Recirculating Aquaculture Systems (RAS) provide efficient fish production with reduced water use and precise environmental control. However, their closed design facilitates susceptibility to pathogen persistence and disease outbreaks, highlighting the need for effective monitoring and treatments. Over a 12-week study, water samples (purified eDNA/eRNA) were evaluated in two freshwater RAS units at a commercial pre-smolt Atlantic salmon () farm as a non-lethal and non-invasive alternative to tissue samples for early pathogen detection. A key aim was furthermore to elucidate the infection dynamics by monitoring five pathogens: salmon gill poxvirus (SGPV), non-virulent infectious salmon anaemia virus (ISAV-HPR0), infectious pancreatic necrosis virus (IPNV), piscine orthoreovirus genotype 1 (PRV-1), and the bacterium . The study revealed similar sequential infection patterns of the four viral pathogens in both RAS units, starting with clinical infection by SGPV, followed by infection with ISAV-HPR0, alongside a concurrent clinical infection with IPNV and sporadic PRV-1 detections. SGPV peaked earlier and caused higher mortality in one system, consistent with elevated SGPV levels detected in water prior to fish transfer. A strong positive correlation was found between gill swabs and water samples for SGPV and ISAV-HPR0. Although high viral loads of IPNV were recorded in fish in one system, with sporadic detections in the other, no consistent correlation could be established between kidney swabs and water samples. No correlation was seen for PRV-1 as well. showed minor fluctuations in gill swabs but higher, yet stable, levels in water samples. Our study elucidates the infection dynamics of key Atlantic salmon pathogens in RAS and demonstrates the potential of eDNA/eRNA as a non-invasive tool for the prediction, early detection, and monitoring of SGPV and ISAV-HPR0 in Atlantic salmon RAS.

[This corrects the article DOI: 10.1016/j.aquaculture.2023.739932.].

The aim of this study was to deepen our understanding of the reproductive biology of male spotted wolffish () using two different experimental approaches involving juvenile and mature broodstock fish. The first approach consisted of a detailed histological examination of the testes to identify the onset of gonadal maturation and characterise the spermatogenic stages in two- and three-year-old juvenile specimens. Light microscopy analysis revealed clear differences between the age groups. Two-year-old fish displayed well-defined interstitial tissue, Sertoli cells and cysts housing spermatogonia stem cells in which meiosis had not yet begun. In contrast, three-year-old fish exhibited cysts containing spermatocytes, spermatids and abundant spermatozoa, indicating the initiation of the spermatogenic cycle, albeit with asynchronous puberty. Histochemical staining revealed a significant presence of smooth myoid cells in the interstitial tissue of sexually mature fish, while electron microscopy further revealed synaptonemal complexes indicating the onset of meiosis and centriolar structures that gave rise to flagella. The second approach focused on optimising semen freezing and cryopreservation procedures in mature broodstock individuals over the age of 10 years. Seven freezing extenders (KT, TS-2, OP, MT, MH, HBSS, or SR), with seawater (SW) as a control, were assessed along with two cryoprotectants dimethylsulfoxide (DMSO) or methanol to evaluate their impact on pre- and post-thaw semen quality. Results showed that the MT and HBSS extenders were superior in total sperm kinetics at 1:3 dilution, and that DMSO showed optimal results in sperm motility and velocity variants. Moreover, the MT and HBSS groups demonstrated consistent sperm viability after cryopreservation, with values similar to fresh samples. Based on the viability results of the SYBR-green-14/PI assay comparing fresh and cryopreserved sperm using MT and HBSS, the MT extender emerged as the most effective freezing medium for cryopreservation of spotted wolffish broodstock sperm. In conclusion, this study provides a comprehensive understanding of the reproductive dynamics of male spotted wolffish, offering valuable insights for both scientific research and aquaculture management.

