Developing a plant-based diet for Cobia Rachycentron canadum

January | February 2012

Feature title: Developing a plant-based diet for Cobia Rachycentron canadum



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FEATURE FEATURE



and overall energy can be determined for the ment sources, or as additives simply to

test ingredient. It is important to note how- enhance growth, health, and palatability.

ever, that the ability to digest plant proteins The biggest issues have arisen when

may be different at different developmental attempting complete fishmeal replacement

stages depending upon the species’ comple- as opposed to simply reducing the amount

ment of digestive enzymes and intestinal flora. of fishmeal utilized in favor of plant proteins.

In our examination of six plant proteins Many researchers and growers have encoun-

Developing a plant-based diet for Cobia (wheat gluten, barley meal, soy protein con- tered lower growth and survival rates when

centrate, corn gluten, soybean meal, and reducing the percentage of fishmeal inclusion



Rachycentron canadum Figure 1. Growth of juvenile cobia

wheat flour) with juvenile cobia (400-700g), in diets for marine fish below 10-20 percent,

only one plant source (barley meal) was depending on the species. There appears to

(30g initial weight) during 9 week deemed to have too low a digestibility to be be at least one essential component found in

by Aaron M Watson MSc, George Wm Kissil PhD, Frederic T. Barrows PhD, and Allen R. Place PhD growth trial. 120 fish per tank, 27°C,

considered a via-

The Institute of Marine and Environmental Technology, Baltimore, USA 25 ppt salinity. Average weight ± s.d.

ble replacement









A

candidate, with

quaculture reached a landmark simply to the cost and inconsistency in the in diets for Cobia, Rachycentron canadum, the rest of the

in 2009, supplying greater than quality and quantity of the product produced. and other high-value marine carnivores. Cobia plant proteins

half of the total fish and shellfish Replacing fishmeal and fish oil for freshwater are a highly carnivorous species (Franks et al. having digest-

for human consumption (Naylor species without loss in production is easier to 1996; Arendt et al. 2001) found tropically and ibility’s similar to

et al. 2009). With global fisheries in decline accomplish than it is with marine species. sub-tropically around the world except for the fishmeal sources R

and human population increasing, the gap This may be due in part to the fact that eastern Pacific, are highly fecund and can be (Table 2), indi-

between protein supply and protein demand many freshwater fish are extensively cultured spawned both naturally and through artificial cating that for

is widening. Aquaculture must continue to and enjoy a much deeper knowledge and induction in captivity, display rapid growth the most part,

The probiotic of choice for an optimal

expand to meet these growing needs, and it experience base than their marine counter- rates and high natural disease resistance, and digestibility itself

must do so in a safe, sustainable manner that parts, but it may also be a result of most are adaptable to a variety of culture and tank Figure 2. Growth of juvenile cobia is not a primary gut function in farm animals

(120g initial weight) during 8 week

decreases the world’s reliance on harvesting freshwater species in culture being herbivores, conditions (Holt et al. 2007). obstacle. The

growth trial. 60 fish per tank, 27°C, 25

fish for fishmeal while still producing a high omnivores, or scavengers in their natural This species is a prime target in the need ppt salinity. Average weight ± s.d. lack of known

quality product. There are several difficult systems. Most marine species that are sought to increase aquaculture production and serves essential amino

hurdles the aquaculture industry now faces for intensive culture on the other hand, are as an excellent model species due to its acids from plant

if this needed growth is to occur. carnivorous, which precludes different dietary rapid growth and limited competition from plant proteins, possible anti-nutritional factors protein sources

habits and requirements. a wild fishery. Several physiological issues are present, palatability, and lack of essential amino can easily be

These include, but are not limited to; the Our research has centered on replacing presented however, with the use of plant pro- acids all must be solved to successfully replace remedied by

continued heavy reliance upon capture and fishmeal with a blend of plant protein sources teins as opposed to other alternative protein fishmeal with plant proteins. Digestibility can their addition

reduction fisheries to supply fishmeal and fish to completely eliminate the need for fishmeal sources such as animal meals. Digestibility of be examined on a species-specific basis, one during the for-

oil as the major base components protein source at a time as we have done with mulation and

for aquatic feeds, build-up of con- Table 1: Composition of diets used for determination of individual ingredient digestibility. juvenile cobia utilizing an inert marker such as manufacture of

taminants from these wild caught Diet

chromium oxide (Table 1). the diet, a com-

ingredients in the final products, and This process involves feeding experimental mon practice

FM1 FM2 WG BM CG SPC SM WF

public perception that aquaculture diets containing a fishmeal base along with in the industry

in its current state is not sustain- each individual protein source, gently stripping already for lysine,

able and is a detriment to local Component (g kg-¹) feces and analyzing them for protein, lipid, and methionine, and

ecosystems (Naylor et al. 2009). Fish Meal 1 978 678 678 678 678 energy content in relation to the concentra- threonine, along

