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This article was downloaded by: [Cornell University] On: 28 November 2012, At: 08:56 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK The Progressive Fish-Culturist Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/uzpf20 A Method for Measuring Digestibility and Metabolizable Energy of Fish Feeds R. R. Smith a a Bureau of Sport Fisheries and Wildlife, Western Fish Nutrition Laboratory Hagerman Field Station, Hagerman, Idaho, 83332, USA Version of record first published: 09 Jan 2011. To cite this article: R. R. Smith (1971): A Method for Measuring Digestibility and Metabolizable Energy of Fish Feeds, The Progressive Fish-Culturist, 33:3, 132-134 To link to this article: http://dx.doi.org/10.1577/1548-8640(1971)33[132:AMFMDA]2.0.CO;2 PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.

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Page 1: A Method for Measuring Digestibility and Metabolizable Energy of Fish Feeds

This article was downloaded by [Cornell University]On 28 November 2012 At 0856Publisher Taylor amp FrancisInforma Ltd Registered in England and Wales Registered Number 1072954 Registered office MortimerHouse 37-41 Mortimer Street London W1T 3JH UK

The Progressive Fish-CulturistPublication details including instructions for authors and subscription informationhttpwwwtandfonlinecomloiuzpf20

A Method for Measuring Digestibility andMetabolizable Energy of Fish FeedsR R Smith aa Bureau of Sport Fisheries and Wildlife Western Fish Nutrition Laboratory HagermanField Station Hagerman Idaho 83332 USAVersion of record first published 09 Jan 2011

To cite this article R R Smith (1971) A Method for Measuring Digestibility and Metabolizable Energy of Fish FeedsThe Progressive Fish-Culturist 333 132-134

To link to this article httpdxdoiorg1015771548-8640(1971)33[132AMFMDA]20CO2

PLEASE SCROLL DOWN FOR ARTICLE

Full terms and conditions of use httpwwwtandfonlinecompageterms-and-conditions

This article may be used for research teaching and private study purposes Any substantial or systematicreproduction redistribution reselling loan sub-licensing systematic supply or distribution in any form toanyone is expressly forbidden

The publisher does not give any warranty express or implied or make any representation that the contentswill be complete or accurate or up to date The accuracy of any instructions formulae and drug dosesshould be independently verified with primary sources The publisher shall not be liable for any lossactions claims proceedings demand or costs or damages whatsoever or howsoever caused arisingdirectly or indirectly in connection with or arising out of the use of this material

A METHOD FOR MEASURING DIGESTIBILITY

AND METABOLIZABLE ENERGY OF FISH FEEDS

R R Bureau of Sport Fsheries and Wildlife

Western Fish Nutrition Laboratory tIagerman Field Station Hagerman Idaho 8333œ

A DIET TESTING AND EVALUATION PROGRAM is

essential to the economical production of fish Composition of diets must be changed occasion- ally due to cost and availability of ingredients A long term feeding trial is the most dependa- ble method of measuring the value of a feed but is often too slow and expensive Chemical methods while giving some indication of feed quality do not always indicate the availability of nutrients in a feed to a particular species Digestion trials and nutrient balance studies are used extensively in studying the nutrition of domestic and laboratory animals The de- velopment of metabolism chambers for fish (Post Shanks Smith 1965) made it possible to extend nutrient balance and digestion trials to fish

Phillips Tunison and Brockway (1948) force-fed gelatin capsules containing the test ingredient to rainbow trout At various inter- vals fish were killed and the contents of the

digestive tract were analyzed Test material not recovered was assumed to have been di-

gested and absorbed Japanese workers (Inaba et al 1963) used chromic oxide indicator to investigate the digestibility of protein and starch The gill excretion and urine were not collected in either of these studies

The objectives of the research reported in this paper were (1) to adapt to fish the meth- ods of nutrient balance and digestion trials which have been used with other animals (2) to determine the metabolizable energy (ME) and digestibility of carbohydrates of varying complexity and (3) to study the effect of car- bohydrates on nitrogen balance