The lumpfish, , holds significant promise as a candidate for large-scale aquaculture production, particularly in its role as a cleaner fish used to manage sea lice infestations in Atlantic salmon farming. Melanomacrophage centers (MMCs) represent polymorphic structures present in the hemolymphopoietic organs of various vertebrates, serving as a widely applicable histological indicator of the fish immune and health status. This study aims to investigate the histochemical characteristics of MMCs within lumpfish livers and to compare MMC density between hatchery-produced (farmed) and wild individuals. Liver samples were collected from 34 lumpfish and subjected to a range of staining techniques, including haematoxylin-eosin, Azan-Mallory's trichrome, Masson-Fontana, Perls-Van Geison, Mallory's hemofuscin, immunohistochemical detection of cytochrome P450 monooxygenase 1 A (CYP1A), and the terminal deoxynucleotidyl transferase-mediated d'UTP nick-end labelling (TUNEL) method. Hepatocytes from hatchery-produced males exhibited notably high lipid content. Additionally, cells showing positive staining with Masson-Fontana, likely associated with the monocyte/macrophage lineage, were identified. Furthermore, small MMCs containing melanin, lipofuscin-ceroids, and ferric ions were detected. While the density of single monocytes/macrophages was markedly higher in hatchery-produced males, no significant discrepancies in MMCs density were observed between wild and hatchery-produced fish, or between males and females of the same origin. The study also revealed the presence of necrotic foci, characterized by hypertrophic hepatocytes positive for both TUNEL and CYP1A staining. These hypertrophic hepatocytes displayed large lipid droplets and pycnotic nuclei, with hatchery-produced males showing a higher numerical density of such foci. In contrast to findings in other fish species, the study found that MMCs did not appear to serve as reliable markers of health status in lumpfish. This conclusion was reached as MMCs density did not exhibit a correlation with necrotic foci or hepatocyte lipid content.

sp. is a harmful cyanobacterial species commonly seen in earthen ponds. The overgrowth of these algae can lead to fluctuations in water parameters, including DO and pH. Also, the microcystins produced by these algae are toxic to aquatic animals. This study applied hydrogen peroxide (7 mg/L) to treat sp. in a laboratory setting and in three earthen pond trials. In the lab we observed a 64.7% decline in sp. And in our earthen pond field experiments we measured, on average, 43% reductions in sp. cell counts within one hour. The treatment was found to eliminate specifically sp. and did not reduce the cell count of the other algae species in the pond. A shift of the algae community towards the beneficial algae was also found post-treatment. Lastly, during the pond trials, the gill status of Tilapia and Giant tiger prawn were not affected by the HO treatment suggesting this may be a good mitigation strategy for reducing cyanobacteria in pond aquaculture.

The global COVID-19 pandemic resulted in an unprecedented economic shock in current times. Previous literature on consumer shopping behaviors during economic downturns is limited, and studies specific to seafood focused primarily on supply-side shocks. A national survey was conducted using an online platform from February 22 to April 6, 2021 that targeted 100 seafood consumers in each of 20 market areas across the U.S. Following data cleaning, 1908 usable responses were obtained. Results documented significant changes in consumer shopping behaviors. Significantly greater percentages of meals (generally and of seafood) were consumed at home and fewer away from home, as expected. Demographic differences were found in shopping behaviors by age, education, income, and gender, but not by ethnic group. Frequency of shopping decreased in 2020, but the expenditure per shopping trip did not, resulting in less overall spending for groceries as compared to 2019. Respondents were less likely to purchase seafood for takeout or for home delivery of prepared meals as compared to general meals because of concerns over quality, freshness, and safety of seafood. Half of respondents consumed approximately the same amount of seafood as before the pandemic; with 31% reporting decreased seafood consumption, and only 19% increased seafood consumption. Thus, study results provide evidence of a pandemic-imposed shift to consuming greater proportions of seafood meals at-home than away-from-home, and not an overall increase in seafood consumption. The choice of species eaten most often did not differ pre- and post-pandemic. Those respondents who reported decreased seafood consumption in 2020 did so primarily because of: 1) its expense, given reduced incomes from working fewer hours or being laid off; 2) unwillingness to prepare fish at home for the smell and "mess", or being uncomfortable preparing it; or 3) simply not preferring or liking seafood well enough to eat it more frequently. Those who reported increasing seafood consumption did so primarily because it was considered to be a healthy food choice. Additional work is needed to further examine consumption and shopping behaviors throughout the recovery in 2021 and 2022.

