Digital re-print - January | February 2009
Feature title: Are you ready for the aquafeed of the future
International Aquafeed is published five times a year by Perendale Publishers Ltd of the United Kingdom. All data is published in good faith, based on information received, and while every care is taken to prevent inaccuracies, the publishers accept no liability for any errors or omissions or for the consequences of action taken on the basis of information published. ©Copyright 2009 Perendale Publishers Ltd. All rights reserved. No part of this publication may be reproduced in any form or by any means without prior permission of the copyright owner. Printed by Perendale Publishers Ltd. ISSN: 1464-0058
Are you ready for the
alleviate increased cost of feed formulations for poultry and pigs. Various types of feed additives have been developed which enhance the digestibility and/or utilization efficiency of nutrients, including exogenous enzymes, compounds aiding in the digestive process by improving absorption, mobilization and transport of nutrients, stimulators of enzyme secretion, feeding stimulants reducing feed/nutrient waste, pre/probiotics and botanical extracts modulating the gut microflora. The feeding biology, digestive physiology and nutritional requirements of warmblooded land animals differ significantly from those of aquaculture organisms. Therefore, the direct application in aquaculture of nutritional concepts developed for livestock is not trivial. The present article illustrates potential advances in the cost efficiency of aquafeeds by the development of novel nutritional concepts specifically for aquaculture species.
of the future
by Peter Coutteau PhD
Co-authors: Ward Spruyt, Alexander Van Halteren, Sam Ceulemans & Wouter Meeus INVE Aquaculture, Hoogveld 91, 9200 Dendermonde, Belgium Email: firstname.lastname@example.org
Natural emulsifiers to enhance lipid digestion in shrimp
Shrimps do not tolerate high levels of dietary fat well. A number of studies show reduced growth at levels above 10 percent of dietary lipid. Nevertheless, shrimp have no or very limited capacity to biosynthesize a number of lipid molecules which are essential for normal growth, including cholesterol, highly unsaturated fatty acids and phospholipids. Cholesterol is a key constituent of cell membranes and precursor for steroid and
moulting hormones. It has been found to be most effective in different species of shrimp at dietary levels ranging from 0.20 to 0.5 percent. Cholesterol levels below 0.10 percent limit growth in Litopenaeus vannamei, even if the other nutrients are formulated to satisfy normal requirements (Duerr and Walsh, 1996). Fishmeal is the major cholesterol source in practical feed formulations for shrimp with some contributions also coming from fish oil, squid and shrimp meal. Shrimp cannot bioconvert highly unsaturated fatty acids (HUFA: 20:5n-3 or EPA; 22:6n-3 or DHA) which need to be provided at 0.8-1 percent in the diet via the marine ingredients, mainly fish oil and fishmeal. Phospholipids are a component of cell
Novel feed supplements can reduce the requirements for traditional ingredients in commercial feeds for Litopenaeus vannamei
Two feeds were formulated at the same cost using either exclusively commercial feed ingredients (‘traditional feed’) or a combination of standard ingredients with the feed supplements Aquasterol and Aquaflavour (‘novel feed’). To balance the cost of the novel feed, significant reductions were made in the formulation for traditional feed ingredients, which resulted in lower analytical levels for various nutrients compared to the ‘traditional’ formula. These are in available phosphorous (water soluble phosphorous), cholesterol, phospholipids and n-3 HUFA which were different by minus seven percent to minus 44 percent (Table 1). Due to some variations in practical ingredients, the ‘novel’ feed also showed lower specifications in crude protein and fat compared to the ‘traditional’ feed. Results showed that shrimp fed the ‘novel’ feed had significantly better growth (1.17g/week versus 1.07g/week) and showed no differences in terms of survival, food conversion and protein efficiency ratio compared to animals fed the traditional feed (Table 1). This seemed contrary to the lower nutritional specifications of the novel feed. Verification trials under pond conditions in Indonesia using similar formulations confirmed the above findings.These results clearly showed the potential for making shrimp formulations less dependent on traditional feed ingredients by enhancing the digestibility and availability of Culture system for Litopenaeus nutrients using vannamei at the INVE Technologies test center in Brackishwater Aquaculture novel feed Development Center, Indonesia supplements.
Table 1: Feed analysis and shrimp performance for two feeds of different nutritional specifications. Data from a 70-day feeding trial with L. vannamei using triplicate tanks of 1m3 stocked with 20 shrimp/tank.