132

METHODS

Diets containing approximately 50 percent protein and 50 percent carbohydrate were force-fed to male rainbow trout in metabolism

chambers The carbohydrates tested were glu- cose dextrin cooked cornstarch raw corn- starch and alpha-cellulose In addition an all- protein diet was fed at two levels the low level providing the same nitrogen intake and the high level the same dry matter intake as the 50 percent protein diets The protein used in all diets was a 7030 casein-gelatin mixture

The chambers used were similar to those

described by Post Shanks and Smith (1965) with the addition of a 12-liter reservoir around

the head end to collect gill excretions (see figure) The temperature in the chambers was held constant at 15 oslash C by partial submersion in running water

Daily each fish was anesthetized and then fed a measured amount of feed at I percent of body weight (dry weight of feed 1)er live weight of fish) A 3-day preliminary period was followed by a 5-day collection period The chamber was drained daily and the waste prod- ucts were sampled pooled with those taken on previous days and preserved for analysis

Wet fecal urine and gill excretion samples were analyzed for nitrogeu by microkjeldahl procedure (AOAC 1950) For energy determi- nations fecal samples were concentrated at re- duced pressure in a rotating evaporator to about 10 percent of the original volume The concentrate was then lyophilized and gross en- ergy determinations were made in a Parr adia- batic bomb calorimeter Pooled urine samples

THE PROGRESSIVE FISH-CULTURIST

Dow

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nell

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Rainbow trout in a metabolism chamber for quantitative collection of feces urine and gill excretions

were lyophilized and gross energy was measured Concentrated and lyophilized sam- ples of the water containing the branchial ex- cretions would not burn in the calorimeter and the energy value was estimated from nitrogen content

The data xvere subjected to analysis of vari- ance and significance was tested at 95 percent by the multiple range test of Duncan (Li 1964)

RESULTS AND DISCUSSION

Suitability o[ method--The method ap- peared to have value in the study of availabili- ty and utilization of fish feeds Good separation of excretions was achieved and quantitative collection of each excretion was possible Most fish adapted to the close confinement of the chambers Occasionally a fish would struggle and fight the chamber until exhausted Some fish regurgitated all or part of the feed Fish were discarded which failed to adapt to con- finement or regurgitated feed Some abrasion and loss of slime occurred in the area of the

diaphragm The contribution of this loss to waste products was not measured but was as- sumed to be small in comparison to other ex- cretions

There was not enough water in the head chamber to dilute ammonia to nontoxic levels Thirty to 40 liters of fresh water was dripped

VOL 33 NO 3 JULY 1971

into the chamber each day and the effluent was collected The water in the head chamber was

mixed with the effluent before samples were taken for nitrogen analysis

Although some problems were encountered the method appeared satisfactory œor deter- mining digestibility ME content and nutrient balance of feeds for large rainbow trout (250 to 500 grams) Further research is necessary to determine if values œound for these fish are

applicable to small trout or to closely related species

Digestion o[ nutrients and ME content-- The apparent digestibility of the protein bullvas equal for all diets except the one containing alpha-cellulose (see table) The large amount of fiber in this diet interfered with the digestion and absorption of protein The small difference in apparent digestibility between the all- protein diets fed at high and low levels was not significant

The digestibility of the nonprotein portion of the diet varied inversely with molecular com- plexity of the carbohydrate Glucose and dex- trin were about equally digested Cooked corn- starch was digested better than raw cornstarch indicating that the cooking process and ac- companying hydrolysis increased the availabili- ty to fish The digestibility of raw starch was lower than previously reported (Phillips et al 1948) It is well known that large quantities of

183

Dow

nloa

ded

by [

Cor

nell

Uni

vers

ity]

at 0

856

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embe

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12

Mean gross energy values of diets and digestion coefficients metabolizable energy and nitrogen balances when these diets were fed to large rainbow trout (250 to 500 grams) at 1 percent of

body weight Each value is mean of five replications [abe k Common superscript indicates means which are not significantly different at 005]

