Animal Feeding Operations Research Articles

Gradual behaviour change towards meat reduction revisited: Applying the decisional balance scale in a Dutch study

Meat moderation is needed to mitigate climate change and to address issues related to animal welfare and public health. Yet little is known on the process that consumers go through towards meat-reduced diets. Strässner and Hartmann (2023) recently developed the decisional balance scale (DB scale) for meat reduction, in order to get a better understanding of the trade-offs that consumers encounter in this dietary shift. The current study sets out to replicate their German study in the Dutch context. A survey has been conducted among a representative sample of Dutch adults (N = 1982). Overall, the present study corroborated Strässner and Hartmann's findings. Similar to the German situation, Legitimation is the most important barrier, and the Downsides of factory farming is the most important motivator for meat reduction in the Netherlands. The present study extends the German study by comparing the DB scale with other established scales in research on meat reduction. Although several motivational elements related to the legitimacy of eating meat, health impact and production of meat appear in different instruments, the DB scale sets itself apart in adding practical elements (feasibility). Finally, the insights in the decision balance of population subgroups at different stages of behaviour change (no intention, intention, performing) showed that the further in the meat reduction process, the more the pros outweigh the cons. With this, the current study provides valuable insights in bolstering consumers in meat moderation. Our findings support the idea of a gradual shift and reveal that there is potential for acceleration in behaviour change towards meat reduction to be found in adjusting the self-evidence of high-intensity livestock farming systems and the meat-centric food consumption culture.

Sentience and the Issue of Animal Welfare

Abstract In this article, I discuss a precondition of moral consideration that sets the bar lower at sentience. The popular sentience thesis identifies the capacity to feel pain as its condition of consideration. By appealing to the capacity to feel, it is possible to address some fundamental questions about anthropocentrism such as a threat to sentient animals in factory farming and unnecessary experimentation on nonhuman animals. This article interrogates the issue of animal welfare and exposes how discussions on moral considerations focusing on animal sentience exclude non-sentience animals from public welfare policy. While the sentience thesis is a well-established approach in the animal welfare literature, I argue that it lacks robust normative force and, as such, is inadequate for promoting animal welfare since it forces fragmentation of our moral life.

Основные подходы к снижению запахового загрязнения окружающей среды предприятиями животноводства (обзор)

Modern industrial livestock production is accompanied by emissions into the environment of a wide range of odorforming substances (OFS), which negatively affect the health and quality of life of the population. The problem of protecting atmospheric air from odour pollution (OP) is of high relevance and practical significance. The review critically appraises scientific publications on the control of OP from livestock and poultry farms. Methods of control include the processing of manure with deodorizing materials (reagents, sorbents, enzymes, etc.); inoculation with microorganism strains; adjustment of animal diets; air purification from pollutants; optimization of dispersion; isolation of ОР sources; and odor masking. Agriculture’s focus on adopting green technologies has increased interest in searching environmentally friendly methods of odor control. These are the use of plant extracts, natural sorbents, effective microorganism strains, biofilters, bioscrubbers, biogas plants, planting of protective forest belts that promote the absorption of dust and dispersion of OFS. Each method of OP control has both advantages and disadvantages. Modern “green” methods effectively eliminate odors in large farms, but require high investment and operating costs, which limits their implementation in practice, and relatively low-cost methods (the use of reagents, sorbents, flavoring agents, feed additives) are usually not effective enough. An acceptable result can be obtained by combining various methods of limiting the OFS emission. Control strategies should be selected based on the source of the odor, the effectiveness of the technology on the particular farm, and the cost/benefit ratio of the odor control technology into practice.

