Stocking Density Stress Research Articles

Effects of several macerated citrus oils on health parameters of rainbow trout (Oncorhynchus mykiss) under high stocking density

The interplay between dietary components and antioxidant systems in fish physiology is crucial for aquaculture. Citrus fruits, renowned for their high content of bioactive antioxidants, have attracted attention for their antioxidant features in fish. The purpose of this study was to investigate the dietary effects of using essential oil from macerated oils of lemon peel (Citrus limon) (MOL), orange peel (Citrus sinensis) (MOO) and grapefruit peel (Citrus paradisi) (MOG) on growth, proximate composition, hematological, antioxidant parameters of rainbow trout (Oncorhynchus mykiss) subjected to high stocking density stress. Fish (110 ± 10.95 g) were randomly introduced to three trial groups (1% of MOL, MOO and MOG). At the end of feeding period (42-day), the results showed that the three trial groups had significant effects on the feed conversion ratio (FCR), especially in the MOG (P<0.05). The FCR value in MOG was remarkably 0.81. In the study, the lowest dry matter and ash levels were detected in MOO, moisture content in MOL, but the highest fat (6.82 ± 0.82) and protein (15.85 ± 0.74) levels were found in MOG. There were significant differences in proximate composition and red blood cell (RBC) (1.73 ± 0.07 in MOG), hemoglobin (Hgb) (8.97 ± 0.43 in MOL), hematocrit (Hct) (23.92 ± 1.09 in MOL), mean corpuscular hemoglobin concentration (MCHC) (38.22 ± 0.34 in MOG) between the control and all groups (P<0.05). The results showed that glutathione peroxidase (GPx), catalase (CAT) and glutathione reductase (GR) activities in all treatment groups were decreased and malondialdehyde (MDA) level was increased in the MOO group activity (P>0.05).

Economic and Behavioral Benefits of Using Aqueous Plant-mixture Extracts in Broiler Production with High Stocking Density

The rising demand for white meat has led to an increased reliance on intensive farming systems involving high stocking density that can cause stress on birds, hinder their growth and behavior, and reduce profitability. This necessitates the use of antioxidant growth enhancers to mitigate the impact of stress. In response to this challenge, this study aimed to determine the effectiveness of natural growth promoters compared to antibiotics in alleviating the negative impact of stocking density stress by conducting an experiment using 300 one-day-old Cobb 500 chicks over 35 days. After 7 days of acclimatization, the chicks were weighed, wing-tagged, and divided into five groups with 60 chicks each, divided into three replicates of 20 birds. The groups were categorized as follows: low stocking density (LSD) with 10 birds/m2, high stocking density (HSD) with 18 birds/m2, HSD+AGP feeding diet with 55 ppm/kg feed Bacitracin Methylene Disalicylate (BMD-50; Zoetis Products, Chicago Heights, IL, USA) as antibiotic growth promoter, HSD+LPEM with a low concentration of aqueous plant extracts mixture (LPEM) (8 ml fennel + 8 ml fenugreek + 8 ml thyme/L of drinking water), and HSD+HPEM with a high concentration of aqueous plant extracts mixture (HPEM) (10 ml fennel + 10 ml fenugreek + 10 ml thyme/L of drinking water). The findings revealed that HSD led to a decline in productivity, behavior, and economic efficiency when compared to LSD. AGP improved these aspects but at a lower level than PEM. In conclusion, to ensure the production of antibiotic-free meat, decrease antibiotic resistance, and achieve better behavioral, productive, and economic outcomes, it is proposed to use a combination of fennel, fenugreek, and thyme aqueous extracts in PEM at a concentration of 8 or 10 mL/L in the drinking water. However, for an optimal cost-benefit ratio, it is recommended to utilize PEM at a concentration of 10 mL per liter of the bird's drinking water.

Effects of dietary chlorogenic acid on ileal intestinal morphology, barrier function, immune factors and gut microbiota of broilers under high stocking density stress.