Recent studies have reported on the importance of RBCs in fish responses to viral infections and DNA vaccines. Surface-displaying recombinant bacterins (spinycterins) are a safe and adaptable prototype for viral vaccination of fish and represent an alternative method of aquaculture prophylaxis, since have been reported to enhance fish immune response. We evaluated the innate immune response of rainbow trout () red blood cells (RBCs), head kidney, and spleen to spinycterins expressing a fragment of the glycoprotein G of viral haemorrhagic septicemia virus (VHSV), one of the most devastating world-wide diseases in farmed salmonids. We first selected an immunorelevant downsized viral fragment of VHSV glycoprotein G (frg16). Then, spinycterins expressing frg16 fused to Nmistic anchor-motif (Nmistic+frg16) were compared to spinycterins expressing frg16 internally without the anchor motif. Nmistic+frg16 spinycterins showed increased attachment to RBCs and modulated the expression of interferon- and antigen presentation-related genes in RBCs and , after intravenous injection. In contrast, the head kidney and spleen of fish injected with frg16, but not Nmistic+frg16, spinycterins demonstrated upregulation of interferon and antigen-presenting genes. Intravenous injection of Nmistic+frg16 spinycterins resulted in a higher innate immune response in RBCs while frg16 spinycterins increased the immune response in head kidney and spleen. Although more studies are required to evaluate the practicality of using spinycterins as fish viral vaccines, these results highlight the important contribution of RBCs to the fish innate immune response to antiviral prophylactics.

Triploid Eastern oysters have been reported to suffer greater mortalities than diploids when exposed to low-salinity (<5) conditions in the U.S. Gulf of Mexico and Atlantic estuaries. As such, the effect of broodstock parentage was investigated on the low-salinity tolerance of triploid progeny produced by mating diploid females (collected from three Louisiana estuaries differing in salinity regimes) with male tetraploids at two hatcheries. Diploid crosses were also produced using the wild broodstocks to verify expected differences in low-salinity tolerance among diploid progeny and between ploidy levels. All progeny were deployed at low and moderate-salinity (averages of 9.3 and 19.4) field sites to monitor monthly growth and mortality. Sex ratio, gametogenic stage, gonad-to-body ratio, condition index, and infection were also measured periodically at both field sites Although high triploid mortality at the low-salinity site prevented complete analysis, results indicated that diploid parentage had little effect on triploid survival at low salinity. Broodstock parentage affected diploid mortality and growth, although results did not match with predictions made based on historical salinity at broodstock collection sites. Ploidy level had the largest effect on triploid survival and growth followed by the hatchery site where the oysters were produced.

Environmental DNA (eDNA) water assays are beginning to be implemented for many important pathogens in confined aquaculture systems. Recirculating systems are rapidly being developed for fin fish aquaculture. Zebrafish () are reared in these systems, and (Microsporidia) represents a serious challenge for zebrafish research facilities. Diagnosis of the pathogen has traditionally used histology or PCR of tissues with lethal sampling. However, with the development of a nonlethal assay to detect in tank water, facilities will be able to integrate the assay into routine surveillance efforts to couple with their established protocols. Here, we first describe a modified protocol to extract and quantify parasite DNA from the environment for nonlethal detection of in adult zebrafish populations. Using this modified assay, we then evaluated water samples from a longitudinal experimental infection study, targeting timepoints during initial infection. The parasite was detectable in the water immediately after initial exposure until week 4 post exposure (pe), when the parasite was undetectable until 7 weeks pe. After that time, the parasite was sporadically detected in the water for the 10-month study, likely correlating with the lifecycle of the parasite. Using water samples from the Zebrafish International Resource Center, we also validated the clinical relevance of the assay in a large zebrafish facility. The integration of this assay at ZIRC will significantly compliment surveillance and control efforts for the microsporidian parasite.

While curbing the spread of Coronavirus Disease 2019 (COVID-19), lockdown policies and "stay-at-home" restrictions caused massive supply chain disruptions worldwide. This led to breaks in spatial market integration, which could further lead to market inefficiency and resource misallocation. Taking daily price data from 2016 to 2021, this study investigates COVID-19's effect on the spatial market integration of fish in China using cointegration tests. We find a high degree of spatial market integration for fish in China before the COVID-19 pandemic. Further, our results show that COVID-19's effect on the spatial market integration of fish varies spatially in China. Specifically, COVID-19 reduces the degree of spatial market integration in most provinces, especially those with high infection rates. Meanwhile, the degree of spatial market integration in provinces with low infection rates remains high. Therefore, the government should be regionally specific when formulating market recovery policies.

