Livestock Research for Rural Development 32 (5) 2020 | LRRD Search | LRRD Misssion | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
An experiment was carried out at the experimental farm of Tra Vinh University to evaluate the effects of replacing fish meal by fresh sea fish by-product (FSFB) on growth performance of ducks. Crossbred ducks (Cherry Valey x Pekin) at four weeks of age were arranged in a completely randomized design with 5 treatments and 3 replicates, with ten birds (balanced for sex) in each experimental unit. The treatments were levels of FSFB replacing fish meal protein at levels of 0, 25, 50, 75 and 100% corresponding to the FSFB0, FSFB25, FSFB50, FSFB75 and FSFB100 treatments.
Replacing fish meal with sea fish byproduct led improvements in live weight gain and feed conversion up to the level of 75% replacement of the fish meal on a protein basis. It is suggested that the increased energy content of the sea fish byproduct, due to higher oil content may be compromised by the decreasing ratio of lysine (and other essential amino acids), relative to the increased energy status of the sea fish broduct as compared wiih fish meal. Carcass traits were not affected by the feedimg of sea fish byproduct.
It is suggested that diets rich in sea fish byproduct may benefit from increased levels of supplementation with lysine and perhaps other essential amino acids.
Key words: amino acids, byproducts, Mekomg delta, Vietnam
Ducks are raised throughout Vietnam but are concentrated in the Mekong Delta. They are managed in scavenging systems, around gardens, along canals and in the rice fields post-harvest. In these systems ducks consume locally available feeds and are normally only supplemented with small amounts of rice. They are also raised in confinement on conventional feeds, often with little profit for producers, because of the high price especially of protein-rich ingrediets.
In the Mekong Delta generally, especially in Tra Vinh province, sea fish production has considerably increased. Sea fish from coastal estuaries in Tra Vinh province are estimated to produce 71,745 tonnes/year (Chi Cuc Thuy San Tra Vinh 2019), of which approximately 30% is by-product containing 45% protein.
The present study aimed to evaluate the use of this byproduct to replace protein from fish meal in diets of crossbred ducks.
The experiment was carried out at the Experimental farm of Tra Vinh University in Tra Vinh City from July to October in 2018.
One hundred and fifty crossbred ducks (Cherry Valey x Pekin) at four weeks of age was arranged in a completely randomized design with 5 treatments and 3 replicates and ten ducks balanced for sex in each experimental unit. The treatments were levels of fresh sea fish by-product (FSFB) replacing fish meal protein at levels of 0, 25, 50, 75 and 100% corresponding to FSFB0, FSFB25, FSFB50, FSFB75 and FSFB100. The control (FSFB0) treatment contained maize (57%), rice bran (28.8%) and fish meal (14.2%). Water spinach was supplied at the same level of 30g/d (fresh weight/duck/day to supply fibre and vitamins.
The experimental period was for six weeks. After selecting the ducklings, they were brooded and fed a conventional diet with 20% CP, 12.5 ME MJ/kg from 1 to 28 days of age. They were vaccinated against Duck Plague and Influenza at two and three weeks of age.
Maize, rice bran and fish meal were bought at a local feed store in Tra Vinh province. Fresh sea fish byproduct (FSFB) plus small size fish were the residues after processing the sea fish for human consumption. It was brought daily from the fish processing factory in Tra Vinh province and was finely ground before feeding.
The experimental diets were offered in mash form. The chemical composition of the feed ingredients of the diets and essential amino acids are shown in Table 1, 2 and 3.
