Supplementary Information for

Feed conversion efficiency in aquaculture: Do we measure it correctly?

Jillian P. Fry1,2,3*, Nicholas A. Mailloux1, David C. Love1,2, Michael C. Milli1, Ling Cao4,5

1 Johns Hopkins Center for a Livable Future, Johns Hopkins University, 615 N. Wolfe Street, Baltimore, Maryland, USA2 Department of Environmental Health and Engineering, Bloomberg School of Public Health, Johns Hopkins University, 615 N. Wolfe Street, Baltimore, Maryland, USA 3 Department of Health, Behavior and Society, Bloomberg School of Public Health, Johns Hopkins University, 624 N. Broadway, Baltimore, Maryland, USA4 Center on Food Security and the Environment, Stanford University, 616 Serra St, Stanford, California, USA5 Institute of Oceanography, Shanghai Jiao Tong University, Shanghai, China

* Correspondence to: Jillian P. Fry, PhD, MPH, 615 N. Wolfe Street, W7010, Baltimore, MD 21205, JFry3@jhu.edu, 410-502-5069

Contents:1. Species selection criteria2. Data extraction for aquatic and terrestrial animal inputs and outputs3. Protein and calorie retention calculations4. Supplementary tables S1-S5

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1. Species selection criteriaWe extracted global aquaculture production data for 2009 through 2013 using United Nations Food and Agriculture Organization (FAO) FishStatJ data software [1]. We identified the top five aquaculture species groups produced globally, which were carps, tilapias, shrimps, catfishes, and salmonids. Four of the five species groups (catfish, salmonids, shrimp, tilapia) contain fish or crustacean species that are among the most commonly consumed seafood in the U.S. [2], and carp is the most widely farmed fish species group in the world [1]. The total production of these five species groups averaged 37.8 million metric tons (MMT), accounting for 60 percent of global aquaculture production per year from 2009 through 2013 (including fed and unfed aquaculture, excluding cultivation of aquatic plants) (Table S2). Within each species group, we selected the two top-produced species per group for analyses (Table S3), excluding species that were largely non-fed (e.g., filter feeders such as silver carp, bighead carp, etc.). Species group information was used for tilapias because species-specific information was not available. Nile tilapia comprise over 71 percent of global tilapia aquaculture production, and most other tilapias are classified by FAO as “nei,” or “not elsewhere included.” The final list of aquatic species included in the study was: common carp, grass carp, channel catfish, pangas catfish, Atlantic salmon, rainbow trout, giant tiger prawn, whiteleg shrimp, and tilapia. The top three terrestrial animal species produced for meat in the U.S. and globally are cattle, chicken, and pigs [3, 4]; these species were included in our analysis for comparison.

2. Data extraction for aquatic and terrestrial animal inputs and outputsWe collected information for each species including feed conversion ratio (FCR), edible portion, feed composition, and nutrition content of edible flesh. When species-specific information was unavailable for aquatic animals, we collected data at the species group level. Below we describe each data element used in the retention equations.

Feed conversion ratioAquatic animal FCRs used in our analyses are values reported for species groups and/or species in Tacon and Metian’s 2008 paper, Global overview on the use of fish meal and fish oil in industrially compounded aquafeeds: Trends and future propects [5]. Livestock FCRs are from Table 4.1 (pg. 140) of Vaclav Smil’s 2013 book: Should We Eat Meat? Evolution and Consequences of Modern Carnivory [6] (the values are based on U.S. Department of Agriculture (USDA) data), and additional sources for each type of livestock: a 2013 report on beef cattle feed efficiency [7], a pig industry report on feed efficiency from 2015 [8], and a 2014 paper in Poultry Science [9].

Edible portionWe collected edible portion values from a variety of sources for each species, including the FAO and other government reports, peer-reviewed literature, industry data, and individual aquaculture experts (Table S4). For seafood, edible portions are reported in different ways, including drawn (gutted, with or without a head), dressed (fins and tail removed, head-on or head-off), and fillets or steaks (edible flesh with or without skin). For our analyses, we excluded values that included heads because fish heads are not typically eaten in the U.S., and including heads would be inconsistent with nutrition values for edible flesh. Some of the values include inedible parts of fish (e.g., skin, tail), which may slightly overestimate yield. Edible portion values for terrestrial animals were extracted from FAO reports and other sources (Table S4).

