If warmwater finfish protein requirements as level in diet is low, absolute intake per day is similar to those of coldwater species. But relation to this requirement with specific growth rate differs for strictly warmwater fishes as tilapia. Analysis of partition between protein and non-protein energy provided and consequently improve their protein retention. Better carbohydrate digestibility and metabolism are propunded as part of the exploration. (Résumé d'auteur

Luquet, Pierre

Moreau, Yann

Horizon / Pleins textes

ADVANCES IN TROPICAL AQUACULTURE Tahrn. Feb 20 . March 4. 1CW 
AOUACOP IFREMER Actes de Colloaue 9 pp 751.755 f 
68 
Energy - Protein management 
by some warmwater finfishes 
P. LUQUET and Y.  MOREAU 
bboratoire d'tlydrobiologie INRA. KOUROU. Guyane Française, 
Abstract - If warmwaterjnfìh protein requirements as level in diet is low, 
absolute intake per day is similar to those of wldwater species. But relation of this 
requirement with specific growth rate diffeen for strictly warmwater f ì h e s  as Tilapias. 
Analysis of partition between protein and non-protein enetgy retention shows that these 
species with Chias make a better use of non-protein energyprovided and consequently 
improve their protein retention. Better carbohydrate digestibility and metabolism are 
propunded as part of the explanation. 
- .  
I NTR O D U CTI O N 
One may discuss the problem of nutrition on aquacultured fish under 
three broad categories : (a) physical and biological modes of feeding, 
@) specific nutritional requirements, and (c) diets formulation. 
In the first category, we have to consider not only the physical texture 
and stability of compounded pellets from which belongs the relative food 
consumed, but also the feeding practices for which too little attention has 
be done. Indeed, meal timing plays a major role in feed utilization by fish. 
It affects .growth rate, feeding efficiency, and body composition. It is 
related to the existence of circadian variations of metabolism and its 
hormonal control (see vol. 113 of the Trans. Am. Fish. Soc., 1984). 
Among nutrients, protein requirements and optimal dietary protein 
levels remain an apparent melting pot even if a sustained literature is 
available in these fl elds. Additionally, both problems - protein require- 
ments and optimal dietary protein levels- are often confused by reason 
of interfering problems of protein to energy relations, calorigenic function 
of proteins, apparent protein sparing effects of fats and carbohydrates, and 
available energy (Cho and Kaushik, 1985). , 
Because of the relationship between protein and energy levels, the 
optimal dietary protein level varies widely between successive experiments 
if diet energy density or feeding rate has been changed. However, in most 
cases the authors cannot conclude in terms of optimal dietary protein level, 
f 
752 P. Luquet and Y. Moreau 
but  only as optimal dietary to energy ratio (Garling and Wilson, 1976; 
Wang et al., 1985 a,b). 
The origin of the energy by itself can also act, and very heavy 
factorial plans have to be mounted. Consequently these types of experi- 
ments are scarce, and when they exist, a doubt often subsists (Berger and 
Halver, 1987). 
These introductory statements have a general value, whatever the 
fishes, but they constitute many aspects to be taken into account to review 
specific nutrient requirements of warm water fishes. As a matter of fact, 
energetic aspects will be more extensively considered than protein requi- 
rements by itself, even if the protein coGer need remains the chief purpose. 
Optimal dietary protein level 
The range for reported optimal dietary protein levels is quite large, 
but some results should be considered with cristicism, either they are 
unique and not corroborated, or too distant of the general tendancies. 
Considering only the most reliable values for growing fish, e.g. when there 
exist various convergent results, obtained with adequate feeding rates and 
diet energy levels, we may establish that there exists a general pattern when 
protein sources of good value are fed. 
Apparent protein level needs seem to disminish when normal life 
temperature increases. For rainbow trout the reported vahres range from 
35 to 45 percent of the diet, and the optimal level is close to 36 % when 
high fat diets are used (Takeuchi et al, 1978a). The same team, thus 
working in the same type of approach, found that optimal protein level 
in diets ranges from 3 1 to 38 % for common carp at 22-25oC, and estimates 
that the optimum content of dietary protein for maximum growth is 
around 3 I % (Takeuchi et al, 1979b). Summing up literature data, Lu- 
quet (1989) concludes that Tilapia species have a protein requirement of 
28-35 % of the diet and that 30 % constitute a safe level for a 23-28oC 
normal temperature range. Channel catfish, living at around 27oC, are 
considered to need 28 % protein in their diet (Garling and Wilson, 1976). 
even if recorded values range from 22 to 36. 