Tacon and Metian (2009) reported Fish Meal 2 978 678 678 tion of the inert marker, and comparing results with other com-

that 36.2 percent of total worldwide to those obtained from diets only containing ponents known

Wheat Gluten 300

catch in 2006 was destined for non- the fishmeal base (Lupatsch et al. 1997). to be lacking in Avda. La llana, 123 . 08191 Rubí (Barcelona) Spain. (+34) 93 212 63 82 . Fax: (+34) 93 588 57 31 . rubinum@rubinum.es . www.rubinum.es



Barley Meal 300

human consumption, meaning the Through this process, digestible protein, lipid, fishmeal replace-

reduction to fishmeal and fish oil for Corn Gluten 300

aquaculture diet formulation, the Soy Protein Concentrate 300









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34 InternatIonal AquAFeed January-February 2012

34 || InternatIonal AquAFeed || January-February 2012 January-February 2012 InternatIonal AquAFeed 35

January-February 2012 || InternatIonal AquAFeed || 35

FEATURE



fishmeal and other animal meals that is lacking EPP1 resulted in poor Table 3: Diet formulations and performance indices for plant based

in plant sources that is responsible for the feed conversion, diets

inability to formulate plant based diets with poor percent weight Diet

complete fishmeal replacement. gain, and poor spe- Ingredient (g kg-¹) EPP1a EPP2b

Taurine, an amino acid that is not incorpo- cific growth rate (4.66, Soy Protein Concentrate 364.3 269.3

rated into any proteins but plays critical roles 199%, 1.09 respec-

Corn Gluten 201.0 211.0

in lipid metabolism, oxidative stress responses, tively, Table 3). Top

muscle activity, and photoreceptor protection coating EPP1 pellets Wheat Flour - 226.5

(Schuller-Levis and Park 2003) is found in with attractants did Barley Meal 104.5 -

high concentrations in many tissue types in not improve accept- Soybean Meal, Solvent Extracted - 121.0

carnivorous fish and their prey (Satake et al. ance. Fish being fed

Wheat Gluten 82.3 -

1988), as well as fishmeal (Kim et al. 2005). the commercial feed

Taurine is not found in high concentra- had normal perform- Menhaden Oil 146.0 84.0

Di-calcium Phosphate 40.7 23.7

Vitamin Pre-mixc 10.0 10.0

Table 2: Apparent digestibility coefficients (ADC) of individual ingredients.

Lysine-HCL 21.5 15.5

Apparent Digestibility (%) Ingredient

Choline CL 6.0 6.0

FM1 FM2 WG BM CG SPC SM WF

Trace Mineral Pre-mixd 1.0 1.0

Magnesium Oxide 0.5 0.5

Crude Protein 91 84 83 53 92 85 76 89

Stay-C 3.0 3.0

Crude Lipid 97 91 52 16 37 25 29 32

DL-Methionine 3.4 5.8

Gross Energy 90 84 62 27 86 43 38 37

Threonine 2.1 2.1

DCPa (g kg-¹) 540 567 685 96 736 558 387 152 Potassium Chloride 5.6 5.6

DLb (g kg-¹) 155 85 24 5 19 5 6 6 Taurine - 15.0

DEc (MJ kg-¹) 18 15 13 5 19 9 7 6 Proximate Compositione Calculated Measured

aDigestible crude protein, bDigestible lipid, cDigestible energy Lipid, % dm 15.1 7.87 ± 1.07

Ash, % dm 4.5 4.98 ± 0.03 (5.15)

tions however, in many fishmeal replacement ance indices (FCR

Protein, % dm 47.4 49.50 (47.3)

sources, most notably plant protein sources 1.32% weight gain

such as wheat flour, soy protein concentrate, 900, and SGR 3.65) Carbohydrate, % dm by difference 32.67 35.14

and corn gluten. Due to its water solubility, that indicated that this Fiber, % dm (0.33) (2.51)

taurine is also often found in low concentra- batch was healthy and Moisture, % 5.3 7.14 (9.96)

tions even in fishmeal based diets and other grew at similar rates as

Energy Content, MJ Kg-1 20.7 19.30 ± 0.77

fishmeal replacement sources, as large quanti- other batches of cobia

Performance Indices EPP1i EPP2j

ties of taurine are often lost in the processing raised in our facility,

of these ingredients. and were larger upon FCRf 4.66 1.35

The re-addition of the stickwater by- completion of the trial Weight Gain (%) 199 379

product, which is high in taurine and other (ANCOVA, p <0.001, Hepatosomatic indexg nt 2.34 ± 0.001

free amino acids, back to the manufacturing with diet as covariate, Specific Growth Rateh 1.09 2.36

of diets has been shown to increase growth Figure 1) than fish fed

Survival 95% 98%

in Atlantic salmon (Kousoulaki et al. 2009). EPP1.