Aims: The purpose of this research was to assess the effect of chlorogenic acid (CGA) in the diet on ileac structure, barrier function, immunological state, and microbial profile of broiler chickens in a high stocking density (HD) environment. Methods: Four hundred and seventy-six male AA broiler chickens were randomly split into four groups, two with a normal stocking density (ND) of fourteen birds per m2 and two with a high stocking density of twenty-two birds per m2. Each of the treatments consisted of five replicates. One of the two ND and HD groups received the usual feed, while the other two were given at 1.5g/kg CGA as part of their dietary regimen. Results: The ND CGA group showed a greater increase in villus height and villus height/crypt depth compared to the ND group at 35 and 42days. The HD group experienced a greater elevation in villus height due to CGA supplementation than the HD group across days 28, 35, and 42. At day 42, the HD group saw a decline in OCLN and ZO-1 mRNA expression in the ileum, but CGA was able to restore them. The HD group experienced a greater rise in OCLN mRNA than the control HD group when supplemented with CGA. The expression of TNF-α, IL-1β, and IL-6 in the ileum was higher in the HD group, and CGA supplementation enhanced this effect. The HD group experienced a greater rise in IL-10 mRNA expression than the control group following the administration of CGA. The HD group showed reduced alpha diversity and an increase in detrimental microbes such as Turicibacter and Shigella in the gut compared to the ND group, while the HD CGA group saw a reduction in Turicibacter, Shigella, and other harmful microbes. These findings reveal that HD stress suppressed the growth of ileac villi, decreased the expression of tight-junction genes, amplified the expression of inflammatory genes, and disturbed the gut microbiota, ultimately leading to increased intestinal permeability. Conclusion: We conclude that when chickens are given dietary CGA, the disruption of the ileac barrier and increased oxidative damage and inflammation due to HD stress are reduced, which increases ileac integrity and the presence of beneficial intestinal bacteria.

EVALUASI GLUKOSA DARAH IKAN BATAK (Tor soro) PADA PADAT TEBAR BERBEDA

This research was conducted with the aim to evaluate the performance of Batak fish (Tor soro) blood glucose in response to stocking density stress. Fish with an average of 2.21 g with a weight of 27 individuals were given stocking density stress by inserting them into 9 cylindrical containers of 200.96 cm2 and 3 L volume of peat water with stocking differently for 72 hours. These stocking density treatments consisted of A (2 fishes/0.02 m2), B (3 fishes/0.02 m2), C (4 fishes/0.02 m2) and E (5 fishes/0.02 m2) with three repetitions. Blood glucose was collected from 1 fish per container during 72 hours. The preliminary test was conducted to determine the oxygen demand of fish through the oxygen consumption level test, in which the oxygen demand from the fish was calculated in accordance to the density used. The average value of blood glucose levels of Batak fish that were given the stress of stocking density 2 fishes/0.02 m2, 3 fishes/0.02 m2, 4 fishes/0.02 m2, and 5 fishes/0.02 m2 tend to be low, as much as 53 mg/dL, 52.67 mg/dL, 49.33 mg/dL and 39.63 mg/dL respectively. The response of blood glucose to stocking density stress resulted in stocking recommendations for culture Batak fish ranging from 100-250 fish/m2 with 2,21-3,12 fish/ gram.

Dietary Supplementation with Chlorogenic Acid Enhances Antioxidant Capacity, Which Promotes Growth, Jejunum Barrier Function, and Cecum Microbiota in Broilers under High Stocking Density Stress.

