Ž .
legumes also tended to have lower ADCs for some amino acids e.g., sulphur amino acids than for other amino acids. Differences in ADCs for nitrogen and individual amino acids indicate the
need for individual amino acid availability data. The data provided a useful starting point for least-cost formulation of diets for silver perch.
q 2000 Elsevier Science B.V. All rights reserved.
Keywords: Nutrition; Bidyanus bidyanus; Digestibility; Meat meal; Legumes; Oilseeds; Cereals
1. Introduction
The shift to more intensive culture practices has contributed to a global increase in Ž
aquaculture production of about 12 per annum from 1984 to 1997 Tacon and
. Dominy, 1999 . This shift has only been possible because of the increased availability of
formulated diets. In Asia, the demand for aquaculture diets increased more than fourfold Ž
. Ž
. between 1986 and 1990 Akiyama, 1991 and Tacon and Dominy 1999 predicted the
Ž .
global market for aquaculture diets was over 11 million t metric tonnes in 1997. Marine based ingredients, especially fish meals are highly sought after as the protein
source of choice for many formulated aquaculture diets. Fish meals provide high contents of essential amino and fatty acids, are low in carbohydrates, are usually well
digested and, provided they are fresh, contain few anti-nutritional factors. However, production of fish meal already uses approximately 35 of the total global fish catch
Ž
. Tacon and Dominy, 1999 . As about 4 kg of wet fish is needed to produce 1 kg dry fish
meal, if diets contain more than 17 fish meal andror the food conversion ratio exceeds 1.5:1, aquaculture entails a net loss of fish protein.
Ž The search for alternatives to fish meal is an international research priority Manzi,
. 1989; Hardy and Kissil, 1997 . In Australia, very little fish meal is produced, although
abundant supplies of lower value agricultural protein sources, such as animal meals, oilseeds, grain legumes and cereals are available. For example, about 460 000 t of meat
meal, 860 000 t of canola, 1.4 million tonnes of lupins, 300 000 t field peas and 19.4
Ž million tonnes of wheat, are produced annually Australasian Agribusiness Services,
. 1993; ABARE, 1998 .
The determination of digestibility is the first step in evaluating the potential of an ingredient for use in the diet for an aquaculture species. In this study, digestibility
coefficients for 29 commercially available ingredients in Australia were researched. Silver perch is a native Australian freshwater finfish, which is being cultured due to its
rapid growth, high production in static earthen ponds and excellent eating qualities.
2. Materials and methods
2.1. Fish Ž
. Juvenile silver perch
Bidyanus bidyanus were obtained from the NSW Fisheries Ž
. Grafton Research Centre and held at the NSW Port Stephens Research Centre PSRC in
10 000-l concrete or 10 000-l fibreglass tanks for at least 1 week prior to each experiment. During this time, fish were fed once daily to apparent satiation on the same
Ž .
Ž reference diet SP35 used in subsequent digestibility studies Allan and Rowland,
. 1992 . Before each experiment, fish were treated with 5 grl NaCl to ensure they were
Ž .
free of ectoparasites and to prevent fungal infection Rowland and Ingram, 1991 . They were then weighed individually or in groups and placed into digestibility tanks via
random interspersion. Any fish that became ill or died during the experiment were replaced with fish acclimated on the same dietary treatment in order to maintain
stocking densities.
During all handling procedures fish were anaesthetised in a bath of 25 mgrl ethyl-p-aminobenzoate for 5 min. Once in the laboratory, all fish were maintained on the
reference diet SP35 and allowed to acclimatise to experimental conditions for 5 to 7 days prior to the introduction of chromic oxide marked diets. Faecal collection com-
menced after fish had been fed experimental diets for at least 3 days.
2.2. Diets Ž
. Ž .
All experimental diets were composed of 69.3 reference diet SP35 Table 1 and
Ž .
29.7 test ingredient Tables 2 and 3 on a dry weight basis. Chromic oxide was used as an inert marker and incorporated into the reference and experimental diets at 1
inclusion level. All ingredients and the reference diet were ground to ensure a maximum Ž
. particle size of 710 mm, then thoroughly mixed in a Hobart mixer Troy, OH, USA .
