Carbohydrate Energy Source Research Articles

Microplastic Contamination in Aquafeed Ingredients Used as Protein and Carbohydrate Sources.

The current study aimed to evaluate the occurrence of microplastics in feed ingredients commonly used as protein and carbohydrate (energy) sources to understand and mitigate microplastic contamination. Microplastics average was 1.27, 0.69, 2.85, 0.55, 0.07, and 0.17 particle g- 1 in fishmeal, soybean meal, poultry by-products, rice bran, wheat bran, and wheat flour, respectively. Notably, poultry by-products demonstrated significantly higher microplastic levels than other ingredients (p < 0.05). The dominant microplastic shape was microfibers, with prevalent sizes ranging from 500 to 1000μm. We estimated that packaging materials are a significant source of pollution due to the high presence of polypropylene and other polymers. Top aquaculture species with the greatest microplastic exposure risk include the Catla catla, Hypophthalmichthys nobilis, and Oreochromis niloticus. This research extends our knowledge of microplastic pathways, contributes to improving aquafeed quality, and provides the basis for determining the risk of microplastic exposure in aquafeed.

Hypoxia tolerance in fish depends on catabolic preference between lipids and carbohydrates.

Hypoxia is a common environmental stress factor in aquatic organisms, which varies among fish species. However, the mechanisms underlying the ability of fish species to tolerate hypoxia are not well known. Here, we showed that hypoxia response in different fish species was affected by lipid catabolism and preference for lipid or carbohydrate energy sources. Activation of biochemical lipid catabolism through peroxisome proliferator-activated receptor alpha (Pparα) or increasing mitochondrial fat oxidation in tilapia decreased tolerance to acute hypoxia by increasing oxygen consumption and oxidative damage and reducing carbohydrate catabolism as an energy source. Conversely, lipid catabolism inhibition by suppressing entry of lipids into mitochondria in tilapia or individually knocking out three key genes of lipid catabolism in zebrafish increased tolerance to acute hypoxia by decreasing oxygen consumption and oxidative damage and promoting carbohydrate catabolism. However, anaerobic glycolysis suppression eliminated lipid catabolism inhibition-promoted hypoxia tolerance in adipose triglyceride lipase (atgl) mutant zebrafish. Using 14 fish species with different trophic levels and taxonomic status, the fish preferentially using lipids for energy were more intolerant to acute hypoxia than those preferentially using carbohydrates. Our study shows that hypoxia tolerance in fish depends on catabolic preference for lipids or carbohydrates, which can be modified by regulating lipid catabolism.

Oxidation of independent and combined ingested galactose and glucose during exercise.

Coingestion of glucose and galactose has been shown to enhance splanchnic extraction and metabolism of ingested galactose at rest; effects during exercise are unknown. This study examined whether combined ingestion of galactose and glucose during exercise enhances exogenous galactose oxidation. Fourteen endurance-trained male and female participants [age, 27 (5) yr; V̇o2peak, 58.1 (7.0) mL·kg-1·min-1] performed cycle ergometry for 150 min at 50% peak power on four occasions, in a randomized counterbalanced manner. During exercise, they ingested beverages providing carbohydrates at rates of 0.4 g.min-1 galactose (GAL), 0.8 g.min-1 glucose (GLU), and on two occasions 0.8 g.min-1 total galactose-glucose (GAL + GLU; 1:1 ratio). Single-monosaccharide 13C-labeling (*) was used to calculate independent (GAL, GLU, GAL* + GLU, and GAL + GLU*) and combined (GAL* + GLU*, COMBINE) exogenous-monosaccharide oxidation between exercise. Plasma galactose concentrations with GAL + GLU [0.4 mmol.L; 95% confidence limits (CL): 0.1, 0.6] were lower (contrast: 0.5 mmol.L; 95% CL: 0.2, 0.8; P < 0.0001) than when GAL alone (0.9 mmol.L; 95% CL: 0.7, 1.2) was ingested. Exogenous carbohydrate oxidation with GAL alone (0.31 g·min-1; 95% CL: 0.28, 0.35) was marginally reduced (contrast: 0.05 g·min-1; 95% CL: -0.09, 0.00007; P = 0.01) when combined with glucose (GAL* + GLU 0.27 g·min-1; 0.24, 0.30). Total combined exogenous-carbohydrate oxidation (COMBINE: 0.57 g·min-1; 95% CL: 0.49, 0.64) was similar (contrast: 0.02 g·min-1; 95% CL: -0.05, 0.09; P = 0.63) when compared with isoenergetic GLU (0.55 g·min-1; 95% CL: 0.52, 0.58). In conclusion, coingestion of glucose and galactose did not enhance exogenous galactose oxidation during exercise. When combined, isoenergetic galactose-glucose ingestion elicited similar exogenous-carbohydrate oxidation to glucose suggesting galactose-glucose blends are a valid alternative for glucose as an exogenous-carbohydrate source during exercise.NEW & NOTEWORTHY Glucose and galactose coingestion blunted the galactosemia seen with galactose-only ingestion during exercise. Glucose and galactose coingestion did not enhance the oxidation of ingested galactose during exercise. Combined galactose-glucose (1:1 ratio) ingestion was oxidized to a similar extent as isoenergetic glucose-only ingestion during exercise. Galactose-glucose blends are a viable exogenous carbohydrate energy source for ingestion during exercise.