Chlorogenic acids (CGA) are widely used as feed additives for their ability to improve growth performance and intestinal health in poultry. However, whether dietary CGAs could reverse the impaired intestinal condition caused by high stocking density (HD) in broiler chickens is unknown. We determined the effect of dietary CGA on growth, serum antioxidant levels, jejunum barrier function, and the microbial community in the cecum of broilers raised under normal (ND) or HD conditions. HD stress significantly decreased growth and body weight, which was restored by CGA. The HD group showed increased serum malondialdehyde, an oxidative byproduct, and decreased SOD and GSH-Px activity. CGA reduced malondialdehyde and restored antioxidant enzyme activity. HD stress also significantly decreased jejunal villus length and increased crypt depth. Compared with ND, the expression of tight-junction genes was significantly decreased in the HD group, but this decrease was reversed by CGA. HD also significantly upregulated TNF-α. Compared with ND, the cecal microbiota in the HD group showed lower alpha diversity with increases in the harmful bacteria Turicibacter and Shigella. This change was altered in the HD + CGA group, with enrichment of Blautia, Akkermansia, and other beneficial bacteria. These results demonstrated that HD stress decreased serum antioxidant capacity, inhibited the development of jejunal villi, and downregulated expression of tight-junction genes, which increased intestinal permeability during the rapid growth period (21 to 35 days). Dietary CGA enhanced antioxidant capacity, improved intestinal integrity, and enhanced beneficial gut bacteria in chickens raised under HD conditions.

Response of Blood Glucose of Brek Fish (Puntius Orphoides) on Stocking Density Stress

This research was conducted with the aim to evaluate the performance of blood glucose of brek fish (Puntius orphoides) in response to stocking density stress. Fish weighing an average of 2.21 g with a weight of 27 individuals were given stocking density stress by inserting them into 9 cylindrical containers of 200.96 cm2 width and 3 L volume of peat water with stocking differently for 72 hours. These stocking density treatments are A (2 fishes/0.02 m2), B (3 fishes/0.02 m2) and C (4 fishes/0.02 m2) with three replicates. Blood glucose collected from 1 fish per container at 72 hours. The preliminary test was conducted to determine the oxygen demand of fish through the oxygen consumption level test which can then be calculated oxygen demand from the fish in accordance with the density used. The average value of blood glucose levels of brek fish that were given the stress of stocking density 2 fishes / 0.02 m2, 3 fishes / 0.02 m2 and 4 fishes / 0.02 m2 tends to be low, that is 53 mg / dL, 52.67 mg / dL and 49.33 mg / dL respectively. The response of blood glucose to stocking density stress results in stocking recommendations for culture brek fish ranging from 100-200 fish / m2.

Effect of Dietary Chlorogenic Acid on Growth Performance, Antioxidant Function, and Immune Response of Broiler Breeders under Immune Stress and Stocking Density Stress.

Simple SummaryImmune stress and high stocking density stress are two major concerns in poultry production, as they can greatly impair the productive and reproductive performance of chickens with serious economic consequences. Chlorogenic acid has been widely used as a feed additive in poultry production due to its potent antioxidant, anti-inflammatory, antibacterial, and antiviral activities. This study aimed to investigate the effects of dietary chlorogenic acid supplementation on growth performance, antioxidant function, and immune response in broiler breeders exposed to immune stress and high stocking density stress. Our study highlights that chlorogenic acid increased feed intake, downregulated serum corticosterone levels, and altered the immune and antioxidant functions of broiler breeders exposed to immune stress or high stocking density stress. Dietary inclusion of 1 g/kg chlorogenic acid could be used to increase feed intake of broiler breeders and alleviate the effects of immune stress and exposure to high stocking density in poultry.The study was conducted to evaluate the effects of dietary chlorogenic acid supplementation on the growth performance, antioxidant function, and immune response of broiler breeders exposed to immune stress or high stocking density stress. The test was divided into two stress models. For the immune stress test, 198 birds were distributed into three experimental treatments with six replicates per treatment. The treatments were: (1) saline control (birds injected with saline and fed basal diet), (2) LPS group (birds injected with 0.5 mg LPS/kg body weight and fed basal diet), and (3) CGA + LPS group (birds injected with LPS and fed basal diet supplemented with 1 g/kg CGA. LPS was intraperitoneally injected from day 14, and then daily for 10 days. For the high stocking density stress model, 174 birds were distributed into three experimental treatments with six replicates per treatment. The treatments were: (1) controls (birds fed basal diet and raised at a stocking density of 14 broilers per m2), (2) high-density group (birds fed with basal diet and raised at a stocking density of 22 broilers per m2), and (3) high density + CGA group (birds fed with 1 g/kg CGA and raised at a stocking density of 22 broilers per m2). Results showed that LPS injection and high stocking density significantly decreased the body weight and feed intake of broiler breeders, while CGA supplementation increased feed intake of broiler breeders under LPS injection and high stocking density stress. Moreover, LPS injection and high stocking density increased the concentration of corticosterone in serum, and CGA addition remarkably downregulated serum corticosterone levels. The GSH level decreased with LPS injection and CGA increased the GSH concentration in the intestines of immune-stressed broiler breeders. LPS injection promoted the production of circulating proinflammatory cytokines (serum IL-1β and TNF-α) by 72 h after LPS injection. Dietary supplementation with CGA prevented the increase in serum TNF-α caused by LPS. These results suggest that dietary inclusion of 1 g/kg CGA could increase the feed intake of broiler breeders and alleviate the effects of inflammatory mediator stress and exposure to high stocking density.