Table 1. Chemical composition of the feed ingredients in the experimental diets |
|||||
Maize |
Rice |
Fish |
Water |
Sea fish |
|
DM, % |
89.6 |
90.7 |
89.0 |
9.55 |
30.8 |
As % in DM |
|||||
OM |
97.5 |
90.3 |
79.0 |
87.7 |
90.9 |
CP |
9.26 |
11.6 |
59.2 |
23.2 |
44.7 |
EE |
3.80 |
11.5 |
11.3 |
9.89 |
31.5 |
CF |
2.90 |
10.5 |
0.80 |
14.7 |
0.90 |
NDF |
24.5 |
28.2 |
14.6 |
38.3 |
4.10 |
Ash |
2.50 |
9.70 |
21.0 |
12.3 |
9.10 |
Ca |
0.16 |
0.51 |
5.64 |
0.12 |
4.15 |
P |
0.60 |
1.31 |
3.19 |
0.05 |
1.92 |
Dry matter (DM), Organic matter (OM), crude protein (CP), crude fiber (CF), ether extract (EE) neutral detergent fiber (NDF) |
Table 2. Essential amino acid composition of the feed ingredients in the experiment |
||||
% |
Maize |
Rice bran |
Fish meal |
Sea fish by-product |
Lysine |
0.27 |
0.56 |
4.33 |
2.67 |
Methionine |
0.17 |
0.25 |
1.45 |
0.90 |
Threonine |
0.39 |
0.52 |
2.77 |
0.21 |
Histidine |
0.33 |
0.37 |
1.42 |
0.21 |
Leucine |
1.11 |
0.91 |
4.51 |
3.94 |
Valine |
0.48 |
0.73 |
2.98 |
1.97 |
Table 3. Feed ingredient composition and chemical composition of diets (%, DM) |
|||||
Item, % |
FSFB0 |
FSFB25 |
FSFB50 |
FSFB75 |
FSFB100 |
Maize |
57.0 |
60.2 |
55.1 |
55.7 |
53.0 |
Rice bran |
28.8 |
24.0 |
27.9 |
25.5 |
26.8 |
Fish meal |
14.2 |
11.0 |
7.30 |
3.80 |
- |
Sea fish by-product |
- |
4.80 |
9.70 |
15.0 |
20.2 |
Composition, % in DM except for DM which is on air-dry basis |
|||||
DM |
89.8 |
82.1 |
75.8 |
69.8 |
64.9 |
CP |
17.0 |
17.0 |
17.0 |
17.0 |
17.0 |
EE |
7.08 |
7.82 |
9.18 |
10.8 |
12.9 |
CF |
4.80 |
4.39 |
4.67 |
4.75 |
4.54 |
NDF |
24.2 |
23.4 |
22.9 |
22.3 |
21.7 |
Methionine |
0.40 |
0.39 |
0.38 |
0.37 |
0.36 |
Lysine |
0.99 |
0.96 |
0.93 |
0.90 |
0.87 |
Ca, |
1.04 |
1.04 |
1.05 |
1.05 |
1.06 |
P, total, % |
1.22 |
1.16 |
1.16 |
1.12 |
1.10 |
The birds were housed in pens separated with nylon net, in a shed with thatched roof and sandy soil floors covered with rice straw. Average density was four birds per m2. The excreta and litter were removed every week. The ducks had free access to water and were offered feed twice a day, at 8:00h and 4:00h. Refusals were collected and weighed daily each morning for calculating feed intake.
Feed ingredients were analyzed according to procedures of AOAC (1990) and (for NDF) according to Van Soest et al 1991). Representative samples of feed ingredients were analyzed for amino acid composition (Amino Quant 1990).
The ducks were weighed individually, at the beginning, weekly and at the end of trial. At the end of the experiment 30 representative ducks (one male and one female from each experimental unit), were slaughtered for carcass evaluation (Bui Huu Doan et al 2011). Breast muscles were separated, weighed, and analyzed for DM, OM, CP, EE, Ash by standard methods (AOAC 1990).
The data were analyzed by the General Linear Model of the ANOVA program of of Minitab Reference Manual Release 16.1.0 (Minitab 2010). Sources of variation were diets and error.
The responses of the ducks (in feed intake, liveweight gain and DM feed conversion), showed curvilinear responses to replacement of fish meal protein by protein from sea fish byproduct (Table 4; Figures 1-3). Performance was improved as the replacemt rate increased to 70-80%, followed by a deterioration in response when all the fish meal protein was replaced by protein from sea fish byproduct.