Apparent digestibility coefficients of carbohydrates and enzymes activity in major carps in response to Chromium Chloride Hexahydrate

This study investigated the effect of carbohydrate-based corn diets with chromium chloride hexahydrate supplementation on nutrient digestibility and enzyme activity in major carps (Cirrhinus mrigala, Catla catla, and Labeo rohita) for a period of 90 days. One control (T1) and five experimental diets (T2, T3, T4, T5, T6) were prepared by using gelatinized and non-gelatinized corn with the combination of various levels (0.0, 0.6, and 0.8 mg/kg) of CrCl3H12O6. After acclimatization with a control diet (T1) (32% CP), twenty fingerlings of these species were randomly stocked in eighteen digestibility tanks, each with one replicate. At the end of the trial, results showed that gelatinized corn with chromium supplementation significantly enhanced (P&lt;0.05) digestibility of nutrients and enzyme activities (amylase and protease) in liver and gut in all treated groups. Crude protein (76.05±0.54), crude lipid (84.53±0.46), carbohydrate (69.15±2.19), and gross energy (76.92±0.74) showed the highest apparent digestibility in Labeo rohita as compared to Catla catla and Cirrhinus mrigala. While highest amylase (liver:3.27±0.126 U/ml and gut: 1.29±0.045 U/ml) and protease activity (liver:1.22±0.116 U/ml and gut 3.42±0.087 U/ml) was recorded in Catla catla subsequently followed by Labeo rohita and Cirrhinus mrigala. Among the treatments, highest amylase activity was observed in the corn gelatinized group at 0.6 mg/kg chromium level, while maximum protease activity was observed at 0.8 mg/kg of chromium level (gelatinized group). Comparison among gelatinized and non-gelatinized corn diets suggested that gelatinization in fish feed performed best as a carbohydrate energy source with chromium supplementation at an appropriate level (0.6 mg/kg) for three major carps as compared to non-gelatinized corn.

The Precious Few Grams of Glucose During Exercise.

As exercise intensity exceeds 65% of maximal oxygen uptake carbohydrate energy sources predominate. However, relative to the meager 4–5 g blood glucose pool size in a postabsorptive individual (0.9–1.0 g·L−1 × 5 L blood = 18–20 kcal), carbohydrate (CHO) oxidation rates of 20 kcal·min−1 can be sustained in a healthy and fit person for one hour, if not longer, all the while euglycemia is maintained. While glucose rate of appearance (i.e., production, Ra) from splanchnic sources in a postabsorptive person can rise 2–3 fold during exercise, working muscle and adipose tissue glucose uptake must be restricted while other energy substrates such as glycogen, lactate, and fatty acids are mobilized and utilized. If not for the use of alternative energy substrates hypoglycemia would occur in less than a minute during hard exercise because blood glucose disposal rate (Rd) could easily exceed glucose production (Ra) from hepatic glycogenolysis and gluconeogenesis. The goal of this paper is to present and discuss the integration of physiological, neuroendocrine, circulatory, and biochemical mechanisms necessary for maintenance of euglycemia during sustained hard physical exercise.