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Feed compositionFor each of the animal species (aquatic and terrestrial), we collected information on commercial feed nutrient composition including energy/calories, protein, lipid/oil/fat, carbohydrate, ash, and/or moisture (Table S5). When limited or no feed nutrient composition information was available for aquatic species, we used nutritional requirements of the fish species or species group. Some commercial feeds are only recommended for use with a single species while others are sufficient for the nutritional needs of several farmed aquatic animal species; feed nutrient composition data were only used for a given species if that species or its species group was listed as a recommended species for the feed. Nutritional requirements were used for grass carp, channel catfish, rainbow trout, giant tiger prawn, and tilapia. Nutritional requirements were combined with actual feed composition information for all of these species except grass carp, where it was the only available feed information. We also communicated with aquaculture experts to fill gaps in the dataset.

The information we collected on protein levels in feed is consistent with protein requirements reported elsewhere. Typical protein requirements for food producing animals (including multiple life-stages) are: beef cattle (5-18%), pigs (13-26%), chickens (18-23%), and farmed fish (26-55%) [10, 11].

The amount of metabolizable energy, or calories (kcal), in feed was generally not reported for aquatic animal species. We estimated caloric content using protein, fat, and carbohydrate content (Equation S1). Approximate calorie values per g of macronutrient are as follows: 4 kcal per g of protein, 9 kcal per g of fat, and 4 kcal per g of carbohydrate [12]. There is some variation in calories per g of macronutrient based on food type, but feed ingredients were not available for most species so we used these approximate values. If carbohydrate content was not reported, we filled in the missing value by subtracting from 100 the percent of protein, fat, moisture, and ash. In cases where carbohydrate content was not reported and moisture and/or ash content was unknown, we used relevant literature, expert opinion, and/or other feed formulations for the same species to estimate those values in order to determine carbohydrate levels in feed.

Equation S1. Energy content in feed

kcal100 g feed

=( g protein100 g feed

× 4 kcalg protein )+( g fat

100 g feed× 9kcal

g fat )+( g carb .100 g feed

× 4 kcalg carb . )

NutritionFor most species, nutrition data was compiled from Release 28 of the USDA Nutrient Database for Standard Reference (NDSR) [13]; this resource did not have information on pangas catfish. We found a nutrition label for pangas catfish on a seafood organization website [14]. We used information from an expert in China (personal communication, Shauhua Zahn, Nanyang Technological University) for species-specific information on carps and a publication from Mississippi State University for channel catfish [15]. All values represent the nutritional

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components of the raw, edible portions of the animal (Table 1). Values for protein and calorie content are reported as g and kcal per 100 g of edible meat, respectively.

Where available, information for aquatic animals was reported to the species level; otherwise, information was collected at the species group level. Some seafood nutrition content was reported for farmed species; otherwise, nutrition data was listed without distinction between wild and farmed.

3. Protein and calorie retention calculationsMany analytical approaches and terms exist for assessing animal production, efficiency, yield, and resource use (See Table S1 for terms used in aquaculture). We developed protein and calorie retention equations to calculate the proportion of protein and calories (kcal) that are fed to an animal that ultimately enter the human food supply. The equation is based on weight of animals produced per unit of feed used (FCR), the portion of the whole animal that is edible, the protein/calorie content of feed, and the protein/calorie content of the edible part of the animal. Equations S2 and S3 are the precursors to Equations 1 and 2 in the manuscript.

