High Stocking Research Articles

Use of Human Intestinal Enteroids for Recovery of Infectious Human Norovirus from Berries and Lettuce.

Norovirus (NoV) is the leading cause of viral foodborne gastroenteritis globally. Currently, the gold standard for detecting NoV in clinical, food, and environmental samples is via molecular-based methods, primarily RT-PCR. Nevertheless, there is a great need for confirmatory assays that can determine the infectivity of viral particles recovered from contaminated matrices. The use of the human intestinal enteroids system (HIEs) has allowed for the expansion of norovirus replication, although it still suffers from limitations of strain preferences and the requirement of high titer stocks for infection. In this study, we wanted to explore the feasibility of using the HIEs to support the replication of NoV that had been recovered from representative food matrices that have been associated with foodborne illness. We first confirmed that HIEs can support the replication of several strains of NoV as measured by RT-qPCR. We subsequently chose two of those strains that reproducibly replicated, GII.4 and GII.6, to evaluate in a TCID50 assay and for future experiments. Infectious NoV could be recovered and quantified in the HIEs from lettuce, frozen raspberries, or frozen strawberries seeded with high titers of either of these strains. While many experimental challenges still remain to be overcome, the results of this study represent an important step toward the detection of infectious norovirus from representative produce items.

A streamlined, automated workflow to screen and triage large numbers of baculoviruses for protein expression

The baculovirus expression system is a powerful and widely used method to generate large quantities of recombinant protein. However, challenges exist in workflows utilizing either liquid baculovirus stocks or the Titerless Infected-Cells Preservation and Scale-Up (TIPS) method, including the time and effort to generate baculoviruses, screen for protein expression and store large numbers of baculovirus stocks. To mitigate these challenges, we have developed a streamlined, hybrid workflow which utilizes high titer liquid virus stocks for rapid plate-based protein expression screening, followed by a TIPS-based scale-up for larger protein production efforts. Additionally, we have automated each step in this screening workflow using a custom robotic system. With these process improvements, we have significantly reduced the time, effort and resources required to manage large baculovirus generation and expression screening campaigns.

Biomass, carbon stock and sequestration in various conditions of mangrove forests in Sungai Apit, Siak, Riau, Indonesia

Abstract. Fatonah S, Hamidy R, Mulyadi A, Efriyeldi. 2023. Biomass, carbon stock and sequestration in various conditions of mangrove forests in Sungai Apit, Siak, Riau, Indonesia. Biodiversitas 24: 5837-5846. The value of aboveground carbon is influenced by differences in conditions of the mangrove. Therefore, this study aimed to estimate biomass, as well as carbon stock and sequestration in various mangrove forests within Sungai Apit Siak, including natural, rehabilitated, and degraded forests. The Line Transect Plot method was used for sampling. Aboveground biomass was determined using an allometric equation based on mangrove stem diameter. Stem diameter measurements were taken from mangrove vegetation in three forest conditions across three villages in Sungai Apit, Siak. The findings revealed that natural forests contained higher values of biomass, carbon stock, and sequestration at 256, 128, and 470 tons/ha, respectively, compared to rehabilitated and degraded forests. The variability in these parameters across different mangrove forests was influenced by stands characteristics, specifically basal area and mean tree diameter, which were associated with the age of mangrove vegetation and recovery duration. Notably, Rhizophora mucronata, Sonneratia caseolaris, and Avicennia alba exhibited the highest carbon sequestration. These results highlighted that Sungai Apit mangrove forests store a relatively high carbon stock, emphasizing the importance of implementing proper conservation and management measures to ensure sustainability.