Comprehensive functional characterization of the glycoside hydrolase family 3 enzymes from Cellvibrio japonicus reveals unique metabolic roles in biomass saccharification.

Lignocellulose degradation is central to the carbon cycle and renewable biotechnologies. The xyloglucan (XyG), β(1→3)/β(1→4) mixed-linkage glucan (MLG) and β(1→3) glucan components of lignocellulose represent significant carbohydrate energy sources for saprophytic microorganisms. The bacterium Cellvibrio japonicus has a robust capacity for plant polysaccharide degradation, due to a genome encoding a large contingent of Carbohydrate-Active enZymes (CAZymes), many of whose specific functions remain unknown. Using a comprehensive genetic and biochemical approach, we have delineated the physiological roles of the four C. japonicus glycoside hydrolase family 3 (GH3) members on diverse β-glucans. Despite high protein sequence similarity and partially overlapping activity profiles on disaccharides, these β-glucosidases are not functionally equivalent. Bgl3A has a major role in MLG and sophorose utilization, and supports β(1→3) glucan utilization, while Bgl3B underpins cellulose utilization and supports MLG utilization. Bgl3C drives β(1→3) glucan utilization. Finally, Bgl3D is the crucial β-glucosidase for XyG utilization. This study not only sheds the light on the metabolic machinery of C. japonicus, but also expands the repertoire of characterized CAZymes for future deployment in biotechnological applications. In particular, the precise functional analysis provided here serves as a reference for informed bioinformatics on the genomes of other Cellvibrio and related species.

Removal of Cr(VI) and phenol using water hyacinth from single and binary solution in the artificial photosynthesis chamber

In this study, water hyacinth (Eichhornia crassipes) was used for the uptake of two important pollutants Cr(VI) and phenol from single and binary solution. Artificial photosynthesis was carried out at 30°C and 60% relative humidity. Experiments were carried out at four concentrations 5, 10, 15 and 20mg/L of Cr(VI) and 10, 20, 30, and 40mg/L of phenol in both single and binary mixtures of Cr(VI) and phenol, respectively. In a single component solution of Cr(VI) 99.00% removal was achieved at 5mg/L in 16 days of operation while in case of single component solution of phenol 99.80% removal was achieved at 10mg/L in 14 days. In a binary solution of Cr(VI) and phenol 99.00% removal of Cr(VI) was achieved at 5mg/L of Cr(VI) and 10mg/L of phenol in 7 days and 11 days of operation, respectively. It was observed that 99.00% removal of Cr(VI) was achieved in less time and also at higher concentration of Cr(VI) in the presence of phenol. The FTIR and EDX analysis was carried out to confirm the uptake of Cr(VI) and phenol. The uptake of Cr(VI) was found more in the presence of phenol which shows the synergistic effect for the removal of Cr(VI). It could be due to the fact that phenol was used as carbon or carbohydrate energy source by the plant at more stressed condition. In case of both single and binary solution, toxic effect was observed at 20mg/L of Cr(VI).

Characterization of the Granule-Bound Starch Synthase I Gene in Chenopodium.

Chenopodium L. is a relatively under-studied genus that includes the cultivated seed crop quinoa (C. quinoa Willd.). Quinoa is an allotetraploid (2n = 4x = 36, AABB genomes) that is cultivated by subsistence farmers and commercial growers in the Andean regions of South America. Approximately 60% of a quinoa seed is starch, a glucose polymer that is an important carbohydrate energy source in the human diet. Seed starch is normally composed of amylose and amylopectin in a 1:3 ratio. The accumulation of the amylose fraction of starch is controlled by a single dominant gene in quinoa, GBSSI. We report the sequencing and characterization of the GBSSI gene in 18 accessions of Chenopodium, including Andean quinoa and the related Mesoamerican chenopod domesticate, C. berlandieri subsp. nuttalliae Saff. Two distinct homeologs (GBSSIa and GBSSIb) were identified in the tetraploid accessions, and 19 different alleles were identified, including three null mutants-one in an accession of quinoa and two in a waxy landrace of C. berlandieri subsp. nuttalliae. Expression analysis of the null mutants revealed that GBSSIa and GBSSIb were both strongly expressed late in seed development. GBSSI sequences were used to analyze the phylogenetic relationships between quinoa and other members of the Chenopodium genus. This study and the discovery of Chenopodium GBSSI null-mutants will assist in the development of new Chenopodium crops with novel starches.

