Effect of replacing dry fish with
cassava leaf meal on the growth rate of Local and Pekin ducks and on
digestibility
Loan Chhum Phithand Chey Montha*
Faculty of Animal Science and Veterinary
Medicine,
Royal University of Agriculture, Phnom
Penh, Cambodia chphloan@yahoo.com
* National School of Agriculture, Prek
Leap
Abstract
Cassava leaves are
normally wasted after harvesting, but can be used as animal feed, which can
reduce the feed cost and increase the income of the farmer. The aim of the two
experiments in this study was to compare the responses to diets containing dried
cassava leaves of local and Pekin ducks with respect to growth and diet
digestibility. The experiments were conducted in the Animal Experimental Station
of the Royal University of Agriculture, Cambodia. In total 300 ducks, 150 local
breed and 150 Pekin ducks, from ten days-old and with mean initial weights of
around 180g (local breed) and 190g (Pekin) were allocated using a Completely
Randomized Design into 5 groups with three replications. The growth experiment
lasted for 42 days. All birds were given a basal diet containing maize, rice
bran, soybean, dry fish, di-calcium phosphate, a vitamin premix, and dry cassava
leaves included at 0 (CL0), 3.5 (CL3.5), 7.0 (CL7), 10.0 (CL10) and 15.0% (CL15)
of the diet. All diets were offered ad-libitum. In the first period (from 1st
to 3rd week) the diets contained 22% crude protein (CP) and in
the second period (from 3rd to 6th week) 20% CP.
In the local breed
feed intake increased from 82.7 g/day in CL0 to 121 g/day in CL10, and then
decreased to 101 g/day in CL15 (P<0.01), and in the Pekin from 117 g/day in CL0
to 171 g/day in CL10, and then decreased to 140 g/day in CL15 (P<0.001). There
was no effect of treatment on average daily gain (ADG) (P>0.05), but the ADG of
the Pekin ducks (55.2 g/day) was higher than of the local breed (23.7 g/day).
Feed conversion ratio (FCR) was poorer in the local breed than in the Pekin, but
there was no effect of treatment on FCR. Digestibility
coefficients of dry matter (DM), organic matter (OM) and nitrogen (N) were
lowest for CL0 (P<0.05), and highest for CL3.5, CL7 and CL10. There was no
difference in DM, OM and N digestibility between the two breeds (P>0.05).
N-retention was lowest in CL0 (P<0.001), but there was no difference among the
other treatments (P>0.05), and was higher in the Pekin compared to the local
breed.
It is concluded
that dried cassava leaves can be included at up to 15% in the diets of growing
local and Pekin ducks without affecting growth rate or feed conversion.
Keywords: Cassava leaves, local ducks, digestibility, growth rate, Pekin
ducks
Introduction
Ducks are birds
that are raised to provide meat and eggs for human food. Shortage of cereals has
recently been a serious issue in several regions of the world, and the use of
cereal products and soybeans as livestock feeds is increasingly unjustified in
economic terms. Therefore, there is a need to exploit cheaper energy and protein
sources, to replace expensive grains for livestock production, and to relieve
the food-feed competition in the future. In this respect it is important to
utilize locally available feed resources and by-products from agricultural
industries to replace more expensive feed components. Cassava leaf meal is rich
in protein, carotene and minerals and for this reason is considered a potential
source of protein in tropical countries (Preston, 2001; Bui Van Chinh and Le
Viet Ly, 2001). Local cassava leaf meal in Cambodia was found to have a crude
protein content of 30.2% (RUA Laboratory, 2005). The disadvantage of fresh
cassava leaves is that their content of hydrocyanic acid can be very high, which
can make fresh cassava top leaves unsafe as an ingredient in poultry feed. It
was found that ensiling and drying cassava leaves can significantly reduce their
HCN content (Bui Van Chinh and Le Viet Ly,2001).
Materials and methods
Experiment I: Effect of including cassava leaf meal on the feed intake
and growth rate of local and Pekin ducks
The
experiment was carried out in the Research Station of the Royal University
of Agriculture, located in Dongkor District, Phnom Penh, Cambodia.
The pens used were 3m long, 1.5m wide and
1m high and made of iron nets and the floors were covered by 10 cm of
rice husks (Photos 1 and 2). Ponds and outside runs were provided. Each
pen (replication) was equipped with one drinker, one feeder, and
one110-watt electric light bulb.