The COVID-19 pandemic and related policy responses have exacerbated global food and nutrition insecurity by disrupting supply chains and destroying livelihoods. Previous studies show that the impact has been particularly severe for poor populations with limited livelihood options, who already faced food insecurity before the pandemic struck. This paper describes how COVID-19-related policy responses have impacted low-income, subsistence-oriented fish farmers in Bhutan. Based on nationally representative data collected between November 2020 and January 2021, the paper documents the responses of 353 Bhutanese fish farmers to the altered operating conditions and market disruptions caused by COVID-19. Results indicate that these farmers' access to inputs such as fish seed have suffered substantial disruptions. However, on the output side of the supply chain, some farmers have made significant gains in terms of increased demand and higher fish prices in informal markets. Furthermore, the food security of most farmers has suffered minimal impact. Overall, Bhutanese fish farmers have proved to be robust to COVID-19-induced adverse outcomes relative to commercial aquaculture producers elsewhere. Small-scale, subsistence-oriented production of fish along with other crops has benefitted the Bhutanese fish farmers by shielding them from the negative economic outcomes associated with market shocks and by directly preserving their food security. Nevertheless, the fish farmers require critical support to access essential inputs and upscale or maintain production infrastructure, so that they can continue fish production during the COVID-19 pandemic and become more robust in the long run.

The COVID-19 pandemic has wreaked havoc on the aquaculture and fisheries sector all around the world, with the impact being exacerbated in developing countries. This study is an endeavor to identify consequences of the COVID-19 on fisheries and aquaculture sectors based on primary data collected from Bangladesh as an empirical case study. The data were collected through face-to-face interviews with different supply chain actors while analyzed using descriptive statistics and a problem confrontation index. As results depicted, income and employment across fish farmers, fishers, and traders were severely hurt, with a drastic fall in the market demand, coupled with a severe drop in their fish consumption. As market demand declined, fish farmers must be stocked mature fish for an extra period, and feed costs raised, eventually increasing the overall production cost. Besides, inaccessibility to inputs also made fish production and catch more troublesome. The price of all the major cultured and captured species plunged, leading to a depressing return to farmers, while inputs price underwent a significant increase except for labor and fingerling. However, traders seemed to be the worst sufferers amid striking disruption in fish value chain, which ostracized the preponderance of the traders from the chain. Some of the prime obstacles that constrained the production and trading process were but not limited to higher transportation costs, labor shortage, inability to pay for the wage, and reduced consumer demand across fish farmers, fishers, and traders. Nevertheless, our article further identified a myriad of strategies that the fish farmers, fishers, and traders followed to heal the scar of the fisheries and aquaculture sector with hands-on actions.

A rapidly growing literature investigates how the recent Covid-19 pandemic has affected international seafood trade along multiple dimensions, creating opportunities as well as challenges. This suggests that many of the impacts of the Covid measures are subtle and require disaggregated data to allow the impacts in different supply chains to be teased out. In aggregate, Norwegian salmon exports have not been significantly impacted by Covid-related measures. Using firm-level data to all export destinations to examine the effects of lockdowns in different destination countries in 2020, we show that the Covid-related lockdown measures significantly impacted trade patterns for four product forms of salmon. The results also illustrate how the Covid measures create opportunities, as increased stringency of the measures increased trade for two of the product forms. We also find significant differences among firms' responses, with large firms with larger trade networks reacting more strongly to the Covid measures. The limited overall impacts and the significant dynamics at the firm level clearly show the resiliency of the salmon supply chains.

A positive perception of aquaculture products is essential to boost production by using more sustainable and eco-friendly solutions. However, consumer perception and resulting purchasing decisions remain poorly understood. In most European countries, the consumer perception tends to be rather negative, which is reinforced by knowledge gaps and misleading information from the media. This is believed to have the greatest impact on the current low consumption rate of farmed fish across Europe. Previous research has suggested that consumers may often be reluctant to change their seafood purchasing behaviour despite having a solid scientific understanding of aquaculture products and their mode of production. In this study, we investigated the extent to which country-specific contexts and degree of scientific knowledge contribute to the purchasing behaviour of consumers across Europe. To this end, interactive poster surveys and semi-structured interviews were conducted at eight different knowledge transfer events (KTEs) across three countries, targeting 383 participants. The application of a yet underutilized method, an interactive poster survey, underscored the need to use new approaches to tackle consumer behaviour. Our results indicate that increased scientific knowledge does not lead to changes in purchasing behaviour per se. Perceptions and purchasing habits are very contextual and vary from culture to culture. This points to the highly interlinked nature of country-specific marine food culture that ranges between individual awareness, scientific knowledge, and socio-cultural contexts, all of which renders in resulting individual purchasing decisions. Our results suggest focusing more on the sustainability of a product and emphasising the ongoing transition towards a circular economy approach in the aquaculture sector may be a promising pathway to foster more sustainability-driven purchasing decisions in the seafood sector. Our findings also question whether trying to educate the public about more sustainable purchasing criteria is really the key to foster more sustainable consumption patterns or whether we are working from misleading assumptions that lead to wrong approaches. In conclusion, a lack of clear and easily accessible information appears to be the main barrier to social acceptance of sustainable aquaculture products in Europe.