A study on the hepatic response to heat stress in Gymnocypris eckloni through an approach combining metabolomic and transcriptomic profiling

Gymnocypris eckloni, an economically important cold-water fish widely cultivated in southwest China, is at increased risk of prolonged exposure to heat stress owing to persistent high temperatures in summer, extreme climate changes, and expansion of factory farming. In this study, G. eckloni was subjected to both chronic and acute heat stress, with subsequent analysis focusing on changes in the pathological and physiological characteristics and transcriptomic and metabolic responses of the liver to high temperature. The results revealed heat stress-induced damage to liver tissues, lipid accumulation and mitochondrial abnormalities in hepatocytes, and an increased number of apoptotic cells, with the damage being more severe under acute heat stress conditions. Assessment of biochemical indices showed that the antioxidant enzyme catalase (CAT) was activated in response to oxidative stress and energy demands increased following heat stress. Transcriptomic analysis showed significant enrichment in the protein processing in the endoplasmic reticulum pathway, along with upregulation of key genes associated with protein degradation (hsp40, hsp70, hsp90, ero1l, and pdia4) and activation of the unfolded protein response (UPR), which effectively reduces or clears the accumulation of misfolded proteins to combat stress. Most identified differential metabolites were associated with amino acid and lipid metabolism under heat stress. Notably, integrated transcriptomic and metabolomic analysis suggested that tryptophan metabolism played an important role in the adaptation of G. eckloni to chronic heat stress. These findings improve the understanding of the mechanisms through which G. eckloni adapts to high temperatures, providing a valuable foundation and novel avenues for developing strategies to alleviate the effects of heat stress and improve the outcomes of aquaculture.

Cultured Meat as a Transitional Step Towards Interspecies Justice?

Abstract For some, cultured animal products ought to be celebrated for the potential they offer to replace factory farming. Others argue that, for the same reason, there is a duty to support their production and consumption. This paper argues that the ethical status of cultured animal products ought to be assessed not just in comparison with factory farming, but also in terms of its potential to bring about interspecies justice. The claim is made that the attitudes embodied within cultured animal products show a lack of proper respect for nonhuman animals and are at odds with those required by justice. Although cultured animal products have the potential to greatly reduce harms done to nonhuman animals, this paper argues that their adoption ought to nevertheless be regarded with some regret. Using a Rawlsian framework for assessing transitional steps towards justice, the paper shows that, whilst the adoption of cultured animal products may be permissible, the case for regarding it as a duty is much weaker. For cultured meats to be permissible, it must first be shown that alternatives that respect the value of nonhuman animals as ends-in-themselves do not exist.

Metagenomics Insight into Veterinary and Zoonotic Pathogens Identified in Urban Wetlands of Los Lagos, Chile.

Wetlands are ecosystems that are essential to ecological balance and biodiversity; nevertheless, human activity is a constant threat to them. Excess nutrients are caused by intensive livestock and agricultural operations, pollution, and population growth, which in turn leads to uncontrolled microbiological development. This impairment in water quality can constitute a risk to animal, human, and environmental health. To thoroughly characterize the microbial communities, shotgun metagenomics was used to characterize the taxonomic and functional pattern of microorganisms that inhabit urban wetlands in the Los Lagos Region of Chile. The main objective was to identify microorganisms of veterinary relevance, assess their potential antibiotic resistance, and characterize the main virulence mechanism. As expected, a high diversity of microorganisms was identified, including bacteria described as animal or human pathogens, such as Pasteurella multocida, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. Also, a diverse repertory of antimicrobial-resistant genes (ARGs) was detected in metagenomic assembled sequences and inside the sequence of mobile genetic elements, genes that confer mainly resistance to beta-lactams, consistent with the families of antibiotics most used in Chile. In addition, a diverse collection of virulence mechanisms was also identified. Given the significance of the relationship between environmental, animal, and human health-a concept known as One Health-there is a need to establish molecular surveillance programs that monitor the environmental biohazard elements using molecular tools. This work is the first report of the presence of these harmful biological elements in urban wetlands subjected to anthropogenic pressure, located in the south of Chile.

