Daily Feeding Rate Research Articles

Study Of The Effect Of Silver And Zinc Nanoparticles Prepared Biologically By The Fungus Beauveria Bassiana On The Feeding Behavior And The Insect Body Content Of Some Materials And Nutrients In The Periplaneta Americana L.

The study was conducted in the laboratories of the Department of Prevention / College of Agriculture / Tikrit University during the years 2023-2024 to study the effect of the nanomaterial resulting from treating the fungus Beauveria bassiana with a solution of silver nitrate and a solution of zinc oxide as it affected the daily feeding rate of the last-age nymphs of the Periplaneta americana, as this rate was 0.015 g / insect on the second day of treatment with the nanomaterial prepared using silver nitrate, while it was 0.04 for the zinc oxide treatment. While it was 0.07 g / insect for the control treatment, and the nanomaterial affected the two solutions in addition to the control treatment in a fluctuating manner during seven days of feeding. Both silver nitrate and zinc oxide treatments and the control treatment recorded 0.007, 0.05, 0.085 gm/insect on the eighth day of treatment. The treatment also affected the percentage of each of the fats for the concentrations of 0.125, 0.250, 0.500 mg/L and the control treatment if it was 23.8, 23.9, 24 and 23.8 mg) respectively for the silver nitrate treatment, while it was 22.3, 20.6, 19.5, 23.8 for the zinc oxide treatment. While the protein weight was 234.24, 127.64, 35.72, 382.81 mg/g for silver nitrate, while it was 304.37, 43.756, 233.125, 43.75 mg/g for zinc oxide. It also affected the potassium element, as the concentrations were recorded as 0.125, 0.250, 0.500 mg/L and the control treatment was 4.65, 2.36, 0.54, 6.22 mg respectively for silver nitrate and 5.14, 3.21, 0.75 and 6.25 mg respectively for zinc oxide. It also affected the weight of the sodium element, as the concentrations were recorded as 0.125, 0.250, 0.500 mg/L and the control treatment was 2.63, 1.22, 0.46, 3.24 mg respectively for silver nitrate and 2.45, 1.08, 0.42 and 3.34 mg respectively for zinc oxide. It affected the percentage of phosphorus element, as the above concentrations were recorded, 4.32, 2.61, 0.40, 6.13 mg for silver nitrate, while they were 5.12, 3.43, 0.70, 6.24 mg for zinc oxide.

Influence of daily feed ration on growth and condition of juvenile pikeperch (Sander lucioperca) reared in a recirculating aquaculture system (RAS)

Influence of daily feed ration on growth and condition of juvenile pikeperch (Sander lucioperca) reared in a recirculating aquaculture system (RAS)

Relationship between stocking rate and production of stocker hybrid tilapia and water quality in a mixtotrophic biofloc system

AbstractIntensified production of stocker‐size tilapia can be accomplished using the biofloc technology production system. Stocker‐size tilapia (ca. 10–200 g/fish) are raised for subsequent stocking for grow‐out to market size. The relationship between stocking rate and the production of stocker‐size hybrid tilapia (Oreochromis aureus × O. niloticus) was evaluated in two studies in outdoor mixotrophic biofloc tanks. Hybrid tilapia were stocked in 18.6‐m2 (15.7‐m3) tanks at 50–150 fish/m2 (59–178 fish/m3) in 25 fish/m2 (30 fish/m3) increments in Study 1 and grown for 141–143 days. Stocking rates evaluated in 4.7‐m2 (3.6‐m3) tanks during Study 2 over 78–79 days ranged from 100 to 300 fish/m2 (132–396 fish/m3) in 25 fish/m2 (33 fish/m3) increments. Linear regression models best described growth to stocker size in both studies. Fish yield increased linearly with stocking rate and ranged from 20.1 to 38.3 kg/m3. Individual weight at harvest was inversely related to stocking rate and ranged from 389.8 to 163.4 g/fish and 155.2 to 81.4 g/fish in Studies 1 and 2, respectively. Partial budget analyses suggested positive net changes in profit with incremental increases in stocking rate for producing a 75‐g stocker. Water quality concentrations were impacted directly by daily feed ration and total feed fed, which increased linearly with stocking rate. In Study 2, whole‐body dry matter, protein, protein retention, and lipid were unaffected by stocking rate, whereas whole‐body ash increased with stocking rate. Whole‐body energy retention significantly decreased with stocking rate. The outdoor mixotrophic biofloc production system is well suited for intensive production of hybrid tilapia stockers. However, additional replicated research and economic analysis are needed to evaluate stocking rate and culture duration to produce specific‐sized stocker hybrid tilapia.

