Fish Feed Research Articles

Potential Effects of Live and Nutrient-Enhanced Food on Growth Performance and Biochemical Composition of Blue Acara (Andinoacara pulcher)

Fish food and feeding play an important role in understanding the rate of growth, development and reproduction in ornamental fish culture. The current study evaluated the impact of different types of food on the growth of Ornamental fish, Andinoacara pulcher. A comparative analysis of live, prepared, and commercial food was conducted in three feeding groups A, B and C, respectively. For live feed, Artemia larvae were cultured from Artemia seeds, and fed. The growth in terms of weight and body length was measured at 15-day intervals throughout the experimental period of 60 days. In addition, the protein, lipid, ash, and moisture composition of fish were estimated and analyzed. From the results, the fish fed with live artemia feed attained maximum growth when compared to other prepared feed and commercial feed. The specific growth rate (SGR) was found to be maximum in group A (1.46%), followed by group B (1.15%) and group C (0.71%). There is a well-defined relationship between the rate of growth and the type of food consumed. The protein, carbohydrate, and fat content of fish revealed a higher biochemical composition. In conclusion, the growth and biochemical study in the present investigation indicated that the live feed contains good constituents of vital nutrient substances that promote the growth and protein content of ornamental fish, Blue Acara.

Turning fishery waste into aquafeed additives: Enhancing shrimp enzymes immobilization in alginate-based particles using electrohydrodynamic atomization

Alternative protein ingredients are gradually replacing fish meal in aquafeeds. However, farmed animals often struggle to digest the provided feed, which leads to inefficient nutrient assimilation. This results in a high feed conversion ratio and in water quality deterioration. Fish waste-derived proteases show great potential as bioactive ingredients to enhance protein digestibility. To achieve this, a suitable carrier is essential to include exogenous proteases in the fish feed formulation. Therefore, this research aimed to immobilize a shrimp enzyme extract into different alginate-based microcapsules through electrodynamic atomization and compare their structural and functional properties. Morphology, physicochemical and thermal properties, and in vitro protein release were evaluated for the following microcapsules made from various materials: alginate (A), alginate-chitosan (AC), alginate-bentonite (AB), alginate-bentonite previously subjected to a sonication treatment (ABs), and a combination of all materials (ABsC or ABC). The average sizes ranged from 360 to 790 μm (wet) and 260–516 μm (freeze-dried), confirming the expected differences, with larger sizes for those including chitosan and bentonite. ABsC proved to be the most suitable system for immobilizing exogenous proteases, as these particles exhibited high encapsulation efficiency in both wet and freeze-dried versions and displayed controlled protein release under typical conditions of the proximal intestine. This was further confirmed through an in vivo trial. Two bioassays were conducted with tilapia (Oreochromis niloticus) (n = 42, 2.6 ± 0.58 g) to evaluate the distribution of ABsC-rodamine labeled particles in digestive organs and digestive enzyme activity. ABsC remained in the intestine for over 7 h, and a significant increase in total proteolytic activity was observed 60 min after feeding. These findings suggest that ABsC microcapsules could serve as effective carriers for exogenous proteases in feeds for aquaculture.

Target and suspect screening approaches for the identification of emerging and other contaminants in fish feeds using high resolution mass spectrometry

Fish feed is essential in aquaculture fish production because, along with beneficial nutrients and components, many suspected compounds can be transferred to fish and ultimately to humans. In this context, a comprehensive analysis was conducted to monitor various pesticides and pharmaceutical compounds in aquaculture fish feed through target analysis and many other groups of chemicals via suspect screening approaches. In this study, the QuEChERS extraction method was optimized, validated, and applied to fifty-four fish feed samples collected from different production batches. This was followed by liquid chromatography-high-resolution linear ion trap/Orbitrap mass spectrometry (LC-HR-IT/Orbitrap-MS) for targeted and suspect screening purposes. In general, pesticides provided satisfactory recoveries (70–105.5 %), with quantification limits lower than 5 ng g−1, whereas pharmaceuticals displayed recoveries ranging from 70.5 to 120.2 %, with quantification limits below 25 ng g−1. In addition, the matrix effects and measurement uncertainty were assessed to provide more accurate and high-confidence results. Pirimiphos-methyl was detected and quantified in 20 of 54 fish feed samples (37 %) at concentrations <77 ng g−1. Finally, suspect screening revealed the occurrence of 10 mycotoxins (e.g., citrinin, aflatoxin G2, zearalenone, and alternariol), two pesticides excluding the target pesticides (tebuconazole and fenazaquin), perfluorooctane sulfonic acid (PFOS) in almost 2 % of the samples, and ethoxyquin (antioxidant), with 12 of its Transformation Products (TPs). Finally, suspect analysis incorporated in routine analyses have proven to have great potential for complete monitoring.