Daily protein requirements 
When expressed in terms of daily allowances (gram of protein by 
kilogram of body weight per day) for optimal growth or maximal protein 
deposition, protein requirements appear more homogeneous. The recorded 
values range from 6.2 to 10.2 for rainbow trout pakeuchi et aL, 1978 a,b,c), 
from 7.0 to 12.1 for carp (Takeuchi et aL, 1978b, 1979a,b), and from 7.2 
to 10.8 for channel catfish (Garling and Wilson, 1976). For tilapias the data 
vary mostly according to the feeding rate (Luquet, 1989). When fed at 
3 % B.W. per day, the data are closed (9.6 to 10.7) to that above; they 
. increase to 15-20 with a 5 6 %  feeding rate, and reach68 with a feeding 
rate as high as 20 % B.W. (Winfree and Stickney, 1981). Thus, protein daily 
requirements of omnivorous *warmwater fishes are similar or higher that 
for carnivorous coldwater fishes when expressed against body weight. , 
! 
i 
I i l  ! 
n 
h 
1: 
1 
3 
753 
Tacon and Cowey(l985) have widely discussed the best way to 
express protein requirements. After the statement that v. it may be more i 
meaningful to express protein requirements as digestible protein energy . ' 
relative to the digestible energy content of the diet D, they show that 
protein daily allowances must also be related to the specific growth rate 
of fishes. They conclude that << there exists .an almost linear relationship 
between daily protein requirement (grams of protein per kilogram body 
weight per day) and specific growth rate (SGR percentage per day) of the 
different species examinated B. The data quoted include the Tilapia 
Oreochromis niloticus, O. aureus, O. mossambicus, and Tilapia ziIlì. 
When adding other results related to the Tilapias, i t  seems therefore 
that Tilapia displays some particular trends. Two reasons may explain this, 
one related to experimental conditions and the other to own species 
characteristic such as strict stenotherm status. Needs values over the 
general trend are associated to feed conversion ratio over the means, 
involving a possible surestimation of needs. On the other hand, lower 
values observed indicate that Tilapia are able to maintain a higher specific 
growth rate without exceeding protein daily allowance. This implies a 
better management of available proteins. 
68 - Energy-protein managemení by some warmwaíer finfish 
t 
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Protein utilization 
Protein utilization, usualy expressed as retained proteidprotein 
intake ratio, constitutes a common criterion to check the synergistic 
interactions between major nutrient classes (protein sparing) or energetic 
cost of nutrient utilization (specific dynamic action = SDA). A dietary 
formulation low in protein entails minimal SDA, and would permit more 
effícient energy utilization. 
Table I presents results of protein and energy efficiency in terms of % 
retained for some species. It is based on literature data selected as the most 
efficient in order to make a comparison of relative potentiality of these 
species in protein and energy utilization., In, addition the body store 
compartiments (protein and non protein stores) are presented, as well as 
the percentage of non protein dietary retention. By this way, Cho and 
Kaushik(198.5) have discussed in detail the partition of the energy and 
protein retention or  losses in trouts 'under different protein to lipids diets. 
The comparison between species allows us to' ascertain that : 
- O. niloticus retains more efficiently protein intake than other 
species. More than 55 % of energy retained is:fixed is a nitrogenous form, 
while other values are below 50 %, 
- energy retention in Tilapias, carp and Clarias is lower than for 
rainbow trout and channel catfish, 
- this is mainly due to the fact that non protein energy is less 
retained (< 35 Ya) in these species, 
- in carcass, most of the energy (more than 60 %) 'is retained as 
protein energy in Clarias and Tilapia, and as non protein energy (lipids) 
in trout, carp and channel catfish, 
- the eurythermal carp and channel catfish appear closer ' to 
\ 
4 ' 
754 P. Luquet and Y. Moreau 
coldwater trout than strict warmwater fishes such as Tilapia even living 
in warmwater. 