Approximately 400 ml distilled waterrkg dry mix was added to the dry mix prior to Ž
. being pelleted through a meat mincer Barnco Australia, Leichhardt, NSW, Australia
with a 1-, 1.5- or 2-mm die, depending on size of experimental fish. Pellets were dried at -
358C in a convection drier for approximately 6 h until the moisture content was between 10 and 15.
2.3. Laboratory facility Twenty-seven 170-l cylindro-conical digestibility tanks, as described in Allan et al.
Ž .
1999 , were used in each experiment. Photo-period was set for a 12-h lightrdark cycle, Ž
beginning the light phase at 0600 h. During each experiment, nine treatments eight .
experimental diets and the reference diet were established. In all cases, three treatment Ž
. replicates n s 3 were randomly allocated to digestibility tanks.
Fish were fed their respective diets once each morning using spring operated, conveyor belt feeders for a period of 3 h. Faeces were then allowed to settle overnight
Ž .
approximately 18 h after tanks and collection chambers were thoroughly cleaned to Ž
. remove any uneaten feed and accumulated waste Allan et al., 1999 . Faecal samples
were collected each morning prior to feeding, dried under a vacuum at room temperature Ž
. Ž
. for 24 h 208C, silica gel and then frozen - 158C . Daily faecal samples from each
tank were pooled over the course of the experiment until sufficient sample for chemical analysis was obtained.
G.L. Allan
et al.
r Aquaculture
186 2000
293 –
310 296
Table 1 Ž
. Typical composition of commercial silver perch diet SP35
U UU
Ingredient Amount in
Vitamin content in diet Mineral content in diet
a a
Ž .
SP35 dry basis Vitamin
IUrkg diet mgrkg diet
Mineral mgrkg diet
Ž . Fish meal
26.20 Retinol A
8000 Calcium carbonate
7500.0 Ž
. Soybean meal
20.19 Cholecalciferol D3
1000 Manganese sulphate monohydrate
300.0 Ž .
Blood meal 2.04
DL
-a-tocopheryl acetate E 125.0
Zinc sulphate monohydrate 700.0
Ž .
Corn gluten meal 3.87
Menadione sodium bisulphite K3 16.5
Copper sulphate pentahydrate 60.0
Ž .
Wheat 27.47
Thiamin hydrochloride B1 10.0
Ferrous sulphate heptahydrate 500.0
Ž .
Sorghum 11.21
Riboflavin B2 25.2
Sodium chloride 7500.0
Ž .
Millrun 2.01
Pyridoxine hydrochloride B6 15.0
Potassium iodate 2.0
Cod liver oil 0.90
Folic acid 4.0
U
Ž . Vitamin premix
0.97 Ascorbic acid C
1000.0
UU
Mineral premix 2.81
Calcium
D
-pantothenate 55.0
Di-calcium phosphate 1.79
Myo-inositol 600.0
Ž . Ž .
DL
-methionine 0.13
d-Biotin H 2
1.0 Choline chloride
1500.0 Ž .
Crude protein 38.7
Nicotinamide 200.0
Ž .
Ž .
Gross energy MJrkg 18.0
Cyanocobalamin B12 0.02
Ž . Ž
. Digestible dry matter
67.4 Ethoxyquin anti-oxidant
150.0 Ž .
Ž .
Digestible protein 34.6
Calcium propionate mould inhibitor 250.0
Ž . Digestible energy
13.9
a
Amount of active ingredient.
Table 2 Dry basis proximate composition and gross energy content of test ingredients
a
Test ingredient Protein
Fat Ash
GE Expt.
Ž . Ž
. MJrkg
Fish meals
b
1. Australian fish meal 73.2
9.9 14.2
21.3 6
2. Danish fish meal 72.9
11.4 13.0
21.5 6
3. Peruvian fish meal 70.2
11.3 17.6
20.9 7
Animal meals Ž
. 4. Blood meal spray dried
94.9 –
3.1 23.9
9 Ž
. 5. Meat and bone meal beef
49.2 9.2
36.0 16.1
5 Ž
. 6. Meat and bone meal lamb
54.3 7.2
34.5 16.2
5 7. Poultry meal
60.3 18.2
15.0 22.7
4 Ž
. 8. Feather meal hydrolysed, ring dried
84.3 11.2
3.0 24.9
4 Oilseeds
Ž .