Unobserved mortality occurs early in larval walleye (Sander vitreus) aquaculture

One of the most persistent challenges in walleye larviculture is the high rate of unobserved mortality occurring within the first 30 days post-hatch. Walleye larviculture is characterized by high mortality rates, but oftentimes, only a fraction of the total mortality in walleye larviculture is observed. Unobserved mortality is frequently attributed to a high rate of cannibalism, but decomposition of larvae and other factors may also be important contributors. Unobserved mortality can make walleye larviculture especially challenging as accurately estimating daily feed rations and forecasting larval production rely on accurate counts of surviving fish. Despite the importance of unobserved mortality, there is little empirical evidence available that assesses the temporal occurrence and causes of unobserved mortality in walleye larviculture. This study assessed when unobserved mortality occurs during walleye larviculture by examining survival at three timepoints (8, 15, and 30 days post-stocking). Tanks were cleaned daily and dead fry were enumerated to account for observed mortality. At the end of each treatment period, the tanks were drained, all remaining fry were enumerated, and the unobserved mortality rate was calculated. While observed mortality trended higher as trial duration increased, unobserved mortality did not increase significantly from the 8-day treatment suggesting that the bulk of unobserved mortality occurs during the first 8 days of walleye larviculture.

Uptake from water and depuration of 137Cs and 90Sr by silver Prussian carp (Carassius gibelio)

To follow up field observations in the Chornobyl Exclusion Zone (ChEZ), a series of controlled model aquarium experiments were conducted to determine the uptake and depuration rates of 137Cs and 90Sr in silver Prussian carp (Carassius gibelio) in fresh water, varying in temperature from 5 to 27 °C, with daily feeding rates of 0–1.5 % fish weight day−1.In the present study, the 137Cs uptake rates in muscle tissues directly from water, 0.05–0.09 day−1 at temperatures of 5–27 °C, were significantly lower than previously reported for fish fed under natural conditions in contaminated lakes within the ChEZ. The rate of 90Sr uptake in bone tissues of silver Prussian carp varied from 0.055 day−1 at a water temperature of 5 °C and feeding rates ≤0.15 % fish weight day−1 to 1.5 ± 0.2 day−1 at a temperature of 27 ± 1 °С and at the highest tested feeding rate of 1.5 % day−1.The rate of decrease of 137Cs concentration in muscle tissues was kb = 0.0028 ± 0.0004 day−1 (T1/2 = 248 ± 35 days) at the lowest water temperature tested (5 °С). At water temperatures between 13 and 26 °С and a feeding rate of 0.15 % day−1, the rate increased to kb = 0.0071–0.0092 day−1 (T1/2 = 75–99 days).The rates of decrease of 90Sr activity concentration in bone tissues at water temperatures between 22 and 25 °С and a feeding rate of 0.5 % day−1 were kb=0.004–0.0014 day−1, and the associated biological half-life T1/2 ranged 50–160 days, respectively. The present work supported conclusions related to the main pathways of 137Cs and 90Sr uptake by silver Prussian carp, and demonstrated the usefulness of combining field and laboratory uptake and depuration experiments.

Zebrafish Feed Intake: A Systematic Review for Standardizing Feeding Management in Laboratory Conditions.

Zebrafish are one of the most used animal models in biological research and a cost-effective alternative to rodents. Despite this, nutritional requirements and standardized feeding protocols have not yet been established for this species. This is important to avoid nutritional effects on experimental outcomes, and especially when zebrafish models are used in preclinical studies, as many diseases have nutritional confounding factors. A key aspect of zebrafish nutrition is related to feed intake, the amount of feed ingested by each fish daily. With the goal of standardizing feeding protocols among the zebrafish community, this paper systematically reviews the available data from 73 studies on zebrafish feed intake, feeding regimes (levels), and diet composition. Great variability was observed regarding diet composition, especially regarding crude protein (mean 44.98 ± 9.87%) and lipid content (9.91 ± 5.40%). Interestingly, the gross energy levels of the zebrafish diets were similar across the reviewed studies (20.39 ± 2.10 kilojoules/g of feed). In most of the reviewed papers, fish received a predetermined quantity of feed (feed supplied). The authors fed the fish according to the voluntary intake and then calculated feed intake (FI) in only 17 papers. From a quantitative point of view, FI was higher than when a fixed quantity (pre-defined) of feed was supplied. Also, the literature showed that many biotic and abiotic factors may affect zebrafish FI. Finally, based on the FI data gathered from the literature, a new feeding protocol is proposed. In summary, a daily feeding rate of 9-10% of body weight is proposed for larvae, whereas these values are equal to 6-8% for juveniles and 5% for adults when a dry feed with a proper protein and energy content is used.