From pollution to resource: advancing swine waste treatment in the USA

Concentrated animal feeding operations (CAFOs) have led to environmental challenges, specifically waste management. Swine CAFOs generate large amounts of waste, requiring proper treatment to avoid air and water pollution. Conventional waste management technologies, such as lagoon and spray field systems, do not prevent air and water pollution impacts. Research for the past few decades led to recommendations for waste treatment technologies superior to lagoons and spray fields. Private environmental sustainability initiatives focused on reducing greenhouse gas emissions in the food supply chain have implemented biogas digester projects for capturing methane in covered swine lagoons to reduce greenhouse gas emissions. However, research indicates that methane capture alone does not solve the broader pollution issues associated with lagoon and spray field systems still in use at these CAFOs to dispose of digested effluents. The Environmentally Superior Technologies (EST) initiative in North Carolina set public standards to eliminate waste discharge, reduce atmospheric emissions, and control odors and pathogens. Research has confirmed that technologies coupling solids separation with water treatments to remove volatile organic carbon, pathogens, and reactive forms of nitrogen can meet EST standards. A designated EST—the Super Soil System—substantially reduced odor by 99.9%; pathogens by 99.99%, nutrients (phosphorus and nitrogen) by >90%, and heavy metals (cooper and zinc) by 99%. The ammonia emissions were reduced by 94.4% for the warm and 99.0% for the cool season with respect to a conventional lagoon system. Corresponding greenhouse gas emission reductions were 96.7%. Components of designated EST can be applied to retrofit covered lagoons and anaerobic digestion systems with significant environmental benefits. Recommendations are proposed, based on the collective experience with EST and current trends in animal production concentration, for environmentally safe technologies to handle excess manure produced in the USA.

Polylactic acid-based composite filter with multi-gradient structure developed for high-efficiency particulate matter filtration and NH3 purification

Particulate matter (PM), ammonia (NH3) and other polluted gases emitted from animal feeding operations have emerged as significant risks to workers, surrounding residents, and the regional environment. Therefore, the development of air filters capable of simultaneously filtering PM and adsorbing toxic gases is particularly important. In this study, a three-layer gradient structure nanofiber filter was prepared by electrospinning technology, consisting of fluorinated Polylactic acid (PLA)/SiO2 as the outer layer, PLA nanofibers as the middle layer, and PLA/UiO-66-NH2 as the inner layer. This gradient structure of composite filter featured gradually decreasing pore sizes, exhibited optimal air filtration performance compared to PLA filter and commercial glass fiber filter. At 5.3 cm/s flow rate, the composite nanofiber filter achieved high filtration efficiency (99.15 % for PM0.5) and low pressure drop (89.65 Pa). Furthermore, the composite nanofiber filter exhibited highest dust holding capacity, indicating longer service life. It also featured excellent self-cleaning capabilities, allowing for reuse after simple water rinsing. Additionally, the results of ammonia (NH3) adsorption tests demonstrated the prepared composite filter’s highest adsorption capacity for NH3. Therefore, this work enhanced the application potential of high-performance air filters in the removal of PM pollution and hazardous gases.

Landscape-scale predictions of future grassland conversion to cropland or development.

Grassland conservation planning often focuses on high-risk landscapes, but many grassland conversion models are not designed to optimize conservation planning because they lack multidimensional risk assessments and are misaligned with ecological and conservation delivery scales. To aid grassland conservation planning, we developed landscape-scale models at relevant scales that predict future (2021-2031) total and proportional loss of unprotected grassland to cropland or development. We developed models for 20 ecoregions across the contiguous United States by relating past conversion (2011-2021) to a suite of covariates in random forest regression models and applying the models to contemporary covariates to predict future loss. Overall, grassland loss models performed well, and explanatory power varied spatially across ecoregions (total loss model: weighted group mean R2=0.89 [range: 0.83-0.96], root mean squared error [RMSE]=9.29ha [range: 2.83-22.77ha]; proportional loss model: weighted group mean R2=0.74 [range: 0.64-0.87], RMSE=0.03 [range: 0.02-0.06]). Amount of crop in the landscape and distance to cities, ethanol plants, and concentrated animal feeding operations had high variable importance in both models. Total grass loss was greater when there were moderate amounts of grass, crop, or development (∼50%) in the landscape. Proportional grass loss was greater when there was less grass (∼<30%) and more crop or development (∼>50%). Some variables had a large effect on only a subset of ecoregions, for example, grass loss was greater when ∼>70% of the landscape was enrolled in the Conservation Reserve Program. Our methods provide a simple and flexible approach for developing risk layers well suited for conservation that can be extended globally. Our conversion models can support conservation planning by enabling prioritization as a function of risk that can be further optimized by incorporating biological value and cost.

