2. Materials and methods
2.1. Experimental diet preparation Ž
. All ingredients were ground using a hammer mill C-E Raymond, IL, USA or sieved
to ensure all particles passed through a 710-mm screen. Dry ingredients were thoroughly Ž
. mixed in a Hobart mixer Troy, OH, USA then combined with approximately 400 ml
y1
Ž distilled water kg
dry mix before being cold pelleted through a meat mincer Barnco .
Ž .
Australia, Leichhardt, NSW, Australia with a 2 mm die Experiment 1 or 2 and 3 mm Ž
. die Experiment 2 . Pellets were dried at 358C in a convection drier for approximately 6
h until the moisture content was between 10 and 15, to produce a dry, sinking pellet. 2.2. Experimental fish and water quality
Ž . Ž
Silver perch Bidyanus bidyanus Experiment 1, mean weight SEM: 6.2 0.3 g
. and Experiment 2, mean weight: 12.1 0.1 g were bred at the Grafton Research Centre
and raised in earthen ponds using similar techniques to those described by Thurston and Ž
. Ž
. Rowland 1995 . Before the experiments, fish were fed SP35 Allan and Rowland, 1992
and were treated with 5 g l
y1
NaCl to ensure they were free of ectoparasites and to Ž
. prevent fungal infection Rowland and Ingram, 1991 .
Prior to stocking, fish were anaesthetised using a bath of ethyl r-aminobenzoate Ž
y1 y1
. Experiment 1, 25 mg l
for 5 min or Experiment 2, 50 mg l for 3 min then caught
Ž .
at random, weighed Experiment 1, individually or Experiment 2, in groups of 5 or 10 and distributed among tanks by systematic interspersion. Fish were also weighed at
harvest using the same technique. Ž
. During both experiments, water temperature range 24.3–26.78C , dissolved oxygen
Ž
y1
. Ž
. above 5.0 mg l
, pH between 7.2 and 8.3 were measured weekly using a Yeo-Kal Ž
. 611 water quality analyser Yeo-Kal Electronics, Brookvale, Sydney, NSW Australia .
Ž
y1 y1
y1
Nitrite and ammonia - 0.55 mg l NO -N l
and - 0.6 mg l total ammonia-N
2 y1
. l
, respectively were measured weekly using colourmetric methods described by Ž
. Ž
. Major et al. 1972 and Dal Pont et al. 1973 .
2.3. Biochemical analyses All chemical analyses were done in duplicate. Feed, faecal and fish samples were
Ž .
analysed for dry matter, ash, crude fat, and energy bomb calorimetry by the AOAC Ž
. Ž
. 1990 procedures. Nitrogen was determined by the method of Havilah et al. 1977
Ž .
crude protein s N = 6.25 . Amino acids were determined by the method of Cohen et al. Ž
. 1989 and analysed following acid hydrolysis using high pressure liquid chromatogra-
Ž .
phy and Waters Pico-Tag Waters, Lane Cove, NSW, Australia . Sulphur amino acids were determined separately following performic acid digestion, and tryptophan, which is
Ž .
lost during acid hydrolysis Cohen et al., 1989 , was not analysed. Chromic oxide was Ž
. determined by the method described in Scott 1978 .
2.4. Experiment 1, digestibility and aÕailability Ž .
Ž . Four meat products, beef and bone meal B , lamb and bone meal L , mixed meat
Ž . Ž .
w
meal reduced ash, no bones M , and Provine , were evaluated in this experiment
Ž .
Ž .
Ž Table 1 . The other components of experimental diets Table 2 were SP35 at about
. Ž
. 70 or 85 inclusion and chromic oxide 1 was used as an inert marker. SP35 was
also the control diet. Ž
. Digestibility tanks were 170-l cylindro-conical tanks conical base sloped at 358 .
Ž .
Their design and operation are described by Allan et al. 1999 . Ž
y1
. Fish were stocked 8 fish tank
7 days before faeces were collected to allow for acclimatisation to experimental conditions. For 4 days, fish were fed SP35 and then 3
days before faeces were collected, fish were fed their respective experimental diets. Fish Ž
y1
. were fed to excess 10 body weight day
using automatic conveyor belt-type feeders
Table 1 Ž
. Analyses of meat meal test ingredients used in Experiment 1 dry basis
Nutrient Ingredient
w
Beef meal Lamb meal
Mixed meat Provine
Peruvian
a b
c d
e
Ž . Ž .
Ž . Ž .
B qbones L qbones
meal M P
fish meal Ž .
Protein 49.2
54.3 60.6
81.0 70.2
Ž . Fat
9.2 7.2
17.2 10.4
11.3
y1
Ž .