9. Soybean meal solvent 47.8
3.7 8.0
17.0 2
Ž .
10. Soybean meal whole, expeller 47.5
6.4 6.3
20.9 2
Ž .
11. Soybean meal dehulled, full-fat 35.8
19.5 5.5
23.3 2
Ž .
12. Canola meal solvent 36.6
2.6 7.4
19.9 2
Ž .
13. Canola meal whole, expeller 31.8
12.5 6.6
21.8 2
14. Peanut meal 41.2
1.3 5.2
19.7 11
Ž .
15. Cottonseed meal dehulled 48.1
4.6 8.3
19.9 10
Ž .
16. Linola linseed meal 29.8
11.3 6.1
21.2 2
Legumes whole Ž
. 17. Lupins-L. angustifolius gungurra
34.1 5.7
2.8 17.9
3 18. Lupins-L. albus
37.6 6.2
3.7 20.9
3 Ž
. 19. Field pea Pisum satiÕum dunn
25.5 1.1
3.4 17.0
1 Ž
. 20. Faba bean Vicia faba fijord
27.7 1.3
3.6 17.3
1 Ž
. 21. Chick pea Cicer arietinum desi
20.8 4.7
3.4 19.4
1 Ž
. 22. Vetch V. satiÕa blanch flur
30.9 0.9
3.3 17.9
1 23. Cow peas Vigna unguiculata
25.2 2.3
3.7 18.8
8 Cereals
24. Wheat gluten 76.9
– –
23.1 6
25. Corn gluten meal 62.0
– 1.1
24.1 9
Ž .
26. Wheat 1 Aust. Std. Wheat 12.2
– –
18.3 6
Ž .
27. Wheat 2 high protein 15.2
– –
18.5 6
28. Millrun 22.3
– 4.3
19.6 9
29. Sorghum 14.5
– 2.3
18.8 9
a
N =6.25.
b
Sea Fish, Triabunna, Tasmania, Australia.
2.4. Water quality Water for use in all experiments was sourced directly from the fresh water treatment
Ž .
plant 0.5 grl salinity at PSRC. In the laboratory, this water was adjusted to the desired Ž
. temperature, treated for pathogens ultraviolet conditioning and subjected to continuous
directional-flow and filtration through sand and diatomaceous earth filters. Water was
G.L. Allan
et al.
r Aquaculture
186 2000
293 –
310 298
Table 3 Dry matter amino acid composition of test ingredients
Ž . Test ingredient
Amino acid Lys
Met Cys
Thr Arg
Gly Ser
His Ile
Leu Phe
Tyr Val
Pro Ala
Glu Asp
Fish meals
a
1. Australian fish meal 6.9
2.3 1.0
3.9 6.0
5.1 3.6
2.7 3.6
5.9 3.3
2.7 4.0
3.4 5.0
10.2 7.6
2. Danish fish meal 6.2
2.2 0.8
3.6 5.9
5.1 3.6
1.9 3.4
5.6 3.0
2.3 3.8
3.2 4.8
10.2 6.7
3. Peruvian fish meal 5.5
2.0 0.7
3.2 5.1
4.8 3.0
2.3 3.5
5.3 2.9
2.3 3.7
3.5 4.6
9.4 6.2
Animal meals Ž
. 4. Blood meal spray dried
8.0 1.5
1.4 5.4
3.9 4.1
6.1 5.6
0.9 12.0
6.6 3.0
8.2 3.7
7.9 9.4
10.3 Ž
. 5. Meat and bone meal beef
2.5 0.7
0.3 1.6
3.9 7.7
2.1 0.8
1.3 2.7
1.5 1.1
2.0 5.0
3.9 5.7
3.3 Ž
. 6. Meat and bone meal lamb
3.5 1.1
0.7 2.1
4.3 6.7
2.4 1.2
1.8 3.5
1.9 1.5
2.4 4.6
4.0 7.0
3.8 7. Poultry meal
4.0 1.5
1.0 2.8
4.5 5.9
3.1 1.7
2.9 4.7
2.6 2.1
3.3 4.0
4.3 9.1
5.5 Ž
. 8. Feather meal hydrolysed, ring dried
2.3 0.7
6.8 4.7
6.7 7.1
11.4 1.1
4.9 8.0
4.6 2.7
7.3 9.3
4.6 10.3
6.6 Oilseeds
Ž .