Effects of rosemary enriched diet on physiological parameters in common carp Cyprinus carpio L reared in cages culture

The current study investigated at how rosemary leaf powder supplementation influenced the growth performance, carcass composition, hematological and biochemical parameters, stress hormones, and heat shock proteins of cage-reared common carp. Nine cylindrical cages of 0.2 m³ (radius = 25 cm, height = 100 cm) were randomly allocated to hold 54 juvenile common carp C. carpio (mean weight=18.18±0.08 g). Three groups of fish were fed a control diet (C) as well as diets containing 1.5% and 3% rosemary powder, respectively. The addition of 3% rosemary resulted in a substantial enhancement in growth parameters and feed consumption. The levels of WBC, Hb, MCHC, RBC, and Hct were significantly elevated by the addition of rosemary to experimental fish. A rosemary-supplemented diet resulted in higher levels of TG, urea, total protein, albumin, lipase, amylase, ferrum, and globulin. However, the addition of substantially reduced the levels of ALT cholesterol, creatinine, and glucose. The value of cortisol, T3, and T4 were considerably reduced with the addition of rosemary to diets of experimental fish. HSP70 and HSP90 levels in fish feed diets administered rosemary increased significantly as supplementation amount increased. According to the findings of this investigation, adding rosemary leaf powder, particularly at a concentration of 3%, in the diet improved growth parameters, hematological and biochemical parameters, and be able to reduce stress responses, thyroid hormone levels, and other stressors that fish exposed in cage culture system.&#x0D;

Vertical habitat preferences shape the fish gut microbiota in a shallow lake.

Understanding the interactions between fish gut microbiota and the aquatic environment is a key issue for understanding aquatic microorganisms. Environmental microorganisms enter fish intestines through feeding, and the amount of invasion varies due to different feeding habits. Traditional fish feeding habitat preferences are determined by fish morphology or behavior. However, little is known about how the feeding behavior of fish relative to the vertical structure in a shallow lake influences gut microbiota. In our study, we used nitrogen isotopes to measure the trophic levels of fish. Then high-throughput sequencing was used to describe the composition of environmental microbiota and fish gut microbiota, and FEAST (fast expectation-maximization for microbial source tracking) method was used to trace the source of fish gut microbiota. We investigated the microbial diversity of fish guts and their habitats in Lake Sanjiao and verified that the sediments indeed played an important role in the assembly of fish gut microbiota. Then, the FEAST analysis indicated that microbiota in water and sediments acted as the primary sources in half of the fish gut microbiota respectively. Furthermore, we classified the vertical habitat preferences using microbial data and significant differences in both composition and function of fish gut microbiota were observed between groups with distinct habitat preferences. The performance of supervised and unsupervised machine learning in classifying fish gut microbiota by habitat preferences actually exceeded classification by fish species taxonomy and fish trophic level. Finally, we described the stability of fish co-occurrence networks with different habitat preferences. Interestingly, the co-occurrence network seemed more stable in pelagic fish than in benthic fish. Our results show that the preferences of fish in the vertical structure of habitat was the main factor affecting their gut microbiota. We advocated the use of microbial interactions between fish gut and their surrounding environment to reflect fish preferences in vertical habitat structure. This approach not only offers a novel perspective for understanding the interactions between fish gut microbiota and environmental factors, but also provides new methods and ideas for studying fish habitat selection in aquatic ecosystems.