The importance of nutrition in alleviating high stocking density stress in poultry - A Review

Abstract In recent decades, the number of birds reared per unit area has dramatically spiked to increase profitability in egg and meat production. However, nowadays, the increase in sensitivity to animal welfare and consumer demands brings along with it a raised interest in stocking density. Stocking density is defined either as the number of animals or body weight per unit area or as the area per animal. High stocking density, which is a stress factor, can be defined as an increase in the number of animals per unit area or a decrease in the area per animal. Stress caused by high stocking density negatively affects the bird’s physiology and performance as well as the quality of the product obtained. The ideal stocking density should be 9 laying hens, 35 kilograms for broilers, and 45 quails per square metre. Otherwise, one will observe stress indicators in birds reared in more than the recommended stocking density per unit area and, consequently, a decrease in bird growth, egg production, feed efficiency, and egg or meat quality. Apart from increasing the concentrations of amino acids such as lysine, methionine, tryptophan and arginine, minerals such as selenium and chromium, and vitamins such as C and E in the diet, the addition of additives such as probiotics, humates, phytophenol compounds, and propolis is also effective in reducing or eliminating these negative effects caused by high stocking density. As a result, regulations in the nutrition of animals are effective in reducing/preventing such negative effects, thus improving animal welfare and ensuring the maintenance of optimum yield.

Dietary flaxseed oil and sunflower oil supplementations support heterophil functions, T cells, and antioxidant defence system in laying hens exposed to stocking density stress

Introduction Birds are more prone to stress than mammals due to their anatomical and physiological differences (Yahav, 2004, Stettenheim, 2000). Moreover, production performance increase-tailored selections have elevated the perceived stress levels

Characterization and expression analysis of heat shock protein 90β from golden pompano (Trachinotus ovatus, Linnaeus 1758) in responses to stock density stress and Cryptocaryon irritans infection