50 percent protein diets All-protein diet

Nonprotein in diets Level of feeding

Cooked Raw Alpha- Glucose Dextrin starch starch cellulose Low High

Gross energy Whole diet kcalg _ 468 494 488 473 460 565 565

Digestion coefficients Whole diet percent __ _ 841 bull 802 bull 710 601 366 844 a 887 bull Protein portion percent 879 b 816 b 858 bull 849 bull 598 844 bull 887 bull Nonprotein portion percent 793 c 774 c 516 240 d 137 d -- --

Metabolizable energy Per gram whole diet kcal 376 oslash 380 oslash 332 268 198 445 bull 464 f From protein per gram diet x kcal 210 237 225 233 181 445 464 From nonprotein per gram diet kcal 166 143 107 035 017 -- Per gram of carbohydrate kcal 312 303 214 072 028 -- --

Nitrogen balance mgkg body vetday 492 g --376 h --]6 gh --464 hj --2116 --952 bulljk --1176 bullk

Based on 45 keal MEg protein

raw starch in diets of monogastric animals may cause digestive disturbances This may have happened with the fish fed 50 percent raw starch as the range of values found for this group was larger than for any other group There was a small but significant diges- tion of cellulose This was surprising due to the small capacity and low temperature of the di- gestive system of fish It does however agree with findings of Buhler and Halver (1961) and with the work of Buhler and Benville bull who

found bull4COe excreted by fish which were fed bull4C-labeled cellulose The ME (see table) was closely correlated with gross energy and digestibility (r--0932) When carbohydrate was digested and absorbed it appeared to be used by the fish as an energy source

The ME of the protein was higher than val- ues generally accepted for mammals including man (45 vs 40 kilocalories per gram) This may be due to the unique system the fish has for excretion of waste nitrogen In these studies about 80 percent of nonfecal waste ni- trogen was excreted as ammonia through the gills of the fish The direct excretion of ammo- nia requires less energy than does synthesis and excretion of urea ME values were not

corrected for nitrogen balance Nitrogen balance--The nitrogen balances

x Unpublished data (1966) Bureau of Sport Fisheries and Wild- life Western Fish Nutrition Laboratory Cook Wash 98605

134

were more negative than expected for the type and amount of food fed These fish were under

considerable stress and this may have led to higher energy requirements and negative ni- trogen balances The data (see table) indicate that when digestible carbohydrate was avail- able it was used by the fish for energy and the more positive balances were obtained when diets contained simple carbohydrates

REFERENCES

ASSOCIATION Of OFFICIAL AGRICULTURAL CHEMISTS

1950 Methods of analysis seventh edition BUHLER DONALD R and JOHN E I-IALYER

1961 Nutrition of salmonid fish IX Carbohydrate requirements of chinook salmon Journal of Nu- trition vol 74 p 307

INABA DENSABURO CHINKICHI OGINO CHAIKI TAKA- MATSU TADASHI UEDA and KEN-ICHI KUROKAWA 1963 Digestibility of dietary protein and starch in

rainbow trout sport fish Summary and tables in English Bulletin of the Japanese Society of Scien- tific Fisheries vol 29 no 3 p 242-244

LI JEROME C R 1964 Statistical Inference Edward Brothers Inc

Ann Arbor Michigan PHILLIPS ARTHUR M Jr A V TUNISON and DONALD

BROCKWAY

1948 Utilization of carbohydrates by trout New York Conservation Department Fishery Research Bulletin 11 44 p

POST GEORGE W E SHANKS and R R SMITH 1965 A method for collecting metabolic excretions

from fish Progressive Fish-Culturist vol 27 no 1 p 2

TI-IE PROGRESSIVE FISI-I-CULTURIST

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Page 2: A Method for Measuring Digestibility and Metabolizable Energy of Fish Feeds