9. Soybean meal solvent 3.3
0.7 0.9
2.1 3.7
2.1 2.9
1.3 2.5
3.8 2.6
1.9 2.6
2.6 2.1
9.3 5.8
Ž .
10. Soybean meal whole, expeller 3.0
0.8 1.0
2.1 3.7
2.1 2.9
1.3 2.4
3.8 2.5
1.8 2.5
2.5 2.1
9.2 5.7
Ž .
11. Soybean meal dehulled, full-fat 2.3
0.6 0.8
1.5 2.6
1.5 2.2
0.9 1.7
2.8 1.8
1.3 1.8
1.8 1.5
6.6 4.1
Ž .
12. Canola meal solvent 2.0
0.9 1.1
1.7 2.2
1.9 1.8
1.0 1.7
2.7 1.5
1.1 2.1
2.4 1.6
6.7 2.5
Ž .
13. Canola meal whole, expeller 1.7
0.9 1.1
1.5 2.1
1.7 1.7
0.9 1.5
2.3 1.3
1.0 1.8
2.1 1.5
6.2 2.4
14. Peanut meal 1.7
0.5 0.7
1.5 7.2
3.1 2.9
1.2 2.0
3.5 2.8
2.1 2.3
3.4 2.2
10.9 6.4
Ž .
15. Cottonseed meal dehulled 2.1
1.0 1.1
1.8 6.0
2.0 2.4
1.4 1.7
3.0 2.7
1.5 2.1
2.2 1.9
10.7 4.8
Ž .
16. Linola linseed meal 1.2
0.7 0.7
1.2 2.9
1.9 1.7
0.7 1.4
1.9 1.5
0.9 1.7
1.3 1.4
6.3 3.0
G.L. Allan
et al.
r Aquaculture
186 2000
293 –
310
299 Legumes whole
Ž .
17. Lupins-L. angustifolius gungurra 1.4
0.2 0.6
1.3 4.0
1.4 2.1
0.9 1.4
2.4 1.3
1.4 1.3
1.6 1.2
8.2 3.8
18. Lupins-L. albus 1.5
0.3 0.9
1.5 4.1
1.5 2.3
0.9 1.7
2.8 1.4
1.8 1.6
1.7 1.3
8.4 4.3
Ž .
19. Field pea P. satiÕum dunn 1.7
0.3 0.5
0.8 2.5
1.0 1.3
0.6 1.1
1.7 1.1
0.8 1.2
1.1 1.1
4.3 2.9
Ž .
20. Faba bean V. faba fijord 1.5
0.3 0.5
0.8 2.8
1.0 1.4
0.6 1.1
1.8 1.1
0.8 1.2
1.3 1.1
4.2 2.8
21. Chick pea C. arietinum 1.5
0.4 0.5
0.8 2.0
0.8 1.3
0.5 1.0
1.6 1.2
0.6 1.0
1.0 0.9
3.6 2.5
Ž .