Equation S2. Protein retention

protein for human consumptionprotein∈feed

=

g edible fleshg wholeanimal

× g protein100 g edible flesh

g feedg whole animal

× g protein100 g feed

Equation S3. Calorie retention

kcal for human consumptionkcal∈feed

=

g edible fleshgwholeanimal

× kcal100 g edible flesh

g feedg whole animal

× kcal100 g feed

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4. Supplementary tables

Table S1. Analytical approaches for assessing aquaculture production, efficiency, yield, and resource use

Name Numerator (units) Denominator (units) Utility of measure Citation exampleCalorie conversion efficiency

FCR * calorie content in feed (%)

culture species calorie content (%)

- -

Dry matter ratio (DMR)

FCR * percent dry matter in feed

percent dry matter in culture species

"The dry matter ratio (DMR) is an indicator of the efficiency with which nutrients in feed are converted to animal biomass"

Boyd et al. (2007)[16]

Feed conversion ratio

total feed used in production (kg/tonnes)

net production of cultured species (kg/tonnes)

“The lower the FCR, the lower the production cost, the greater the efficiency of feed use and the smaller the waste load” (Boyd et al. 2015)

“Excellent measure of feed use and economic efficiency” (Boyd 2005)

Boyd (2005)[17]; Boyd et al. (2015)[18]

Fish in / fish out ratio

wild fisheries inputs (kg/tonnes)

farmed fish outputs (kg/tonnes)

- Naylor et al. (2009)[19]

Fish in / fish out ratio

[fishmeal or oil in diet (g/kg)]/ [fishmeal or oil reduction efficiency from foraged fish (g/kg)] * FCR

- Two conversion ratios: 1. "conversion ratio of forage fish into fish meal and fish oil", "condensation efficiency is a more appropriate term"; 2. FCR

Ytrestøyl et al. (2014)[20]

Forage fish dependency ratio

percent fishmeal/oil in feed from forage fisheries * FCR

meal yield "quantity of forage fish required to produce the amount of fishmeal and oil used to produce a unit of farmed fish"

Ytrestøyl et al. (2014)[20]

Marine protein dependency ratio

weight of marine-derived protein in feed (kg/tonnes)

fish protein weight gain (kg/tonnes)

“Reflect resources used by aquaculture because feed manufacturers use proteins and lipids, not whole fish”

“Allow for comparison of MNDRs (marine nutrient dependency ratios) between farmed species, despite differences in the body composition of these species”

Crampton et al. (2010)[21]

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Marine oil dependency ratio

weight of marine-derived oil in feed (kg/tonnes)

fish oil weight gain (kg/tonnes)

“Reflect resources used by aquaculture because feed manufacturers use proteins and lipids, not whole fish”

“Allow for comparison of MNDRs [marine nutrient dependency ratios] between farmed species, despite differences in the body composition of these species”

Crampton et al. (2010)[21]

Nutrient retention Amount of nutrient or energy incorporated in animal (whole body or edible part)

Amount of nutrient or energy used in feed

“[Nutrient-to-nutrient ratios] are ameasure of the proportion of the dietary nutrients and energy that is retained in the animal product.”

Ytrestøyl et al. (2014)[20]

Protein conversion efficiency

FCR * crude protein content in feed (%)

culture species crude protein content (%)

"Protein efficiency is an estimate of the ratio of feed protein applied to protein contained in the net harvest biomass of the culture species"

Boyd (2005)[17]

Protein conversion ratio

[FCR * feed crude protein content (%)]/100

- "The protein conversion ratio (PCR) is the ratio of feed protein to net harvest biomass"

Boyd (2005)[17]

Protein efficiency ratio

body weight or biomass produced (kg/tonnes)

protein fed (kg/tonnes)

Describes protein utilization as a measure of weight increase per amount of protein fed

Ytrestøyl et al. (2014)[20]

Protein production value

fish crude protein weight gain * 100

crude protein weight in feed

- Pucher et al. (2014) [22]

Waste production ratio

[[DMR - 1] * percent dry matter in culture species]/100

- "The waste production ratio (WPR) is the ratio of waste to live weight production of the culture species"

Boyd et al. (2007)[16]

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Table S2. Global aquaculture production (in million metric tons) for selected species groups