Growth, Feed Utilization, Lipid Metabolism, and Metamorphosis of Bullfrog (Aquarana catesbeianus) Tadpoles Fed Diets With Different Lipid Levels

This study investigated the effect of dietary lipid levels on growth performance, lipid metabolism, antioxidant capacity, digestive enzyme activity, and metamorphosis rate of bullfrog (Aquarana catesbeianus) tadpoles. A total of six isonitrogenous diets were prepared, each containing 4.46% (L5), 6.95% (L7), 9.10% (L9), 10.90% (L11), 12.34% (L13), and 15.00% (L15) crude lipid content. The experimental diets were administered to triplicates of tadpoles (stage 25, 0.007 g) twice daily for 75 days with a daily feeding rate of 6.50% of their body weight. Weight gain (WG), specific growth rate (SGR), crude protein content of the whole body, apparent digestibility of dry matter and gross energy, intestinal lipase (LPS) capacity, lipoprotein lipase (LPL), and carnitine palmitoyltransferase‐I (CPT‐I) and contents of growth hormone (GH) and insulin‐like growth factor‐1 (IGF‐1) in the liver, high‐density lipoprotein cholesterol (HDL‐C) content in the serum, and metamorphosis rate at stages 40 and 41 increased as the dietary lipid level increased from 4.46% to 12.34% and then decreased. As the dietary lipid level increased from 4.46% to 10.90%, the protein efficiency ratio (PER), protein deposition rate (PDR), lipid deposition rate (LDR), crude lipid content and gross energy of the whole body, apparent digestibility of the crude lipid, superoxide dismutase (SOD), catalase (CAT) activities in the liver, and the intestinal trypsin (TPS) activity all increased and then decreased. According to the second‐order polynomial regression analysis of the WG and metamorphosis rate at stage 41 to the dietary lipid level, the ideal dietary lipid content for tadpoles was 11.08% and 10.72%, respectively. Overall, the appropriate dietary lipid level for bullfrog tadpoles was found to be 10.72%–11.08% of the diet.

Dietary Wood and Activated Charcoal Improved Ammonium Removal, Heavy Metals Detoxification, Growth Performance, Blood Biochemistry, Carcass Traits, and Histopathology of European Seabass.

A 120-day growth trial was completed to assess rearing water quality and fish performance in terms of growth, feed efficacy, digestive enzymes, immunity, and antioxidant activity of seabass fed an experimental diet (ED) supplemented with commercial wood charcoal (WC) and activated wood charcoal (AC). Three levels (0, 10, and 20 g) of WC and AC were administered, representing five treatments: control (CD) fish-fed ED without additives, (WC-1) fish-fed ED containing 10 g kg-1 WC, (WC-2) fish-fed ED containing 20 g kg-1 WC, (AC-1) fish-fed ED containing 10 g kg-1 AC, and (AC-2) fish-fed ED containing 20 g kg-1 AC. Three hundred fish (60.12 ± 0.20 g/fish) were stocked in 15 cement tanks (4.0 m × 2.0 m × 1.2 m, water volume 5 m3 each) at 20 fish/tank and a daily feed ration of 3% of body weight. Results revealed significant improvements with increased growth variables (final weight, weight gain, and specific growth rate), decreased FCR, and decreased ammonia levels and heavy metals (Cu, Cd, Fe, Mn, and Zn) content in rearing water, muscle, and liver with fish fed WC and AC supplemented diets. Furthermore, considerable improvements in digestive enzymes, immunity, and antioxidant activity, with enhanced kidneys, liver, intestines, gills, and spleen. Fish fed the WC-1 diet had a higher final weight (171.90 g), better FCR (1.25), and improved internal organs than the other groups.

Growth patterns and feeding characteristics in early developmental stages of Takifugu rubripes cultured in a recirculating aquaculture system

The growth patterns and feeding characteristics of Takifugu rubripes at different developmental stages (0–50 days after hatching, DAH) were investigated under artificial breeding conditions using ecological and traditional biological methods. The results revealed rapid growth in head length, head height, and eye diameter from hatching to 50 DAH, and the inflection point for body length growth occurred at 27 DAH. From 27 to 50 DAH, the growth rate slowed. In the swimming organs, the inflection points for tail, pectoral, dorsal, and anal fin growth occurred from 29 to 31 DAH. The growth rate for fins slowed after this period, suggesting the preferential development of important organs related to sensation, locomotion, and feeding during early development, with varied developmental periods. An investigation of the feeding rhythm of T. rubripes larvae, juveniles, and young fish showed that feeding activities mainly occurred during the daytime, a behavior typical of daytime feeders. The average daily feeding rate of T. rubripes was 12.61% for the early-stage larvae at 6 DAH, 43.89% for the late-stage larvae at 15 DAH, 40.05% for juveniles at 30 DAH, and 28.46% for young fish at 46 DAH. In addition, the satiation time for juveniles tended to decrease with increasing age, whereas the time for digestion tended to increase. These data can be used as a reference for the daily feeding of T. rubripes at different developmental stages. Comprehensive understanding of the growth and feeding characteristics of early-stage T. rubripes developed in this study will be useful for the management of artificially bred fry and will aid in promoting the growth and survival rates of aquaculture fish larvae.