A METHOD FOR MEASURING DIGESTIBILITY

AND METABOLIZABLE ENERGY OF FISH FEEDS

R R Bureau of Sport Fsheries and Wildlife

Western Fish Nutrition Laboratory tIagerman Field Station Hagerman Idaho 8333œ

A DIET TESTING AND EVALUATION PROGRAM is

essential to the economical production of fish Composition of diets must be changed occasion- ally due to cost and availability of ingredients A long term feeding trial is the most dependa- ble method of measuring the value of a feed but is often too slow and expensive Chemical methods while giving some indication of feed quality do not always indicate the availability of nutrients in a feed to a particular species Digestion trials and nutrient balance studies are used extensively in studying the nutrition of domestic and laboratory animals The de- velopment of metabolism chambers for fish (Post Shanks Smith 1965) made it possible to extend nutrient balance and digestion trials to fish

Phillips Tunison and Brockway (1948) force-fed gelatin capsules containing the test ingredient to rainbow trout At various inter- vals fish were killed and the contents of the

digestive tract were analyzed Test material not recovered was assumed to have been di-

gested and absorbed Japanese workers (Inaba et al 1963) used chromic oxide indicator to investigate the digestibility of protein and starch The gill excretion and urine were not collected in either of these studies

The objectives of the research reported in this paper were (1) to adapt to fish the meth- ods of nutrient balance and digestion trials which have been used with other animals (2) to determine the metabolizable energy (ME) and digestibility of carbohydrates of varying complexity and (3) to study the effect of car- bohydrates on nitrogen balance

132

METHODS

Diets containing approximately 50 percent protein and 50 percent carbohydrate were force-fed to male rainbow trout in metabolism

chambers The carbohydrates tested were glu- cose dextrin cooked cornstarch raw corn- starch and alpha-cellulose In addition an all- protein diet was fed at two levels the low level providing the same nitrogen intake and the high level the same dry matter intake as the 50 percent protein diets The protein used in all diets was a 7030 casein-gelatin mixture

The chambers used were similar to those

described by Post Shanks and Smith (1965) with the addition of a 12-liter reservoir around

the head end to collect gill excretions (see figure) The temperature in the chambers was held constant at 15 oslash C by partial submersion in running water

Daily each fish was anesthetized and then fed a measured amount of feed at I percent of body weight (dry weight of feed 1)er live weight of fish) A 3-day preliminary period was followed by a 5-day collection period The chamber was drained daily and the waste prod- ucts were sampled pooled with those taken on previous days and preserved for analysis

Wet fecal urine and gill excretion samples were analyzed for nitrogeu by microkjeldahl procedure (AOAC 1950) For energy determi- nations fecal samples were concentrated at re- duced pressure in a rotating evaporator to about 10 percent of the original volume The concentrate was then lyophilized and gross en- ergy determinations were made in a Parr adia- batic bomb calorimeter Pooled urine samples

THE PROGRESSIVE FISH-CULTURIST

Dow

nloa

ded

by [

Cor

nell

Uni

vers

ity]

at 0

856

28

Nov

embe

r 20

12

Rainbow trout in a metabolism chamber for quantitative collection of feces urine and gill excretions

were lyophilized and gross energy was measured Concentrated and lyophilized sam- ples of the water containing the branchial ex- cretions would not burn in the calorimeter and the energy value was estimated from nitrogen content

The data xvere subjected to analysis of vari- ance and significance was tested at 95 percent by the multiple range test of Duncan (Li 1964)

RESULTS AND DISCUSSION

Suitability o[ method--The method ap- peared to have value in the study of availabili- ty and utilization of fish feeds Good separation of excretions was achieved and quantitative collection of each excretion was possible Most fish adapted to the close confinement of the chambers Occasionally a fish would struggle and fight the chamber until exhausted Some fish regurgitated all or part of the feed Fish were discarded which failed to adapt to con- finement or regurgitated feed Some abrasion and loss of slime occurred in the area of the

diaphragm The contribution of this loss to waste products was not measured but was as- sumed to be small in comparison to other ex- cretions