Fish Feeding and Rapid Foraging Behavior Switching by Gray Whales (Eschrichtius robustus) in California

Gray whales (Eschrichtius robustus) evolved to suction feed on benthic invertebrates and typically do not consume adult fish. Yet, these whales are flexible foragers, occasionally skim feeding on planktonic invertebrates and rarely lunge feeding on fish, the latter according to anecdotal accounts. We documented the unusual phenomenon of multiple gray whales predating dense schools of anchovy over a sustained period (22 days) in June 2022 at Pacifica, California, in the Gulf of the Farallones. Analysis of 11,265 photos and 11 video clips (totaling 4 min 16 s) for behavior and whale identification resulted in a total of 165 foraging events by six identified gray whales. Attribution of foraging behavior to the most active individuals was achieved by matching left pectoral fins, visible during lateralized feeding behavior. Whales rolled onto their right sides in 96% of near-surface side-swimming bouts. Another behavior, first photographed here, was dynamic surface lunge feeding by one gray whale. Five gray whales interspersed fish feeding with benthic suction feeding evidenced by sediment streaming: prey type switching was executed rapidly, in less than 1 minute in several instances, the shortest intervals reported for a baleen whale. Similar results were obtained for foraging behavior switching (continuous side-swimming or intermittent lunging) in pursuit of fish. Four photo-identified Pacifica whales were sighted in San Francisco Bay/Gulf of the Farallones, one of which was also matched to the Pacific Coast Feeding Group. Such local and regional connections warrant efforts to determine whether gray whales use this area as a migratory stopover site or for summer foraging, or both. Our observations confirm gray whale behavioral plasticity and opportunistic exploitation of food resources in mid-latitudes, which may enhance their resilience to climate change.

Pembuatan Pelet Ikan Bergizi Tinggi untuk Peternak Ikan di Kampung Lampaya dan Weuraya Kecamatan Lhoknga Aceh Besar

The service was carried out in Weuraya Village and Lampaya Village, Lhoknga District, Aceh Besar Regency with the target of fish farmer business groups. At first, the need for fish in Lhoknga and its surroundings only relied on fishing at sea by fishermen. Over time, the need for fish and employment for the community here eventually led to fish farming. Seeing the potential of fish farming that is getting better in this area, a group of people in this area took the initiative to form a fish farming business group located in Lampaya and Weuraya Villages, Lhoknga District, Aceh Besar. These two villages are located not far from the center of the Banda Aceh city market, estimated at about 25 km from the location of the farm which can be reached for approximately 1 hour drive. Determining the composition of fish feed ingredients is an important issue because not all compositions will provide the best results for fish growth. The high price of fish feed in the market with low protein content causes fish farmers to experience difficulties in cultivating fish. The objectives of this activity are first, to concoct their own animal feed from tofu dregs, snails or rice snails, wheat flour, rice bran, and coconut meal which are very widely available around Lhoknga. The second training was for the Lampaya and Weuraya fish farmer groups in Lhoknga sub-district to make fish feed. All members of the Lampaya and Weuraya fish farmer groups are involved in the two scopes of work above, so that these two groups will have the knowledge and skills to make quality and healthy fish feed for fish. From the results of the monitoring of the service team, it is clear that the high enthusiasm of the community can be measured by the crowd of socialization and training participants, as well as the many questions that arise during the practice of making fish pellets. At the end of the activity, the community has mastered how to make their own fish feed and can save 60% of the total cost

Strategy to remove ammonium compounds released from fish feed in aquaculture using natural filtration materials.

The effects of addition of adsorbent mixture at two different stages in aquaculture system were investigated for the first time in this study. In the first stage, in order to determine the effects of natural adsorbents in an environment without feed, a trial consisting of four treatment groups with three replications was conducted. In this trial, individual and combined effects of two natural adsorbents on water parameters in absence of feed were assessed for five days.In the second stage for 9 experimental days, a total of 18 aquaria consisting of three treatment groups with three replications for two different fish feeds were used. Of these aquaria, the first six received only two types of feeds containing 33 and 40% protein, designated as two control groups (C1 and C2). Other two groups (T1 and T2) were prepared by adding a leonardite: zeolite mixture (at 2:1 ratio) to next six replicates simultaneously. The last six replicates received a leonardite: zeolite mixture (at 2:1 ratio) after the 8th day of the study, and formed the last two treatment groups (T3 and T4).In this study, mean pH values varied between 7.01 and 7.82 and ammonia values were found to be maximum of 94.96% and minimum of 38.73% lower compared to the control group when 3g adsorbent mixture (2L: 1Z) was used to balance pH and ammonium (NH4+) values in an aquatic environment containing 0.5l freshwater and 0.5g fish feed with 33-40% protein contents. It was demonstrated that the combined use of zeolite and leonardite had positive effects on ammonium removal and providing optimum pH levels for aquaculture. The combined use of these two adsorbents helped balance the pH-reducing effect of leonardite with zeolite, and the pH-reducing effect of leonardite contributed to the NH4+ adsorption efficiency of zeolite.