Shrimp feed formula
Crude Protein (%) Crude Fat (%) Crude Ash (%) Moisture (%) Watersoluble Phosphorous (%) Cholesterol (GLC, %) Phospholipids (Iatro scan, %) EPA (mg/g DM) DHA (mg/g DM) n-3 HUFA sum (mg/g DM)
Nevertheless, a number of promising additive concepts have become available recently to improve the sustainability of feed for fish and shrimp, both in terms of farm economics and ecological responsibility.
quaculture is the world’s fastest-growing sector in food production. Since 1970 it has sustained an average growth rate of almost nine percent – compared with 2.8 percent for land-based animal production. Global feed production for farming fish and shrimp has followed this expansion, estimated between 20.2-22.7 million tonnes in 2006 and expected to reach 32 million tonnes by 2012 (FAO, 2006; Tacon and Metian, 2008). Despite its tremendous growth over the past decades, aquafeed production represented in 2006 only four percent of total global animal feed production (Gill, 2007). Furthermore, global aquafeed volume is fragmented over many species produced under different conditions and mostly in developing countries. This lack of critical mass complicates focused developments, particularly for tropical species of fish and shrimp.
26 | InternatIonal AquAFeed | January-February 09
35.8 8.7 9.1 9.59 0.48 0.18 0.93 4.8 5.7 11.9
34.8 8.2 9.4 9.64 0.32 0.1 0.85 5 4.8 11.1
For some of the bulk production species, knowledge on nutrient digestibility, nutrient interactions and stage-specific requirements is still rudimentary. In recent years, all major aquafeed ingredients - including fishmeal, fish oil, vegetable proteins and fats, wheat flour, feed phosphates, additives, vitamins and
minerals - have shown significant price increases, in some extreme cases amounting to several 100 percent. In the livestock industry, combined research efforts from producers, feed and additive suppliers and academic institutes have resulted in a vast knowledge basis and a wide range of additives to
Figure 1: Formulating ecologically and economically sustainable aquafeeds is supported by the development of innovative feed additives
Results growth trial 70 days L. vannamei
Survival ( percent) Initial weight (g) Final weight (g) Gram/week Feed Intake (%/ABW/day) FCR PER (weight gain/protein intake) 91.7 1.02 11.31 1.03 5.45 2.29 1.23 93.3 1.02 12.74 1.17 5.61 2.31 1.25 ns ns +13 %* +14 %* ns ns ns
ns= not significantly different; *= significantly different P<0.05
January-February 09 | InternatIonal AquAFeed | 27
% difference (novel vs traditional)
-3% -6% 4% 1% -34% -44% -9% 4% -16% -7%
The animal feed industry has faced tremendous increases of ingredient prices over the past years. This has accelerated a search for alternative formulations and feed additives to improve the cost efficiency of feed at the farm. Contrary to the livestock industry, developments in aquaculture are still hampered by the limited nutritional knowledge and the lack of critical mass in a relatively small-scale feed industry.
originally developed to improve growth and food conversion of shrimp fed diets deficient in cholesterol (Coutteau et al., 2002). However, current applications in white shrimp farms in Ecuador, Mexico, Thailand and Indonesia have shown a variety of beneficial effects from supplementing the emulsifying concept to commercial shrimp feeds including improved growth, survival, food conversion, hepatopancreas condition and molting. By improving the utilization efficiency of dietary lipids, shrimp formulations can be made more cost-effective by reducing the formulated values for phospholipids, cholesterol and n-3 HUFA. The compensation of lower dietary specifications for essential lipids by the application of the natural emulsifying concept was recently demonstrated in a nutritional trial in Indonesia with white shrimp (see insert). different conditions of age, crowding, disease status and environmental conditions is still very poor due to experimental difficulties to study feeding behaviour under production conditions in ponds. The most realistic way to measure feed attractiveness is probably by quantifying the rate at which the feed disappears from a feeding tray in a stocked shrimp pond. Although this technique is difficult to standardise and assumes good feed stability, it has proven to be valuable in comparing the effect of different attractants under field conditions (Ceulemans et al., 2003). Feeding attractants are key compounds in shrimp nutrition as they attract the shrimp to the feed and stimulate them to consume it (Lee & Meyers, 1997). Attractants compensate the lack of attractiveness of formulations (for example, due to the replacement of proteins of marine origin with vegetable protein) and stimulate the appetite of shrimp that show poor feeding responses (eg due to stressful environmental conditions or disease).
