. The review further outlines the feed formulation challenges, and research gaps in tilapia nutrition. It was noted that proper feeding management strategies are very critical for the sustainability of tilapia aquaculture. In conclusion, dietary sources for tilapia are slowly shifting to plant-based products. However, these come with a lot of antinutritional factors and digestibility problems; hence, the right feeding strategies have to be employed to enable efficient nutrient utilization. The review discovered that there are a lot of strategies which employed research gaps in tilapia nutrition, especially on nutrient utilization of feed and feed formulation.

Leptin: A Potential Link Between Obstructive Sleep Apnea and Obesity.

Chronic intermittent hypoxia (CIH), a pathophysiological manifestation of obstructive sleep apnea (OSA), is strongly correlated with obesity, as patients with the disease experience weight gain while exhibiting elevated plasma levels of leptin. This study was done to determine whether a relationship may exist between CIH and obesity, and body energy balance and leptin signaling during CIH. Sprague-Dawley rats were exposed to 96 days of CIH or normoxic control conditions, and were assessed for measures of body weight, food and water intake, and food conversion efficiency. At the completion of the study leptin sensitivity, locomotor activity, fat pad mass and plasma leptin levels were determined within each group. Additionally, the hypothalamic arcuate nucleus (ARC) was isolated and assessed for changes in the expression of proteins associated with leptin receptor signaling. CIH animals were found to have reduced locomotor activity and food conversion efficiency. Additionally, the CIH group had increased food and water intake over the study period and had a higher body weight compared to normoxic controls at the end of the study. Basal plasma concentrations of leptin were significantly elevated in CIH exposed animals. To test whether a resistance to leptin may have occurred in the CIH animals due to the elevated plasma levels of leptin, an acute exogenous (ip) leptin (0.04 mg/kg carrier-free recombinant rat leptin) injection was administered to the normoxic and CIH exposed animals. Leptin injections into the normoxic controls reduced their food intake, whereas CIH animals did not alter their food intake compared to vehicle injected CIH animals. Within ARC, CIH animals had reduced protein expression of the short form of the obese (leptin) receptor (isoform OBR100) and showed a trend toward an elevated protein expression of the long form of obese (leptin) receptor (OBRb). In addition, pro-opiomelanocortin (POMC) protein expression was reduced, but increased expression of the phosphorylated extracellular-signal-regulated kinase 1/2 (pERK1/2) and of the suppressor of cytokine signaling 3 (SOCS3) proteins was observed in the CIH group, with little change in phosphorylated signal transducer and activator of transcription 3 (pSTAT3). Taken together, these data suggest that long-term exposure to CIH, as seen in obstructive sleep apnea, may contribute to a state of leptin resistance promoting an increase in body weight.

Evaluation of the ability of Pichia guilliermondii to improve growth performance and disease resistance in rainbow trout (Oncorhynchus mykiss)

AbstractThis study examined supplementation of a novel yeast product containing Pichia guilliermondii on juvenile rainbow trout, Oncorhynchus mykiss, growth, and disease resistance. In two separate trials, fish (initial weight 6.2 and 10.6 g, respectively), were fed an extruded diet (41% digestible protein and 18% crude lipid) supplemented with 0.3 or 0.6% P. guilliermondii alone or 0.3% P. guilliermondii with a dietary gut supplement at 0.1%. Prior to the end of each trial, a subsample of fish from each tank was exposed by immersion to Yersinia ruckeri (Trial 1) or injection with Flavobacterium pyschrophilum (Trial 2). At the conclusion of the trials, supplementation of either P. guilliermondii or the gut supplement improved growth and food conversion efficiency in rainbow trout when fed for 16‐weeks. No effects of supplementation on mortality were observed. These results suggest potential as functional additives; however, additional investigation regarding the efficacy of whole‐cell and disrupted wall components of P. guilliermondii is needed to better assess their potential effects on rainbow trout immune responses.

Acaricide-impaired functional and numerical responses of the predatory mite, Amblyseius largoensis (Acari: Phytoseiidae) to the pest mite Raoiella indica (Acari: Tenuipalpidae)

The suppression of pest populations by a predator depends on two basic components of the predator-prey interaction: the functional and the numerical responses of the predator. Such responses can be affected by exposure to acaricides. In the present study, the effects of acaricides (abamectin, azadirachtin, fenpyroximate, and chlorfenapyr) on the functional and numerical responses of the predatory mite, Amblyseius largoensis (Acari: Phytoseiidae) an important natural enemy of the pest mite, Raoiella indica (Acari: Tenuipalpidae), were investigated. The exposure of A. largoensis to acaricides occurred through contact with a surface contaminated with dried acaricide residue. Subsequently, A. largoensis exhibited a type II functional response, which was not altered by exposure of any acaricides. However, exposure to abamectin resulted in a decrease in the average mean numbers of prey consumed by a predator. Exposure to acaricides increased prey handling time by 67%, 25%, 38%, and 35% for abamectin, azadirachtin, fenpyroximate, and chlorfenapyr, respectively. Exposure to abamectin reduced the attack rate of A. largoensis by 52%. The numerical response of A. largoensis was only affected by exposure to abamectin, where just 60% of the females oviposited, and regardless of the prey density, the average mean numbers of eggs/female/day was always less than 0.4. The food conversion efficiency into biomass of A. largoensis eggs decreased with increasing prey density, and this trend was not altered by exposure to any acaricides. However, exposure to abamectin drastically compromised the oviposition of A. largoensis, showing no increase in egg production with increasing prey density.