Feasting in mussel farms fattens up snapper (Chrysophrys auratus) compared to snapper in adjacent natural habitats

AbstractThe presence of wild fish in and around aquaculture habitats is often assumed a response to food resources within these habitats, either from input feed, the presence of cultured species, and/or the assemblage of biofouling that naturally colonises aquaculture structures. The nutritional quality of the food resources consumed by wild fish in aquaculture habitats is also important in determining their nutritional condition and subsequent productivity. Few studies have investigated the nutritional quality of prey in aquaculture habitats, and these have mostly focused on fed aquaculture by tracking manufactured fish pellets into the diets of wild fish. However, in non‐fed aquaculture, the assemblage of cultured and biofouling species may also provide a nutritional benefit to fish feeding in these habitats. The Australasian snapper, Chrysophrys auratus, are commonly present as adults within coastal mussel farms in New Zealand and tend to become a resident species. This study investigated the nutritional quality of the gut contents of snapper in soft‐sediment habitats within and outside of New Zealand green‐lipped mussel farms. Total lipid, protein, carbohydrate and total calorific content were measured from the gut contents of snapper sampled from mussel farm and natural (i.e. control) habitats. Snapper in mussel farms had double the dietary intake of lipid (16% vs. 8%) from consuming lipid‐rich bivalves and barnacles which are in abundance in mussel farms. Higher lipid intake can contribute to improved nutritional condition, reproduction and growth in snapper. However, the higher dietary lipid intake of snapper in mussel farms did not increase their overall body condition (i.e. Fulton condition index). This may be due to the coarse nature of this measure, or the use of the additional lipid in more rapid somatic growth or reproductive outputs, possibilities that warrant examination through further research. Overall, this study shows for the first time the potential ecosystem benefits of shellfish aquaculture in provisioning nutritionally valuable prey for coastal fish populations.

Effect of Monosodium Glutamate in Artificial Food on Feed Utilization Efficiency, Growth, and Survival of Fingerling Tilapia (Oreochromis niloticus)

Tilapia (Oreochromis niloticus) is one of the leading freshwater fish commodities in Indonesia. The problem often faced by tilapia farmers is the low level of feed utilization, especially protein, which is still low, resulting in suboptimal growth. The glutamate content in monosodium glutamate (MSG) can act as a precursor for the formation of arginine and glutamine, which can increase the production of protease and lipase enzymes that are excreted into the intestines during the feed hydrolysis process, which is useful in increasing the absorption of nutrients in the form of protein and fat. This research was conducted using fingerling tilapia as a test fish with an average individual length of 6.59 ± 0.21 cm/fish and an average individual weight of 5.33 ± 0.27 g/fish. This research was carried out in an aquarium container measuring 40x30x30 cm with a water volume of 27 l and a density of 15 fish/aquarium. The aim of this research was to determine the effect of MSG in fish feed on total feed consumption (TKP), feed utilization efficiency (FUE), protein efficiency ratio (PER), protein retention, relative growth rate (RGR), and survival (SR) in fingerling tilapia. This research used an experimental method with a completely randomized design (CRD) of 4 treatments with 3 replications. Treatments A, B, C, and D are fed with the addition of 0 MSG in commercial feed; 0.75; 1.5; and 2.25 g/kg. Variables observed included TKP, FUE, PER, protein retention, RGR, and SR. The research results showed that MSG in feed had a significant effect (P &lt; 0.05) on the FUE, PER, protein retention, and RGR values but had no effect (P &lt; 0.05) on the TKP and SR values. FUE value; PER, protein retention; The highest RGR was obtained in treatment D (2.25 g/kg); FUE (87.21±2.28); PER(1.83±0.05); protein retention (50.47±0.76); The RGR (3.06 ± 0.03) and survival value for all treatments were found to be 100%. The water quality during the research was in optimal condition.

