Beneficial roles of feed additives as immunostimulants in aquaculture: a review

Similar to other industries, aquaculture constantly requires new techniques to increase production yields. Modern technologies and different scientific fields, such as biotechnology and microbiology, provide important tools that could lead to a higher quality and a greater quantity of products. New feeding practices in farming typically play an important role in aquaculture, and the addition of various additives to a balanced feed formula to achieve better growth is a common practice of many fish and shrimp feed manufacturers and farmers. As ‘bio-friendly agents’, immunostimulants, such as biological factors, probiotics and vitamins, can be introduced into the culture environment to control and kill pathogenic bacteria, as well as to promote growth of the cultured organisms. In addition, immunostimulants are non-pathogenic and non-toxic and do not produce undesirable side effects when administered to aquatic organisms. In this review, we summarize previous studies performed with both traditional immunostimulants and the most promising new generation of immunostimulants, such as polysaccharides, nutrients, oligosaccharides, herbs, microorganisms, prebiotics and different biological factors. This review primarily focuses on their protective efficacies and on what is known concerning their effects on the immune systems of aquatic organisms when delivered in vivo.

Application of immunostimulants in aquaculture: current knowledge and future perspectives

The advancement of probiotics research and its application in fish farming industries.

Aquaculture is emerging as one of the most viable and promising enterprises for keeping pace with the surging need for animal protein, providing nutritional and food security to humans, particularly those residing in regions where livestock is relatively scarce. With every step toward intensification of aquaculture practices, there is an increase in the stress level in the animal as well as the environment. Hence, disease outbreak is being increasingly recognized as one of the most important constraints to aquaculture production in many countries, including India. Conventionally, the disease control in aquaculture has relied on the use of chemical compounds and antibiotics. The development of non-antibiotic and environmentally friendly agents is one of the key factors for health management in aquaculture. Consequently, with the emerging need for environmentally friendly aquaculture, the use of alternatives to antibiotic growth promoters in fish nutrition is now widely accepted. In recent years, probiotics have taken center stage and are being used as an unconventional approach that has numerous beneficial effects in fish and shellfish culture: improved activity of gastrointestinal microbiota and enhanced immune status, disease resistance, survival, feed utilization and growth performance. As natural products, probiotics have much potential to increase the efficiency and sustainability of aquaculture production. Therefore, comprehensive research to fully characterize the intestinal microbiota of prominent fish species, mechanisms of action of probiotics and their effects on the intestinal ecosystem, immunity, fish health and performance is reasonable. This review highlights the classifications and applications of probiotics in aquaculture. The review also summarizes the advancement and research highlights of the probiotic status and mode of action, which are of great significance from an ecofriendly, sustainable, intensive aquaculture point of view.

Probiotics in fish and shellfish culture: immunomodulatory and ecophysiological responses.

Non-digestible long chain beta-glucans as novel prebiotics

The major hindrance in the development and sustainability of aquaculture industry is the occurrence of various diseases in the farming systems. Today, preventive and management measures are central concern to overcome such outbreak of diseases. Immunostimulants are considered as an effective tool for enhancing immune status of cultured organisms. Among different immunostimulants used in aquaculture practices, β-glucan is one of the promising immunostimulant, which is a homopolysaccharide of glucose molecule linked by the glycoside bond. It forms the major constituents of cell wall of some plants, fungi, bacteria, mushroom, yeast, and seaweeds. Major attention on β-glucan was captivated with the gain in knowledge on its receptors and the mechanism of action. The receptor present inside the animal body recognizes and binds to β-glucan, which in turn renders the animal with high resistance and enhanced immune response. This review highlights β-glucan as an immunostimulant, its effective dosages, and route of administration and furthermore provides an outline on role of β-glucan in enhancing growth, survival, and protection against infectious pathogens pertaining to fishes and shellfishes. Study also summarizes the effect of β-glucan on its receptors, recognition of proteins, immune-related enzymes, immune-related gene expression and their mechanisms of action.

Beta-glucan: an ideal immunostimulant in aquaculture (a review).

The present study investigates the relationship between Motivation and Job Satisfaction. Motivation has been treated as a dependent and Job Satisfaction as an independent variable. The respondents were the employees of one of the public sector giants of India, BSNL and the data has been colleted from 45 white color employees (supervisors and above) of BSNL, Saharanpur. Primary data has been collected by the researcher through two different standard structured questionnaires based on a five pointer likert scale. The results show a positive correlation between motivation and job satisfaction i.e., motivation increases with increase in job satisfaction and vice-versa. The results of the study also indicate that, motivation remains unaffected of both age as well as the length of the service of the employees. It may be because of the fact that the factors responsible for motivation and satisfaction seem to be present in the working environment of the organization. The paper also finds the relative importance of different factors that contribute to the satisfaction of employees; Compensation Package emerged as the most important factor, whereas the Self Actualization appears to be the least important factor.

Relationship between Motivation and Job Satisfaction of the White Collar Employees: A Case Study

To develop an effective conservation and management strategy, it is required to assess the biodiversity status of an ecosystem, especially when we deal with Indo-Myanmar biodiversity hotspot. Importance of this reaches to an entirely different level as the hotspot represents the area of high endemism which is under continuous threat. Therefore, the need of the present study was conceptualized, dealing with molecular assessment of the fish fauna of Indo-Myanmar region, which covers the Indian states namely, Manipur, Meghalaya, Mizoram, and Nagaland. A total of 363 specimens, representing 109 species were collected and barcoded from the different rivers and their tributaries of the region. The analyses performed in the present study, i.e. Kimura 2-Parameter genetic divergence, Neighbor-Joining, Automated Barcode Gap Discovery and Bayesian Poisson Tree Processes suggest that DNA barcoding is an efficient and reliable tool for species identification. Most of the species were clearly delineated. However, presence of intra-specific and inter-specific genetic distance overlap in few species, revealed the existence of putative cryptic species. A reliable DNA barcode reference library, established in our study provides an adequate knowledge base to the groups of non-taxonomists, researchers, biodiversity managers and policy makers in sketching effective conservation measures for this ecosystem.

DNA Barcoding of Freshwater Fishes of Indo-Myanmar Biodiversity Hotspot.

https://www.fs.fed.us/rm/pubs_journals/2021/rmrs_2021_dar_s001.pdf

Soibam Khogen Singh

Papers

Beta-glucan: an ideal immunostimulant in aquaculture (a review).

Relationship between Motivation and Job Satisfaction of the White Collar Employees: A Case Study

DNA Barcoding of Freshwater Fishes of Indo-Myanmar Biodiversity Hotspot.

Projected climate change threatens Himalayan brown bear habitat more than human land use

Comparative efficacy of different inducing agents on breeding performance of a near threatened cyprinid Osteobrama belangeri in captivity