There was not enough water in the head chamber to dilute ammonia to nontoxic levels Thirty to 40 liters of fresh water was dripped

VOL 33 NO 3 JULY 1971

into the chamber each day and the effluent was collected The water in the head chamber was

mixed with the effluent before samples were taken for nitrogen analysis

Although some problems were encountered the method appeared satisfactory œor deter- mining digestibility ME content and nutrient balance of feeds for large rainbow trout (250 to 500 grams) Further research is necessary to determine if values œound for these fish are

applicable to small trout or to closely related species

Digestion o[ nutrients and ME content-- The apparent digestibility of the protein bullvas equal for all diets except the one containing alpha-cellulose (see table) The large amount of fiber in this diet interfered with the digestion and absorption of protein The small difference in apparent digestibility between the all- protein diets fed at high and low levels was not significant

The digestibility of the nonprotein portion of the diet varied inversely with molecular com- plexity of the carbohydrate Glucose and dex- trin were about equally digested Cooked corn- starch was digested better than raw cornstarch indicating that the cooking process and ac- companying hydrolysis increased the availabili- ty to fish The digestibility of raw starch was lower than previously reported (Phillips et al 1948) It is well known that large quantities of

183

Dow

nloa

ded

by [

Cor

nell

Uni

vers

ity]

at 0

856

28

Nov

embe

r 20

12

Mean gross energy values of diets and digestion coefficients metabolizable energy and nitrogen balances when these diets were fed to large rainbow trout (250 to 500 grams) at 1 percent of

body weight Each value is mean of five replications [abe k Common superscript indicates means which are not significantly different at 005]

50 percent protein diets All-protein diet

Nonprotein in diets Level of feeding

Cooked Raw Alpha- Glucose Dextrin starch starch cellulose Low High

Gross energy Whole diet kcalg _ 468 494 488 473 460 565 565

Digestion coefficients Whole diet percent __ _ 841 bull 802 bull 710 601 366 844 a 887 bull Protein portion percent 879 b 816 b 858 bull 849 bull 598 844 bull 887 bull Nonprotein portion percent 793 c 774 c 516 240 d 137 d -- --

Metabolizable energy Per gram whole diet kcal 376 oslash 380 oslash 332 268 198 445 bull 464 f From protein per gram diet x kcal 210 237 225 233 181 445 464 From nonprotein per gram diet kcal 166 143 107 035 017 -- Per gram of carbohydrate kcal 312 303 214 072 028 -- --

Nitrogen balance mgkg body vetday 492 g --376 h --]6 gh --464 hj --2116 --952 bulljk --1176 bullk

Based on 45 keal MEg protein

raw starch in diets of monogastric animals may cause digestive disturbances This may have happened with the fish fed 50 percent raw starch as the range of values found for this group was larger than for any other group There was a small but significant diges- tion of cellulose This was surprising due to the small capacity and low temperature of the di- gestive system of fish It does however agree with findings of Buhler and Halver (1961) and with the work of Buhler and Benville bull who

found bull4COe excreted by fish which were fed bull4C-labeled cellulose The ME (see table) was closely correlated with gross energy and digestibility (r--0932) When carbohydrate was digested and absorbed it appeared to be used by the fish as an energy source

The ME of the protein was higher than val- ues generally accepted for mammals including man (45 vs 40 kilocalories per gram) This may be due to the unique system the fish has for excretion of waste nitrogen In these studies about 80 percent of nonfecal waste ni- trogen was excreted as ammonia through the gills of the fish The direct excretion of ammo- nia requires less energy than does synthesis and excretion of urea ME values were not

corrected for nitrogen balance Nitrogen balance--The nitrogen balances

x Unpublished data (1966) Bureau of Sport Fisheries and Wild- life Western Fish Nutrition Laboratory Cook Wash 98605

134

were more negative than expected for the type and amount of food fed These fish were under

considerable stress and this may have led to higher energy requirements and negative ni- trogen balances The data (see table) indicate that when digestible carbohydrate was avail- able it was used by the fish for energy and the more positive balances were obtained when diets contained simple carbohydrates