Community Empowerment of PCM Kokap on Sustainable Municipal Waste Management through Black Soldier Fly Farming

Municipal waste management is one of complicated environmental problems found in many areas of Yogyakarta, including in Kokap, Kulon Progo. In addition, the awareness from local society towards the importance of waste management has not well built yet due to the lack of knowledge on this issue. Therefore, this program was aimed to promote better understanding and technical skill of Pimpinan Cabang Muhammadiyah (PCM) Kokap members regarding black soldier fly-mediated waste management. This community empowerment program involved 15 PCM members (aged ranging from 40-55 years old) and carried out using the experiential learning method through participatory approach. It started with focus group discussion and followed by the trial of BSF farming using municipal waste performed by the members for 40 days. Intensive supervision was provided through WhatsApp Group. Results showed that all PCM members were success in cultivating a complete cycle of BSF. Some of the BSF larvae had been used as feed for poultry and fish. The success of this trial was associated to the high enthusiasm from the members in following the technical guidelines provided virtually. Overall, this program has successfully educated the targeted community marked by the accomplishment of PCM Kokap members in executing the trial of municipal waste management. It also conferred the increased member’s understanding regarding the economic value of BSF products to be alternative source of secondary income. The success of this program could be a pilot project to generate society awareness and capacity for higher responsibility with the municipal wastes produced.

Effects of partial replacement of fishmeal with Spirulina platensis powder and addition of Spirulina platensis polysaccharide on growth, nutrition, antioxidant capacity and gut microbiota of Micropterus salmoides

Fish is currently considered a primary protein in the human diet, and the high demand for fish will stimulate the growth of aquaculture. However, a lack of high-quality fish feed (fishmeal) has led to a decline in the quality and yield of aquatic products. Therefore, an alternative high-quality protein source for fish meal is required to sustain the industry. This study assessed the effects of incorporating Spirulina platensis (SP) dried powder as a partial replacement for fishmeal and supplementing with S. platensis purified polysaccharides (PSP) on the growth, nutritional value, and health status of the largemouth bass, Micropterus salmoides, to address the challenges of fishmeal scarcity and promote sustainable development in fish aquaculture. Juveniles were fed four isonitrogenous and isolipidic diets containing SP at 0% (SP0), 3% (SP3) and 6% (SP6) and PSP at 0.3% for 56 days. The results showed that both the SP3 and SP6 groups displayed significantly (P < 0.05) improved growth performance and lower hepatosomatic indices than the control diet (SP0). Whole-body crude protein and protein efficiency significantly increased in both the SP3 and SP6 groups compared with SP0 (P < 0.05). Conversely, crude lipid content notably (P < 0.05) decreased in SP3 (5.96%) and SP6 (5.41%) in contrast to SP0 (6.59%). The muscle amino acid composition of the PSP, SP3, and SP6 groups also improved significantly (P < 0.05) compared to that of the SP0. Liver SOD activity was significantly increased from 1.11 U/mg in SP0 to 1.22–1.24 U/mg in SP3 and SP6 (P < 0.05), while MDA levels declined accordingly. Serum triglyceride levels were significantly lower in SP3 than in SP0 (P < 0.05) but remained stable in the SP6 and PSP groups. Low-density lipoprotein cholesterol decreased significantly in the SP3 and SP6 groups, but no significant effect was observed in the PSP group. Alanine aminotransferase activity was significantly (P < 0.05) lower in the PSP, SP3, and SP6 groups than in SP0. Aspartate aminotransferase activity in PSP and SP3 was significantly lower than in SP0 (P < 0.05), but showed no significant difference with SP6 (P > 0.05). Intestinal trypsin and amylase activities significantly improved in the PSP, SP3, and SP6 groups (P < 0.05), and lipase activities in PSP and SP3 increased significantly compared to those in SP0 (P < 0.05). The intestinal microbiome displayed significantly higher Shannon index scores for SP3 (0.83) and SP6 (0.93) than for SP0 (0.61). The relative abundances of the phylum Fusobacteria and genus Cetobacterium were significantly increased, whereas Proteobacteria and Plesiomonas were significantly decreased in the PSP and SP3 groups compared with that in SP0 (P < 0.05). The present study indicated that the replacement of fishmeal with 3–6% SP and 0.3% PSP addition could improve the growth performance, protein efficiency, muscle nutritional value, liver health, antioxidant capacity, intestinal digestive enzyme activity, and intestinal microbiota diversity of the largemouth bass. Therefore, the partial replacement of SP or the addition of PSP has great potential in promoting healthy aquaculture of largemouth bass.