Species group Average 2009 2010 2011 2012 2013Carps a 23.4 21.6 22.5 23.1 24.3 25.7Tilapias b 4.0 3.1 3.5 3.9 4.5 4.8Shrimps c 4.1 3.5 3.8 4.2 4.4 4.5Catfishes d 3.5 2.8 3.2 3.4 3.9 4.3Salmonids e 2.8 2.4 2.4 2.7 3.2 3.1Subtotal 37.8 33.5 35.3 37.3 40.3 42.4Total global production f 62.7 55.7 59.0 62.0 66.6 70.2

Data source: FAO FishStatJ; FAO World Fisheries and Aquaculture 2014 [1, 23]

a Grass carp, silver carp, common carp, bighead carp, catla, crucian carp, etc.b Nile tilapia, tilapias nei, blue-Nile tilapia hybrid, Mozambique tilapia, blue tilapia, etc.c Whiteleg shrimp, giant tiger prawn, Penaeus shrimps nei, Kuruma prawn, fleshy prawn, etc.d Pangas catfish nei, torpedo-shaped catfish nei, channel catfish, Amur catfish, yellow catfish, etc.e Atlantic salmon, rainbow trout, coho salmon, trout nei, etc.f Includes fed and unfed aquatic animal production, excludes aquatic plants.

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Table S3. Production (in million metric tons) and top countries for selected aquaculture species

Species Group Species

Average MMT (2009-2013)

Top producing countries

Carps Common carp 3.8 China, Indonesia, Myanmar, Viet NamGrass carp 4.7 China

Catfish Channel catfish 0.4 China, United StatesPangas catfish 1.4 Viet Nam, Indonesia

Salmonid Atlantic salmon 1.8 Norway, Chile, United Kingdom, CanadaRainbow trout 0.8 Chile, Iran, Turkey, Norway

Shrimp Giant tiger prawn 0.8 Viet Nam, Indonesia, IndiaWhiteleg shrimp 3.0 China, Thailand, Ecuador

Tilapia Nile tilapia 2.9 China, Egypt, Indonesia, ThailandTilapias nei a 0.7 Brazil, Viet Nam, Bangladesh, Philippines

Data source: FAO FishStatJ; FAO World Fisheries and Aquaculture 2014 [1, 23]

a nei: not elsewhere included

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Table S4. Edible portion data and sources

Species Edible Portion No. of values used Source

Carps Common carp 0.36-0.54 2 FAO (1989)[24] Grass carp 0.36-0.54 2 FAO (1989)[24]

Catfish Channel catfish 0.35-0.63 7 Gregory Whitis (personal comm.); Silva and Dean (2001)[25] Pangas catfishes 0.35-0.63 7 Lynch (2007)[26]; Gregory Whitis (personal comm.)

Salmonids Atlantic salmon 0.58-0.88 13 Crapo et al. (1993)[27]; FAO (2001)[28]; Lynch (2007)[26]; Seafish [29] Rainbow trout 0.40-0.82 15 Crapo et al. (1993)[27]; Ron Hardy (personal comm.); Lynch (2007)[26]; Seafish [29]

Shrimp Giant tiger prawn 0.40 1 FAO (2001)[28] Whiteleg shrimp 0.62-0.65 2 Monterey Bay Aquarium Seafood Watch Report [30]

Tilapias0.37-0.45 4 FAO (1989)[24]; Lynch (2007)[26]; Seafish [29]

Cattle 0.52-0.64 4 MSU Extension (adapted from Principles of Meat Science, 4th Ed.)(2011)[31]; FAO (n.d.)[32]

Chicken 0.70-0.78 4MSU Extension (adapted from Principles of Meat Science, 4th Ed.)(2011)[31]; FAO (n.d.)[32]

Pigs 0.68-0.76 4MSU Extension (adapted from Principles of Meat Science, 4th Ed.)(2011)[31]; FAO (n.d.)[32]

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Table S5. Feed nutrient composition data and sources Feed Content (g per 100 g of feed) Data Sources

Species Protein (g) Fat (g) Carbohydrate (g) Calories (kcal) No. of feed profiles used