Simultaneous biomass concentration and subsequent quantitation of multiple infectious disease agents and antimicrobial resistance genes from community wastewater

Wastewater-based surveillance (WBS) of infectious disease agents is increasingly seen as a reliable source of population health data. To date, wastewater-based surveillance efforts have largely focused on individual pathogens. However, given that wastewater contains a broad range of pathogens circulating in the population, a more comprehensive approach could enhance its usability. We focused on the simultaneous detection of SARS-CoV-2, sapovirus, Campylobacter jejuni, Campylobacter coli, Salmonella spp., pathogenic Escherichia coli, Cryptosporidium spp., Giardia spp. and antimicrobial resistance genes (ARGs) of clinical relevance. To achieve this goal, biomass concentration and nucleic acid extraction methods were optimized, and samples were analyzed by using a set of (RT)-qPCR and (HT)-qPCR methods. We determined the prevalence and the spatial and temporal trends of the targeted pathogens and collected novel information on ARGs in Finnish wastewater. In addition, the use of different wastewater concentrates, namely the ultrafiltered concentrate of the supernatant and the centrifuged pellet, and the effect of freezing and thawing wastewater prior to sample processing were investigated with the indicator microbe crAssphage. Freeze-thawing of wastewater decreased the gene copy count of crAssphage in comparison to analyzing fresh samples (p < 0.001). Campylobacters were most abundant in two of the four studied summer months (30 % detection rate) and in wastewaters from regions with intensive animal farming. Salmonella, however, was detected in 40 % of the samples without any clear seasonal trends, and the highest gene copy numbers were recorded from the largest wastewater treatment plants. Beta-lactamase resistance genes that have commonly been detected in bacteria isolated from humans in Finland, namely blaCTX-M, blaOXA48, blaNDM, and blaKPC, were also frequently detected in wastewaters (100, 98, 98, and 70 % detection rates, respectively). These results confirm the reliability of using wastewater in public health surveillance and demonstrate the possibility to simultaneously perform WBS of multiple pathogens.

Swine fecal waste source tracking on household surfaces proximal to swine concentrated animal feeding operations in southeastern North Carolina, USA

Swine fecal waste source tracking on household surfaces proximal to swine concentrated animal feeding operations in southeastern North Carolina, USA

Meowmy, Pawrents and Menschenwelpen ‘human puppies’: Linguistic practices of Doing Interspecies Families on German Instagram

Looking at cute animal images and videos has become a popular online pastime and animals themselves increasingly appear as actors in social media who have their own accounts and profiles from which they ‘speak’ to and ‘interact’ with us. This development goes hand in hand with a change in human-animal relations in most of Western cultures, where pets – especially cats and dogs – are more and more often seen and treated as family members while the animals we eat are rendered invisible in factory farms that are spatially detached from everyday human life. The familial relationships between humans and their pet companions are constructed by a variety of sociocultural means, one of which is language. By talking about pets as babies and children and oneself as cat or dog moms, the connection between the human and the pet is discursively established as one of kinship and intimacy rather than one of ownership and obedience. Social media have become a prolific space for performing “interspecies families” (Owens, 2015), where self-acclaimed pet parents can interact with each other and build communities of practice in which pet accounts post and engage with each other from an imagined pet perspective. This article uses a quantitative corpus-based approach to study the discursive construction of interspecies families on German-speaking Instagram. By analysing more than 20,000 posts from dog and cat accounts offering first person narratives, the article provides insights into the ways human pet owners speak about themselves and their relations with their pets from an imagined pet perspective. The analysis shows that the caption texts accompanying the posted pictures and videos are highly anthropocentric: at the centre of these short texts stands the – usually female – human pet owner. Using family terminology for both humans and other animals in these posts serves the linguistic construction of interspecies families in which pets and their human companions are held together by love and kinship ties rather than ownership.