Participation in a 1,000-mile race increases the oxidation of carbohydrate in Alaskan sled dogs.

The Alaskan Husky has been specifically bred for endurance performance and is capable of extreme endurance performance. We examined sled dogs in the trained state at the beginning of the race season and after a 1,600-km race (Iditarod). Our hypothesis was that lipids would be the predominant substrate during submaximal exercise in long-distance racing sled dogs, and a 1,600-km race would increase the reliance on lipids during an exercise bout at the same absolute exercise intensity. The experiments were completed over three testing periods, which were completed in January of two different years before participation in a 1,600-km race, or in March shortly after completion of a 1,600-km race. After determination of H(13)CO3 (-) recovery, the dogs were tested with primed continuous infusions of [1,1,2,3,3-(2)H]glycerol, [3-(13)C]lactate, or [6,6-(2)H2]glucose. During exercise, respiratory exchange ratio was significantly higher in raced (0.92 ± 0.01) compared with nonraced (0.87 ± 0.01) dogs. During exercise, glucose rate of appearance was potentially sustained by a large glycerol rate of disappearance with an increase in lactate rates of oxidation after a 1,600-km race. Therefore, contrary to our hypothesis, the sled dogs were dependent on carbohydrate energy sources, a reliance that increased further after participation in a 1,600-km race.

A.S.P.E.N. Clinical Guidelines: Nutrition Support of the Critically Ill Child

careful selection of the appropriate mode of feeding and monitoring the success of the feeding strategy. The use of specific nutrients, which possess a drug-like effect on the immune or inflammatory state during critical illness, continues to be an exciting area of investigation. The lack of systematic research and clinical trials on various aspects of nutrition support in the PICU is striking and makes it challenging to compile evidence based practice guidelines. There is an urgent need to conduct well-designed, multicenter trials in this area of clinical practice. The extrapolation of data from adult critical care literature is not desirable and many of the interventions proposed in adults will have to undergo systematic examination and careful study in critically ill children prior to their application in this population. In the following sections, we will discuss some of the key aspects of nutrition support therapy in the PICU; examine the literature and provide best practice guidelines based on evidence from PICU patients, where available. While some PICU popu lations include neonates, A.S.P.E.N. Clinical Guidelines for neonates will be published as a separate series.

Lactate-utilizing bacteria, isolated from human feces, that produce butyrate as a major fermentation product.

The microbial community of the human colon contains many bacteria that produce lactic acid, but lactate is normally detected only at low concentrations (<5 mM) in feces from healthy individuals. It is not clear, however, which bacteria are mainly responsible for lactate utilization in the human colon. Here, bacteria able to utilize lactate and produce butyrate were identified among isolates obtained from 10(-8) dilutions of fecal samples from five different subjects. Out of nine such strains identified, four were found to be related to Eubacterium hallii and two to Anaerostipes caccae, while the remaining three represent a new species within clostridial cluster XIVa based on their 16S rRNA sequences. Significant ability to utilize lactate was not detected in the butyrate-producing species Roseburia intestinalis, Eubacterium rectale, or Faecalibacterium prausnitzii. Whereas E. hallii and A. caccae strains used both D- and L-lactate, the remaining strains used only the d form. Addition of glucose to batch cultures prevented lactate utilization until the glucose became exhausted. However, when two E. hallii strains and one A. caccae strain were grown in separate cocultures with a starch-utilizing Bifidobacterium adolescentis isolate, with starch as the carbohydrate energy source, the L-lactate produced by B. adolescentis became undetectable and butyrate was formed. Such cross-feeding may help to explain the reported butyrogenic effect of certain dietary substrates, including resistant starch. The abundance of E. hallii in particular in the colonic ecosystem suggests that these bacteria play important roles in preventing lactate accumulation.