Experimental treatments and design
In total
150 Pekin and 150 local ducks at ten days of age were divided randomly into
5 treatments with 3 replications per treatment. The dietary treatments were:
a basal diet (CL0), and then inclusion of 3.5 (CL3.5), 7.0 (CL7), 10.0
(CL10) and 15.0% (CL15) dried cassava leaves. The composition of the
experimental ingredients and diets is shown in Tables 1 and 2. The diets
were formulated to contain 22% CP from 1-3 weeks of age, and 20% CP from 4-6
weeks to meet requirements (Pingel, 1985).
Table 1: Chemical composition of the
diet ingredients
Ingredient %
DM
CP
ME, Kcal/kg
Ca
P
Maize meal
87.7a
8.75 a
3350c
0.02c
0.28c
Rice bran
91.1a
8.98a
2980c
0.07c
0.22c
Dried fish
88.2a
38.3a
3223d
5.0e
2.5e
Soya bean
88.8a
39.4a
3300c
0.25c
0.58c
Dried cassava leaves
90.2a
27.5a
2800c
0.37b
0.58b
DCP
0
0
0
23-26d
18-21d
Snail shell
0
0
0
30d
0
Source: (a) Laboratory of
Animal Feedstuff Analysis of RUA (2004); (b) Devendra
(1977);
(c)
NRC (1994); (d) Chea Neng (1996); (e)
Smith (2001).
Table 2: Ingredient and chemical
composition of the diets (1-3 weeks)
Ingredient (%)
Treatment
CL0
CL3.5
CL7
CL10
CL15
Maize meal
37.5
36.6
35.7
34.7
33.7
Rice bran
16.1
15.7
15.3
14.9
14.5
Dried fish
17.8
17.1
14.1
10.9
7.47
Soya bean meal
26.6
25.1
25.9
26.6
27.4
Dried cassava leaves
0
3.43
7.05
10.9
15.0
Salt
0.5
0.5
0.5
0.5
0.5
Premix
1
1
1
1
1
Snail shell
0.5
0.5
0.5
0.5
0.5
Total
100
100
100
100
100
Nutritive value
Crude protein (%)
22
22
22
22
22
ME (kcal/kg)
3187
3075
3116
3141
3124
Ca (%)
1.16
1.14
1.00
0.86
0.70
P (%)
0.74
0.73
0.68
0.62
0.59
Table 3: Ingredient and chemical
composition of the diets (3-6 weeks)
Ingredient (%)
Treatment
CL0
CL3.5
CL7
CL10
CL15
Maize meal
42.2
41.5
40.7
39.0
38.1
Rice bran
18.1
17.8
17.5
16.7
16.4
Dried fish
13.2
10.7
7.96
5.16
2.13
Soya bean meal
24.5
50.2
25.9
26.8
27.6
Dried cassava leaves
0
2.90
5.97
9.29
12.8
Salt
0.5
0.5
0.5
0.5
0.5
Premix
1
1
1
0.5
0.5
Snail Shell
0.5
0.5
0.5
1
1
DCP
0
0
0
1
1
Total
100
100
100
100
100
Nutritive value
Crude protein (%)
20
20
20
20
20
ME (Kcal/kg)
3187
3175
3162
3117
3102
Ca (%)
0.93
0.82
0.69
0.77
0.78
P (%)
0.63
0.58
0.54
0.67
0.62
Photo 1. Pekin ducks
Photo 2. Local ducks
Data collection
Ducks were weighed
at ten-days old and weekly until the end of the experiment. Feed intake (FI),
feed remaining, temperature and mortality were recorded every day.
Experiment 2: Effect of including cassava leaf meal on diet digestibility in
local and Pekin ducks
Experimental
treatments and design
The
24 ducks were allocated according to a 5*2 factorial arrangement into the 5
dietary treatments used in experiment 1.with 2 breeds.
Management
The
ducks were kept in individual metabolism cages throughout the trial (50 days).
Feed residues and faeces were collected every morning in the last 5 days of the
10 day collection period (first 5days for diet adaptation and last 5 days for
data collection). The birds were fed three times daily at 7:00h, 11:00h and
17:00h.
Data collection and chemical
analysis
Feed residues and faeces were collected and weighed each morning of each period
before feed was offered and were kept frozen in plastic bags until chemical
analysis. At the end of each period, feed residues and faeces were mixed and
sub-samples taken for analysis of DM, N and Ash (AOAC 1990).
Statistical Analysis
The
data were subjected to analysis using ANOVA (Analysis of Variance) according to
the GLM in SPSS 11.0.
Results and
discussion
Experiment 1
The effects of treatment and breed on feed intake, growth performance, feed
conversion and mortality are shown in Table 4.