Heat shock protein 90 family, a class highly conserved protein and important molecular chaperone and its plays a role in enhancing animal adaptability to environmental stress and improving immunity. In this study, a full-length HSP90β cDNA (ToHSP90β) sequence was identified from Trachinotus ovatus. The cDNA of ToHSP90β was 2648 base-pairs (bp) long and contained a 5′-terminal untranslated region of 130 bp, a 3′-terminal untranslated region of 334 bp, and the open reading frame length 2184 bp, which can encode 728 amino acids. The ToHSP90β has a heat shock protein 90 family signature. The ToHSP90β amino acid sequence has high homology with other fish HSP90β amino acids (92.5-99.17%) and contains five conserved signal regions and a structural feature of the cytoplasmic HSP90 family. Phylogenetic tree analysis indicated that ToHSP90β was most closely related to Seriola dumerili HSP90β. Tissues expression analysis showed that the ToHSP90β was expressed in all nine tissues of T. ovatus, and its expression was the highest in the intestine. The stocking density significantly affected the expression of ToHSP90β in the kidney and brain tissues, and its expression levels increased significantly with increasing stocking densities, indicating that it plays an important regulatory role in the process of T. ovatus’ chronic stress response. After Cryptocaryon irritans infection, the mRNA expression of ToHSP90β was significantly increased in liver and kidney tissues, indicating that ToHSP90β would be involved in the immune regulatory response. This study was the first to analyze the expression pattern of HSP90β mRNA in T. ovatus tissues and their expression responses to stocking density stress and C. irritans infection. To provide a theoretical basis for further study of the function of fish HSP90 and its physiological mechanism in environmental stress and parasite infection.

Effects of Scopoletin Supplementation and Stocking Density on Growth Performance, Antioxidant Activity, and Meat Quality of Korean Native Broiler Chickens.

Stocking density stress is one of the most common management stressors in the poultry industry. The present study was designed to investigate the effect of dietary Sophora koreensis (SK; 0 and 20 mg/kg diet) and stocking density (SD; 14 and 16 chickens/m2) on the antioxidant status, meat quality, and growth performance of native Korean chickens. There was a lower concentration of malondialdehyde (MDA) and a higher concentration of catalase, superoxide dismutase (SOD), and total antioxidant capacity in the serum and leg muscle with the supplementation of SK. The concentration of MDA was increased and concentrations of SOD were decreased in the leg muscle of chickens in low SD treatments. The SK-supplemented treatments showed an increased 3-ethylbenzothiazoline-6-sulfonate-reducing activity of leg muscles. The higher water holding capacity of breast muscle and a lower cooking loss and pH were shown in the SK-supplemented treatments. The addition of dietary SK resulted in a greater body weight gain and greater spleen and bursa Fabricius weight, as well as lower feed intake and abdominal fat. The low SD and supplementation of SK increased the concentrations of cholesterol. The concentration of glucose was increased in the low SD treatment. Corticosterone level was decreased in the SK-supplemented and low SD treatments. In conclusion, SK supplementation reduced the oxidative stress and increased meat quality and antioxidant status of chickens apart from the SD stress.

Effects of alpha-lipoic acid on the behavior, serum indicators, and bone quality of broilers under stocking density stress

The objective of present study was to investigate the effects of alpha-lipoic acid (ALA) dietary supplementation on the behavior, physiological and oxidant stress indicators, and bone quality in broilers under high stocking density (HSD) stress. A total of one thousand eight hundred 22-day-old Arbor Acres male broiler chicks were randomly allocated to 18 pens (2.97 × 2.03 m) in 3 groups: 14 birds/m2 (NSD, normal stocking density) or 18 birds/m2 (HSD) or 18 birds/m2 plus 300 mg/kg ALA dietary supplement (HSD + ALA, high stocking density + alpha-lipoic acid). Each treatment had 6 replicates, and the experiment lasted 3 wk. The HSD group was significantly lower than the NSD group (P < 0.05) in the frequency of eating, walking, and preening behavior. The alkaline phosphatase activity and serum calcium content were significantly higher, and the parathyroid hormone (PTH) level was significantly lower in the HSD group than in the NSD group (P < 0.05). When compared with the NSD group, the HSD group showed an increase (P < 0.05) in serum heterophil/lymphocyte ratio (H/L ratio), corticosterone (CORT), malondialdehyde (MDA) content, and catalase (CAT) activity, whereas a decrease (P < 0.05) in total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) concentrations. The HSD group was also significantly lower (P < 0.05) than the NSD group in the tibia and femur breaking strength, bone mineral density, and BMC. Importantly, the addition of ALA into the diets of the HSD group enabled the HSD + ALA group to recover to the levels of NSD group (P > 0.05) in the standing and preening behavior, alkaline phosphatase activity, PTH concentration, H/L ratio, CAT, T-AOC, MDA, SOD, and GSH-Px. These results indicate that the increase of stocking density lowered the bone quality, increased the physiological and oxidative stress indicators, and modified the behavior of broilers, whereas ALA dietary supplementation could counteract the reduction in the performance and physiological responses of broilers under high-density environmental stress.