REFERENCES

ASSOCIATION Of OFFICIAL AGRICULTURAL CHEMISTS

1950 Methods of analysis seventh edition BUHLER DONALD R and JOHN E I-IALYER

1961 Nutrition of salmonid fish IX Carbohydrate requirements of chinook salmon Journal of Nu- trition vol 74 p 307

INABA DENSABURO CHINKICHI OGINO CHAIKI TAKA- MATSU TADASHI UEDA and KEN-ICHI KUROKAWA 1963 Digestibility of dietary protein and starch in

rainbow trout sport fish Summary and tables in English Bulletin of the Japanese Society of Scien- tific Fisheries vol 29 no 3 p 242-244

LI JEROME C R 1964 Statistical Inference Edward Brothers Inc

Ann Arbor Michigan PHILLIPS ARTHUR M Jr A V TUNISON and DONALD

BROCKWAY

1948 Utilization of carbohydrates by trout New York Conservation Department Fishery Research Bulletin 11 44 p

POST GEORGE W E SHANKS and R R SMITH 1965 A method for collecting metabolic excretions

from fish Progressive Fish-Culturist vol 27 no 1 p 2

TI-IE PROGRESSIVE FISI-I-CULTURIST

Dow

nloa

ded

by [

Cor

nell

Uni

vers

ity]

at 0

856

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r 20

12

Page 3: A Method for Measuring Digestibility and Metabolizable Energy of Fish Feeds

Rainbow trout in a metabolism chamber for quantitative collection of feces urine and gill excretions

were lyophilized and gross energy was measured Concentrated and lyophilized sam- ples of the water containing the branchial ex- cretions would not burn in the calorimeter and the energy value was estimated from nitrogen content

The data xvere subjected to analysis of vari- ance and significance was tested at 95 percent by the multiple range test of Duncan (Li 1964)

RESULTS AND DISCUSSION

Suitability o[ method--The method ap- peared to have value in the study of availabili- ty and utilization of fish feeds Good separation of excretions was achieved and quantitative collection of each excretion was possible Most fish adapted to the close confinement of the chambers Occasionally a fish would struggle and fight the chamber until exhausted Some fish regurgitated all or part of the feed Fish were discarded which failed to adapt to con- finement or regurgitated feed Some abrasion and loss of slime occurred in the area of the

diaphragm The contribution of this loss to waste products was not measured but was as- sumed to be small in comparison to other ex- cretions

There was not enough water in the head chamber to dilute ammonia to nontoxic levels Thirty to 40 liters of fresh water was dripped

VOL 33 NO 3 JULY 1971

into the chamber each day and the effluent was collected The water in the head chamber was

mixed with the effluent before samples were taken for nitrogen analysis

Although some problems were encountered the method appeared satisfactory œor deter- mining digestibility ME content and nutrient balance of feeds for large rainbow trout (250 to 500 grams) Further research is necessary to determine if values œound for these fish are

applicable to small trout or to closely related species

Digestion o[ nutrients and ME content-- The apparent digestibility of the protein bullvas equal for all diets except the one containing alpha-cellulose (see table) The large amount of fiber in this diet interfered with the digestion and absorption of protein The small difference in apparent digestibility between the all- protein diets fed at high and low levels was not significant

The digestibility of the nonprotein portion of the diet varied inversely with molecular com- plexity of the carbohydrate Glucose and dex- trin were about equally digested Cooked corn- starch was digested better than raw cornstarch indicating that the cooking process and ac- companying hydrolysis increased the availabili- ty to fish The digestibility of raw starch was lower than previously reported (Phillips et al 1948) It is well known that large quantities of

183

Dow

nloa

ded

by [

Cor

nell

Uni

vers

ity]

at 0

856

28

Nov

embe

r 20

12

Mean gross energy values of diets and digestion coefficients metabolizable energy and nitrogen balances when these diets were fed to large rainbow trout (250 to 500 grams) at 1 percent of

body weight Each value is mean of five replications [abe k Common superscript indicates means which are not significantly different at 005]