Evaluation of High Stocking Densities on the Water Quality and Growth Performance of Pacific White Shrimp Litopenaeus vannamei Reared in a Mixotrophic Biofloc Nursery System

The present study aimed to explore the effects of intensive culture densities on the water quality and growth performance of the Pacific white shrimp Litopenaeus vannamei reared in a mixotrophic biofloc system (heterotrophic/chemoautotrophic) at three stocking rates of 5,000, 4,000, and 3,000 PL/m3 (namely G5000, G4000, and G3000, respectively) for 21 days. At the end of the study, the mean values of water temperature, dissolved oxygen, dissolved oxygen saturation level, pH, oxidation-reduction potential, free carbon dioxide, alkalinity, total ammonia nitrogen (TAN), nitrite-nitrogen (NO2-N), nitrate-nitrogen, and settleable solids did not substantially differ among study groups ( p > 0.05 ). In addition, the highest mean levels of TAN and NO2-N recorded were 1.27 mg/l (G4000) and 9.23 mg/l (G3000), respectively. The results of growth performance revealed that final body weight, weight gain, weekly growth rate, and specific growth rate were not affected by the studied densities ( p > 0.05 ). Although no significant differences were observed ( p > 0.05 ), the G3000 treatment exhibited the highest survival rate (80.66% ± 8.56%), followed by G4000 (75.05% ± 0.31%) and G5000 (71.63% ± 2.11%). However, the shrimp yield was meaningfully higher for G5000 treatment (1.72 ± 0.0.09 kg/m3, 0.69 ± 0.03 kg/m2) compared with G3000 group (1.27 ± 0.0.12 kg/m3, 0.48 ± 0.04 kg/m2) ( p < 0.05 ). Our results indicate L. vannamei can be reared at intensive nursery densities of up to 5,000 PL/m3 (2,000 PL/m2) until reaching 0.5 g without significant retardation in water quality, growth, and survival.

Examining supply chain vulnerability via an analysis of ESG-Prioritized firms amid the Russian-Ukrainian conflict

This research study explores the impact of the ongoing Russian-Ukrainian conflict on ESG-enabled global supply chains, resulting in disruption to worldwide industries. The conflict has caused product shortages, food scarcity, and significantly impacted the global economy. From the extant literature, there is a lack of understanding about the effect of the conflict on different industries from a supply chain perspective, as well as the ESG-prioritized companies. Therefore, this study aims to evaluate the influence of the Russian-Ukrainian conflict on the performance of companies with respect to different regions and industries of their upstream and downstream customers. The top-100 companies in the S&P 500 index which are actively participating in the ESG development are selected and grouped according to customer regions and industries, and the event study analysis is applied to evaluate abnormal returns from stock prices due to the disruption events. Through the empirical analysis, no matter how the ESG-prioritized companies are grouped according to their supply chain structures, it is found that the occurrence of companies obtaining the abnormally high stock return is higher than the occurrence of the opposite. Moreover, the active involvement in ESG disclosure and environmental management demonstrates significant results to withstand disruptions to their supply chains. The findings in this study contribute to a growing body of ESG-related business research, implying that companies which prioritize ESG policies may be better equipped to manage supply chain disruptions during crises.

Unprecedentedly high soil carbon stocks and their spatial variability in a seasonally dry Atlantic Forest in Brazil

There is a significant gap in the literature concerning the potential of tropical soils to stock carbon in the Brazilian Atlantic Forest biome. Furthermore, the key drivers responsible for the variability in carbon storage in tropical soils remain unknown. Therefore, experimental studies are crucial to highlight the importance of Atlantic Forests in storing organic matter, considering that forest soils are one of the most important carbon reservoirs on Earth. This study aimed: (i) to determine soil carbon stocks at the depths of 0–5 cm, 5–10 cm, 10–20 cm, 20–30 cm, 30–40 cm, 40–60 cm, and 60–100 cm in a forest fragment located in the Atlantic Forest hotspot; (ii) to describe the temporal variability of soil carbon stocks; and (iii) to identify the main biotic and abiotic drivers that influence their temporal and spatial variations. Soil carbon stocks at a 1-meter depth ranged from 201 to 396 Mg C/ha, with a spatial variability of 22.3 %. The highest accumulation of soil carbon in the 1-meter depth was in December (290.8 Mg C/ha), while the lowest was in August (246.1 Mg C/ha), highlighting the soil carbon stocks’ seasonality in the Atlantic Forest. Concerning the vertical distribution, ∼50 % of the soil carbon stocks were found in the 0–30 cm layer. The main drivers of carbon spatial distribution varied across different soil layers: (i) litterfall and long-term spatiotemporal patterns of throughfall were the primary drivers in the shallower layers (0–5 cm and 5–10 cm), while (ii) variability in tree sizes and long-term temporal dynamics of soil moisture were the main drivers in the deeper layers. Oxisols’ characteristics were crucial for the unprecedently high carbon stocks observed in the deep layers (67.7 Mg C/ha). Thus, the Atlantic Forest-Oxisol association is a prominent strategy to improve carbon stocks in Brazilian tropical soils.