The administration of an oral carbohydrate-containing fluid prior to major elective upper-gastrointestinal surgery preserves skeletal muscle mass postoperatively—a randomised clinical trial

Aim: Recent evidence suggests that the provision of energy-containing fluids is safe and may impact positively on markers of recovery. The aims of this study were to assess the tolerance of preoperative carbohydrate fluid administration and to determine its effect on postoperative metabolic and clinical responses.Methods: Patients admitted to the Royal Infirmary of Edinburgh for major, elective abdominal surgery were recruited to this double-blind, randomised study and received either a placebo drink or carbohydrate (12.6g/100ml) drink (CHOD). Patients consumed 800ml of their drink on the evening before surgery and 400ml on the day of surgery 2–3h before the induction of anaesthesia. Nutritional status was determined using body mass index (BMI) and upper arm anthropometry; all measurements were taken preoperatively, postoperatively and at discharge. Blood glucose and insulin concentrations were also measured preoperatively and on the first post operative day. Length of hospital stay (LOS) and postoperative complications were recorded.Results: Seventy-two patients were recruited and 65 (34 male:31 female) completed this study. Thirty-four patients were randomised to receive the placebo drink (control group) and 31 patients to receive the carbohydrate drink (CHOD group). Groups were well-matched in terms of gender and age. There were no differences between the two groups at baseline for BMI (control: −25.1±1.7kg/m2; CHOD −25.2±1.2kg/m2), upper arm anthropometry or surgical procedure. At discharge loss of muscle mass (arm muscle circumference) was significantly greater in the control group when compared with the CHOD group (control: −1.1±0.15cm; CHOD: −0.5±0.16cm; P<0.05). Baseline insulin (control: 20.7±4.9mU/l; CHOD: 24.6±6.2mU/l) and glucose (control: 6.0±1.4mmol/l; CHOD 5.7±1.4mmol/l) were comparable in the two groups and did not differ postoperatively. No complications were recorded as a result of preoperative fluid consumption. Postoperative morbidity occurred in six patients from each group. Median LOS in the control group was 10 days (IQR=6), and 8 days (IQR=4) in the CHOD group.Conclusion: Preoperative consumption of carbohydrate-containing fluids is safe. Provision of a carbohydrate energy source prior to surgery may attenuate depletion of muscle mass after surgery. Further studies are required to determine if this preservation of muscle mass is reflected in improved function and reduced rehabilitation time.

Effect of dietary non-protein energy levels on condition and oxidative status of Senegalese sole ( Solea senegalensis) juveniles

The effects of dietary non-protein energy levels on growth, oxidative status and condition were studied in juveniles of Senegalese sole ( Solea senegalensis). Four isonitrogenous diets with four energy levels were used: A—low (11% lipid, raw carbohydrate); B—intermediate (11% lipid, digestible carbohydrate); C—intermediate (21% lipid, raw carbohydrate); and D—high (21% lipid, digestible carbohydrate). Survival, relative growth rate (RGR) and feed conversion rate were not significantly affected by the dietary treatments. The fatty acid composition of the fish muscle varied little among the treatments, but trans 18:2 n−6, total n−6 and EPA/DHA ratio, tended to be higher in fish fed diets with low lipid level. Cellular energy allocation (CEA) results (indicative of metabolic status and net energy budgets) showed significant differences in liver, but not in muscle samples. Livers of fish fed diet C contained the lowest carbohydrate, protein and CEA values, but the highest cellular energy consumption. Fish fed diet A had the highest CEA for growth, followed by fish fed diets B and D and then diet C. The liver and muscle peroxidation and antioxidant activity were measured by thiobarbituric acid reactive substances (TBARS) test and the enzymatic activities levels of catalase (CAT) and superoxide dismutase (SOD). TBARS values were higher for fish fed diets with high lipid content. However, no clear relation was found between HUFA level and TBARS value. The activity levels of the antioxidant enzymes CAT and SOD were higher in livers of fish fed diets with a high lipid level. Furthermore, CAT and SOD activity and TBARS values were influenced by the type of dietary starch in the diet. Higher oxidation rates were observed in fish fed diets containing raw carbohydrate. These data suggest that lipid and carbohydrate energy sources affect the oxidative status of Senegalese sole. Diets containing low levels of lipid and digestible starch reduce the susceptibility of the fish to oxidation and may enhance growth rate.