Energy MJ kg 16.1
16.2 23.5
25.7 20.9
Ž . Ash
36.0 34.5
12.1 3.0
17.6 Amino acids
Alanine 3.9
4.0 4.3
5.3 4.6
Arginine 3.9
4.3 4.5
6.8 5.1
Aspargine 3.3
3.8 4.9
6.9 6.2
Cystine 0.3
0.7 0.8
1.1 0.7
Glutamine 5.7
7.0 7.9
9.9 9.4
Glycine 7.7
6.7 6.6
7.9 4.8
Histidine 0.8
1.2 1.2
1.6 2.3
Isoleucine 1.3
1.8 2.1
3.7 3.5
Leucine 2.7
3.5 4.3
6.2 5.3
Lysine 2.5
3.5 3.7
4.9 5.5
Methionine 0.7
1.1 1.1
1.6 2.0
Phenylalanine 1.5
1.9 2.3
3.4 2.9
Proline 5.0
4.6 4.5
5.2 3.5
Threonine 1.6
2.1 2.6
3.6 3.2
Tyrosine 1.1
1.5 1.9
3.0 2.3
Serine 2.1
2.4 3.0
3.6 3.0
Valine 2.0
2.4 3.0
4.3 3.7
a
Supplied by Beef City, Toowoomba QLD, Australia.
b
Supplied by Fletcher International, Dubbo NSW, Australia. After lamb meal was used in the growth experiment at GRC, Fletchers International raised the price of lamb meal to 799rt as a new export market
was identified for this product.
c
Supplied by Midco, Maxwell NSW, Australia.
d
Supplied by Aspen Technology, Preston VIC, Australia.
e
Analysed from previous experiment.
Table 2 Ž
. Formulation of diets used in Experiment 1 dry basis
Ingredient Treatment
1 2
3 4
5 6
7 8
9
a
Ž .
Reference diet SP35 99.0
84.2 69.3
84.2 69.3
84.2 69.3
84.2 69.3
Ž .
Beef meal with bones –
14.8 29.7
– –
– –
– –
Ž .
Lamb meal with bones –
– –
14.8 29.7
– –
– –
Mixed meat meal –
– –
– –
14.8 29.7
– –
w
Provine –
– –
– –
– –
14.8 29.7
Chromic oxide 1.0
1.0 1.0
1.0 1.0
1.0 1.0
1.0 1.0
a
Formulation and composition of SP35 described in Table 3.
for 3 h each day from 0830 to 1130 h. Faecal samples were collected by settlement as Ž
. described by Allan et al. 1999 .
Ž .
The indirect method of Cho and Kaushik 1990 was used to calculate apparent Ž
. Ž
. digestibility or availability coefficients, with chromic oxide 1 dry basis as the inert
indicator. The ADCs for energy, protein and the AACs for essential amino acids in Ž
. experimental diets were calculated as described by Cho and Kaushik 1990 . Then,
Ž . apparent digestibility for dry matter, protein and energy, and apparent availability
Ž . for amino acids for test ingredients were calculated using the methods described by
Ž .
Sugiura et al. 1998 . 2.5. Experiment 2, growth
Using the digestibility and availability data obtained from Experiment 1, five diets with approximately the same levels of digestible energy and protein were formulated
Ž using a linear least-cost diet formulation computer program ‘Feedmania’ Mania Soft-
. Ž .
ware, Brisbane, Australia Table 3 . The meat meal products considered for the least
cost diet formulation were Provine
w
, lamb meal, and beef meal. Beef meal was not selected in the formulation by the least-cost program. The mixed meat meal product was
excluded as it is not yet commercially available. The experimental diets comprised a Ž
. reference diet SP35 with 27 fish meal and three others with 13, 6 or 0 fish
meal with the remainder replaced by a mixture of Provine
w
and lamb meal. For these three diets,
L
-lysine,
DL
-methionine and
L
-threonine were added if necessary to adjust the content of amino acids to that of the reference diet. The fifth diet was formulated
without fish meal or added synthetic amino acids. Experimental tanks were 10 000-l in capacity. Recirculated freshwater was filtered
through a rapid rate sand filter before being supplied to experimental tanks at a flow rate of 17 l min
y1
. Effluent water from each tank flowed from the bottom of the tank via a 50 mm diameter drain leading to an external stand pipe. Overflow water from the
standpipes was collected and ducted into a 7000-l reservoir passed through a 1 m
3
biological filter, pumped through a sand filter and then recirculated to the fish tanks. Each tank was aerated using two air-stone diffusers.
Table 3 Ž
. Formulation of SP35 Diet 1 and other experimental diets to evaluate meat meal as a substitute for fish meal
Ž .
in rations for silver perch Experiment 2 Ž .
Ingredient Diet
Ingredient cost
a
Ž .
AUSrt 1
2 3
4 5
Ž .
