lbs farmed fish per capita consumption lbs farmed fish per capita consumption

Transcription

1 Delbert M. Gatlin III Department of Wildlife and Fisheries Sciences and Intercollegiate Faculty of Nutrition Texas A&M University System lbs farmed fish per capita consumption lbs farmed fish per capita consumption 2006 farm gate value was over $6,000,000,000 USD per year 2011 fish farming provided over 50% of the world s seafood consumed by humans The future aquaculture production expected to double next years due to increasing human population and demand for seafood as well as static capture fisheries 1

2 FAO, 2012 FAO,

3 FAO, 2012 Courtesy of: The International Fishmeal and Fish Oil Organization (IFFO) 3

4 6/21/2014 Red Tilapia Nile Tilapia Outdoors in: Ecuador Indonesia Indoors in the U.S. 4

5 5

6 6

7 7

8 Proper nutrition not only affects production efficiency but also may influence the health of aquatic species and quality of resulting products Good husbandry practices also are crucial for maintaining optimal health of the cultured organism The desire to maximize production per unit area or water volume may increase fish density and social interactions, leading to compromised water quality and increased disease susceptibility of the cultured species Nutritional intervention can help manage disease by applying nutritionbased strategies which support optimal growth and immune system function Such nutritional strategies including functional feeds must be integrated into production and management practices of the aquacultural operation 8

9 In recent years it has become increasing apparent that nourishing the GI tract by providing specific nutrients and fuel as well as influencing its microbial population can significantly alter the host s growth performance, nutrient utilization and disease resistance. 9

10 The gastrointestinal (GI) tract may have profound effects on fish health because: Its integrity is vital for normal nutrient absorption GI tract modulates many aspects of innate and adaptive immunity due to the presence of significant numbers and types of immune cells GI tract may guard against pathogen entrance into the body Essential oils and herbal extracts Organic acids Probiotics Prebiotics 10

11 Live microbial feed supplement which beneficially affects the host animal by improving its intestinal microbial balance (Fuller 1989) Use in aquaculture was initially focused on altering the microbial community of the aquatic medium Various bacterial species have proven efficacious Feed processing effects must be considered Unlike terrestrial animals where lactic acid bacteria predominate, a diverse range of bacteria have been used in aquaculture (Newaj-Fyzul, al-harbi and Austin (2013): Gram-negative bacteria 18 species including Aeromonas, Enterobacter, Pseudomonas and Vibrio Some concern if these organisms could acquire virulence genes by horizontal gene transfer Gram-positive bacteria 19 species including Bacillus, Clostridium, Lactobacillus and Streptomyces Non-bacterial candidates include bacteriophages, unicellular algae and yeasts 11

12 Bacillus species such as Bacillus subtilis, B. licheniformi Endospore-forming members of this genus Tolerant to adverse environments Suitable for pelleting but not extrusion processing Have extracellular cellulolytic and amylolytic activities Inhibit growth of pathogenic bacteria by releasing acetic acid and lactic acid Microbiota changes in the GI tract due to probiotics have been noted to have various modes of action including: Host immunostimulation by up- or down-regulation of genes involved in immunity; both innate and cellular immunity Competitive exclusion of pathogenic bacteria through the production of inhibitory compounds (bacteriocins) and competition for adherence sites in the mucosal epithelium Enhancement of feed utilization and production of digestive enzymes (alginate lyases, amalyses and proteases) 12

13 In many cases the viability of probiotic bacteria in feed has not be confirmed over time. Inactivated cells have been found in some instances to be just as effective as live preparations As such, feed processing effects are not as much of a concern Also, inactivated preparations eliminate the potential safety concerns involving the acquisition of virulence genes Should probiotics be considered feed additives or veterinary medicines, i.e., heterologous vaccines?? Prebiotics: non-digestible food ingredients that beneficially affect the host by stimulating growth and/or activity of a limited number of beneficial bacteria in the gastrointestinal tract (Gibson and Roberfroid 1995) Fructooligosaccharide (FOS) of various chain lengths Mannanoligosaccharide (MOS) Galactooligosaccharides (GOS) GroBiotic -A (GBA) - a mixture of partially autolyzed brewers yeast, dairy components and dried fermentation products Previda - galacto-gluco-mannan 13

14 6/21/2014 Various positive effects have been shown including: Stimulation of growth of Lactobacillus spp. and Lactococcus spp. in the GI tract of fish and alteration of GI tract microbiota in shrimp Stimulation of volatile fatty acid (VFA) production to provide energy to the enterocyte and increase mineral absorption Enhancement of immunity and resistance of various fish species to bacterial and parasitic diseases Enhancement of nutrient and energy availability of soybeanmeal-based diets to red drum (Sciaenops ocellatus) and Atlantic salmon (Salmo salar) Alteration of intestinal cell morphology and histometrics in various fish species 14

15 Ingredient (%) Basal 1% GBA 2% GBA Menhaden Meal Soybean Meal Dextrin Menhaden Oil Vitamin Premix Mineral Premix CMC CaPO4, dibasic Corn oil Casein Celufil GroBiotic A Total Basal 1.0% GBA 2.0% GBA Tracks with less than 80% similarity indicate the microbial populations are not related 15

16 Lysozyme activity units/ml Basal 1% GBA 2% GBA Diet ab a 0.6 nmol/super oxided b Basal 1% GBA 2% GBA Diet P =

17 % Survival Basal 1% GBA 2% GBA Day Timing and duration of prebiotic feeding to optimize effects Dose-response relationships not well established Feed processing effects on structure and function of various prebiotics Environmental conditions (especially water quality) and their effects on microbiota of the GI tract as influenced by prebiotics Relative influence of prebiotics on autochthonous and allochthonous bacteria 17

18 The impact of culture systems on microbial ecology and impacts on indigenous microbes of cultured organisms Underlying molecular mechanisms and signaling pathways Synbiotics have been evaluated to only a limited extend in aquaculture 18

19 Dietary modulation of disease resistance holds promise as a relatively inexpensive and environmentally responsible alternative to chemical therapy for disease control Further refinement of administration protocols for various probiotics and prebiotics are needed to optimize changes in the GI tract microbiota to achieve beneficial effects The effects of probiotics and prebiotics on functions of the GI tract related to absorption efficiency, enzyme production, immunity and disease resistance should be further characterized Integrated health management practices must continue to be pursued to enhance the efficiency of aquacultural production 19