50 percent protein diets All-protein diet

Nonprotein in diets Level of feeding

Cooked Raw Alpha- Glucose Dextrin starch starch cellulose Low High

Gross energy Whole diet kcalg _ 468 494 488 473 460 565 565

Digestion coefficients Whole diet percent __ _ 841 bull 802 bull 710 601 366 844 a 887 bull Protein portion percent 879 b 816 b 858 bull 849 bull 598 844 bull 887 bull Nonprotein portion percent 793 c 774 c 516 240 d 137 d -- --

Metabolizable energy Per gram whole diet kcal 376 oslash 380 oslash 332 268 198 445 bull 464 f From protein per gram diet x kcal 210 237 225 233 181 445 464 From nonprotein per gram diet kcal 166 143 107 035 017 -- Per gram of carbohydrate kcal 312 303 214 072 028 -- --

Nitrogen balance mgkg body vetday 492 g --376 h --]6 gh --464 hj --2116 --952 bulljk --1176 bullk

Based on 45 keal MEg protein

raw starch in diets of monogastric animals may cause digestive disturbances This may have happened with the fish fed 50 percent raw starch as the range of values found for this group was larger than for any other group There was a small but significant diges- tion of cellulose This was surprising due to the small capacity and low temperature of the di- gestive system of fish It does however agree with findings of Buhler and Halver (1961) and with the work of Buhler and Benville bull who

found bull4COe excreted by fish which were fed bull4C-labeled cellulose The ME (see table) was closely correlated with gross energy and digestibility (r--0932) When carbohydrate was digested and absorbed it appeared to be used by the fish as an energy source

The ME of the protein was higher than val- ues generally accepted for mammals including man (45 vs 40 kilocalories per gram) This may be due to the unique system the fish has for excretion of waste nitrogen In these studies about 80 percent of nonfecal waste ni- trogen was excreted as ammonia through the gills of the fish The direct excretion of ammo- nia requires less energy than does synthesis and excretion of urea ME values were not

corrected for nitrogen balance Nitrogen balance--The nitrogen balances

x Unpublished data (1966) Bureau of Sport Fisheries and Wild- life Western Fish Nutrition Laboratory Cook Wash 98605

134

were more negative than expected for the type and amount of food fed These fish were under

considerable stress and this may have led to higher energy requirements and negative ni- trogen balances The data (see table) indicate that when digestible carbohydrate was avail- able it was used by the fish for energy and the more positive balances were obtained when diets contained simple carbohydrates

REFERENCES

ASSOCIATION Of OFFICIAL AGRICULTURAL CHEMISTS

1950 Methods of analysis seventh edition BUHLER DONALD R and JOHN E I-IALYER

1961 Nutrition of salmonid fish IX Carbohydrate requirements of chinook salmon Journal of Nu- trition vol 74 p 307

INABA DENSABURO CHINKICHI OGINO CHAIKI TAKA- MATSU TADASHI UEDA and KEN-ICHI KUROKAWA 1963 Digestibility of dietary protein and starch in

rainbow trout sport fish Summary and tables in English Bulletin of the Japanese Society of Scien- tific Fisheries vol 29 no 3 p 242-244

LI JEROME C R 1964 Statistical Inference Edward Brothers Inc

Ann Arbor Michigan PHILLIPS ARTHUR M Jr A V TUNISON and DONALD

BROCKWAY

1948 Utilization of carbohydrates by trout New York Conservation Department Fishery Research Bulletin 11 44 p

POST GEORGE W E SHANKS and R R SMITH 1965 A method for collecting metabolic excretions

from fish Progressive Fish-Culturist vol 27 no 1 p 2

TI-IE PROGRESSIVE FISI-I-CULTURIST

Dow

nloa

ded

by [

Cor

nell

Uni

vers

ity]

at 0

856

28

Nov

embe

r 20

12

Page 4: A Method for Measuring Digestibility and Metabolizable Energy of Fish Feeds