Table 4: Effect of including cassava
leaf meal on the feed intake (g/day) average daily gain, feed
conversion ratio (kg feed/kg gain) and mortality of local and Pekin
ducks
Parameter
Treatment
P-value
CL0
CL3.5
CL7
CL10
CL15
Initial
weight, g
Local
176
182
180
191
180
Pekin
207
204
215
210
213
Final weight, g
Local
1141
1187
1184
1148
1220
0.11
Pekin
2481
2472
2594
2490
2578
0.49
ADG, g
Local
23.0
23.9
23.9
22.7
24.8
0.81
Pekin
54.2
54.3
56.7
54.5
56.4
0.61
Intake, g/day
Local
82.7a
119b
119b
121b
101bc
0.01
Pekin
117a
178c
152bc
171c
140ab
0.00
FCR, kg/kg
Local
4.42
4.44
4.34
4.58
4.48
0.94
Pekin
3.29
3.22
3.24
3.34
3.53
0.67
Mortality,
percent
Local
3.4
3.6
3.4
3.4
6.7
Pekin
0
3.57
3.45
0
0
The
results in Table 4 show that there was no effect of dietary treatment on ADG,
which was over 100% higher for the Pekin than for the local breed. There was
also a significant difference in feed intake (p<0.01) between breeds, with the
mean intakes of the Pekin being around 50% higher than of the local breed, and
among treatments (P<0.01). In the local breed feed intake increased from 82.7
g/day in CL0 to 121 g/day in CL10, and then decreased to 101 g/day in CL15
(P<0.01), and in the Pekin from 117 g/day in CL0 to 171 g/day in CL10, and then
decreased to 140 g/day in CL15 (P<0.001). Feed conversion ratio was higher for
the local breed, and there was no effect of treatment on FCR (P>0.05). Mortality
was low, and not affected by treatment.
Experiment 2
The
results in Table 5 show that daily DM feed intake for the local breed duck
increased as the proportion of cassava leaves in the diet increased, reaching a
maximum on CL3.5 and CL10, before decreasing slightly (CL15), and a similar
trend was seen for the Pekin breed. The increased intake with inclusion levels
of up to 10% would have been a result of the decreasing energy density of the
diets, as the birds attempted to maintain a constant energy intake. With 15%
inclusion the bulkiness of the feed, and/or reduced palatability resulted in a
numerically lower intake, although the difference was not significant.
Dry
matter, organic matter and nitrogen digestibility and retention were highest in
the CL3.5, CL7 and CL10 diets and lowest in CL0. This is difficult to explain,
as cassava leaves contain high levels of fibre, but possibly could be a result
of the poor quality of the dried fish used. There was no difference between the
two breeds in diet digestibility (Table 6).
Table 5: Effect of dietary treatment on
daily feed intake (g/bird/day), dry matter and nutrient
digestibility (%) and daily nitrogen retention (g)
Parameter
Dietary treatment
P-value
CL0
CL3.5
CL7
CL10
CL15
DM intake, g /day
Local
91.5a
129b
131b
128b
114ab
0.01
Pekin
129a
196c
166bc
181bc
159b
0.00
Apparent digestibility, %
Dry matter
Local
73.3a
82.1c
80.4bc
79.4bc
77.0b
0.00
Pekin
75.4a
81.8b
83.2b
82.1b
71.6a
0.00
Nitrogen
Local
72.0a
83.0b
81.8b
80.5b
79.9b
0.03
Pekin
79.0ab
85.2c
86.4c
83.3bc
76.4a
0.00
Organic matter
Local
77.9a
85.7c
83.9ab
82.9ab
81.7b
0.00
Pekin
79.6a
84.8b
86.4b
84.9b
77.6a
0.00
N retention, g / day
Local
2.79a
4.94b
5.02b
4.22b
4.14b
0.00
Pekin
4.12a
7.59c
6.75bc
6.18b
5.52b
0.00
Table 6: Effect of breed on dry matter,
organic matter and nitrogen digestibility, %
Dry matter
Nitrogen
Organic matter
Local breed
78.2
79.8
82.4
Pekin breed
78.8
82.0
82.6
P-value
0.09
0.34
0.12
Conclusions
ˇInclusion of up to 15% of cassava
leaf meal in diets of local and Pekin ducks did not affect growth rate, even
though nutrient digestibility and nitrogen retention were higher compared to the
basal diet.
ˇFeed intake, growth performance and
nitrogen retention were significantly higher for the Pekin than for the local
breed
Acknowledgement
We
acknowledge the Research Committee of the Sida-SAREC MEKARN programme that
provided the research budget for this experiment carried out in RUA.
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