Molecular characterization of GRP94 and HSP90α from Trachinotus ovatus, Linnaeus 1758 and their expression responses to various levels of stocking density stress and Cryptocaryon irritans infection

Heat shock proteins (HSPs) are a class of molecular chaperones with a wide range of biological activities. To understand the stress responses of 94-kDa glucose-regulated protein (GRP94) and heat shock protein 90 alpha (HSP90α) under stocking density stress and C. irritans infection, we obtained their cDNA sequences from T. ovatus and performed bioinformatic analysis on their structures. Meanwhile, the tissue-specific expression patterns of these genes were also detected by qPCR. The ToGRP94 cDNA contains an open reading frame of 2394 bp, which encodes a protein of 797 amino acids, while ToHSP90α contains an open reading frame of 2190 bp, which encodes a protein of 730 amino acids. Amino acid sequence analysis showed that these proteins have highly conserved characteristic family domains or motifs, such as the heat shock hsp90 protein family signature (Y [k/s] NKEIFLRE). ToGRP94 was recently related to S. dumerili GRP94 with amino acid sequence homology up to 96.86%, and ToHSP90α had a higher evolutionary correlation with M. armatus and A. testudineus HSP90α with sequence homology of 98.49% and 97.67%, respectively. ToGRP94 and ToHSP90α mRNAs were widely expressed in all tissues tested under normal conditions. ToGRP94 mRNA was most strongly expressed in gill tissue followed by fin and kidney tissues, while ToHSP90α was most strongly expressed in blood tissues followed by brain, kidney and gill tissues. Under stocking density stress, ToGRP94 mRNA in the liver was significantly higher in the LD group, but it did not change in the kidney and spleen tissues with increasing stocking density; however, the expression level of ToHSP90α gene increased significantly in liver, spleen, and kidney tissues under high stocking densities, which indicates that ToHSP90α was closely related to density chronic stress. After C. irritans infection, the expression of ToGRP94 was significantly increased in liver, spleen, and kidney tissues. Similarly, ToHSP90α gene expression was significantly increased in liver and kidney tissues, but there was no difference in spleen tissue. The results indicate that these two genes may be involved in the immune response of T. ovatus. In summary, ToHSP90α would be involved in chronic stress and the immune response, while ToGRP94 would be mainly involved in the immune regulatory response. These results may provide a reference for further research studying the function of fish HSP90 and its mechanism under environmental stress.

A natural additive in the diet to improve growth and reduce energy expenditure of gilthead seabream (Sparus aurata L.): Attenuation of high stocking density stress responses

Fish welfare is gaining momentum due to consumers' trends and legal regulations. Therefore, aquaculture industry is in the way of mitigating stress to the animals and, thus, improving the physiological status, with the consequent increase in economical profits. As a consequence, feed additives have been proposed as potential stress relievers through the diet. However, the effectiveness of these extracts on stress responses and growth regulation is still to be defined for different species and stressors. Here we show the effects of the commercial natural-additive “Relaquax” on growth performance, endocrine regulation of hypothalamic-pituitary-interrenal (HPI) and somatotropic (GH/IGF-I) axes, as well as intermediary metabolism, of gilthead seabream (Sparus aurata L.) reared in low and high stocking density conditions. For this purpose, S. aurata juveniles were maintained for 3 months at different combined conditions of feeding (control diet or supplemented with the additive) and initial stocking density (low or high; 4.0 or 11.5 kg m−3, respectively). At the end of the experimental period, brain, pituitary, head kidney and liver gene expression of endocrine factors involved in stress and growth regulation were determined. In addition, liver and muscle enzyme activities of the intermediary metabolism of carbohydrates, lipids and amino acids were assessed. Our results showed an increased growth performance in fish fed with the additive, mediated through hepatic igf1 enhanced expression at both stocking densities. In the same way, higher body mass was associated to inhibition of lipid catabolism in muscle (decreased GPDH and HADH activities), as a consequence of diet supplementation. The additive has also reduced amino acid catabolism in liver (decreased AST activity), as well as enhanced glycolysis in muscle (increased PK activity). In conclusion, this additive was confirmed as a natural alternative to improve aquaculture and welfare of seabream, especially under high stocking density conditions.