Several researchers have noted increased In the second trial

feeding and growth rates in marine fish fed with EPP2, a plant- aExperimental Plant Protein 1

diets supplemented with taurine, especially based trout diet bExperimental Plant Protein 2

when attempting to replace fishmeal either (Gaylord et al. 2007)

cContributed per kg diet; vitamin A, 9650 IU; vitamin D, 6.6 IU;

partially or completely (Martinez et al. 2004, was modified for use

vitamin E, 132 IU;

Matsunari et al. 2008, Lunger et al. 2007, with marine spe-

Gaylord et al. 2007). cies. The changes in menadione sodium bisulfite, 4.7 mg; thiamine mononitrate, 9.1

mg; riboflavin, 9.6 mg; pyridoxine hydrochloride, 13.7 mg;

Based on the digestibility of the individual formulation between

pantothenate, DL-calcium, 101.1 mg; cyanocobalamine, 0.03 mg;

ingredients examined, two experimental plant EPP1 and EPP2 include nictonic acid, 21.8 mg; biotin, 0.33 mg; folic acid, 2.5 mg

protein based diets (EPP1 and EPP2) were reducing the lipid con-

dContributed in mg kg-¹ of diet; zinc 37; manganese, 10; iodine,

formulated (Table 3) with equivalent protein tent from 15 percent to

5; copper, 1

(~45%) and energy (~20Mj Kg-1) digestibility eight percent, replac-

eValues in parentheses were determined by New Jersey Feed Labs,

to commercially available feeds. Grow-out ing barley meal with

Inc

trials were conducted at the Institute of wheat flour because

fFeed conversion ratio (g fed/g gained)

Marine and Environmental Technology (IMET) of the low digestibil-

in eight foot diameter, four cubic meter, ity of barley meal, and gLiver weight/body weight*100 ± standard deviation

recirculating systems sharing mechanical and replacing wheat gluten hSGR=specific growth rate= ((lnBW2-lnBW1)*(days of growth trial-

bio-filtration as well as life support systems. with solvent extracted 1))*100iInitial Weight 30g, final weight 62g, 27°C, 25ppt, 8 week

Both trials were conducted at 27°C and 25 soybean meal. Taurine growth trialjInitial Weight 120g, final weight 572g, 27°C, 25ppt, 8

ppt, with 120 fish per tank in the first trial and was absent in the for- week growth trial

60 fish per tank in the second. mulation of EPP1, and

The results of the first growth trial with due to taurine’s known



36 | InternatIonal AquAFeed | January-February 2012

FEATURE









WHO CARES...

physiological roles and that it has been shown most important difference in the formulations is possible with marine carnivores in intensive

to increase growth in a variety fish species of the diets in this study is the addition of aquaculture systems. Reducing the industry’s

(Gaylord et al. 2007; Kim et al. 2005a; Takagi taurine to EPP2. Taurine is not incorporated reliance upon the reduction fisheries to supply

et al. 2008), including cobia (Lunger et al. into any known proteins and therefore is only fishmeal and fish oil for diets will not only

2007), it was included in the formulation of considered semi-essential in most species but allow the needed expansion of aquaculture to

EPP2 at 1.5 percent. is considered essential for at least one strict supply the world’s growing protein demands,

Fish fed EPP2 performed better than carnivore, felines. but will also immensely benefit the recovery

fish fed EPP1, with better feed conversion, The findings from the digestibility portion and sustainability of the oceans forage and …if profits in the aquaculture industry are as appetising as a salmon dinner?

higher percent weight gain, and higher specific of our study demonstrate that several plant food fishes and the ecosystems that have

growth rates (1.35, 379 percent, 2.36 respec- protein sources are highly digestible and suita- decimated by decades of over fishing and As feed prices soar and formulation moves towards sustainability, aquaculture producers must maximise

tively for the EPP2; Table 3), even given the ble fishmeal replacements for cobia, which are poor fishing practices. ■

larger starting size of individuals in the second strict carnivores. The results of the grow out

feed efficiency to stay on the menu. In all phases of the fish’s life, proper nutrition will improve health.

trial. Fish fed the commercial diet during the trials present evidence that taurine needs to Acknowledgements With decades of dedicated research, the “Alltech Aqua Advantage” programme responds to the challenges

second trial had significantly lower growth be added to diets for carnivorous marine fish-

of today’s aquaculture producers through nutritional innovation.