Effects of sand substrate removal on the intestinal antioxidant and metabolism in Marsupenaeus japonicus

M. japonicus is an important specie for factory farming, and factory farming requires an environment with sand at the bottom of the pond. However, the physiological responses as well as survival in the process of factory farming without laying sand are currently unknown. In the present study, we explored the effect of sand substrate removal on the intestinal histomorphology, antioxidant enzyme activity, and metabolic profile of M. japonicus. Our results indicate a gradual increase in the mortality rate of kuruma shrimp in ponds lacking sand substrate. The intestinal mucosa exhibited necrosis and the presence of vacuoles, with their number gradually increasing over time. The intestinal villi showed significant erosion, accompanied by a decrease in intestinal superoxide dismutase (SOD) activity and catalase (CAT) activity, and consistent with an upregulation in the expression of apoptosis-related genes such as caspase-3, indicating an adaptive response to the adverse environmental conditions. Additionally, the metabolomic analysis revealed that most significantly differential metabolites were linked to amino acid and lipid metabolism. These findings enhance our understanding of the sand substrate removal on the intestinal health of kuruma shrimp, which provides a basis for the factory farming.

Local and Global Public Health and Emissions from Concentrated Animal Feeding Operations in the USA: A Scoping Review.

Up to 1.6 million tons of waste is produced annually by each of more than 21,000 concentrated animal feeding operations (CAFOs) located in the United States (USA). These operations give rise to externalities, including adverse local and global health impacts from CAFO waste emissions, which can potentially outweigh their economic viability. However, a shortage of evidence synthesis research exclusively on the impacts of USA-based CAFO waste emissions may hinder effective policy development. This scoping review (ScR) study, adhering to the guidelines from the Joanna Briggs Institute, conducted a search in databases including Scopus, Web of Science, PubMed, and Embase in May 2020, resulting in ten publications that met the inclusion criteria. The results suggest possible exposure of CAFO workers to multidrug-resistant Staphylococcus aureus (MDRSA), campylobacteriosis, and cryptosporidiosis. Communities near CAFOs experienced higher rates of adverse health impacts compared to those in non-CAFO areas, with patterns suggesting that proximity may correlate with increased odds of detrimental health effects. Implicit global health threats include methicillin-resistant Staphylococcus aureus (MRSA), MDRSA, campylobacteriosis, tuberculosis, and cryptosporidiosis. These studies provide foundational insights into CAFO proximity, density patterns, and adverse public health effects, indicating a need for evidence-informed environmental health policies to minimize local and global risks.

Zinc Protects against Swine Barn Dust-Induced Cilia Slowing.