Effect of insecticides on food consumption and utilization behaviour of different populations of Spodoptera litura (Fabricius)

Spodoptera litura (Fabricius) is an economically important pest causing damage to wide range of agricultural crops worldwide. The effect of different insecticides viz. emamectin benzoate 5 SG, spinosad 45 SC, indoxacarb 14.5 SC, cyantraniliprole 10.26 OD and fenvalerate 20 EC on food consumption and utilization in S. litura larval populations of Punjab were studied in the laboratory. Among all insecticides, emamectin benzoate has the most potent effect on the feeding of S. litura larvae recording the lowest relative consumption rate (RCR), relative growth rate (RGR), the efficiency of conversion of ingested food to body substance (ECI), the efficiency of conversion of digested food to body substance (ECD) while highest approximate digestibility (AD). The value of all nutritional indices, except approximate digestibility (AD) was higher for larvae of S. litura fed on untreated food followed by treated food with fenvalerate, spinosad, indoxacarb, cyantraniliprole and emamectin benzoate. The RCR, RGR, ECI and ECD were higher for Amritsar larval populations followed by Kapurthala, Malerkotla, Ludhiana and susceptible populations. On the other hand, approximate digestibility (AD) was recorded higher for larvae of susceptible population followed by Ludhiana, Malerkotla, Kapurthala and Amritsar populations of S. litura.

Effect of different protein based feed on the growth of mahseer.

For the proper growth of fish, it is necessary to feed the fish with a proper and balanced diet. A study was conducted to find out the effect of different protein-based diets on fingerlings of Tor putitora (mahseer). A feed with dietary protein levels of 35%, 40%, 45%, and 50% were prepared. The effect of different protein-based feed on weight gain, standard growth rate (SGR), food conversion ratio (FCR), percent weight gain, food conversion efficiency (FCE), and protein efficiency ratio (PER) was studied. An increase was observed in the growth rate with an increase in protein concentration up to 45%. The fingerlings fed a 45% protein diet shown the highest growth, followed by 50%, 40%, and 35%. The SGR value was greatest for 45% protein diet (8.56) followed by 50% and 40%, while the least values were observed for 35% protein feed (1.57). The same trend was observed for FCE. The highest PER values was observed in fishes fed 45% protein-based feed (0.65) followed by 50% (0.56), 40% (0.38) and35% (0.17). The food conversion ratio was lowest for 45% protein diet (3.41), while the greatest for 35% protein feed (16.85). It was concluded that a 45% protein-based diet was the best feed formulation for higher production of Tor putitora. However, research on the same percentage of protein diet is recommended for yearlings.

An unusually high upper thermal acclimation potential for rainbow trout.

Thermal acclimation, a compensatory physiological response, is central to species survival especially during the current era of global warming. By providing the most comprehensive assessment to date for the cardiorespiratory phenotype of rainbow trout (Oncorhynchus mykiss) at six acclimation temperatures from 15°C to 25°C, we tested the hypothesis that, compared with other strains of rainbow trout, an Australian H-strain of rainbow trout has been selectively inbred to have an unusually high and broad thermal acclimation potential. Using a field setting at the breeding hatchery in Western Australia, thermal performance curves were generated for a warm-adapted H-strain by measuring growth, feed conversion efficiency, specific dynamic action, whole-animal oxygen uptake (ṀO2) during normoxia and hypoxia, the critical maximum temperature and the electrocardiographic response to acute warming. Appreciable growth and aerobic capacity were possible up to 23°C. However, growth fell off drastically at 25°C in concert with increases in the time required to digest a meal, its total oxygen cost and its peak ṀO2. The upper thermal tipping points for appetite and food conversion efficiency corresponded with a decrease in the ability to increase heart rate during warming and an increase in the cost to digest a meal. Also, comparison of upper thermal tipping points provides compelling evidence that limitations to increasing heart rate during acute warming occurred well below the critical thermal maximum (CTmax) and that the faltering ability of the heart to deliver oxygen at different acclimation temperatures is not reliably predicted by CTmax for the H-strain of rainbow trout. We, therefore, reasoned the remarkably high thermal acclimation potential revealed here for the Australian H-strain of rainbow trout reflected the existing genetic variation within the founder Californian population, which was then subjected to selective inbreeding in association with severe heat challenges. This is an encouraging discovery for those with conservation concerns for rainbow trout and other fish species. Indeed, those trying to predict the impact of global warming should more fully consider the possibility that the standing intra-specific genetic variation within a fish species could provide a high thermal acclimation potential, similar to that shown here for rainbow trout.

Cultivation of different densities of common carp ( Cyprinus carpio L.1758 ) in floating cages in the Euphrates River in Nasiriyah city

current study was conducted to show the effect of culturing common carp Cyprinus carpio with different densities in floating cages in the Euphrates River in Nasiriyah city, Dhi Qar governorate, on some growth indicators, for a period of (10/17) 2020 until 10/6/2021). Four different treatments were used in the density of culture (200, 300, 400, 500) respectively, and the average weight ranged between (42-55) g. Floating cages made of PVC were used, the same diet was used to feed fish for the four treatments. The results of the current study were evaluated according to growth criteria (total weight gain, daily weight gain, relative growth rate, specific growth rate, food conversion factor, food conversion efficiency, protein efficiency ratio). The results showed that the first treatment, followed by the second treatment, outperformed the third and fourth treatments. It was concluded from the current study that the lowest densities of common carb achieve the best rates of growth indicators.