From the beginning of March 2020 and for the following two and half months, many European countries comprising Italy have been forced into an unprecedented lockdown, allowing only the opening of essential economic activities needed to address the problems created by the pandemic (e.g. sanitary, food provision). Like many sectors of the Italian economy, aquaculture has also slowed down due to the ongoing emergency and the consequent closure of business. In our study we provided a 'snapshot' of the socio-economic effects of the lockdown on the aquaculture sector in Italy, immediately following the adoption of the COVID-19 restrictions as they were perceived by the workers. Although it was surveyed for a short-time period, differences in perception have been detected both in relation to the type of aquaculture as well as to the geographic locations where farms were placed, partially reflecting the economic gaps already existing within the northern and the southern part of the country before the lockdown.

Machine learning is a powerful tool to improve efficiency of industrial processes, but it has not yet been well utilized in aquacultural and hatchery applications. The goal of the present study was to evaluate the feasibility of using a broad array of machine learning approaches (testing of > 200 vectorization and model combinations, reporting on 20) to classify ultrasound images spanning annual ovarian development (i.e., from undeveloped to mature) of channel catfish (). The specific objectives were to: 1) establish dataset preprocessing to standardize image features; 2) develop and train image classification models with deep learning methods; 3) develop and train models with traditional machine learning methods; 4) compare performance of deep learning and traditional methods on two classification problems (2-class and 5-class), and 5) propose insights to deploy models in practical aquaculture applications for research and hatchery use. A total of 931 ultrasound images of catfish ovaries were used to train and evaluate models for a 2-class problem (as a 'yes' or 'no' answer) to support hormone-injection decisions for spawning management in hatcheries, and a 5-class problem for classifying gonadal development stages for research. By using feature extraction, cropping, dimension reduction, and histogram normalization, a preprocessing method was created to standardize images to develop traditional (i.e., vector input), and deep learning convolutional neural network (CNN) (i.e., image input) approaches. Traditional machine learning models with image classification achieved 100% median accuracy on the 2-class problem (with the models RN-50 and RN-152), and 96% median accuracy for the 5-class problem (with VGG-19 image vectorization). The deep learning approach for the 2-class problem had a median accuracy of > 98% for 15models. The 5-class deep learning models produced a steady increase in median accuracy with training net size, achievable through expansion of the dataset. These models can be developed further, but traditional models (using CNN architectures to simply calculate image vectors) outperformed the deep learning approach. These models can be directly applicable to aquaculture in hatcheries and reproductive biology research, in addition to a wide variety of other image-based applications.

COVID-19 pandemic presents both a challenge and an opportunity to the Indian shrimp sector. With revitalizing the institutional arrangements and redirecting the focus, the Indian shrimp industry can flourish just by adapting to the needs of the local demand, even when the export prospects are uncertain. This paper takes a historical perspective of Indian shrimp farming and exports and suggests a domestic alternative/supplementary market for Indian farmed shrimp, resulting from COVID-19.

Cichlid fish of the genus form the basis of the global tilapia aquaculture and fisheries industries. Broodstocks for aquaculture are often collected from wild populations, which in Africa may be from locations containing multiple species. However, many species are difficult to distinguish morphologically, hampering efforts to maintain good quality farmed strains. Additionally, non-native farmed tilapia populations are known to be widely distributed across Africa and to hybridize with native species, which themselves are important for capture fisheries. The morphological identification of these hybrids is particularly unreliable. Here, we describe the development of a single nucleotide polymorphism (SNP) genotyping panel from whole-genome resequencing data that enables targeted species identification in Tanzania. We demonstrate that an optimized panel of 96 genome-wide SNPs based on F outliers performs comparably to whole genome resequencing in distinguishing species and identifying hybrids. We also show this panel outperforms microsatellite-based and phenotype-based classification methods. Case studies indicate several locations where introduced aquaculture species have become established in the wild, threatening native species. The novel SNP markers identified here represent an important resource for assessing broodstock purity in hatcheries and helping to conserve unique endemic biodiversity.