A fish appetite assessment method based on improved ByteTrack and spatiotemporal graph convolutional network

The appetite of fish significantly influences aquaculture efficiency and fish welfare. However, accurately assessing fish appetite has posed a challenging problem. Currently, the study of fish feeding behaviour relies primarily on the overall information obtained from images of fish schools, often overlooking the distinctive behavioural traits of individual fish. Analysing the behaviour of individual fish is hindered by challenges such as intraclass variation and cross-occlusion within real aquaculture environments. To address these challenges, this paper introduces a novel method for assessing appetite based on individual fish behaviour. The ByteTrack model was improved to enable stable tracking of each fish within a school under complex conditions. Additionally, this paper employs the spatiotemporal graph convolutional neural network (ST-GCN) to extract the movement characteristics of individual fish, facilitating accurate appetite assessment. The experimental results demonstrate that the proposed method achieves 98.47% accuracy in appetite assessment, surpassing the performance of other state-of-the-art methods. This paper provides a new opportunity and effective means for analysing fish behaviour and appetite in intricate environments.

The fish weight at slaughter influences energy and environmental performance of fish farming: The case of Nile tilapia production in cages

The goal of this study was to evaluate the energy and environmental performance over the life cycle of Nile tilapia production for harvesting in different weight. The reference flow was 1 t (megagram – Mg) of fished Nile tilapia with the following weight: 0.6 kg, 0.9 kg, 1.2 kg, 1.5 kg, 1.8 kg and 2.0 kg. The inventory was defined for the stages of feed production and fish production with the processes for fingerlings, followed by rearing of juvenile and fattening of adult in cage. In addition, the inventory covered the supply of the remaining material and energy inputs, transport, infrastructure and waste management. The assessed categories were area occupation, water consumption, energy demand, global warming, acidification and eutrophication. Even though the smaller-sized fish demanded more fingerlings to produce 1 t of Nile tilapia than the larger ones, the feed conversion of the smaller-sized fish was more favorable compared to that of the larger-sized fish. The energy and environmental burden of Nile tilapia showed a tendency to increase with larger-sized fish. The largest contribution of area occupation, water consumption, energy demand and global warming was from feed production, while that of acidification and eutrophication was from the rearing and fattening processes of fish production. The choice of feed ingredient suppliers from more efficient and clean sources at feed production and the control of feed loss at fish production are key strategies to improve the energy and environmental performance of the fished Nile tilapia. Therefore, the sustainability of pisciculture must consider feed production from more eco-efficient ingredients, higher efficiency in feed conversion, control of feed loss, and the use of production effluent.

Toward sustainable food systems: can spirulina (Arthrospira platensis) become a sustainable source of protein to enhance the nutritional benefits of cultured Nile tilapia (Oreochromis niloticus)?

Hunger affected 278 million people in Africa in 2021, and in Kenya, the proportion of the population unable to afford a healthy diet is 81%. To combat hunger and increase resilience throughout the food system, spirulina (Arthrospira platensis) has been shown to have remarkable properties. The main aim of this study is to investigate whether protein from spirulina is a suitable alternative to protein sourced from fish meal in fish feed for juvenile Nile tilapia (Oreochromis niloticus). In a trial investigating the use of spirulina biomass for fish feed on juvenile Nile tilapia, it has been proven that tilapia fingerlings fed diets with spirulina, replacing up to 30% of fish meal protein, were not affected in terms of growth performance compared to the fish fed the commercial diet. This shows that, nutritionally, protein from spirulina can replace fish meal protein fed to juvenile Nile tilapia. This offers promising opportunities for enhanced food and nutrition security. If produced affordably, spirulina can have a significant impact on the income level of low-income fish farmers in Kenya, who often spend more than 50% of their income on commercial fish feed. Affordability can be made possible if small-scale farmers can produce spirulina using animal manure that is available on the farm instead of using highly priced commercial fertilizer. The additional environmental benefits of spirulina include carbon dioxide sequestration and the removal of nitrogenous and phosphorous waste from the wastewater. Spirulina can therefore increase the sustainability of a whole food system.