Mean gross energy values of diets and digestion coefficients metabolizable energy and nitrogen balances when these diets were fed to large rainbow trout (250 to 500 grams) at 1 percent of

body weight Each value is mean of five replications [abe k Common superscript indicates means which are not significantly different at 005]

50 percent protein diets All-protein diet

Nonprotein in diets Level of feeding

Cooked Raw Alpha- Glucose Dextrin starch starch cellulose Low High

Gross energy Whole diet kcalg _ 468 494 488 473 460 565 565

Digestion coefficients Whole diet percent __ _ 841 bull 802 bull 710 601 366 844 a 887 bull Protein portion percent 879 b 816 b 858 bull 849 bull 598 844 bull 887 bull Nonprotein portion percent 793 c 774 c 516 240 d 137 d -- --

Metabolizable energy Per gram whole diet kcal 376 oslash 380 oslash 332 268 198 445 bull 464 f From protein per gram diet x kcal 210 237 225 233 181 445 464 From nonprotein per gram diet kcal 166 143 107 035 017 -- Per gram of carbohydrate kcal 312 303 214 072 028 -- --

Nitrogen balance mgkg body vetday 492 g --376 h --]6 gh --464 hj --2116 --952 bulljk --1176 bullk

Based on 45 keal MEg protein

raw starch in diets of monogastric animals may cause digestive disturbances This may have happened with the fish fed 50 percent raw starch as the range of values found for this group was larger than for any other group There was a small but significant diges- tion of cellulose This was surprising due to the small capacity and low temperature of the di- gestive system of fish It does however agree with findings of Buhler and Halver (1961) and with the work of Buhler and Benville bull who

found bull4COe excreted by fish which were fed bull4C-labeled cellulose The ME (see table) was closely correlated with gross energy and digestibility (r--0932) When carbohydrate was digested and absorbed it appeared to be used by the fish as an energy source

The ME of the protein was higher than val- ues generally accepted for mammals including man (45 vs 40 kilocalories per gram) This may be due to the unique system the fish has for excretion of waste nitrogen In these studies about 80 percent of nonfecal waste ni- trogen was excreted as ammonia through the gills of the fish The direct excretion of ammo- nia requires less energy than does synthesis and excretion of urea ME values were not

corrected for nitrogen balance Nitrogen balance--The nitrogen balances

x Unpublished data (1966) Bureau of Sport Fisheries and Wild- life Western Fish Nutrition Laboratory Cook Wash 98605

134

were more negative than expected for the type and amount of food fed These fish were under

considerable stress and this may have led to higher energy requirements and negative ni- trogen balances The data (see table) indicate that when digestible carbohydrate was avail- able it was used by the fish for energy and the more positive balances were obtained when diets contained simple carbohydrates

REFERENCES

ASSOCIATION Of OFFICIAL AGRICULTURAL CHEMISTS

1950 Methods of analysis seventh edition BUHLER DONALD R and JOHN E I-IALYER

1961 Nutrition of salmonid fish IX Carbohydrate requirements of chinook salmon Journal of Nu- trition vol 74 p 307

INABA DENSABURO CHINKICHI OGINO CHAIKI TAKA- MATSU TADASHI UEDA and KEN-ICHI KUROKAWA 1963 Digestibility of dietary protein and starch in

rainbow trout sport fish Summary and tables in English Bulletin of the Japanese Society of Scien- tific Fisheries vol 29 no 3 p 242-244

LI JEROME C R 1964 Statistical Inference Edward Brothers Inc

Ann Arbor Michigan PHILLIPS ARTHUR M Jr A V TUNISON and DONALD

BROCKWAY

1948 Utilization of carbohydrates by trout New York Conservation Department Fishery Research Bulletin 11 44 p

POST GEORGE W E SHANKS and R R SMITH 1965 A method for collecting metabolic excretions

from fish Progressive Fish-Culturist vol 27 no 1 p 2

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