Effects of alternative dietary substrates on competition between human colonic bacteria in an anaerobic fermentor system.

Duplicate anaerobic fermentor systems were used to examine changes in a community of human fecal bacteria supplied with different carbohydrate energy sources. A panel of group-specific fluorescent in situ hybridization probes targeting 16S rRNA sequences revealed that the fermentors supported growth of a greater proportion of Bacteroides and a lower proportion of gram-positive anaerobes related to Faecalibacterium prausnitzii, Ruminococcus flavefaciens-Ruminococcus bromii, Eubacterium rectale-Clostridium coccoides, and Eubacterium cylindroides than the proportions in the starting fecal inoculum. Nevertheless, certain substrates, such as dahlia inulin, caused a pronounced increase in the number of bacteria related to R. flavefaciens-R. bromii and E. cylindroides. The ability of three strictly anaerobic, gram-positive bacteria to compete with the complete human fecal flora was tested in the same experiment by using selective plating to enumerate the introduced strains. The Roseburia-related strain A2-183(F) was able to grow on all substrates despite the fact that it was unable to utilize complex carbohydrates in pure culture, and it was assumed that this organism survived by cross-feeding. In contrast, Roseburia intestinalis L1-82(R) and Eubacterium sp. strain A2-194(R) survived less well despite the fact that they were able to utilize polysaccharides in pure culture, except that A2-194(R) was stimulated 100-fold by inulin. These results suggest that many low-G+C-content gram-positive obligate anaerobes may be selected against during in vitro incubation, although several groups were stimulated by inulin. Thus, considerable caution is necessary when workers attempt to predict the in vivo effects of probiotics and prebiotics from their effects in vitro.

Biochemical characterization of Thermotoga maritima endoglucanase Cel74 with and without a carbohydrate binding module (CBM)

The genome of the hyperthermophilic bacterium Thermotoga maritima (Tm) encodes at least eight glycoside hydrolases with putative signal peptides; the biochemical characteristics of seven of these have been reported previously. The eighth, Tm Cel74, is encoded by an open reading frame of 2124 bp corresponding to a polypeptide of 79 kDa with a signal peptide at the amino-terminus. The gene (lacking the signal peptide) encoding Tm Cel74 was expressed as a 77 kDa monomeric polypeptide in Escherichia coli and found to be optimally active at pH 6, 90°C, with a melting temperature of approximately 105°C. The cel74 gene was previously found to be induced during T. maritima growth on a variety of polysaccharides, including barley glucan, carboxymethyl cellulose (CMC), glucomannan, galactomannan and starch. However, while Tm Cel74 was most active towards barley glucan and to a lesser extent CMC, glucomannan and tamarind (xyloglucan), no activity was detected on other glycans, including galactomannan, laminarin and starch. Also, Tm Cel74 did not contain a carbohydrate binding module (CBM), versions of which have been identified in the amino acid sequences of other family 74 enzymes. As such, a CBM associated with a chitinase in another hyperthermophile, Pyrococcus furiosus, was used to create a fusion protein that was active on crystalline cellulose; Tm Cel74 lacked activity on this substrate. Based on the cleavage pattern determined for Tm Cel74 on glucan-based substrates, this enzyme likely initiates recruitment of carbohydrate carbon and energy sources by creating oligosaccharides that are transported into the cell for further processing.

High-Amylose Starches: From Biosynthesis to Their Use as Food Ingredients

Starch is a versatile food ingredient and is widely used in numerous food and industrial applications. Whether in its native form, or modified1 through chemical substitution and/or physical modification (e.g., annealing), starch is used as a texturizer, gelling agent, thickener, adhesive, and moisture-retainer. Starches also provide an essential carbohydrate energy source and are obtained from roots, rootlike or tuberous plants, and cereals, all of which possess unique starch chemistries that impact their properties and function as food ingredients.