Оптимизация производства красноклешневых раков в УЗВ на раковой ферме Алтая

Experimental work has been carried out to optimize the feeding conditions and keeping of red claw crayfish in the conditions of a recirculation aquaculture system (RAS) to increase growth during artificial cultivation and to determine design standards. The lack of functional complete feed and methodological approaches to the maintenance of red claw crayfish necessitated developing the effective methods for the practical implementation of feeding technology and minimizing the impact of side factors. The experiment involved 105 species of Cherax quadricarinatus weighing more than 10 g, which were kept in containers with an area of 1.5 m2 and a volume of 0.3 m3, equipped with shelters, with water artificial aeration, filtration and heating. Three options for compound feed formulations are proposed based on the low-calorie compound feed “Coppens Vital”, which was supplemented with vegetable and animal additives (pollock, cereals, gammarus, bloodworm, pumpkin, carrots). With a daily feeding rate making 4-6% of body weight, there was established a feeding regimen 2 times a day. The absolute and average daily growth in three experimental groups of hydrobionts, the average daily growth rate and the mass accumulation coefficient were calculated. As a result, the composition of a complete diet has been optimized, which makes it possible to increase and stabilize the percentage of leaders and the average group in terms of growth. It is noted that the uneven population growth rate requires sorting depending on the mass and planting density while maintaining the composition of the diets. The study of different stocking densities in fish tanks was carried out on the basis of measuring fish-breeding and biological indicators, which complement the general characteristic of the limiting values of RAS operation when keeping objects, which can be used as regulatory documentation for stabilizing economically important features of grown aquaculture objects. The information obtained is opportune and helps avoid technological losses in the production of aquaculture products.

Effects of dietary isoleucine level on growth and expression of genes related to nutritional and physiological metabolism of swimming crab (Portunus trituberculatus)

A six-week feeding trial was conducted to evaluate the effects of dietary isoleucine level on growth, myofiber histology, and mRNA levels of genes related to amino acid, glucose and lipid metabolism in swimming crab (Portunus trituberculatus). Six isonitrogenous and isolipidic diets (45% protein and 8% lipid) were formulated to contain graded levels of isoleucine (Ile), with the analyzed levels of isoleucine being 0.69%, 1.06%, 1.32%, 1.78%, 2.03% and 2.38%, respectively. A total of 180 crabs (initial weight 16.30 ± 0.01 g) were housed individually in 180 plastic baskets with 30 crabs assigned to each diet, divided randomly into three replicates of 10 crabs. Each crab was fed twice at 08:00 and 18:00 with a daily feeding ration of 6–8% of crab body weight. Eight crabs from each replicate group were sampled and dissected after the feeding trial to provide hemolymph for biochemical analysis, hepatopancreas for proximate composition, amino acid profile enzyme activity, and gene expression, and muscle for proximate composition, amino acid profile and histology. The results indicated that final weight, percent weight gain and specific growth rate increased significantly as dietary isoleucine level increased from 0.69% to 1.78%, and then decreased with further increased dietary isoleucine. Crabs fed the diets with 1.78%, 2.03% and 2.38% isoleucine showed significantly higher muscle protein contents (17.80%, 17.99% and 17.65% of wet mass) than crabs fed lower levels of isoleucine. The highest concentrations of IGF1R and CHH in hemolymph (187.95 and 529.42 pg ml−1, respectively) and hepatopancreas (24.18 and 38.69 pg ml−1, respectively) were observed in crabs fed the diet with 1.32% isoleucine. Hepatopancreas expression levels of genes related to amino acid metabolism, including s6k1, bcat, alt and ast, were up-regulated in crabs fed 1.32% isoleucine compared to the other groups, whereas the expression level of tor decreased as dietary isoleucine increased. Expression levels of genes related to glucose intake, such as pi3k, igf1r and glut1, were significantly higher in crabs fed 1.32% isoleucine compared to crabs fed 0.69% isoleucine. Expression levels of genes related to gluconeogenesis (pepck and g6pase) were significantly higher in crabs fed 0.69% isoleucine than in crabs fed the diets with 1.32% and 1.78% isoleucine. In contrast, expression levels of genes related to glycolysis, including hk, gk and pk, were up-regulated in crabs fed 1.32% isoleucine compared to crabs fed 0.69% isoleucine. Gene expression levels of regulatory factors related to lipid metabolism (foxo, sirt1 and sirt3) were significantly higher in crabs fed 1.32% isoleucine compared to crabs fed the other treatments, while expression levels of genes related to lipolysis (hsl and cpt2) were significantly up-regulated in crabs fed the diets with 1.32% and 1.78% isoleucine. Expression levels of key lipogenesis genes (fas and acc) were down-regulated in crabs fed the diets with 1.32% and 1.78% isoleucine compared to those fed 0.69% isoleucine. Muscle histology indicated that crabs fed the diets with 1.32% and 1.78% isoleucine had significantly lower densities of myofibers (21.67 and 17.33 N/ mm2) compared to crabs fed 0.69% isoleucine. In conclusion, based on percent weight gain, the optimal isoleucine requirement of juvenile swimming crab was calculated to be 1.57% of diet (3.49% dietary protein) by quadratic curve model. Thus, appropriate dietary isoleucine levels (1.32–1.78%) promoted amino acid metabolism and protein synthesis, increased protein deposition, and altered myofiber structure of muscle and, in addition, promoted lipolysis and glycolysis, and reduced lipogenesis and gluconeogenesis in juvenile swimming crab.