Agricultural workers exposed to organic dust from swine concentrated animal feeding operations (CAFOs) have increased chances of contracting chronic lung disease. Mucociliary clearance represents a first line of defense against inhaled dusts, but organic dust extracts (ODEs) from swine barns cause cilia slowing, leading to decreased bacterial clearance and increased lung inflammation. Because nutritional zinc deficiency is associated with chronic lung disease, we examined the role of zinc supplementation in ODE-mediated cilia slowing. Ciliated mouse tracheal epithelial cells were pretreated with 0-10 µg/mL ZinProTM for 1 h, followed by treatment with 5% ODE for 24 h. Cilia beat frequency (CBF) and protein kinase C epsilon (PKCε) activity were assayed. ODE treatment resulted in cilia slowing after 24 h, which was reversed with 0.5 and 1.0 µg/mL ZinPro pre-treatment. No zinc protection was observed at 50 ng/mL, and ciliated cells detached at high concentrations (100 µg/mL). ZinPro alone produced no changes in the baseline CBF and showed no toxicity to the cells at concentrations of up to 10 µg/mL. Pre-treatment with ZinPro inhibited ODE-stimulated PKCε activation in a dose-dependent manner. Based on ZinPro's superior cell permeability compared to zinc salts, it may be therapeutically more effective at reversing ODE-mediated cilia slowing through a PKCε pathway. These data demonstrate that zinc supplementation may support the mucociliary transport apparatus in the protection of CAFO workers against dust-mediated chronic lung disease.

ASPECTS OF FOOD SAFETY ISSUES IN MODERN AGRICULTURE

Foodborne illnesses remain a persistent public health threat, with thousands of outbreaks each year caused by contaminated produce, meat, and dairy. The study analyzed food safety risks associated with traditional industrial farming practices, including concentrated animal feeding operations (CAFOs), large-scale produce production, and nationwide processing and distribution networks. Quantitative analysis of outbreak data reveals hot spots of contamination in commodities and the food system. Qualitative research and interviews contextualize the complex contamination pathways and challenges of preventing the spread of pathogens in modern agriculture. The main risks include inappropriate manure use, contaminated irrigation water, undersized buffer zones and inadequate sanitation at processing facilities. Policy improvements related to livestock density, water treatment, and implementation of protection plans may help reduce future threats. Ultimately, enhancing food safety in a way that does not compromise productivity and affordability requires a comprehensive, systems-level approach across the farm, processing facility, and regulatory agency. KEYWORDS: food safety, foodborne illness, industrial agriculture, commodities, contamination, pathogens, policy

Research on the matching relationship of multi-energy collaborative temperature control in factory farming system based on TRNSYS

In light of the escalating energy crisis and the imperative to address climate change, there exists a pervasive global consensus advocating the reduction of carbon emissions and the exploration of novel energy sources. Despite this consensus, the realm of factory farming continues to rely upon conventional energy sources for heating purposes. This study focuses on the investigation into the multi-energy heating system employed by an aquaculture company in Dalian City. We undertook the optimization of critical parameters within this system and formulate a comprehensive model for the multi-energy system using the TRNSYS transient simulation platform. The optimization process employs the Hooke-Jeeves algorithm, implemented through GenOpt software, with the system annual value cost serving as the objective function. Optimization variables include solar collector area, solar collector slope, thermal storage tank volume, seawater source heat pump power, and wastewater plate heat exchanger area. The findings of this investigation reveal a marked enhancement in the Coefficient of Performance (COP) and overall system performance after optimization. The resultant annual operating cost was $3133.61, indicating a substantial reduction of $1151.86 compared to the pre-optimization period’s cost. The static payback period is determined to be 9.43 years. During the heating period, in contrast to traditional boiler heating, the optimized system manifests a reduction in coal consumption of 4485.03 kg, accompanied by a cumulative decrease in pollutant emissions totaling 11544.46 kg. This substantiates the system’s cumulative economic and environmental viability.

Catalytic fixation of hydrogen sulfide over CuO-CaCO3 co-impregnated tea stalk-derived biochar