Grazing for biodiversity: Assessing the effects of cattle management practices on wetlands and amphibian communities in central Argentina

Argentina is widely recognized as a key player in the production and consumption of beef, occupying a prominent position in the global context. However, there is a lack of comprehensive research on the environmental consequences of beef production, particularly concerning wetlands and aquatic biodiversity. We aim to assess the effects of cattle management practices (grazing types and stocking density) on wetland attributes and associated amphibian diversity in central Argentina. During two amphibian breeding seasons, we surveyed 117 wetland sites in paddocks with different cattle grazing types (continuous grazing, glyphosate-promoted pastures and rotational grazing) and stocking densities (low and high). We analyzed the effects of cattle management practices on wetland attributes, including water quality parameters, nutrient concentrations, wetland morphometry, and vegetation cover. Effects on amphibian communities were explored using richness, abundance, and species occurrence. General Mixed-effects Models revealed significant increases in nutrients (total solid dissolved, total nitrogen and soluble reactive phosphorous) and a significant decrease in vegetation cover in sites with high cattle stocking density. Likewise, we observed increased soluble reactive solids in wetlands associated with rotational grazing and decreased vegetation cover in those wetlands related to glyphosate-promoted pastures. Generalized Mixed-effects Models revealed that amphibian communities were negatively affected mainly by high stocking density, while abundance and species occurrence of hylids (Boana pulchella and Scinax squalirostris) were also affected by glyphosate-promoted pastures and rotational grazing treatments. Our results indicate that different types of grazing at low stocking density favor amphibian diversity and improve wetland water quality, therefore, reduced stocking density may result in improved wetland conditions and more diverse amphibian communities. Our results also suggest that glyphosate-promoted pastures and rotational grazing, although beneficial in terms of pasture management, may have unintended consequences on water quality in wetlands and amphibian communities. This study will contribute to our understanding of how cattle management practices influence wetland ecosystems and aquatic biodiversity in the most important cattle breeding area of South America, providing valuable insights for conservation efforts in cattle ranching landscapes.

An analysis of spatial effects of terrorism on stock market returns in the Middle East countries

PurposeStock markets are highly sensitive to foreign and domestic events. Stock exchange markets react promptly to news and are known as an indicator of good and bad trading conditions. Terrorist attacks leave adverse effects on the economy and cause stock price volatility and, consequently, stock return volatility. Therefore, this paper aims to analyze the spatial effects of terrorism on stock market returns in the Middle East from 2008 to 2019.Design/methodology/approachThis paper uses analytical research design and estimates spatial model. Before estimating the spatial model, the spillover effects were confirmed for the spatial autoregressive model using Moran’s diagnostic test for spatial dependence, Geary’s C test and Akaike statistic.FindingsThe results of this study on spatial panel data and based on spatial autoregressive estimator indicated that terrorism and associated neighborhood effects had a negative impact on stock returns in Middle East countries. Also, the corruption index and oil price negatively affected stock market return in these countries, while the democracy index had a positive effect on stock market returns. According to the results, to achieve a high and stable stock market return, it is recommended that high-level consultation is pursued with leaders of involved countries to reduce the devastating effects of terrorist activities, increase political and economic stability, attract stockholders to stock markets and spend corresponding incomes developing the infrastructures in this sector in countries of this region.Originality/valueMost of the studies have investigated the impact of terrorism on the stock market returns at the national or provincial level. However, the effect of terrorism on the stock market index in the tense region of the Middle East, which is the center of terrorist attacks in the world, has not been dealt with by considering the spatial econometric effects. Thus, to the best of the authors’ knowledge, this research is a first attempt to study the impact of terrorism on the stock market returns in Middle East countries using the spatial econometric approach.