Influence of daily feeding ration of cattle on the transfer of 137Cs and 90Sr to animal organisms and manure in the agroecosystems of Central Forest-Steppe

The ration of feeding for large cattle was investigated and analyzed in terms of the transfer of 137Cs and 90Sr to muscle tissue, bones, milk, and manure biomass. The specific activity of radionuclides 137Cs and 90Sr was determined in the daily feeding ration of animals. It was found that the soil contamination density of 137Cs at the «Nadiya» farm ranged from 104.2 to 396.5 Bq/m2, while for 90Sr, it ranged from 9.4 to 36.2 Bq/m2. The fields at the «Ivanivske» farm had soil contamination densities of 137Cs ranging from 37.5 to 283.6 Bq/m2 and 90Sr ranging from 7.4 to 32.1 Bq/m2. The soil contamination density of 137Cs at the NNDC BNAU ranged from 4.18 to 8.66 Bq/m2, while for 90Sr, it ranged from 0.44 to 0.88 Bq/m2. The results of the ration assessment indicate that the average daily intake of 137Cs from feed into the animal’s body at the «Nadiya» farm was 375.3±84.2 Bq/kg, and for 90Sr, it was 345.1±98.2 Bq/kg. Significantly lower amounts of radionuclides from the ration entered the animals’ bodies at the «Ivanivske» farm, with an average daily intake of 137Cs at 174.9 Bq/kg and 90Sr at 236.0 Bq/kg. The lowest transfer coefficients of 137Cs and 90Sr from the daily ration to the body were observed at the NNDC BNAU, with 8.56 Bq for 137Cs and 9.69 Bq for 90Sr. It was determined that, overall, the muscle tissue of animals received 6.37% of 137Cs and 0.06% of 90Sr from the ration at the «Nadiya» farm; 2.0% of 137Cs and 0.02% of 90Sr at the «Ivanivske» farm, and 2.22% of 137Cs at the NNDC BNAU. In the case of bones, it was 6.47% of 90Sr at the «Nadiya» farm; 5.47% of 90Sr at the «Ivanivske» farm, and 0.41% of 90Sr at the NNDC BNAU. The obtained results confirmed that 137Cs is capable of evenly accumulating in all organs of the animal, while 90Sr selectively or predominantly accumulates in specific organs. It was established that under conditions of prolonged intake of radionuclides through the ration into the body of large cattle, 85–90% is excreted with the manure biomass.

Potential Detritivorous Diet of the Invasive Apple Snail (Pomacea canaliculata Lamarck, 1822) in Mangroves: The Relationship between Feeding Indicators and Chemical Characteristics of Decaying Leaf Litter

Invasive species have had substantial impacts on global mangrove forests. Apple snails (Pomacea canaliculata) have invaded mangrove forests in China. To clarify the potential detritivorous diet of P. canaliculata, the growth and feeding indicators of invasive juvenile snails collected from mangroves in Guangzhou, China, were studied using decaying leaf litter from five mangrove species, including Acanthus ilicifolius, Acrostichum aureum, Kandelia candel, Aegiceras corniculatum, and Sonneratia apetala. The growth indicators of the survival ratio and specific growth rate were calculated by measuring the live weight of the snails and the number of dead snails after 30 days. The feeding indicator of the weight-specific daily feeding rate (WDR) was calculated by measuring the snail weight and the amount of leaf litter ingested after 120 h. A multiple-choice experiment was performed on the snails by providing the decaying leaf species together, while a no-choice experiment was performed using a single species of decaying leaf litter. The survival and specific growth ratio of P. canaliculata feeding on decaying leaf litter of A. ilicifolius were higher than those for A. aureum. The WDR values of P. canaliculata feeding on the decaying leaf litter of A. ilicifolius and S. apetala were both significantly higher than those for A. corniculatum, A. aureum, and K. candel. The lowest WDR value of P. canaliculata feeding on decaying leaf litter was observed for A. aureum in the no-choice experiment. P. canaliculata mainly fed on decaying leaf litter of A. ilicifolius and S. apetala. The phosphorous contents and ash of the decaying leaf litter positively affected the WDR values of P. canaliculata obtained in the multiple-choice and no-choice experiments. The contents of lignin, tannin, and flavonoid negatively affected the WDR values of P. canaliculata. The potential diet of invasive P. canaliculata in mangroves was closely tied to the chemical characteristics of the decaying leaf litter. P. canaliculata can invade A. ilicifolius and/or S. apetala mangroves by utilizing the debris on the mangrove ground. Understanding the potential detritivorous diet of P. canaliculata in invaded mangroves can help us to assess this species’ dispersal risk and provide support for mangrove management.