Carps Common carp a 17-45 2.2-15 22-59.8 175.8-554.2 12 Aller Aqua (Poland)*

Haltap Kft. (Hungary)*

Coppens International (Holland)*

FAO Feed information

Grass carp b 25 4-5.5 47.5-49 326-345.5 2 FAO Feed information

Catfish Channel catfish c 28-32 5-6 47-52 345-390 7 USDA Southern Regional Aqu. Center (2013)

[33]Greg Whitis (personal comm.)Robinson and Li (2005)[15]Chapman (2015)[34]

Pangas catfish d 26-32 5-6 47.5-51.5 339-388 3 Greg Whitis (personal comm.) (USA) Nhut (person comm.) (Vietnam)

Salmonids Atlantic salmon e 35.5-44 20-32.5 12.5-21.5 372-554.5 3 EWOS (multiple countries)*

Ytrestoyl, Aas, and Asgard (2015)[35]Ye, Anderson, and Lall (2016)[36]

Rainbow trout 40-47 21-24 8.5-12.5 383-454 3 Bio-Oregon (USA)*

FAO Feed informationRon Hardy, personal communication

Shrimps Giant tiger prawn e 25-45 5-9 20-43 225-433 8 Cargill*

Zeigler*

Presidents Feeds (Taiwan)*

FAO Feed information

Whiteleg shrimp e 25-45 9 24-39 277-417 4 Cargill*

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Zeigler (multiple feeds)*

Tilapias 20-32 4-8 25-51.1 216-404.4 18 Charoen Pokphand (Thailand)*

San Miguel Foods, Inc. (Philippines)*

Santeh Feeds Corp. (Philippines)*

Vitarich Corp. (Philippines)*

Aquanutro (S. Africa)*

Cargill Viet Nam (Vietnam)*

FAO Feed information

Cattle 7-15.4 - - 188-339 - Protein: USDA NRCS [37] Calories: Galyean et al. (2016) review article [38]; feed profiles included in this study were published in 2005 or later.

Chicken 18-23 - - 320 - Protein: National Research Council (1994) [39] Table 2-6 Calories: National Research Council (1994) Table 2-6; FAO document

Pigs 13.2-20.9 - - 326.5-335.1 - Protein: National Research Council (1998) [40] Table 10-1 Calories: National Research Council (1998) Tables 10-1, 10-3; US Pork Center

a Common carp: Assumes 10% moisture content based on:http://www.hkaffs.org/en/images/GAP1.pdfhttp://mafes.msstate.edu/publications/bulletins/b1200.pdfand 11% ash content based on:https://www.researchgate.net/publication/269455708_FEEDING_AND_GROWTH_EFFICIENCY_OF_COMMON_CARP_CYPRINUS_CARPIO_L_FRY_FED_FISH_BIOSILAGE_AS_A_PARTIAL_ALTERNATIVE_FOR_FISH_MEALb Grass carp: Assumes 10% moisture based on: http://www.hkaffs.org/en/images/GAP1.pdfhttp://mafes.msstate.edu/publications/bulletins/b1200.pdfc Channel catfish: Assumes 10% moisture content based on:http://www.hkaffs.org/en/images/GAP1.pdfhttp://mafes.msstate.edu/publications/bulletins/b1200.pdf

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and 5% ash based on personal communication with Greg Whitisd Pangas catfish: Assumes 5% ash and 10% moisture based on Channel catfish feed and http://www.hkaffs.org/en/images/GAP1.pdfhttp://mafes.msstate.edu/publications/bulletins/b1200.pdfe Atlantic salmon, Giant tiger prawn, and Whiteleg shrimp: Some moisture and/or ash values were filled in based on other feed profiles for that species.

* Information source is a commercial feed company.

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References

[1] FishStatJhttp://www.fao.org/fishery/statistics/software/fishstatj/en (2016).[2] NOAA Fisheries. The Surprising Sources of Your Favorite

Seafoodshttp://www.nmfs.noaa.gov/aquaculture/archive/09_13_12_top_seafood_consumed.html (accessed 27 July 2016).