Effective treatment of hydrogen sulfide (H2S) is crucial for minimizing nuisance odors from intensive livestock and poultry operations. The development of high-performance desulfurizers holds practical significance in this context. Herein, a novel CuO-CaCO3 co-impregnated biochar desulfurizer (CuxCay/BCT) was synthesized by impregnation-pyrolysis method, using waste tea stalks and metal salts as raw materials, and it is intended for the treatment of H2S at room temperature. The optimized Cu0.75Ca0.25/BC800 shows an excellent H2S removal capacity of 182.67 mg/g, which is 31 times and 5.6 times that of inactivated biochar (BC800) and copper-oxide-impregnated biochar (Cu0.75/BC800). The desulfurization mechanism of Cu0.75Ca0.25/BC800 involves synergistic effect of reactive adsorption and catalytic oxidation. CaCO3’s alkaline adsorption sites and copper-mediated activation of superoxide radicals (∙O2-) were critical in this reaction. Besides, Cu0.75Ca0.25/BC800 demonstrated excellent reusability, retaining approximately 85 % of its initial H2S removal capacity after seven cycles of desulfurization and regeneration. This study aims to develop a metal oxide- and carbonate-impregnated biochar-based desulfurizer, with the goal of advancing the technology for catalytic removal of H2S in a more environmentally friendly and effective manner.

Inorganic Nitrogen Gas‐Aerosol Partitioning in and Around Animal Feeding Operations in Northeastern Colorado in Late Summer 2021

AbstractAmmonia (NH3) from animal feeding operations (AFOs) is an important source of reactive nitrogen in the US, but despite its ramifications for air quality and ecosystem health, its near‐source evolution remains understudied. To this end, Phase I of the Transport and Transformation of Ammonia (TRANS2Am) field campaign was conducted in the northeastern Colorado Front Range in summer 2021 and characterized atmospheric composition downwind of AFOs during 10 research flights. Airborne measurements of NH3, nitric acid (HNO3), and a suite of water‐soluble aerosol species collected onboard the University of Wyoming King Air research aircraft present an opportunity to investigate the sensitivity of particulate matter (PM) formation to AFO emissions. We couple the observations with thermodynamic modeling to predict the seasonality of ammonium nitrate (NH4NO3) formation. We find that during TRANS2Am northeastern Colorado is consistently in the NH3‐rich and HNO3‐limited NH4NO3 formation regime. Further investigation using the Extended Aerosol Inorganics Model reveals that summertime temperatures (mean: 23°C) of northeastern Colorado, especially near the surface, inhibit NH4NO3 formation despite high NH3 concentrations (max: ≤114 ppbv). Finally, we model spring/autumn and winter conditions to explore the seasonality of NH4NO3 formation and find that cooler temperatures could support substantially more NH4NO3 formation. Whereas NH4NO3 only exceeds 1 μg m−3 ∼10% of the time in summer, modeled NH4NO3 would exceed 1 μg m−3 61% (88%) of the time in spring/autumn (winter), with a 10°C (20°C) temperature decrease relative to the campaign.

Effects of temperature on the growth, total lipid content and fatty acid composition of Skeletonema dohrnii

The potential of diatoms as aquatic bait, attribute to their abundance in highly unsaturated fatty acids, has been extensively studied. Temperature plays a crucial role in the synthesis of these fatty acids. This study specifically investigated the impact of temperature on the growth, total lipid content, and fatty acid composition of Skeletonema dohrnii, a planktonic diatom commonly associated with red tides and water blooms in China. The aim is to evaluate its suitability as an aquatic bait and provide insights for large-scale factory farming. Results indicated that the highest biomass and maximum growth rate occurred at 28°C, with no significant deviation from the control group at 25°C. At 28°C and 15°C, there was a significant increase in the total lipid content and the total fatty acid content, with a more pronounced effect at 15°C. At 28°C, EPA and DHA content measured at 0.97 ± 0.01 mg.DW.L-1 and 0.264 ± 0.01 mg.DW.L-1 respectively, surpass those at 15°C due to lower biomass. Conversely, at 15°C, substantial synthesis of long-chain polyunsaturated fatty acids, with EPA constituting up to 32.24 ± 0.24% of the total fatty acids, is observed. Modulating the temperature could optimize the utilization of S. dohrnii as an aquatic feed source. These findings underscore the potential of S. dohrnii as a high-quality aquafeed and lay the groundwork for its success in ocean warming scenarios.