22. Vetch V. satiÕa blanch flur 1.7
0.3 0.5
0.8 2.4
1.1 1.4
0.6 1.2
1.9 1.1
0.8 1.3
1.2 1.2
5.1 3.4
23. Cow peas Vig. unguiculata 1.8
0.4 0.3
1.0 2.2
1.1 1.4
0.8 1.2
2.0 1.4
0.9 1.3
1.3 1.1
4.7 3.0
Cereals 24. Wheat gluten
1.7 1.3
2.1 2.8
3.4 3.3
5.3 2.0
3.7 6.7
5.1 3.5
3.9 12.2
2.5 35.6
3.3 25. Corn gluten meal
1.1 1.6
1.4 2.2
2.0 1.6
3.6 1.1
3.0 11.3
4.1 3.4
3.1 5.8
5.8 14.6
4.2 Ž
. 26. Wheat 1 Aust. Std. Wheat
0.3 0.2
0.4 0.3
0.5 0.5
0.6 0.2
0.4 0.8
0.5 0.3
0.5 1.1
0.4 3.3
0.6 Ž
. 27. Wheat 2 high protein
0.3 0.3
0.5 0.4
0.6 0.5
0.7 0.3
0.5 1.0
0.6 0.5
0.6 1.4
0.5 4.4
0.7 28. Millrun
1.0 0.5
0.6 0.8
1.5 1.1
1.1 0.4
0.7 1.4
0.8 0.6
1.0 1.3
1.1 4.1
1.6 29. Sorghum
0.3 0.3
0.3 0.5
0.6 0.4
0.7 0.3
0.6 1.8
0.7 0.6
0.7 1.2
1.2 3.1
1.0
a
See Table 2.
then supplied to experimental tanks at a flow rate of approximately 600 mlrmin. Effluent water drained from experimental tanks via standpipes and 20–25 of this water
was discarded. The rest was collected in a common sump and recirculated through a 2000-l biological filter for re-use in the laboratory. Each digestibility tank contained two
air stone diffusers. During all experiments, dissolved oxygen was maintained above 5.0 mgrl, pH between 7.2 and 8.5 and water temperature between 23.28C and 28.08C.
Ž .
Ž .
Nitrite NO –N and ammonia total ammonia–N was measured weekly following
2
Ž .
methods described in Allan et al. 1990 , and levels did not exceed 0.2 and 0.3 mgrl, respectively.
2.5. Chemical analyses All chemical analyses of feed and faecal samples were done in duplicate. Dry matter,
Ž .
ash and energy bomb calorimetry were determined using procedures described in Ž
. AOAC 1990 . Nitrogen was determined using Kjeldahl or semi-micro Kjeldahl methods
Ž .
AOAC, 1990 and crude protein content estimated by multiplying nitrogen by 6.25. Ž
. Chromic oxide was determined by the method described in Scott 1978 . Amino acids
were analysed following acid hydrolysis using high pressure liquid chromatography and Ž
. Waters Pico-Tag Waters, Lane Cove, NSW, Australia . Sulphur amino acids were
determined separately following performic acid digestion, and tryptophan, which is lost Ž
. during acid hydrolysis, was not determined Cohen et al., 1989 .
2.6. Digestibility determinations Ž
. Apparent digestibility coefficients
ADCs for dry matter, energy, nitrogen and
availability of amino acids for the reference and test diets were calculated by the Ž .
w Ž
.x formula, ADC s 100 = 1 y FrD = DC rFC
where F is the percent of nutrient
r r
or energy in faeces, D is the percent of nutrient or energy in diet, DC is the percent of
r
Ž chromic oxide in diet and FC
is the percent of chromic oxide in faeces Cho and
r
. Ž
. Kaushik, 1990 . Then, ADCs availability for ingredients were determined after the
individual contribution of nutrients or energy from the reference diet and test ingredients Ž .
Ž were considered. The following formula was applied: AD
s Nutr =
AD y
ING TD
TD
. Ž .
0.69 = Nutr =
AD r 0.29 = Nutr
, where AD is apparent digestibility
RD RD
ING ING
Ž .
availability of nutrient or energy in the test ingredient, Nutr is the nutrient or energy
TD
Ž .
concentration in test diet, AD is the apparent digestibility availability of the nutrient
TD
or energy in the test diet, Nutr is the nutrient or energy concentration in the reference
RD
Ž .
diet, AD is the apparent digestibility availability of nutrient or energy in the
RD
reference diet and Nutr is the nutrient or energy concentration in the test ingredient
ING
Ž .
Sugiura et al., 1998 .
3. Results