Fish meal Danish 27.0
13.0 6.0
0.0 0.0
1300 Soybean meal
20.0 20.0
20.0 20.0
20.0 495
Blood meal 2.0
3.4 3.0
3.9 3.9
900 Lamb meal
– 6.3
7.8 8.9
8.9 453
w
Provine –
9.1 14.7
18.1 18.9
775 Wheat
26.9 22.1
21.9 22.0
22.2 180
Sorghum 11.0
11.0 11.0
11.0 11.0
180 Corn gluten meal
4.0 6.0
6.0 6.0
6.0 700
Millrun 2.0
2.0 2.0
2.0 2.0
190 Fish oil
1.0 1.1
1.1 1.1
1.1 800
DL
-Methionine 0.2
0.3 0.4
0.5 –
5500
L
-Lysine –
0.1 0.2
0.3 –
4250
L
-Threonine –
– 0.7
0.1 –
8500 Di-calcium phosphate
2.0 1.7
1.9 2.0
2.0 610
b
Vitamin premix 1.0
1.0 1.0
1.0 1.0
4000
c
Mineral premix 3.0
3.0 3.0
3.0 3.0
4000 Diet ingredient cost AUDr t
756 699
727 652
607 Composition calculated
Ž . Digestible protein
32.1 34.0
34.1 34.1
34.0
y1
Ž .
Digestible energy MJ kg 13.0
13.4 13.3
13.2 13.3
Ž . Ash
6.9 7.5
7.5 7.5
7.5 Ž .
ADF 3.1
3.3 3.3
3.3 3.4
Ž . Fat
6.4 6.2
6.0 5.7
5.8 Ž .
Linolenic series fatty acids 0.3
0.3 0.3
0.3 0.3
Ž . Available arginine
2.0 2.1
2.1 2.1
2.1 Ž .
Available histidine 0.8
0.9 0.8
0.8 0.8
Ž . Available isoleucine
1.4 1.4
1.3 1.3
1.3 Ž .
Available leucine 2.9
3.1 3.0
3.0 3.0
Ž . Available lysine
2.1 2.2
2.0 2.0
1.8 Ž .
Available metqcys 1.4
1.4 1.4
1.4 0.9
Ž . Available pheqtyr
2.7 2.8
2.7 2.7
2.7 Ž .
Available threonine 1.4
1.4 1.4
1.4 1.3
Ž . Available valine
1.7 1.7
1.6 1.6
1.6
a
Diet ingredient cost does not include the cost of processing. Prices from NSW Agriculture, Sydney Retail Ž
. Feed Ingredient Prices or from commercial feed ingredient manufacturers, 1995 does not include freight .
b
Ž
y1
. Ž .
Ž .
Ž . Ž
y1
IU kg diet : retinol A , 8000; cholecalciferol D3 , 1000; a-tocopheryl acetate E , 125; mg kg
. Ž . Ž
. Ž
. diet : ascorbic acid C
ROVIMIX STAY C 25; Roche , 1000; biotin 2 , 1; d-calcium panothenate, 55; Ž
. calcium propionate, 250; choline chloride, 1500; cyanocobalamin B12 , 0.02; ethoxyquin, 150; folic acid, 4;
Ž .
Ž .
menadione sodium bisulphite K3 , 16.5; myo-inositol, 600; nicotinamide, 200; pyridoxine B6 , 15; riboflavin Ž
. Ž
. B2 , 25.2; thiamin HCl B1 , 10.
c
Ž
y1
. mg kg
diet : calcium carbonate, 7500; manganese sulphate, 300; zinc sulphate, 700; copper sulphate, 60; ferrous sulphate, 500; sodium chloride, 7500; potassium iodate, 2.
Ž w
x .
Eighty-five silver perch were stocked November spring 1995 into each of the 15 Ž
. 10 000-l tanks three replicate tanks for each diet . Fish were fed by hand to satiation
twice daily at 0800 and 1500 h, 7 days a week, for a period of 65 days. Waste feed was minimised by observing fish during feeding and when fish lost their appetite feeding
Ž w
x .
was ceased. Fish were then harvested February late summer 1996 and survival mean Ž
. weight increment and feed conversion ratio FCR were calculated from each tank.
Proximate analyses on the whole body composition of five fish randomly selected Ž
. from each tank were also conducted and the indices for protein deposition PD , fat
Ž .
Ž .
Ž .
deposition FD , protein efficiency ratio PER , protein retention efficiency PRE , and Ž
. energy retention efficiency ERE were calculated.
2.6. Statistical analysis Ž
. The digestibility and availability experiment Experiment 1 was designed for analy-
Ž .
sis using two-factor ANOVA with meat products B, L, M or P as the first factor Ž
. Ž
. Ž
. fixed and inclusion level 15 or 30 as the second factor also fixed . Single factor
ANOVA was used to assess the difference between proximate body composition of fish fed experimental diets.
Ž .
The growth experiment Experiment 2 was designed for analysis using single-factor Ž
. ANOVA. Homogeneity of variances was assessed using Cochran’s Test Winer, 1971
and comparison between means were made using Student–Newman–Kuels multiple- range test. Differences between means were considered significant at P - 0.05. Unless
Ž .
otherwise stated, all results appear as mean standard error of mean n s 3 .
3. Results
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