Anemia in salmonid aquaculture is a recognized blood disorder resulting from the reduction of hemoglobin concentration and/or erythrocyte count. Because of sub-optimal oxygen supply to the tissues, as a negative impact of anemia fish will experience reduced growth and poor health. This health challenge may be linked with several factors including anthropogenic changes in the marine environment, infectious etiology (viral, bacterial, and parasitic), nutritional deficiencies, or hemorrhaging. From the mid-late summer of 2017 to 2019, Scottish salmon farming companies began to report the occurrence of anemic events in open-net marine sites. At that time, the industry had little understanding of the pathogenesis and possible mechanisms of anemia and limited the ability to formulate effective mitigation strategies. Clinical examination of fish raised suspicion of anemia and this was confirmed by generating a packed cell volume value by centrifugation of a microhematocrit tube of whole anticoagulated blood. Company health team members, including vets and biologists, reported discoloration of gills and local hemorrhages. This paper reviews various commercially significant cases and lesser-known cases of anemia in cultured salmonid species induced by various biological factors. The current methods available to assess hematology are addressed and some future methods that could be adopted in modern day fish farming are identified. An account of the most recent anemic event in Scottish farmed Atlantic salmon () is presented and discussed as a case study from information provided by two major Scottish salmon producers. The percent of total marine sites ( = 80) included in this case study, that reported with suspected or clinical anemia covering the period mid-late summer 2017 to 2019, was between 1 and 13%. The findings from this case study suggest that anemia experienced in most cases was regenerative and most likely linked to blood loss from the gills.

Assessment of seawater readiness of freshwater salmon smolts is a crucial husbandry step with economic implications in salmon aquaculture but current methods rely on delayed centralised enzymic activity measurement. The efficiency of a qRT-PCR assay for sodium potassium ATPase (NKA) α1a mRNA was tested in a 3-year study on 19 hatcheries across Scotland incorporating environmental factors such as temperature and metal contamination. The NKA qRT-PCR assay was transferred to a mobile laboratory and on-site testing was carried out at 3 hatchery sites. For the first two years standard enzymatic and gene expression assays had similar success rates in detecting smoltification (NKA activity 60%, qRT-PCR 57%). In the third year, all but one site were determined as sea water ready by qRT-PCR but only at 4 by enzymatic testing. On site testing with mobile qRT-PCR was successfully performed on four farm sites. Altogether, high sensitivity was shown for the in lab (98.9%, SE 0.24) and mobile (93.43%, SE 0.119) assays when tested using a quantitative RNA standard. Some indication for obscured smoltification assay results due to environmental increased heavy metal contamination was observed. Our results prove it is possible to test a smoltification marker on site and provide results on the day of testing during the smolt period allowing for informed decisions on seawater transfer.

A simple bioassay that quantifies feed intake as an estimation of relative attractability of feeds containing different ingredients in the Pacific white shrimp is described. Fish meal (FM), fish protein hydrolysate (FPH), squid meal (SqM) and casein (CN) were assessed at the same dietary level for their relative influence on feed intake rates of . A bland diet containing 92% whole wheat grain meal, 6% diatomaceous earth and 2% alginate with a known low attractability was used as the standard control or base diet. Ingredients were added to the bland base control diet at a level of 3% as fed. Shrimp were stocked into 80 L glass tanks (n= 20 per tank) in a recirculating aquaculture system. Tanks were randomly assigned to one of five diet treatments (3tanks/treatment). Experiments measuring the attractability of each feed were conducted twice daily at 0900 hours and 1330 hours over a five day period. For each experiment, 40 feed pellets (ca. 1 g) corresponding to the assigned treatment were provided to each tank. To calculate the rate of feed intake, pellets remaining in each tank were counted at six minute intervals for a seventy-two minute period. Differences in rate of feed intake among diets were evaluated using Cox Regression Analysis. This attractability assay required only small amounts of ingredients and incorporated ingredients into a bland feed, which significantly reduces the influence from other ingredients or compound in the pellets. All of the test protein ingredients, especially SqM, in the feeds significantly increased the feed consumption rate. The diet containing SqM was consumed at a significantly higher rate than those containing casein and FM but not FPH. FPH and CN containing diets were not significantly different but consumed at a higher rate than the diet containing FM. Results of these trials indicate that the presence of certain ingredients can increase feed intake, thereby increasing nutrient availability of the diets. This reported method to determine consumption of diets containing certain ingredients can be considered as a valid method to estimate attractability.