Portfolio Construction: A Network Approach

A key parameter when investing is Time Horizon. One of the biggest mistakes investors make is not aligning the timeline of their goals with their investment portfolio. In other words, time horizons determine the investment portfolio you should construct. We examine which portfolios are the best for long-term investing, short-term investing, and intraday trading. This study presents a novel approach for portfolio construction based on Network Science. We use daily returns of stocks that compose the Dow Jones Industrial Average (DJIA) for a 25-year period from 1998 to 2022. Stock networks are estimated from (i) Pearson correlation (undirected linear statistical correlations), as well as (ii) Transfer Entropy (directed non-linear causal relationships). Portfolios are constructed in two main ways: (a) only four stocks are selected, depending on their centrality, with Markowitz investing weights, or (b) all stocks are selected with centrality-based investing weights. Portfolio performance is evaluated in terms of the following indicators: return, risk (total and systematic), and risk-adjusted return (Sharpe ratio and Treynor ratio). Results are compared against two benchmarks: the index DJIA, and the Markowitz portfolio based on Modern Portfolio Theory. The key findings are as follows: (1) Peripheral portfolios of low centrality stocks based on Pearson correlation network are the best in the long-term, achieving an extremely high cumulative return of around 3000% as well as high risk-adjusted return; (2) Markowitz portfolio is the safest in the long-term, while on the contrary, central portfolios of high centrality stocks based on Pearson correlation network are the riskiest; (3) In times of crisis, no portfolio is always the best. However, portfolios based on Transfer Entropy network perform better in most of the crises; (4) Portfolios of all stocks selected with centrality-based investing weights outperform in both short-term investing and intraday trading. A stock brokerage company may utilize the above findings of our work to enhance its portfolio management services.

Vegetation structure and carbon stock of restored mangrove on abandoned shrimp pond in the International Mangrove Botanical Garden Rama IX, Thailand

Abstract. Wongprom J, Maneeanakekul S, Tara A, Chandaeng W, Duangnamon D, Rueangket A, Wechakit D, Wanthongchai P, Maknual C. 2023. Vegetation structure and carbon stock of restored mangrove on abandoned shrimp pond in the International Mangrove Botanical Garden Rama IX, Thailand. Biodiversitas 24: 5821-5830. The conversion of mangrove forest into shrimp aquaculture has severely impacted biodiversity and increased carbon emissions. Restoration program is thus urgently needed for such mangrove forests. In this study, we investigated the vegetation structure and composition, and biomass and carbon stock of restored mangrove on abandoned shrimp pond. Observation plots at restoration sites with age of 3-year-old (MF3) and 14-year-old (MF14) were established in the International Mangrove Botanical Garden Rama IX, Chanthaburi Province, Thailand and at abandoned shrimp pond (ASP) and protected mangrove forest (PMF) as reference sites. The diameters and heights of mangrove species were measured and identified in order to determine the vegetation structure, composition, biomass, and carbon stock. Soil samples from four soil depths, i.e. 0-15, 15-30, 30-50, and 50-100 cm, were collected to quantify the soil carbon stock. The results showed the good growth of Rhizophora stand planted at the restored sites with high vegetation biomass and carbon stock. This species also promoted species diversity, suggesting that Rhizophora spp. are suitable species for the restoration of abandoned shrimp pond. The vegetation biomass and carbon stock of MF14 (230.99 t ha-1 and 102.54 t C ha-1, respectively) was higher than that of PMF (133.84 t ha-1 and 64.94 t C ha-1, respectively). Higher vegetation and soil carbon stocks of the restored mangrove forest was positively influenced by the Rhizophora stand. However, the ecosystem carbon pool of PMF was higher (366.38 t C ha-1). This result indicates that the conservation of mangrove forest is significant to maintain the forest diversity, ecosystem function, and reducing carbon emissions, while mangrove forest restoration is essential to improve the vegetation structure and increase the soil and vegetation carbon stocks.