Feeding rates of malaria vectors from a prototype attractive sugar bait station in Western Province, Zambia: results of an entomological validation study

BackgroundAttractive targeted sugar bait (ATSB) stations are a promising new approach to malaria vector control that could compliment current tools by exploiting the natural sugar feeding behaviors of mosquitoes. Recent proof of concept work with a prototype ATSB® Sarabi Bait Station (Westham Co., Hod-Hasharon, Israel) has demonstrated high feeding rates and significant reductions in vector density, human biting rate, and overall entomological inoculation rate for Anopheles gambiae sensu lato (s.l.) in the tropical savannah of western Mali. The study reported here was conducted in the more temperate, rainier region of Western Province, Zambia and was designed to confirm the primary vector species in region and to estimate corresponding rates of feeding from prototype attractive sugar bait (ASB) Sarabi Bait Stations.MethodsThe product evaluated was the Sarabi v1.1.1 ASB station, which did not include insecticide but did include 0.8% uranine as a dye allowing for the detection, using UV fluorescence light microscopy, of mosquitoes that have acquired a sugar meal from the ASB. A two-phase, crossover study design was conducted in 10 village-based clusters in Western Province, Zambia. One study arm initially received 2 ASB stations per eligible structure while the other initially received 3. Primary mosquito sampling occurred via indoor and outdoor CDC Miniature UV Light Trap collection from March 01 through April 09, 2021 (Phase 1) and from April 19 to May 28, 2021 (Phase 2).ResultsThe dominant vector in the study area is Anopheles funestus s.l., which was the most abundant species group collected (31% of all Anophelines; 45,038/144,5550), had the highest sporozoite rate (3.16%; 66 positives out of 2,090 tested), and accounted for 94.3% (66/70) of all sporozoite positive specimens. Of those An. funestus specimens further identified to species, 97.2% (2,090/2,150) were An. funestus sensu stricto (s.s.). Anopheles gambiae s.l. (96.8% of which were Anopheles arabiensis) is a likely secondary vector and Anopheles squamosus may play a minor role in transmission. Overall, 21.6% (9,218/42,587) of An. funestus specimens and 10.4% (201/1,940) of An. gambiae specimens collected were positive for uranine, translating into an estimated daily feeding rate of 8.9% [7.7–9.9%] for An. funestus (inter-cluster range of 5.5% to 12.7%) and 3.9% [3.3–4.7%] for An. gambiae (inter-cluster range of 1.0–5.2%). Feeding rates were no different among mosquitoes collected indoors or outdoors, or among mosquitoes from clusters with 2 or 3 ASBs per eligible structure. Similarly, there were no correlations observed between feeding rates and the average number of ASB stations per hectare or with weekly rainfall amounts.ConclusionsAnopheles funestus and An. gambiae vector populations in Western Province, Zambia readily fed from the prototype Sarabi v1.1.1 ASB sugar bait station. Observed feeding rates are in line with those thought to be required for ATSB stations to achieve reductions in malaria transmission when used in combination with conventional control methods (IRS or LLIN). These results supported the decision to implement a large-scale, epidemiological cluster randomized controlled trial of ATSB in Zambia, deploying 2 ATSB stations per eligible structure.