January-February 09 | InternatIonal AquAFeed | 29
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Caption: Set up for fish trials at INVE’s testing facilities at Caditec Testing (Spain) membranes, building blocks for lipoproteins (essential for lipid mobilization in the haemolymph) and constitute a highly available source of choline and inositol (Coutteau et al., 1997). tion of suboptimal dietary levels of cholesterol and phospholipids may be particularly detrimental to shrimp nutrition due to the interaction between phospholipids and cholesterol requirements (Gong et al., 2000). processes by reducing the size of the fat globules released from the diet and increasing the efficiency of the lipase activity. Furthermore, emulsifiers assist the bile acids in the formation of micelles, which are the transportation vehicles for absorption of lipids through the membranes of the digestive system. Emulsifying agents enhance the fat digestibility and growth performance in nursery and fattening of broilers and pigs (Smulders, 2008). Contrary to land animals, lipid digestion in shrimp occurs for a big proportion intracellular in the hepatopancreas epithelium from where it is transported to the target organs via the haemolymphe under the form of lipoproteins. The formation and absorption of lipid micelles from the lumen of the hepatopancreas tubuli is therefore a limiting step in the lipid digestive process. Specific blends of natural emulsifying agents, selected for their compatibility with the shrimp’s digestive system, are capable of complementing the process of emulsification and absorption of dietary fats in the hepatopancreas. This in turn improves the efficiency of shrimp to use fats as essential components and as source of energy for growth (Figure 2). The natural emulsifying concept was
Attractants and palatability enhancers to stimulate feeding in shrimp
Good feed management is a key factor in any animal production system. In shrimp farming, feed management is a true challenge as shrimp are grown ‘hidden from the eye of the farmer’ in large ponds and their appetite is fluctuating rapidly in function of temperature, salinity, quality of water and pond bottom, feed quality, life stage, health status and molting cycle. Since feed constitutes generally around 50 percent of total production cost in shrimp farming, the efficiency of feed and feeding management strongly influence profitability. It is crucial that shrimp locate and consume fast the feed distributed in the pond as this will reduce the loss of valuable water-soluble nutrients leaching from the feed (including essential vitamins and amino acids) and the accumulation of wasted feed which will in turn affect the quality of water and soil and subsequently oxygen consumption in the pond. All nutritional compounds wasted as leached nutrients in the water column or un-eaten feed on the pond bottom are deteriorating the culture environment and not converted into shrimp biomass. Feed attractiveness is therefore a key factor to maximize feed conversion and growth in shrimp farming, particularly under low and medium stocking densities. Current knowledge of the effects of formulation on feed uptake by shrimp under
Figure 2: Specific blends of natural emulsifying agents are complementing the process of emulsification and absorption of dietary fats in the hepatopancreas, which in turn improves the efficiency of shrimp to use fats as essential nutrients and as source of energy for growth
Although the optimal level may depend on the formulation and culture conditions, phospholipid requirements are estimated around one-to-two percent (equivalent to 1.5-3 percent liquid lecithin). The combina-
Emulsifying agents are a diverse class of compounds, which are able to disperse fat in water under the form of small droplets (as in milk). In land animals, emulsifiers are added to the feed to complement the lipid digestive
28 | InternatIonal AquAFeed | January-February 09
Optimised formulations of water-soluble nitrogenous compounds including amino acids, short-chain peptides and nucleotides – applied either as topdressing or included in the feed during processing - have shown to be effective in improving feed uptake in feeding trays (Ceulemans et al., 2003). Culture trials under controlled lab conditions have demonstrated that the addition of these formulated attractants to practical feed formulations improves feed intake, growth and food conversion (Figure 3). Furthermore, compared to protein concentrates based on fish hydrolysates, chicken hydrolysates or by-products from amino acid production, the supplementation of formulated attractants give superior results on growth and food conversion (Figure 4). Small inclusions of formulated attractants may have several additional nutritional benefits due to the stimulation of enzyme secretion and digestive processes (short-chain peptides), balancing amino acid nutrition (essential amino acids) and improved function of epithelia in gut and hepatopancreas (nucleotides). These additional benefits contribute to release more nutrients from feeds formulated to contain lower levels of digestible nutrients (see insert). tive system. Herbal digestive properties include appetite enhancement, stimulation of gastric and bile secretions, and hepato protection. Recent screening work under controlled lab conditions at INVE Technologies test facilities at Caditec Testing (Spain) has revealed the potential of several natural products for improving the feed utilisation in fish. The addition of a blend of digestive herbal extracts to practical feed formulations for Nile Tilapia (Oreochromis niloticus) significantly improved growth, food conversion and protein efficiency (Figure 5). The improved availability of dietary nutrients and energy for muscle growth was illustrated by the reduction of visceral wastes consisting of digestive system and fat deposits in the belly and liver of the fish, resulting in reduced hepatosomatic and viscerosomatic indexes. Reducing processing wastes and maximising filleting yield has important consequences for the profitability of the production of fillet fish such as Tilapia.