Grassland vegetation decline is exacerbated by drought and can be mitigated by soil improvement in Inner Mongolia, China

Grassland activity is highly susceptible to drought while drivers from climate and soil attributes can largely affect drought propagation. However, understanding how these drives regulate the risk of vegetation decline under drought conditions remains limited, potentially impeding the adoption of appropriate adaptation strategies. To address this knowledge gap, we conducted a case study focusing on grassland activity in Inner Mongolia, China. In this study, we applied copula theorem to estimate the conditional probabilities of vegetation decline under drought conditions. Additionally, we utilized a structural equation model and a machine learning approach to identify the relative contributions of external drivers to the risk of vegetation decline. Our findings demonstrated a positive correlation between anomalies in vegetation activity and the status of water balance, and grassland vegetation in drier regions exhibited a more rapid response to water deficit. Increasing water deficit continuously reduced vegetation activity with risks of 77.27 %, 83.83 %, and 88.35 % under moderate, severe, and extreme drought conditions, respectively. Furthermore, the risks of vegetation decline under drought conditions were primarily governed by climate attributes, followed by soil properties and topography. Soil with high soil organic carbon stock content contributed significantly to mitigating the adverse effects of drought on grassland vegetation. In addition, we detected nonlinear patterns among environmental drivers and vegetation decline risks caused by drought. These findings highlight the importance of climate, soil properties, topography, and their intricate interconnections in regulating vegetation decline. This knowledge provides valuable insights into drought risk management for vegetation in advance and offers potential solutions to enhance vegetation resistance in the face of extreme drought events.

Insights into the interaction between stocking density and feeding rate in fish Megalobrama ambylcephala based on growth performance, innate immunity, antioxidant activity, and the GH-IGF1 axis

The interaction between stocking density and feeding rate was investigated in juvenile blunt snout bream (Megalobrama ambylcephala) (11.94 ± 0.04 g) based on growth performance and health status. A 2 × 4 factorial design was adopted, containing two stocking densities (10 and 20 fish/m3) and four feeding rates (3%, 4%, 5% and 6% body weight/day). After the 12-weeks feeding trial, high stocking density (20 fish/m3) significantly (P < 0.05) reduced weight gain rate (WGR), feed intake (FI), protein efficiency ratio (PER), nitrogen and energy retention efficiency (NRE and ERE), plasma immunoglobulin M (IgM) level, plasma lysozyme (LZM), myeloperoxidase (MPO) and alkaline phosphatase (AKP) activities, as well as hepatic superoxide dismutase (SOD) and catalase (CAT) activities, while the opposite was observed in feed conversion rate (FCR), condition factor (CF) and plasma complement 4 (C4) level. The highest feeding rate (6%) significantly (P < 0.05) increased WGR, FI, FCR, CF, the intraperitoneal fat ratio and the protein expression of growth hormone receptor, but significantly (P < 0.001) decreased PER, NRE and ERE. Moderate feeding rates (4%–5%) significantly (P < 0.05) increased body lipid and energy contents, the activities of SOD, CAT, glutathione peroxidase, LZM, MPO, AKP and acid phosphatase, the levels of complement 3 and 4 (C3 and C4), and the transcriptions and protein levels of growth hormone and insulin-like growth factor 1, while the opposite was noted in the malondialdehyde content. Furthermore, an interactive effect between stocking density and feeding rate was also noted in WGR, FI, plasma ACP, AKP and MPO activities, and liver malondialdehyde content. In summary, stocking density and feeding rate interactively affect the growth performance and health status of blunt snout bream. The optimum feeding rate of this species increased when cultured under high-density conditions.

Effects of phytogenic feed additives in growing and finishing pigs under different stocking density.