Effects of feed, carbohydrate addition and stocking density on Pacific white shrimp (Litopenaeus vannamei) production

Shrimp culture rearing systems are dynamic with numerous processes influencing system performance. This research investigated the effects of stocking density, feeding level and C:N ratio on shrimp production, water quality and microbial community composition in a biofloc shrimp rearing system, using a 3 × 3 factorial design. Pacific white shrimp (Litopenaeus vannamei) were stocked at 27, 120, or 300 individual m−3 and fed 100, 80 or 60% of the recommended daily feed ration. For each combination of stocking density and feeding level, C:N ratios of 7.4, 12 or 16 were created by feeding a mixture of casava and rice bran besides the daily pelleted feed input to culture tanks. After 12 weeks of culture, the harvested shrimp biomass was the highest in the rearing tanks with the highest stocking density, feeding level and C:N ratio (P < 0.05), while the individual shrimp size at harvest decreased with increasing stocking density (P < 0.05). Biofloc biomass (e.g. total suspended solids TSS, volatile suspended solids VSS) and, to a lesser degree, water quality (total ammonia nitrogen TAN, NO2-N) were affected by 2 and 3-way interactions of the main tested factors. The ash, protein, fat and nitrogen free extract (NFE) content in biofloc were affected by stocking density (P < 0.05), and ash and NFE content by C:N ratio (P < 0.05). Regarding the microbial community composition in the biofloc at the highest stocking density, increasing feeding level and C:N ratio led to an increasing microbial richness and diversity (P < 0.05) as a result of nutrient input. Overall, the shrimp production and biofloc biomass were influenced in a similar way by the stocking density, feeding level and C:N ratio applied in the biofloc system. Future research should focus on how the type of carbohydrates and methods of administration affect shrimp growth and biofloc formation, and how this may promote health benefits through the microbial community manipulation.

Effect of diet composition and temperature on the gastric evacuation rate of European sardine: implication for egg predation estimates

Cannibalism and intraguild predation of fish eggs are frequently observed for small and medium pelagic fish and can be an important cause of natural mortality. The European sardine Sardina pilchardus is the major predator of pelagic fish eggs in Atlantic Iberian waters. Estimates of egg mortality due to predation rely on a number of parameters that are frequently unknown for most species, such as gastric evacuation rate (GER) and feeding periodicity, and rates obtained for other fish species are generally used. These assumptions can severely affect egg mortality estimates. We conducted laboratory experiments to estimate the GER of European sardine that were fed diets composed of different proportions of fish eggs and other food types, such as Artemia franciscana nauplii, Brachionus plicatilis and microalgae, at different temperatures experienced by sardine in the wild (15, 17 and 21°C). Temperature, predator size and sex did not influence the gastric rates. Prey type significantly affected the GER of sardines, with slower evacuation when offered diets containing a higher concentration of fish eggs rather than microalgae, rotifers and Artemia nauplii. Fish eggs are more nutritionally rich compared to microalgae, rotifers and Artemia nauplii, and therefore more difficult to digest. GERs obtained here for S. pilchardus were similar to those obtained for Sardinops sagax in South Africa. This study provides important information that allows for improving estimates of daily feeding rates and egg mortality by predation, thus increasing our understanding of small pelagic fish population dynamics.

Dietary Niacin Requirement of Juvenile Chinese Mitten Crab, Eriocheir sinensis.

Effects of dietary niacin on the growth performance, intestinal histomorphology, body composition, and antioxidant capacity were investigated in the present study to determine the optimum requirement of niacin for juvenile Eriocheir sinensis. All 360 crabs (initial average weight 1.14 ± 0.04 g) were randomly divided into 6 groups with 3 replicates in each group and 20 crabs in each replicate. Crabs were fed with the control diet (0.89 mg/kg) or niacin-supplemented diets (170.54 mg/kg, 347.05 mg/kg, 587.59 mg/kg, 784.85 mg/kg, and 1248.86 mg/kg) for 12 weeks (named as G1, G2, G3, G4, G5, and G6, respectively). The results showed that appropriate dietary niacin (above 347.05 mg/kg) significantly increased the weight gain rate (WGR) and specific growth rate (SGR) (p < 0.05), but did not affect the survival rate (SR), feed conversion ratio (FCR), daily feeding rate (DFR), and molting frequency (MF) of crabs (p > 0.05). The niacin content in the hepatopancreas of crabs in G1 and G2 was significantly lower than that of the other four groups (p < 0.05). Moreover, dietary niacin significantly affected the intestinal histomorphology of crabs, including the number of folds (NF), height of folds (HF), height of microvillus (HMV), and thickness of muscularis (TM) (p < 0.05). Additionally, moderate dietary niacin levels significantly affected the nonspecific immune responses of crabs, by improving the activity of catalase (CAT), glutathione s-transferase (GST), glutathione peroxidase (GSH-Px), and total superoxide dismutase (T-SOD) (p < 0.05). Based on the broken-line model analysis of SGR against dietary niacin level, the dietary niacin requirement of juvenile crabs was suggested to be 419.4 mg/kg.