[3] U.S. Department of Agriculture Economic Research Service. Livestock & Meat Domestic Datahttps://www.ers.usda.gov/data-products/livestock-meat-domestic-data/livestock-meat-domestic-data/#All meat statistics (2016, accessed 25 January 2017).

[4] Alexandratos N, Bruinsma J. World agriculture towards 2030/2050: The 2012 revision. 12–3, Romewww.fao.org/economic/esa (2012, accessed 29 June 2016).

[5] Tacon AGJ, Metian M. Global overview on the use of fish meal and fish oil in industrially compounded aquafeeds: Trends and future prospects. Aquaculture 2008; 285: 146–158.

[6] Smil V. Should We Eat Meat? : Evolution and Consequences of Modern Carnivory. West Sussex, UK: Wiley-Blackwell, 2013.

[7] Shike DW. Beef Cattle Feed Efficiencyhttp://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1027&context=driftlessconference (2013, accessed 2 November 2017).

[8] Rabobank Food & Agribusiness Research. Pigs Might Fly: Peak Pork Production Potentialhttps://research.rabobank.com/far/en/sectors/farm-inputs/Pigs_Might_Fly.html (2015, accessed 2 November 2017).

[9] Zuidhof MJ, Schneider BL, Carney VL, et al. Growth, efficiency, and yield of commercial broilers from 1957, 1978, and 2005. Poult Sci 2014; 93: 2970–2982.

[10] Natural Resources Conservation Service (NRCS). Nutrient Management Documents and Technical Referenceswww.nrcs.usda.gov/wps/portal/nrcs/detail/national/plantsanimals/mnm/pub/?cid=nrcs143_022384 (2003, accessed 24 January 2017).

[11] Council NR. Nutrient Requirements of Fish and Shrimp. Washington, D.C.: National Academies Press. Epub ahead of print 25 May 2011. DOI: 10.17226/13039.

[12] UN FAO. Calculation of the Energy Content of Foods. In: Food energy- methods of analysis and conversion factors. Romehttp://www.fao.org/docrep/006/y5022e/y5022e00.htm#Contents (2002).

[13] USDA National Agricultural Library. National Nutrient Database for Standard Reference, Release 28https://ndb.nal.usda.gov (2016).

[14] Seafood Health Facts- Pangasiushttp://www.seafoodhealthfacts.org/description-top-commercial-seafood-items/pangasius.

[15] Robinson E, Li M. A Summary of Catfish Nutrition Researchhttp://www.ag.auburn.edu/~davisda/practical_information/bulletin1144_catfishnutrition.pdf (2005, accessed 28 July 2016).

[16] Boyd CE, Tucker C, Mcnevin A, et al. Indicators of Resource Use Efficiency and Environmental Performance in Fish and Crustacean Aquaculture. Rev Fish Sci 2007; 15: 327–360.

[17] Boyd CE. Feed Efficiency Indicators for Responsible Aquaculturehttp://pdf.gaalliance.org/pdf/GAA-Boyd-Dec05.pdf (2005, accessed 26 January 2017).

[18] Boyd CE, McNevin AA, Clay JW. Resource Use Efficiency in Aquaculture: Examining the Known and Unknown. World Aquac Sochttps://www.was.org/articles/Resource-use-

13

efficiency-in-aquaculture.aspx#.WIpXdZJagfI (2015, accessed 26 January 2017).[19] Naylor RL, Hardy RW, Bureau DP, et al. Feeding aquaculture in an era of finite resources.

Proc Natl Acad Sci U S A 2009; 106: 15103–10.[20] Ytrestøyl T, Aas TS, Åsgård TE. Resource utilisation of Norwegian salmon farming in

2012http://hdl.handle.net/11250/283692 (2014, accessed 29 June 2016).[21] Crampton VO, Nanton DA, Ruohonen K, et al. Demonstration of salmon farming as a net

producer of fish protein and oil. Aquac Nutr 2010; 16: 437–446.[22] Pucher J, Mayrhofer R, El-Matbouli M, et al. Pond management strategies for small-scale

aquaculture in northern Vietnam: fish production and economic performance. Aquac Int 2015; 23: 297–314.