Then Tilapia appears to be very efficient to utilize both protein and 
energy. For proteins this is evident insofar as the fixed/ingested ratio is 
high. For non protein energy, reverse reasoning must be done : less the 
retention is high, better is their utilization efficiency. Indeed, energy 
incorporation in diets is for fuel purpose for metabolism or for protein 
synthesis. Then, in fish cultivated for food, the fixed.energy, except that 
bound in proteins, must be considered as misused because not burnt. 
I 
I.E.(MJ 
WOg(l) 
1.760 . 
1.870 
1.967 
1.549 
1.703 
1.151 
1.02 1 
1.507 
1.632 
I578 
Tab. 1. - Protein and energy efficience in  ferm of % retained for some species 
N.retained 
% intake 
47 
34 
47.9 
39. I 
35 
49.8 
38 
62.3 
55 
25.6 
Specia 
Rainbow trou 
M 
I l  
Carp 
Catfish 
U 
Clarias 
gariepinus 
o. niloticus 
O. mossam 
Diet Charaaeristia 
?rot. % 
14 
55 
33.8 
31.5 
36. 
24. I 
50.4 
31.2 
31.4 
42 
Fat % 
22 
13 
19.5 
14.6 
5.5 
25 
9.83 
E. retained K 
of DE intake 
63 
53 
58.8 
42.5 
55 
62.2 
32' 
51.5 . 38.5 
20.8 
YI of non prol 
E. retained 
73 
88 
58 
39 
65 
83 
24' 
35 
21 
I O  
Gross Energy bask 
(1) Energy value are calculated. if not given. on proximate analysis basis. 
Coefficient are 22.2 CP: 38.9 EE; 172 NFE for gross energy and 18.8 CP: 37.7 EE: 16.7 NFE for 
digestible energy. 
Energy availability and fate 
:. * 
Non proteii,energy supply in diets is obtained by addition of high 
lipids or carbohydrate compounds. Their utilization involves a good 
acceptability\of fishes either during digestive or metabolism process. 
Lipids are reported to be highly available with an emphasized 
digestibility coefficient bf fat as ambiant temperature increases (Andrews 
et a¿, 1978). Carbohydrates do not display any general performances. As 
a monosaccharide requires no digestion to be assimilated, a polysaccharide 
must first be hydrolised. The polysaccharides mainly used are starch and 
r' i 
L 
dextrin. With salmonids, starch digestion is depressed with increasing 
intake and could be largely enhanced by a precooking treatment (Bergot 
and Breque, 1984). The ability of Tilapias to digest starch is not depen- 
close to lipids values (over 15 %) even with an intake as great as 6 mg/g 
body weighb'day (Wang et al., 1985a). 
dent on such kind of constraint, apparent digestibility of crude starch being I 
I 
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P 
7 
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68 - Energy-protein management bu Some warmwater finfisfi 
Energy efficiency of different digested carbohydrates must be campal 
rable. Their utilization by O. nilOtimS is relatively homogeneous except for 
glucose which efficient use could be handicapped by a too fast assimilation 
(Anderson et al., 1984). Recalculated non-protein energy retention is about 
the same ranging from 17 to 23 % for starch, dextrin, sucrose and glucose 
incorporated to diet at a rather high level, 40 %. Taking pelleting process 
into account, lipids could be added in diet. Rates over I5 % are well used 
(Takeushi et QL, 1978a), but unsaturated fatty acids composition must be 
regarded with care. Excess amount of n-3 has adverse effect on growth and 
lipid metabolism (Takeushi et al., 1983; Robinson and Wilson, 1985). Once 
essential fatty acid needs are content, saturated fatty acids containing 
sources prevail as they dont show unfavourable propensity (Takeuchi et 
al,  1978a: Cho et al,  198.5). 
CON CLUS ION 
Warmwater fishes may use better provided protein. This is not only 
due to a better protein retention capacity. but also to a better utilization 
of furnished non-protein energy. Being less retained, the protein sparing 
objective of this energy is more fulfilled. Better polysaccharides digesti- 
bility should play one of the leading parts of non-protein energy utiliza- 
tion, but the metabolic fate of nutrients has to be considered as fishes have 
to manage an e unconventionally N large amount of energy metabolites 
compared to traditionnal coldwater species. 