077 In Vitro Growth of Immature Peach [Prunus persica (L.) Batsch] Embryos Related to Carbohydrate Source

Carbohydrate energy source of various tissue culture media has an effect on growth and survival of the explants. Sucrose is the standard carbohydrate used in most tissue culture systems. The objective of the study was to determine the effect of five carbohydrate sources (fructose, glucose, maltose, sorbitol, and sucrose) at two levels (2% and 3%) on germination, growth, and survival of immature peach embryos (9.7 to 14.7mm) in vitro. Five cultivars were used. Overall, fructose, maltose, and sucrose each stimulated germination and growth as the primary carbohydrate energy source of peach embryo culture to the same degree; glucose and sorbitol were inferior. However, fructose was superior to sucrose in one cultivar. In general, sugar level did not affect survival, although cultivars did vary somewhat. Survival was found to be highly dependent upon embryo maturity.

Evaluation of heat-processed cocoa pod husk meal as an energy feedstuff in production diets for the clariid catfish, Clarias isheriensis (Sydenham)

Isoproteic and isoenergetic diets containing 0%, 15%, 30% or 45% heat-processed cocoa pod husk meal (CPHM) were fed to Clarias isheriensis (16.8 ± 2.4 g) for 180 days. Growth rates of catfish fed varying levels of CPHM were similar (P > 0.05). Differences in feed-gain ratio (FGR) or protein efficiency ratio (PER) between treatments were not significant (P > 0.05). Histology of the liver showed no pathological effects of incorporation of CPHM. In a second experiment, C. isheriensis (19.1 ± 3.5 g) were fed isoenergetic diets containing 250, 300, 350 and 400 protein g kg−1 (protein: energy ratios of 21, 25, 29 and 33 mg protein.kJ−1 DE, respectively). Growth rate and FGR improved (P < 0.05) in proportion to the dietary protein level. PER decreased with increase in dietary protein. Carcass protein was lowest (P < 0.05) in catfish fed 250 g protein kg−1, but did not differ among the other diets (P > 0.05). Body fat was highest in catfish fed 250 g protein kg−1 and lowest in fish fed 350 g protein kg−1. These results indicate that CPHM may be a suitable carbohydrate energy source for clariids at a P:E ratio of approximately 29 mg protein.kJ−1 DE.

Mass rearing, larval behaviour and effects of plant age on the rice caseworm, Nymphula depunctalis (Guenée) (Lepidoptera: Pyralidae)

The mass-rearing method for efficient production of rice caseworm Nymphula depunctalis (Guenée) was improved. Moths oviposit most in ventilated cages on the undersides of floating cut rice leaves aged 4–8 weeks after transplanting (WT). There was no effect of leaf width on oviposition. Greatest egg production occurs with a 12 h scotophase. Moths are highly tolerant of crowding in oviposition cages, as up to 40 females averaged 86–115 eggs per female in 0.14 m 3 cages. Honey as a carbohydrate energy source increases the rate of oviposition but not total oviposition. Larvae require standing water to fill their cases as respiration occurs with tracheal gills. Larval survival was equal when reared in distilled water, pesticide-free ricefield water, or chlorinated tap water, whether aerated or not. Larvae survive better, grow larger, mature more rapidly, and become more fecund adults when reared on plants 2–6 WT. Pupae are non-aquatic. The caseworm's inability to develop satisfactorily on post-vegetative rice may be attributed to poor nutrition and less favourable oviposition substrates. Females prefer to oviposit on dropping leaves floating on the water surface. As the crop matures, fewer leaves touch or float on the water surface. Eggs desiccate if laid on aerial portions of plants and are more exposed to natural enemies.

Comparison of Diets of Two Fire Ant Species (Hymenoptera: Formicidae): Solid and Liquid Components

Diets of the red imported fire ant, Solenopsis invicta Buren, and the native fire ant, Solenopsis geminata [F.], were studied in adjacent field colonies in south central Texas. A comparison of solid food diets of the two species revealed a 59% overlap of identifiable arthropods and other solid food matter. The major difference was that S. geminata collected eight times more seeds than did S. invicta. Both species collected liquid food much more frequently than solid food; in fact, an average of 70–80% of successful foragers returned with liquid. Rates of liquid collection were approximately 40% higher for S. invicta than for S. geminata. Foraging rates fluctuated with season but the percent of successful foragers returning with liquid remained relatively constant. Plants and honeydew producing homopterans are the most probable sources of this liquid based on sugar and amino acid analyses of S. invicta foragers. Use of liquid carbohydrate energy sources helps explain how fire ant colonies can collect sufficient food to sustain extremely dense field populations.