Effect of varying proportions of the daily feed rations on the performance of Juveniles of Clarias gariepinus (Burchell, 1882)

African catfish Clarias gariepinus (Burchell, 1882) constitutes a bulk of farmed freshwater fish, particularly in Africa. Its optimal production relies on an optimal feeding regime as feed covers about 50% of operation cost. Studies on feeding regimes have mostly been on feeding frequency and the daily required rations. This study was therefore designed to evaluate the impact of varied proportions of normal daily rations on the performance of C. gariepinus juveniles. Clarias gariepinus Juveniles of 17.6 ± 3.7 g were stocked at a density of 15 juveniles per 50 L of water in 80 L plastic tanks and cultured indoors for 42 days. They were fed a standard specific feed at 5% total biomass three times daily (8:00, 13:00 and 18:00). Treatment 1 received 33.33% of its daily ration at each feeding period, while treatments 2 and 3 received (50%, 25% and 25%) and (25%, 25% and 50%) of the daily rations at 8:00, 13:00 and 18:00, respectively. Fish biomass and survival rate were determined weekly and individual fish weights and lengths were determined at the end of the experiment. Water was aerated continuously and half the volume was renewed daily; temperature and pH were monitored twice daily. The specific growth rate, weight and length gained were best in treatment 3 although not significantly different (p&gt;0.05) among treatments. However, feed conversion ratio and condition factor in treatment 3 were significantly (p&lt;0.05) better when compared to treatments 1 and 2 although temperature and pH in the different treatments were not significantly different (p&gt;0.05). The estimated investment cost was 3891, 4136 and 3907 FCFA, with profit index of 0.95, 0.87 and 1.09 in treatments 1, 2 and 3, respectively. Therefore, administering about 50% of the daily ration in the evening as was the case in treatment 3 is more profitable in the culture of C. gariepinus juveniles.

Energy conversion of biogas from livestock manure to electricity energy using a Stirling engine

• Stirling engine performance prediction is evaluated, and specific biogas consumption, biomethane production and number of animals required for a continuous operation are calculated. • When biogas is composed of 60% of methane and engine is heated to 1000 K, 88 pigs or 26 dairy cows are needed to produce 2.1 kW of shaft power or 50 kWh per day. • When biogas is composed of 60% of methane and engine is heated to 1000K, 710 and 1090 liters of daily water feeding rate and 190 and 340 kg of daily biomass feeding rate are required in a biodigester with a capacity of 26 and 40 m 3 when operating with pig and cow waste, respectively. • When the engine hot chamber is at 1000 K the output power is 2089 W. In this condition, the required mass flow is 20.0 m 3 /h for biogas with 80% of CH4 and 47.0 m 3 /h, in case of having low quality biogas (e.g. 40% concentration). • The mathematical modelling proposed in this work allows the extrapolation for other Stirling engines and other operating conditions. The use of biogas can present an interesting alternative for energy production, especially in regions far from conventional centers of power production and distribution, such as estates with agricultural and livestock activity, in addition to representing an environmentally adequate manner of dealing with its bio-waste. In order to prove this potential, the present work evaluates, through simplified mathematical models, a decentralized biogas production system from the livestock tailings biodigestion and its use for power generation using a Stirling engine. For this, the Stirling engine, the burner combustion and the bio-digestion, which work in a dependent way, were modeled. Thus, the biogas consumption, the cattle or swine population size necessary to supply the biomass demand, the amount of water needed in the process and the biodigester volume were estimated. The influence of the methane concentration and air humidity in combustion are evaluated, as well as the convective coefficient of heat transfer between the combustion gases and the engine during energy generation. Through this analysis, it is concluded that when biogas is composed of 60% of methane and engine is heated to 1000 K, 88 pigs or 26 dairy cows are needed to produce 2.089 kW of shaft power or 50 kWh per day, with 535 and 325 liters of daily water feeding rate and 180 and 325 kg of daily biomass feeding rate in a biodigeste with a capacity of 18.7 and 11.3 m 3 when operating with pig and cow waste, respectively.

The Feeding Behaviour Habits of Growing-Finishing Pigs and Its Effects on Growth Performance and Carcass Quality: A Review.

Based on the available data of feeding behaviour habits (FBHs), this work aimed to discuss which type of pig, according to its FBHs, performs better and is more efficient. As pigs grow, average daily feed intake, meal size, and feeding rate increase, whereas small variations or even decreases in time spent eating and daily feeder visits have been reported. Moreover, the sex, breed, space allowance, feeder design, feed form, diet composition, and environmental conditions modify FBHs. On the other hand, the literature indicates the existence of four types of pigs: pigs that eat their daily feed intake in many short meals (nibblers) or in few large meals (meal eaters) combined with eating fast (faster eaters) or slow (slow eaters). The available scientific literature about ad libitum fed pigs suggests that pigs eating faster with bigger meals eat more, gain more weight, and are fatter than pigs eating less, slower, and with smaller meals. However, the feeding rate and the meal size do not influence feed efficiency. In conclusion, studies comparing growing-finishing pigs with similar feed intake, but different feeding rate and meal size are needed to better understand the influence of FBHs on feed efficiency.