This study was to investigate effects of different phytogenic feed additives (PFA) in grower finishing pigs with stressed by high stocking density. A total of 84 growing pigs ([Landrace × Yorkshire] × Duroc) with initial body weight (BW) of 28.23 ± 0.21 kg were used for 10 weeks (4 replicate pens with 3 pigs per pen). The dietary treatment consisted of basal diets in animal welfare density (positive control [PC]), basal diet in high stocking density (negative control [NC]), NC + 0.04% bitter citrus extract (PT1), NC + 0.01% microencapsulated blend of thymol & carvacrol (PT2), NC + 0.10% mixture of 40% bitter citrus extract and 10% microencapsulated blend of thymol and carvacrol (PT3), NC + 0.04% premixture of grape seed and grape marc extract, green tea and hops (PT4), and NC + 0.10% fenugreek seed powder (PT5). The reduction of space allowance significantly decreased (p < 0.05) growth performance (average daily gain, average daily feed intake, feed efficiency) and nutrient digestibility (dry matter, crude protein). Also, the fecal score of NC group increased (p < 0.05) compared with other groups. In blood profiles, lymphocyte decreased (p < 0.05), and neutrophil, cortisol, TNF-α increased (p < 0.05) when pigs were in high stocking density. Basic behaviors (feed intake, standing, lying) were inactive (p < 0.05) and singularity behavior (biting) were increased (p < 0.05) under high stocking density. However, PFA groups alleviated the negative effects such as reducing growth performance, nutrient digestibility, increasing stress indicators in blood and animal behavior. In conclusion, PFA groups improved the health of pigs with stressed by high stocking density and PT3 is the most effective.

National assessment and variability of blue carbon in seagrass ecosystems in Thailand

Seagrass ecosystems are important organic carbon (Corg) sinks with great potential to contribute to climate change mitigation strategies. However, the high spatial and temporal variability is a barrier to the accurate assessment of national Corg stocks. This study provides a national assessment of Corg within seagrass meadows, including spatial and temporal variations. The highest Corg stocks were within mangrove-associated (44.3 ± 8.27 Mg ha−1), while near-surface sediments were highest in reef-associated meadows (10.20 ± 3.69 Mg ha−1). Regionally, the highest stocks were in the Upper Andaman coast in monospecific meadows (51.7 ± 7.14 Mg ha−1). Corg stocks in near-surface sediments were significantly different across historical trends (p < 0.001), with the highest stocks in stable meadows (9.28 ± 3.39 Mg ha−1). The national Corg stock within seagrass meadows sediment was 40.45 ± 11.59 Mg C ha−1. The results of this study highlighted the complexity of blue carbon in seagrass meadows and the associated impacts on national Corg assessments, carbon accounting, and conservation strategies.

Effects of dietary synbiotic supplementation on growth performance, digestive enzyme activities, and physiological resistance against high stocking density in rainbow trout (Oncorhynchus mykiss)

Effects of dietary synbiotic supplementation on growth performance, digestive enzyme activities, and physiological resistance against high stocking density in rainbow trout (Oncorhynchus mykiss)

The Effects of Stocking Density and Food Deprivation on Mucous Cells and Lysozyme Activity in the Skin and Gills of Silver Catfish.

This study aimed to identify the regions of the body surface of silver catfish (Rhamdia quelen) with a higher population of mucous cells in the skin. Additionally, the effects of stressful conditions, such as different stocking densities and food deprivation, on the proliferative response of mucous cells in the skin and gill epithelium and their impact on cutaneous mucous lysozyme activity were investigated. Silver catfish were divided into four experimental groups: high stocking density (32 kg/m3) and fed (HSD-F), high stocking density and fasted (HSD-FS), low stocking density (2.5 kg/m3) and fed (LSD-F), and low stocking density and fasted (LSD-FS). Fish in the fed groups received commercial feed twice a day, amounting to 1% of the tank biomass. After a 14-day experimental period, the fish were anesthetized and euthanized. Samples of cutaneous mucous and skin fragments from seven different points and the second left branchial arch were collected. Histological slides of the skin and gills were stained with PAS + Alcian Blue at pH 2.5, and the epidermal mucous lysozyme activity was assessed using the turbidimetric method. The ventral point in front of the ventral fin was found to be the optimal location for collecting cutaneous epithelia due to its higher density of mucous cells. The population of mucous cells in both the skin and gills varied based on the collection point and treatment applied. The highest lysozyme activity in the epidermal mucous was observed in fish from the HSD-F group. Overall, these findings suggest that stocking density and food deprivation create stressful conditions for silver catfish, which modulate their mucosal response to each situation.