Table 4. Mean values of feed intake, weight gain and feed conversion for ducks fed fish meal replaced by sea fish byproduct (as % of the protein [CP]) |
||||||||
Item |
Fish meal CP replaced by sea fish byproduct CP, % |
SEM |
p |
|||||
0 |
25 |
50 |
75 |
100 |
||||
Live weight, g |
||||||||
Initial |
912 |
919 |
913 |
907 |
911 |
23.2 |
0.997 |
|
Final |
2,117b |
2,230ab |
2,379a |
2,302ab |
2,267ab |
41.2 |
0.013 |
|
Daily gain |
28.7b |
31.2ab |
34.9a |
33.2a |
32.3ab |
0.90 |
0.007 |
|
DM intake, g/d |
154 |
157 |
160 |
164 |
155 |
3.55 |
0.386 |
|
FCR# |
5.37 |
5.04 |
4.61 |
4.92 |
4.82 |
0.17 |
0.084 |
|
ab Means in the same row without common superscript differ at p<0.05 #DM intake/LW gain |
Figure 1. Effect on feed intake of ducks of replacing fish meal by sea fish byproduct |
Figure 2. Effect on live weight gain of ducks of replacing fish meal by sea fish byproduct |
Figure 3. Effect on feed conversion of ducks of replacing fish meal by sea fish byproduct |
There were no differences in carcass traits due to dietar treatments other then weight of carcass which reflected the treatment effectson live weight gain (Tables 5 and 6).
Table 5. Mean values for slaughter weight, carcass traits and internal organs of ducks |
||||||||
Item |
Fish meal CP replaced by sea fish byproduct CP, % |
SEM |
p |
|||||
0 |
25 |
50 |
75 |
100 |
||||
Live weight, g |
2.147b |
2.232ab |
2.355a |
2.340a |
2.285ab |
38.8 |
0.020 |
|
Carcass weight, g |
1.390b |
1.460ab |
1.515a |
1.472ab |
1.425b |
19.3 |
0.010 |
|
Carcass, % |
64.7 |
65.4 |
64.3 |
62.9 |
62.3 |
2.46 |
0.677 |
|
Breast muscle, g |
232b |
248a |
258a |
250a |
247a |
2.75 |
0.002 |
|
Breast muscle, % |
16.7 |
16.9 |
17.0 |
16.0 |
17.3 |
0.75 |
0.519 |
|
Thigh muscle, g |
171b |
177 ab |
185 a |
179 ab |
169 b |
2.46 |
0.003 |
|
Thigh muscle, % |
12.3 |
12.1 |
12.2 |
12.2 |
11.9 |
0.32 |
0.638 |
|
Liver, g |
58.4 |
57.8 |
65.6 |
63.6 |
61.9 |
3.68 |
0.542 |
|
Gizzard, g |
77.5 |
77.9 |
79.0 |
77.1 |
76.6 |
5.42 |
0.998 |
|
Heart, g |
16.1 |
16.9 |
15.7 |
16.0 |
15.8 |
0.82 |
0.856 |
|
Abdominal fat, g |
190 |
186 |
189 |
188 |
187 |
2.52 |
0.827 |
|
Small intestine, cm |
15.8 |
14.6 |
15.0 |
16.3 |
16.0 |
0.67 |
0.409 |
|
Large intestine, cm |
15.3 |
15.4 |
16.4 |
20.0 |
16.6 |
3.19 |
0.833 |
|
Cecum, cm |
17.4 |
17.2 |
19.4 |
17.7 |
17.5 |
0.59 |
0.150 |
|
ab Means in the same row without common superscript differ at p<0.05 |
The trends in improvement of performance traits as far as 75% replacement of the protein in fish meal by that in sea fish byproduct, followed by a decline at 100% replacement, could be related to the composition of the sea fish byproduct which had three times more ether extract (31.5%) than the fish meal (11.3%). By comparison, the lysine content of the protein in the sea fish byproduct was 20% lower (6.0% of the protein compared with 7.3% of the protein in the fish meal (Tables 1-3). Thus the improvement in dietary eenergy status of the diet (due to increase in ether extract content of the sea fish byproduct) could have been cmpromised at the highest rate of substitution, due to the declining proportion of lysine (and probably other essential amino acids) relative to the increased dietary ether extract caused by the substitution of the sea fish byprodct for the fish meal. It can be expected that diets rich in sea fish byproduct would benefit from increased levels of supplementation with lysine and perhaps other essential amino acids such as methionine.
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Received 11 March 2020; Accepted 21 March 2020; Published 1 May 2020