Farmed cricket (Acheta domesticus, Gryllus assimilis, and Gryllodes sigillatus; Orthoptera) welfare considerations: recommendations for improving global practice

Abstract Orthoptera, such as crickets, is currently the most reared group of hemimetabolous insects in the insects as food and feed industry, with over 370 billion individuals slaughtered and/or sold live annually. The most-farmed cricket species is Acheta domesticus, however there is growing interest in farming at least two additional species, Gryllus assimilis and Gryllodes sigillatus. Crickets are largely being explored for use as human protein, and exotic animal or pet feed – as well as, to a lesser extent, livestock and fish feed. Insect welfare is of growing interest to consumers who are considering incorporating insect protein into their diets, as well as to many producers. However, no studies have considered the welfare concerns of farmed crickets under current industry conditions. Using an established model for assessing farmed insect welfare, we assess potential welfare concerns for the three most-farmed cricket species, including: interspecific interactions (including parasites and pathogens), temperature and humidity, light cycles, electrical shocks, atmospheric gas levels, nutrition and hydration, environmental pollutants, injury and crowding, density, handling-associated stress, genetics and selection, enrichments, transport-related challenges, and stunning, anesthesia, and slaughter/depopulation methods. From our assessment of these factors, we make recommendations for improving cricket welfare now and as the industry continues to grow; in addition, we identify research directions that will improve our understanding of cricket welfare. We conclude by broadly discussing the importance of addressing the welfare challenges presented by the insects as food and feed industry for the animals and for the growth and health of the industry itself.

Influence of nitrogen substitution at an equivalent total nitrogen level on bacterial and fungal communities, as well as enzyme activities of the ditch bottom soil in a rice-fish coculture system.

Rice-fish coculture system (RFS) operates through effectively utilizing water and land resources in a complementary form, but it requires more efficient utilization of fertilizer and feed without compromising rice yield. However, the knowledge of how to regulate the proportion of nitrogen (N) supplied from fertilizer and feed at an equivalent total N levelto improve the benefits of RFS remains limited. Therefore, four treatments (S0: RFS with 0% N fromfertilizer and 100% N from feed; S25: RFS with 25% N from fertilizer and 75% N from feed; S50: RFS with 50% N from fertilizer and 50% N from feed; S75: RFS with 75% N from fertilizer and 25% N from feed) were conducted to assess the variation of ditch bottom soil properties, microbial communities and enzyme activities, as well as to obtain the optimal ratio of N supplied from fish feed and fertilizer. The experiments showed that the contents of soil organic matter, total carbon and total N, and the activities of urease, N-acetyl-β-D-glucosaminidase, protease, β-1,4-glucosidase and catalase in the ditch bottom soil significantly reduced in S25 treatment, compared with the other three treatments. Ammonium N content decreased with increasing percentage of the basal fertilizer, whereas nitrate N content and pH value showed an adverse trend. However, the bacterial and fungal communities were unaffected by the ratio shifts between fertilizer-N and feed-N, but their dominant phyla were influenced by the ditch bottom soil N level. Moreover, the bacterial community composition was positively related to nitrate N, whereas fungal diversity was positively correlated with pH, ammonium N and nitrate N, and urease. We also found that the treatment of N input with 25% N from fertilizer and 75% N from feed can reduce N deposition in the ditch bottom soil in the rice-fish coculture system. Our findings indicate that under the equivalent total N input level, the relative higher ratio of N from fish feed increased (S0 treatment) or reduced (S25 treatment) the deposition of N in the ditch bottom soil, and improved fish production, but decreased rice yield; while the higher ratio of N from basal fertilizer increased the transportation of nutrients into the ditch bottom soil and rice yield, but reduced fish production. So when considering multi-balance and multiple benefits, we recommend that a selective substitution ratio within 50% ~ 75% from fish feed to substitute for the basal fertilizer under the equivalent total N input may achieve a good balance of rice and fish production improvement, and reduce nutrients wastage to the ditch bottom, as well as alleviate the potential of non-point source pollution. This study also provides an evidence for regulating and optimizing the ratio of N supplied from fertilizer and fish feed at an equivalent total N level through monitoring the nutrient accumulation in ditch bottom soil in the rice-fish coculture system. © 2024 Society of Chemical Industry.