Transcriptome analysis and discovery of genes involved in immune pathways in large yellow croaker (Larimichthys crocea) under high stocking density stress

The large yellow croaker, Larimichthys crocea, is an economically important maricultured species in southeast China. Owing to the importance of stocking densities in commercial fish production, it is crucial to establish the physiological responses and molecular mechanisms that govern adaptation to crowding in order to optimize welfare and health. In the present study, an extensive immunity-related analysis was performed at the transcriptome level in L. crocea in response to crowding stress. Over 145 million high-quality reads were generated and de novo assembled into a final set of 40,123 unigenes. Gene Ontology and genome analyses revealed that molecular function, biological process, intracellular, ion binding, and cell process were the most highly enriched pathways among genes that were differentially expressed under stress. Among all of the pathways involved, 16 pathways were related to the immune system, among which the complement and coagulation cascades pathway was the most enriched for differentially expressed immunity-related genes, followed by the chemokine signaling pathway, toll-like receptor signaling pathway, and leukocyte transendothelial migration pathway. The consistently high expression of immune-related genes in the complement and coagulation cascades pathway (from 24 to 96 h after being subjected to stress) suggested its importance in both response to stress and resistance against bacterial invasion at an early stage. These results also demonstrated that crowding can significantly induce immunological responses in fish. However, long-term exposure to stress eventually impairs the defense capability in fish.

Growth, biochemical, fatty acid composition, and mRNA levels of hepatic enzymes in genetically improved farmed tilapia (GIFT,Oreochromis niloticus) (Linnaeus, 1758) at different stocking densities

Investigated were the effects of stocking density on juvenile growth performance, serum biochemistry, fatty acid composition, and mRNA levels of enzymes involved in lipid metabolism in genetically improved farmed tilapia (GIFT), Oreochromis niloticus. Juvenile fish (n = 900) were distributed into 15 tanks at five initial stocking densities (75, 150, 225, 300, and 375 g/m3 per 800-L tank, represented as D1–D5, respectively). Temperature was maintained at 28 ± 0.3°C, and water flow rate into the tanks was about 8 L/min. The fish accepted floating pelleted feed (crude protein 28%, crude lipid 6%, and gross energy 149.2 KJ/g diet). The feed amount offered was 4%–8% of body weight. At the end of the 60-day experiment, the final stocking densities were 1,454.18, 2,010.60, 2,913.13, 3,819.73, and 4,380.80 g/m3, respectively. Growth and body mass coefficient of variation were significantly affected (p < .05). No differences in feed conversion rate or survival were found (p > .05). Muscle lipid contents decreased with stocking density from D1 to D5. Serum total protein and cholesterol levels were not affected by the stocking density but the D5 group produced the highest serum cortisol and lactate levels and the lowest glucose levels compared to those of the other groups. Lower muscle saturated fatty acid and n−3 polyunsaturated fatty acid contents were observed in the D4 group than in the other groups, whereas the reverse was found in the n−6 polyunsaturated fatty acid content. Hepatic glucose 6-phosphate dehydrogenase, fatty acid synthetase, hormone-sensitive triglyceride lipase, and lipoprotein lipase mRNA levels were significantly upregulated in response to a high density. These data suggest that the GIFT adapted to high-density conditions by altering the composition of muscle fatty acid and stimulating lipid metabolic enzymes. These mechanisms may help fish respond to high stocking density stress in intensive aquaculture systems.