CONFERENCE

The authors would like thank the staff of the

(FCR 1.85, percent weight gain 255, and SGR es, especially when attempting to completely Aquaculture Research Center at the Institute

1.93) and were smaller upon completion replace fishmeal with alternate sources that

of the trial compared to those from EPP2 may be naturally devoid of taurine. In addition,

of Marine and Environmental Technology; Steve

AquateTM, a unique, cost-effective solution, is designed to help improve growth and performance,

Rodgers, Chris Tollini, and Joy Harris as well

(ANCOVA, p=0.018, with diet as covariate, the growth rates observed with EPP2, an eight as Matteo Avella, Gordon Taylor, and Michele feed efficiency, flesh quality and immunity …naturally.

Figure 2). percent lipid diet, were equivalent to growth Thompson for assistance in the digestibility trials

During the first growth trial with diet EPP1 seen on the commercial diet, a 15 percent and analysis. Special thanks, to Ernest Williams

So when asked who cares about your profits? Remember

fish grew very poorly as evidenced by the lipid diet, indicating that cobia may be able to for laboratory assistance throughout the study

slow growth rate and high feed conversion. utilise lower lipid diets, helping to reduce the and Jason Frost, USDA/ARS for assistance in

manufacturing of the experimental diets.

This poor performance clearly suggests an overall cost of feed required to reach market

issue outside of protein digestibility since

several highly digestible protein sources are

size. Interestingly, regardless of lipid content

of the diet, fillets from fish fed either EPP2

This work was funded by award

#NA080AR4170821 from the NOAA National

Marine Aquaculture Initiative. Parts of this work DOES!nference!

the one-day co

egister now for

included in the blend. Although poor palat- or the commercial diet maintained equivalent

ability is another possibility, the addition of lipid levels within their fillets (~12-13 percent have also been featured on Earth Focus @ linkTV;

feeding stimulants to EPP1 did not alter feed-

ing behavior.

dry weight).

Upon completion of these pilot-scale trials,

http://www.linktv.org/video/6868/oceans-turning-

the-tide R

Growth on EPP2 resulted in much higher several more questions involving the use of

feeding rates and greatly increased perform- plant proteins and taurine have arisen that

ance characteristics such as fillet yield and are currently being examined in our lab with About the Authors

lower feed conversion ratios (Table 3). Fish juvenile cobia as well as other high-value

in the other tank of the paired system being species such as gilthead seabream and striped Aaron M. Watson MSc

fed the in-house, commercially available feed bass. The next hurdles are to determine what Allen R. Place Ph.Da

S SECTORS

had slightly and significantly lower FCR, SGR, the effects may be on the final fillet in terms Institute of Marine and

S & OILSEED

OUR, CEREAL

and percent weight gain from 120g to 355g of taste and texture when eliminating fishmeal Environmental Technology

during the trial. Growth and FCR observed in favor of plant proteins. Can the fish oil com- University of Maryland Center

CE FOR TH E RICE, FL

on EPP2 are equivalent to results found by

other researchers with various sizes of juvenile

ponent of the diet also be replaced without

detrimental effects to production character-

for Environmental Science

701 East Pratt St.

A CONFEREN

cobia, using diets based on fishmeal as well as istics or final fillet quality? Will raising farmed Baltimore, MD 21202. USA.

several fishmeal replacement trials (Lunger et fish on plant-based diets reduce contaminants

al. 2007; Salze et al. 2010). such as mercury and PCB’s that are known George Wm. Kissil Ph.D @ VICTAM ASIA, BANGKOK,THAILAND

Although there were several differences to accumulate in fish raised on traditional, Israel Oceanographic and





FEBRUARY 15, 2012

in the plant protein blends used for the two fishmeal based diets as well as found in wild- Limnological Research National

experimental diets in the current study (barley caught fish brought to market? Is taurine an Center for Mariculture, Eilat, Israel.

meal and wheat gluten in EPP1 replaced by essential amino acid for marine carnivores?

wheat flour and soybean meal in EPP2) other Although our research is now focused Frederic T. Barrows Ph.D

Bangkok International Trade

differences in the two formulations include

the addition of taurine and reduced lipid

primarily on taurine and its biosynthesis path-

way in an effort to establish taurine as an

U.S. Department of Agriculture

Agricultural Research Service,

& Exhibition Centre (BITEC)

content of EPP2. Due to the roles that taurine essential amino acid for marine carnivores, Hagerman Fish Culture Experiment

has been shown to play, such as a possible encouraging results to all of these questions Station Hagerman, ID 83332, USA.

feed attractant (Brotons Martinez et al. 2004) have been obtained in our work so far. This

and its involvement in bile salt conjugation work, and that of many others in the field is

(Kim et al. 2007), it is our opinion that the indicating that complete fishmeal replacement









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38 | InternatIonal AquAFeed | January-February 2012

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