Anderson J, AJ. Jackson, U. Matty and B S .  Capper, 1984. Effects of dietary 
carbohydrate and fibre on the tilapia Oreochromir niloticus (Linn.). Aqua- 
cuIture, 37 : 303 - 3 14. 
Andrews J.W, M.W. Murray and J.M. Davis, 1978. The influence of dietary fat 
levels and environmental temperature on digestible energy and absorbability 
of animal fat in catfish diets. J. ffutr, 108 : 749 - 752. 
Berger Amnd J.E. Halver, 1987. Effects of dietary protein, lipid and carbohydrate 
mntent on the growth, feed emciency and carcass composition of striped 
bass, Morone Smt i l i s  (Walbaum), fingerlings. Aquaculture and Fuheries 
Management, 18 : 345 - 356. 
Bergot F. and J. Breque, 1983. Digestibility of starch by rainbow trout : effects of 
the physical state of starch and of the intake level. Aquaculture, 34 : 203 - 202. 
Cho CY, C.B. Cowey and T. Watanabe, 1985. Finfish nutrition in Asia : methodo- 
logical approaches to research and development. IDRC, Ottawa, 154 p.. 
Cho C Y .  and Sd. Kaushik, 1985. Effects of protein intake on metabot'ktble and net 
energy values of fish diets. In 3 Nutrition and feeding in fish, C.B. Cowey, 
AM. Mackie, J.G. Bell Eds., Academic Rcss, London, 95-1 17. 
Garling D.L Jr. and R.P. WiIson, 1976. Optimum dietary protein to energy ratio for 
channel catfish fingerling, Ictalurur punctatus. J. Nutr., 106 : 1368 - 1375. 
Henken AM, J.B. Boon, B.C. Cattel and H.WJ. Lobee, 1987. Differences in growth 
rate and feed utilization between male and female african catfish, Clarias 
goriepinru (Burchell 1822). Aquacdture, 63 : 221 - 232. 
756 P. Luquel and Y. Moreau 
Jauncey K, 1982. The effects of varying dietary protein level on the growth; food 
conversion, protein utilization and body composition of juvenile tilapias 
(Sarotherodon mossambicus). Aquaculture. 27 : 43 - 54. 
hquet P, 1989. Practical considerations on the protein nutrition and feeding of 
tilapia. Aquat. Living Resour, 2 (in press). 
Robinson EH. and R.P. Wilson, 1985. Nutrition and feeding. I n  : Channel catfish 
culture, C.S. Tucker (Ed.), Elsevier, Amsterdam, 323-404. 
Tacon GJ. and CB. Cowey, 1985. Protein and amino acid requirements. I n  : Fish 
energetics : new perspectives, P. Titler, P. Calow (Eds.), Croom Helm, 
London, 155-183. 
Takeuchi T, T. Watanabe and C. Ogino, 1978a. Optimum ratio of protein to lipid 
in diets of rainbow trout. Bull. Japan. Soc. Fîh, 44 (6) : 683 - 688. 
Takeuchi T, T. Watanabe and C. Ogino, 1978b. Use of hydrogenated fish oil and 
beef tallow as a dietary energy source for carp and rainbow trout. Bull. Japan. 
Takeuchi T, M.'Yokoymma, T. Watanabe and C. Ogino, 1978~. Optimum ratio of 
dietary energy to protein for rainbow trout. Bull. J Q ~ Q ~ .  Soc Fish,44 : 
Takeuchi T, T. Watanabe and C Ogino, 1979a. Availability of carbohydrates and 
lipid as dietary energy sources for carp. Bull. Japan. Soc. Fîh,45(8) : 
Takeuchi T, T. Watanabe and C. Ogino, 1979b. Optimum ratio of energy to protein 
for carp. Bull. Japan. Soc. Fîh, 45 (8) : 983 - 987. 
Takeushi T, S. Satoh and T. Wmtanabe, 1983. Dietary lipids suitable for the 
practical feed of Tilapia nilotice Bull. Japan. Soc Frrh, 49 (9) : 136 I - 1365. 
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i 
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141 - 146. 
J. Nu~c ,  111 : 1001 - 1012. 
! 


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