Recycling of animal protein wastes in the formulation of feed for Labeo rohita and Mystus vittatus—a comparative evaluation

Lactic acid bacteria (LAB) are key players in the fermentation of organic wastes and their recycling as feedstuff for fish. Whey, a common dairy byproduct in India, is a cheap source of LAB and can be used to ferment animal byproducts. An experimental study was designed to explore whether the whey fermented animal protein blend (WFAPB) could be used as a fishmeal replacer in the formulation of feed for both stomach-less carp fish Labeo rohita and stomach-bearing catfish Mystus vittatus. Experiments were performed with five isoproteinous, isolipidous, and isoenergetic feeds with WFAPB replacing fishmeal (FM) by 0% (T1), 25% (T2), 50% (T3), 75% (T4), and 100% (T5). Fifteen days of laboratory experiments with these experimental feeds revealed that more than 50% FM replacement level could result in excess postprandial absorption (6 h) of some essential and non-essential amino acids in the plasma of both fish. The postprandial absorption was more in M. vittatus than L. rohita. Ninety-day experiments were conducted in outdoor cement vats to measure growths and deposition of amino acids (AA) in muscle. Regression analysis was performed to find the optimal FM replacement based on four growth parameters and fifteen AA deposition in muscle. A two-phase fuzzy methodology was used to obtain Pareto-optimal replacement levels for each fish. The results demonstrated that FM replacement levels were 7.63% and 36.79% respectively for L. rohita and M. vittatus when only four growth parameters were considered. However, based on the FM replacement level that maximized deposition of 15 amino acids and growth parameters, it was found that 12.23% and 40.02% replacement of FM by the WFAPB was ideal respectively for L. rohita and M. vittatus. The results revealed that only a fraction of both essential and non-essential amino acids absorbed in plasma could be converted into protein and deposited as bound amino acids in the muscle. It is concluded that fermentation by whey is an inexpensive, easily available, and environmentally sustainable technique to recycle animal protein in the formulation of feed for fish, and the stomach-bearing carnivorous fish are more efficient in utilizing fermented animal protein blend than the stomach-less carps.

Predation risk-mediated indirect effects promote submerged plant growth: Implications for lake restoration

Biological manipulation, involving fish stockings, is commonly used to counteract the deterioration of submerged vegetation in eutrophic lakes. Nevertheless, the non-consumptive effects (NCEs) of stocked carnivorous fish are often overlooked. Using a controlled experimental system, we investigated the NCEs of a native carnivorous fish, snakehead (Channa argus), on two key biological factors, herbivore-dominated grass carp (Ctenopharyngodon idella) and disturbance-dominated loach (Misgurnus anguillicaudatus), influencing submerged plants growth. Additionally, we conducted a meta-analysis on predation risk and primary productivity. The results reveal that predation risk induces oxidative stress damage and affects grass carp growth. Non-significant changes in cortisol and glucose may be linked to predation risk prediction. Simultaneously, predation risk reduces fish feeding and disturbance behavior, relieving pressure on submerged plants to be grazed and disturbed, thereby supporting plant development. The presence of submerged plants, in turn, enhances loach activity and influences water body characteristics through negative feedback. Furthermore, the meta-analysis results indicate the facilitative effect of predation risk on primary producers. Our findings contribute to the understanding of biological manipulation theory. We demonstrate that the predation risk associated with introducing carnivorous fish can promote the growth of submerged plants through behaviorally mediated indirect effects. This highlights the potential utility of predation risk in lake restoration efforts.

Herbivorous fish feeding dynamics and energy expenditure on a coral reef: Insights from stereo-video and AI-driven 3D tracking.

Unveiling the intricate relationships between animal movement ecology, feeding behavior, and internal energy budgeting is crucial for a comprehensive understanding of ecosystem functioning, especially on coral reefs under significant anthropogenic stress. Here, herbivorous fishes play a vital role as mediators between algae growth and coral recruitment. Our research examines the feeding preferences, bite rates, inter-bite distances, and foraging energy expenditure of the Brown surgeonfish (Acanthurus nigrofuscus) and the Yellowtail tang (Zebrasoma xanthurum) within the fish community on a Red Sea coral reef. To this end, we used advanced methods such as remote underwater stereo-video, AI-driven object recognition, species classification, and 3D tracking. Despite their comparatively low biomass, the two surgeonfish species significantly influence grazing pressure on the studied coral reef. A. nigrofuscus exhibits specialized feeding preferences and Z. xanthurum a more generalist approach, highlighting niche differentiation and their importance in maintaining reef ecosystem balance. Despite these differences in their foraging strategies, on a population level, both species achieve a similar level of energy efficiency. This study highlights the transformative potential of cutting-edge technologies in revealing the functional feeding traits and energy utilization of keystone species. It facilitates the detailed mapping of energy seascapes, guiding targeted conservation efforts to enhance ecosystem health and biodiversity.