Different lipid levels in the Pacific white shrimp (Litopenaeus vannamei) nursery in systems grown in super-intensive biofloc systems

High stocking densities can decrease growth, feed conversion, and depletion of the shrimp immune system, therefore lipids can serve as a highly energetic source capable of meeting the metabolic demands of cultured organisms. This work aimed to evaluate the influence of different lipid levels (50 g kg−1, 70 g kg−1, 90 g kg−1, 110 g kg−1, and 130 g kg−1 extract ether-EE) in diets of Litopenaeus vannamei post-larvae raised in super-intensive biofloc systems, on growth, antioxidant capacity, and feeding costs. The experimental period lasted 30 days and the shrimp of 0.018 ± 0.001 g (PL 20) were stored (5000 PL m-³) in 20 tanks (50 L) in quadruplicates. Significant differences in water quality were not recorded (P > 0.05). The final weight and weight gain were not affected by the different treatments; however, the lowest survival rates were found in the 110 EE and 130 EE treatments and the 50 and 70 EE treatments had the highest productivity and lowest feeding cost (P < 0.05). Furthermore, no significant differences were found in the antioxidant capacity against peroxide radicals (ACAP) and thiobarbituric acid reactive species (TBARS) results (P > 0.05), which might be related to a protective effect proportionated by the biofloc consumption. The quadratic regression for productivity indicated that dietary lipid requirements for L. vannamei nursery is 67.8 g kg−1.

PSXI-23 Effects of Dietary Threonine, Tryptophan, and Glycine Supplementation on Growth Performance and Intestinal Barrier Function in Broiler Chickens Raised Under Multiple Stress Conditions

Abstract The objective of the current study was to compare the effects of dietary threonine, tryptophan, and glycine supplementation on growth performance and intestinal barrier function in broiler chickens raised under multiple stress conditions. All birds were allotted to 1 of 5 treatments with 8 replicates in a completely randomized design. Positive control (PC) treatment was normal condition and other treatments are multiple stress conditions with heat stress and high stocking density. Multiple stress conditions were exposed to a cyclic heat stress condition (30 ± 0.3°C for 10 h/d and 23 ± 0.2°C for 14 h/d). In addition, 10 birds per cage (16.9 birds/m2) were allotted in multiple stress conditions, but 15 birds per cage (25.3 birds/m2) were allotted in normal conditions. Basal diet was fed to broiler chickens in PC (normal condition) and negative control (NC; multiple stress conditions) treatments. Three additional diets were prepared by adding 0.68% threonine (99%), 0.19% tryptophan (99%), or 1.60% glycine (99%) to the basal diet. Four treatment diets such as NC, threonine, tryptophan, and glycine treatments were provided to birds in multiple stress conditions. All experimental diets and water were provided ad libitum for 14 d. The body weight gain (BWG) and feed intake (FI) were recorded at the end of the experiment. The feed efficiency (FE, g/kg) was calculated by dividing BWG with FI after mortality correction for FI. The intestinal barrier function was analyzed by trans-epithelial electrical resistance (TEER) value in a two-channel Ussing chamber system. Statistical analysis was conducted as a completely randomized design by using the PROC MIXED procedure of SAS (SAS Institute Inc., Cary, NC). The replicate was considered an experimental unit. Outlier data were confirmed by the UNIVARIATE procedure of SAS. The LSMEANS procedure was conducted to calculate treatment means. In addition, if the difference was significant, the PDIFF option of SAS was conducted to separate the means. The significance for statistical tests was considered at P &amp;lt; 0.05. Results indicated that all treatments under multiple stress condition (i.e., NC, Thr, Trp, and Gly treatments) caused a significant reduction (P &amp;lt; 0.05) in BW, BWG, FI, and FE as compared with PC treatment (Table 1). Dietary Thr supplementation under multiple stress conditions was similar FE compared with PC treatment (Table 2). Dietary threonine, tryptophan, and glycine supplementation under multiple stress condition induced intermediated values for TEER with dietary threonine supplementation having similar values to PC treatment. In conclusion, dietary supplementation of threonine seems the most effective functional amino acid. In addition, it can be a novel dietary treatment to improve growth performance and gut health in broiler chickens raised under multiple stress condition.