Phytase products, like any other enzymes, have inherent limitations on the Figure 4: Formulated attractants result in superior effects on growth and food activity range in terms of temperature, pH conversion compared to other protein and inactivation by proteolytic enzymes concentrates, possibly due to their in the digestive system. The digestive additional nutritional benefits (amino physiology is very different among the acid balance, nucleotides and peptides). different commercially important species Data from a 56-days feeding trial with Litopenaeus vannamei using triplicate of fish and shrimp, which are in turn tanks of 1m3 per diet; growing shrimp from different from warm-blooded poultry approx. 1.1 to 7.7g over eight weeks (control and pigs. Therefore, major progress on diet). All diets formulated to 37 percent CP/6 enzyme efficacy will result from the percent CF; containing 21.5 percent prime selection of the enzymes compatible Chilean fishmeal; test products included at two percent inclusion level: by-product from with the digestive physiology and feeding amino acid production (AA Byprod); protein biology of aquaculture organisms. hydrolysates based on poultry by-products The standard processing conditions (Chick Hydro) or fish (Fish Hydro); a during aquafeed production (temperaformulated attractant (Aquaflavour) ture, humidity, pressure) are inactivating (Ceulemans et al., in prep.) enzymes. Consequently, special equipment is required to apply enzymes in the tion of phytase in aquafeeds is still very aquafeed mill, such as pellet coating or limited due to uncertainties on its efficacy liquid spraying systems (Lorenz-Meyer, 2008). in formulations, processing and farming conProvided these bottlenecks are overditions typical for aquaculture. come, the wide diversity of enzymes presents an interesting potential to improve Figure 5: Effects of a blend of digestive the utilization of lowherbal extracts (Easy Digest) on growth, cost plant ingredients, food conversion, protein efficiency ratio, and liver/viscera weight in Nile Tilapia. Data which are often rich from a 70-day lab trial with Nile Tilapia in non-digestible using triplicate tanks of 100l per diet. carbohydrates, antiFish were grown at 26°C in a freshwater nutritional factors and recirculation unit from 40g to ± 90g while unavailable nutrients fed on a practical tilapia grow out diet with CP/CF of 33/7.6; SGR=growth rate (percent/ for fish and shrimp. day); FCR=feed conversion ratio (kg feed consumed/kg weight gain; PER= protein Note: Literature efficiency ratio (kg weight gain/kg protein references can be consumed; HSI=liver weight (percent body obtained from the author. weight) VSI=Viscera weight (percent body weight). Ceulemans et al. (in prep) Email: email@example.com
Screening shrimp feed attractants under field conditions: measuring feed attractiveness by quantifying the rate at which the feed disappears from a feeding tray in a stocked shrimp pond
Although many studies have demonstrated that phytase supplementation makes the chelated phytate-P available to fish (reviewed by Cao et al. 2007), the applica-
Phytobiotics to enhance digestive processes and feed efficiency
The increasing pressure on the use of feed antibiotic growth promoters in animal nutrition has boosted the research for alternative growth promoters based on natural substances. Phytobiotics is a term used to describe plant-derived natural bioactive compounds, which affect animal growth and health due to their antimicrobial, digestive or metabolic stimulating properties. Phytobiotics are successfully used as alternatives to antibiotics in weaning and ongrowing pigs (Marin-Gusman, 2005). Since the gut is the main entry port for bacte-
Figure 3: The addition of a formulated attractant (Aquaflavour) to practical shrimp feed formulations improves feed intake, growth and food conversion. Data from a 70-days feeding trial with Litopenaeus vannamei using triplicate tanks of 1m3 per diet; growing shrimp from approximately one-to-9g over 10 weeks (control diet). All diets formulated to 37 percent CP/6 percent CF; containing 21.5 percent prime Chilean fishmeal (Ceulemans et al., in prep.)
Enzymes – challenging but promising application in aquafeeds
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rial and viral infections in fish and shrimp, the capability of specific plant extracts to modulate the composition of the gut microflora offers interesting perspectives for protection against bacterial and viral infections in aquaculture organisms (Decamp et al., 2007). Spices are widely used to flavour our food but also exert stimulant actions on the diges30 | InternatIonal AquAFeed | January-February 09
Soaring prices and in some cases limited availability of feed phosphates has stimulated the use of phytases enzymes in animal feeds. Phytases are enzymes capable of releasing the phosphorus (P) present under the form of phytate in plant feed ingredients. The better use of plant P present in the formula is economically interesting and reduces the P output into the environment.
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