Peas in Tilapia Feed Formulations
By
Howard Hill, AgriSource Co. Ltd.
Timothy Welsh, USA Dry Pea and Lentil Council
The use of feed peas, Pisum sativum, as a substitute for other vegetable sources of protein
and energy has been well researched and proven (Welsh, 2002; Welsh and Creswell, 2003).
Peas have long been known as an alternative crude protein source, as well as a source of
energy and starch, in other animal feeds (Tables 1 and 2).
Small-scale trials using feed pea as a protein substitute have indicated that, based on prices of
soybean meal and fishmeal, peas can be used as an economic substitute. Further trial work
has identified peas as an effective pellet binder (Hill & Welsh, 2006) and showed that the
addition of peas to an aqua formulation had a binding effect which improved the fines and
water stability of feed pellets. Plant breeding of peas is carried out using traditional methods,
which further enhances the value of feed peas as a non-GMO ingredient.
Table 1: Proximate composition of feed peas
Nutrient in % as is
Range
Moisture
Crude Protein
Crude Fat
Crude Fiber
Ash
Gross energy (kcal/kg)
(Source: Allan 1997)
10.0 - 11.0
22.0 - 25.0
1.0 - 1.5
4.0 - 7.0
3.0 - 3.5
4000-4200
Table 2: Carbohydrates in feed peas
Carbohydrate type
Starch
Cellulose
Sugar
Oligosaccharides
Crude fiber
Acid Detergent Fiber
Neutral Detergent Fiber
%
34.8 –54.1
2.4 - 7.9
1.0 - 5.7
3.7
4.9 - 6.3
6.0 - 8.7
10.0 - 12.0
The USA Dry Pea and Lentil Council contracted research with a large feed miller in the
Philippines in order to conduct replicated tilapia, Oreochromis niloticus, feeding trials utilizing
pea inclusion at all growth stages from starter to final harvest. The trial was done using cages
on Sampaloc Lake, San Pablo City.
The objectives of the trials were:
1). To compare Average Daily Gain (ADG) and feed efficiency, measured by Feed
Consumption (FC) and Feed Conversion Ratio (FCR)
2). To measure fish dimensions (length and width) in order to establish a possible
correlation between feed and size
Nile tilapia figerlings were obtained from the Sandigan Cooperative, Samplac Lake, San Paulo.
The fingerlings were put into 6 cages measuring 10 x 10 x 7 meters each, with the preparation
and setup following standard practice. The 6 cages allowed for 3 replications of two
treatments. Each of the 6 cages received 5,000 fingerlings. Before the experiment, the
fingerlings received a standard fry mash for 24 days. By the start of the experiment, the fish
were 45 days old and weighed 14 grams. Up to this point, all fingerlings were kept in the same
conditions and received the same standard fry mash; therefore, similar weight gain and losses
can be assumed. The trial had 3 phases: Starter, Juvenile and Adult. Feeding with the starter
formulation containing 12% pea lasted 35 days. Feeding of the juvenile formulation containing
20% pea lasted 22 days, while an adult formulation containing 25% pea was fed for 36 days.
(Table 3)
Table 3: Trial Feeds and Treatments with Pea Content
Feeding Days
35
Formulation
Starter
22
Juvenile
36
Adult
Treatment
T1
T2
T1
T2
T1
T2
Component
12% Peas
No Peas
20% Peas
No peas
25% Peas
No Peas
The formulations were designed to provide similar nutrients, based on combinations of
different raw materials. Composition and prices of the major raw materials are shown in Table
4. Peas mainly replaced soybean meal and materials that contain energy, such as high fat rice
bran or tapioca. Ingredient prices are rounded figures in $US, and based on market survey
information for prevailing prices in the Philippines during March 2005 (USDPLC).
Table 4: Feed Composition, Nutrient Analysis, and Cost
Starter
Ingredients*
Cost
$US/
mt
Peas
225
Corn, yellow
165
Pollard/Midds
150
Rice Bran HF
170
Tapioca Pellets
135
Corn GM 60%CP
485
SBM 47% CP
310
Other materials
Total Cost ($US/mt)
Analysis
Moisture
Crude Protein
Crude Fat
Crude Fiber
Ash
Juvenile
Adult
T1
T2
T1
T2
T1
T2
12 % Peas
No Peas
20% Peas
No Peas
25% Peas
No Peas
%
Cost
%
12
10
27
17
Cost
10
17
3
5
11
19
6
43
26
29
133
105
316
6
47
26
29
146
106
317
%
Cost
20
6
6
15
45
10
9
26
36
17
112
62
264
%
Cost
10
6
15
7
17
9
26
10
44
18
136
69
267
%
Cost
25
56
%
Cost
20
20
30
34
25
20
11
38
34
15
24
11
76
42
238
34
10
104
43
234
%
%
%
%
%
%
11.0
35.1
5.2
3.7
6.8
11.2
35.0
6.4
3.7
7.2
10.8
28.8
6.2
4.8
6.7
11.3
28.6
6.4
4.4
7.3
10.0
13.0
25.2
25.0
5.9
6.2
5.5
5.5
8.2
8.7
* Formulas used are solely for demonstration purposes and based on analysis of the specific materials used in the trial and are not applicable
to raw materials with different composition. Other materials were similar in their inclusion and added to obtain similar nutrient composition in all
treatments.