[23] UNFAO. State of World Fisheries and Aquaculture. Romehttp://www.fao.org/3/a-i3720e/index.html (2014, accessed 1 August 2014).

[24] UN FAO. Yield and nutritional value of the commercially more important fish species. Rome: Food and Agriculture Organization of the United Nationshttp://www.fao.org/docrep/003/t0219e/T0219E00.HTM (1989, accessed 26 January 2017).

[25] Silva JL, Dean S. Processed Catfish Product Forms, Packaging, Yields and Product Mixhttps://articles.extension.org/sites/default/files/w/e/e9/Processd_Catfish_Product_forms,_packaging,_yeilds,_and_produ.pdf (2001, accessed 26 January 2017).

[26] Lynch FT. The book of yields : accuracy in food costing and purchasing. Wiley, 2007.[27] Crapo C, Paust B, Babbitt J. Recoveries and Yields from Pacific Fish and Shellfish. Sea

Grant, 1993. Epub ahead of print 1993. DOI: 10.4027/rypfs.2004.[28] UN FAO. Measures, stowage rates and yields of fishery products.

Romehttp://www.fao.org/wairdocs/tan/x5898e/x5898e00.htm (2001, accessed 26 January 2017).

[29] Seafish. The Seafood Guidehttp://seafoodacademy.org/Documents/Seafood Guide.pdf (accessed 26 January 2017).

[30] Treece G. Whiteleg Shrimphttps://www.seafoodwatch.org/-/m/sfw/pdf/reports/s/mba_seafoodwatch_usfarmedshrimpreport.pdf (2014, accessed 11 May 2017).

[31] Michigan State University Extension. Carcass Dressing Percentage and Cooler Shrinkhttp://msue.anr.msu.edu/news/carcass_dressing_percentage_and_cooler_shrink (2011, accessed 26 January 2017).

[32] UN FAO. Technical Conversion Factors For Agricultural Commoditieshttp://www.fao.org/economic/the-statistics-division-ess/methodology/methodology-systems/technical-conversion-factors-for-agricultural-commodities/en/ (accessed 26 January 2017).

[33] Li MH, Robinson EH. Feed Ingredients and Feeds for Channel Catfishhttp://fisheries.tamu.edu/files/2013/09/SRAC-Publication-No.-1806-Feed-Ingredients-and-Feeds-for-Channel-Catfish.pdf (2013, accessed 11 May 2017).

[34] Chapman F. Farm-raised Channel Catfish. University of Floridahttp://edis.ifas.ufl.edu/fa010 (2015, accessed 30 June 2017).

[35] Ytrestøyl T, Aas TS, Åsgård T. Utilisation of feed resources in production of Atlantic salmon (Salmo salar) in Norway. Aquaculture 2015; 448: 365–374.

14

[36] Ye CL, Anderson DM, Lall SP. The effects of camelina oil and solvent extracted camelina meal on the growth, carcass composition and hindgut histology of Atlantic salmon (Salmo salar) parr in freshwater. Aquaculture 2016; 450: 397–404.

[37] Feed and Animal Management for Beef Cattlehttps://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1044378.pdf (2003, accessed 30 June 2017).

[38] Galyean ML, Cole NA, Tedeschi LO, et al. BOARD-INVITED REVIEW: Efficiency of converting digestible energy to metabolizable energy and reevaluation of the California Net Energy System maintenance requirements and equations for predicting dietary net energy values for beef cattle. J Anim Sci 2016; 94: 1329.

[39] Council NR. Nutrient Requirements of Poultry. Washington, D.C.: National Academies Press. Epub ahead of print 1 January 1994. DOI: 10.17226/2114.

[40] Council NR. Nutrient Requirements of Swine. Washington, D.C.: National Academies Press. Epub ahead of print 3 April 1998. DOI: 10.17226/6016.

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