Impacts of Pro-Grow® on Growth Performance, Physiological, Immune Responses and Economic Efficiency of Adult Oreochromis niloticus (Linnaeus, 1758) under Stocking Density Stress

Impacts of Pro-Grow® on Growth Performance, Physiological, Immune Responses and Economic Efficiency of Adult Oreochromis niloticus (Linnaeus, 1758) under Stocking Density Stress

Effects of dietary organic and inorganic manganese supplementation on performance, carcass and hematological parameters in broiler reared under stocking density stress

Effects of dietary organic and inorganic manganese supplementation on performance, carcass and hematological parameters in broiler reared under stocking density stress

닭의 고밀도사양 스트레스가 품종 간 체내대사 유전자 발현에 미치는 영향

Chickens are exposed to the external and internal stressors such as low and high temperature, high stocking density, feed restriction and disease. There have been a few studies on gene expressions through the investigation of chickens under direct exposure to the stress of high stocking density. The objective of the present study was to determine the expressions of genes associated with stress, endoplasmic reticulum (ER)-stress, lipid and glucose metabolism in two strains of chickens, Korean Native Chicken (KNC) and White Leghorn (WL), raised in high stocking density. A total of 164 chickens aged 40 weeks were randomly allotted to a 540 cm 2 /bird stocking density (control), whereas the chickens in a high density group were assigned in a 311 cm 2 /bird stocking density with feeding ad libitum for 10 weeks. Total RNA was extracted from the live for qRT-PCR. The expression levels of hsp70 and hsp90α were higher in WL subjected to stress with high stocking density compared with those genes in control (P<0.05), while the expressions of genes were not affected in KNC. ER stress marker gene XBP1 was also highly expressed in WL with stress (P<0.05), but the stress of high stocking density did not influence to ER stress marker genes in KNC. Lipid metabolism associated genes including FABP4, FATP1 and ACSL1 were highly expressed in WL compared with KNC when subjected to high stocking density stress (P<0.05). The expression of glucose transport gene GLUT2 and GLUT8 were increased in chickens exposured to the stress of high stocking density (P<0.05). The data indicate that WL is more sensitive to the stress of high stocking density compared with KNC and the stress may influence the modulation of lipid and glucose metabolism in the liver of chickens.

The effect of stocking density during 4 hour transport to slaughter on behaviour, blood constituents and carcass bruising in Friesian steers

The aim of this work was to assess the response of Friesian steers to road transportation at low, medium and high ( ca 200, 300 and 600 kg/m 2) stocking densities in terms of physiology, behaviour and carcass bruising. Stocking density was determined by adjusting the number of animals per pen (3 runs) or by adjusting pen size (3 runs). Plasma cortisol and glucose increased ( P < 0·001) with stocking density, as did plasma CK activity ( P < 0·001) and carcass bruising ( P < 0·01) both of which indicate muscle damage. At constant stocking density stress increased with pen location towards the tail of the truck, as reflected by a significant increase in plasma cortisol. Stocking density influenced standing orientation within the truck. At low stocking density animal movement was unrestricted and the preferred orientation was standing parallel to the direction of travel; there was a strong bias against diagonal orientations. Losses of balance were associated with specific driving events, notably braking and cornering. Minor losses of balance were observed at all stocking densities, but major losses of balance including animals going down underfoot were associated with high density. When an animal went down at high stocking density it did so involuntarily and was sometimes trapped down, destabilizing other members of the group in a domino effect. Exploratory, sexual and aggressive behaviours were inhibited at high stocking density, with the exception of mounting and pushing, which increased in frequency with stocking density. It was concluded that the high stocking density adversely affected animal welfare and lowered carcass quality when compared with the medium and low stocking densities.