Results – Dimension – Size of fish
Sampling within this “live” type situation provides some difficulties, with accurate
measurements only able to be obtained at the start and at harvest. Only small sample sizes
were taken in the intermediate phases between starter and juvenile, and juvenile and adult.
Fish length and width measurements can be seen in Table 5. There was no significant
difference between the treatments.
Table 5: Length and Width Measurements of Fish
T1 – with Peas
Length / Width cm
T2 - without Peas
Length / Width cm
L 7.0 - 9.0
n = 15 AVG = 7.6
W 3.0 - 4.5
n = 15 AVG = 3.5
L 7.0 - 9.0
n = 15 AVG = 7.6
W 3.0 - 4.5
n = 15 AVG = 3.5
14 days from start of culture
L 10.0 - 12.0
n = 10 AVG = 10.8
W 4.0 - 5.0
n = 10 AVG = 4.5
L 10.0 - 12.0
n = 10 AVG = 10.5
W 4.0 - 5.0
n = 10 AVG = 4.6
93 days from start of culture (harvest)
L 17.5 - 20.0
n = 14 AVG = 19.1
W 7.5 - 9.5
n = 14 AVG = 8.8
L 17.0 - 21.5
n = 16 AVG = 19.1
W 7.5 - 9.5
n = 16 AVG = 8.5
Gain during trial
ΔL = 11.5, ΔW = 5.3
ΔL = 11.5, ΔW = 5.0
Stage
Start of culture (14 g)
L = Length, W = Width
Results – Weights
T1 pea-fed tilapia had a slightly higher initial weight (2.5% or 1.4 kg; see Table 6) compared to
the non-pea group. This difference remained constant till harvest, when T1 final weight was
18.3 kg higher, showing an additional 16.6 kg weight gain. The Average Daily Gain (ADG) was
7.4 kg for pea-fed tilapia and 7.2 kg for non-pea group. These results were achieved with the
same level of total feed consumption of 15.1 kg/day. The feed conversion ratio (FCR) for T1
with pea was slightly (numerically +2.5%) better than T2 with no pea inclusion.
Table 6: Estimated Bio Mass Change & Final Growth Performance Bio-Mass
Treatment
Feeding
days
Init. Wt.
kg
Final Wt.
kg
Weight
Gain kg
ADG
kg
Total FC
kg
ADFC
kg/day
FCR
T1 Replicate 1
T1 Replicate 2
T1 Replicate 3
93
93
93
48.2
61.5
61.5
835.0
711.0
696.0
786.8
649.5
634.5
8.5
7.0
6.8
1368.9
1426.2
1426.2
14.7
15.3
15.3
1.74
2.20
2.25
93
57.1
747.3
690.3
7.4
1407.1
15.1
2.04
T2 Replicate 1
T2 Replicate 2
T2 Replicate 3
93
93
93
44.0
61.5
61.5
660.5
805.5
721.0
616.5
744.0
659.5
6.6
8.0
7.1
1368.4
1426.2
1426.2
14.7
15.3
15.3
2.22
1.92
2.16
T2 - Without Peas
93
55.7
729.0
673.3
7.2
1406.9
15.1
2.09
T1 – With Peas
Average
Average
The evaluation of the results has been limited to a comparison of numerical averages because
the small number of observations (3 replicates) limits statistical comparisons.
The total feed cost of the various formulations can be seen in Table 7. Some advantages can
be seen in the pea formulations for starter and juvenile, which equate to some reductions in
the overall cost of feed through these stages. At the adult stage the pea formulation has a
higher cost, which equates to an additional cost. Over the entire feeding program, the
additional cost for using pea within the formulation equates to $US1.94, or 0.5% more
expensive than the non-pea formulation. In this trial however, the extra 16.6 kg harvested
covered the extra cost.
Table 7: Cost of Feed
Starter
T1
T2
12% Peas
Juvenile
T1
T2
20% Peas
Adult
T1
25% Peas
T2
Total
T1
With Peas
T2
Cost
($US/mt)
kg Used
316
257.3
317
257.2
264
293
267
293
238
856.7
234
856.7
1407.0
1406.9
Cost
($US/mt)
81.29
81.48
77.33
78.14
203.80
200.87
362.43
360.49
Conclusions
It can be concluded that the inclusion of peas into the formulations gave similar results as
formulations based entirely on soybean meal as the major protein source. Depending on the
cost of peas, they can be a viable alternative to soybean meal, especially in times where
soybean meal is expensive.
Increasingly, trial results are showing that feed pea can act as a plant protein substitute in fish
feeds without affecting growth performance.
References
Allan, G.L., 1997. Potential for pulses in aquaculture systems. Proceedings of International
Food Legume Research Conference III, Sept. 22–26, 1997, Adelaide, Australia. 13 pp.
Welsh, Timothy; Feed Pea Offers Attractive Opportunities As An Aqua Feed Ingredient, Aqua
Feed International, October-December 2002, pp 22-24
Welsh, Timothy and Creswell, David; Cheaper Plant protein Source for Shrimp, Tilapia and
Milkfish, Asian Aquaculture Magazine, September/October 2003, pp 23-25.