181 Effects of Moderate Exercise Regimen on Reproductive Development of Replacement Beef Heifers Reared in Drylots at a High Stocking Density

Abstract This experiment evaluated the physiological and reproductive responses of beef heifers reared at a high stocking density and provided with access to an exercise area. Ninety Angus × Brahman heifers were ranked by age (257 ± 2 days), body weight (BW; 216 ± 2 kg), and temperament score on day 0 and assigned to a) 1 of 6 drylot pens (10x14 m pens; 10 heifers/pen) resulting in a stocking density of 14 m2/heifer (DENS), or b) 1 of 3 paddocks (2-ha paddocks; 10 heifers/paddock) resulting in a stocking density of 2,000 m2/heifer (CON). On day 15, 3 DENS pens were randomly selected and given access to an exercise area (DENS-EX) for 1 hour three times weekly. Negligible forage was available for CON heifers, whereas all heifers received the same limit fed diet which averaged 13 kg/heifer daily of a corn-based diet. Heifer shrunk BW was recorded after 16 h of feed and water withdrawal on days -3 and 225 for average daily gain calculation. On day 0, heifers were fitted with a pedometer behind their shoulder and an ear tag (CowManager, Select Sires, Plain City, OH) to record behavioral responses. Each week, pedometer results were recorded, and blood samples were collected for puberty evaluation via plasma progesterone. Heifers from CON had more (P &amp;lt; 0.05) steps per week compared with DENS and DENS-EX, and DENS-EX heifers had more (P &amp;lt; 0.05) steps per week compared with DENS. Heifers from CON spent more (P &amp;lt; 0.05) time ruminating and eating compared with DENS and DENS-EX. No treatment effects (P ≥ 0.12) were detected for heifer BW gain or temperament variables. Heifers from DENS experienced delayed puberty attainment given a greater (P &amp;lt; 0.05) proportion of CON heifers were pubertal by day 98 compared with DENS and DENS-EX, whereas a greater (P &amp;lt; 0.05) proportion of DENS-EX heifers were pubertal by day 154 compared with DENS heifers (treatment × day interaction, P &amp;lt; 0.01). Collectively, results from this experiment demonstrate that providing heifers reared at a high stocking density access to an exercise area does not result in similar reproductive responses as those reared on pasture at a low stocking density. This work is supported by the USDA National Institute of Food and Agriculture (#2021-67015-34083).

Low optimal fisheries yield creates challenges for sustainability in a climate refugia

AbstractReducing resource depletion and promoting ecosystem‐based management are considered key climate change adaptation policies. Therefore, the resource status of an identified climate refugia in a semi‐enclosed bay on the Kenya–Tanzania border was evaluated for sustainability. Both fisheries stock and catch assessment methods found low production and excess effort. Stock recovery in closures (up to 45 years) determined the best‐fit r and K values, which established a maximum sustainable production (MSY) of 2.98 ± 0.45 (SEM) tons/km2/year. Stock estimates in the bays' fishing grounds indicated that biomass was below the MSY and predicted to produce 1.8 ± 1.0 (SEM) or 1.1 ton/km2/year below the optimal MSY. However, landed fish at five studied fishing villages varied greatly from 0.22 to 2.9 tons/km2/year. MSY in the refugia was therefore considerably lower than estimates in nearby ocean‐exposed locations, which has been estimated at 5–7 tons/km2/year. Therefore, low to modest capture rates of fish will be required to allow the recovery needed to achieve sustainability and restore the refugia's ecology. The refugia's highest stocks and near‐MSY yields were captured in the national reserve. Therefore, broader implementation of the reserve's gear‐restriction policies should restore fisheries. High spatial variability in yield patterns indicate interactions between fisheries management, compliance, trade connections, and governance. In climate refugia, reducing cumulative impacts will require knowing and managing for lower fisheries production limits.