Citation of this paper |
90 growing snails (Archachatina marginata) of mean weight 64.3 ± 2.56g were used to investigate the nutritive potential of the peels of mango, plantain, cocoyam and pawpaw. Fresh pawpaw leaf served as the control. The study lasted 180 days.
The peels of the different fruits had similar composition but were considerable lower in DM, crude protein and ash content compared with the pawpaw leaves. Growth performance was adequate on all the fruit peels but was best with ripe pawpaw peel, which gave results comparable to the control diet of pawpaw leaves.
It is concluded that all the the peels were suitable for feeding as the sole diet of snails.
Key words: Carcass, fruits, peels, snail
The problem of animal protein intake in Nigeria has encouraged researchers to look for source of protein from animals which can be reared with little or no capital. Micro live stock such as snails, grass-cutters and rabbits have been domesticated and a lot of work is going on aimed to increase their availability at a reduced price. Snail farming is environmentally friendly and can be done with little skill (Akinnusi 1998; NRC 1991). The protein content of snail meat is between 16 and 18% which compares favourably with other livestock's products like mutton, beef and pork (FAO 1986). The low fat content in snail meat makes it a good antidote for fat-related diseases such as hypertension and is now readily accepted by many people (Imevbore 1990).
There are recent research findings on the use of pawpaw leaf and fruit, cocoyam tubers and mango fruits for feeding snails (Imevbore 1990; Awah 1992) but there is a paucity of information on the use of the peel of these crops in the diet of snails. Hence this study was conducted to investigate growth and carcass analysis of snails fed peels of plantain, cocoyam, mango and pawpaw.
The experiment was carried out at the Snail unit of the Institute of Agricultural Research and Training (IAR and T), Ibadan, located on longitude 03051E, latitude 07023N and altitude 650", in the humid zone of South western Nigeria. 90 growing snails (Archachatina marginata) of mean weight 64.0g (range: 63.4 to 65.7g) were used for the feeding trial. A completely randomized design was used for the study. The trial had 5 treatments: Pawpaw leaf (PL), which served as control, ripe mango peel (MP), pawpaw peel (PP), cocoyam peel (CP) and ripe plantain peel (PLP). Each treatment was replicated three times with 6 snails per treatment / replicate. The feeding trial lasted for 180 days.
The snails were reared in a cage with 0.25 x 0.25 x 0.5m3 compartments. The bottom of the cage was filled with moist sandy loan soil to a depth of 15cm and the top was covered with mosquito net reinforced with wire netting for aeration. The fruit peels and paw-paw leaves were obtained daily from the local market and were given to the snails ad libitum on a fresh basis, served in flat containers . The feed intake was taken on a daily basis by subtracting the left over from the feed offered. The weight gain, shell length and shell width were measured on a weekly basis.
At the end of the feeding trial, 6 snails were randomly selected from each treatment for carcass analysis. The snails were killed by breaking the shell. The foot (edible portion), the shell and the visceral material were weighed separately. The dressing percent was calculated as ratio of the foot to the live weight. The proximate composition of the experimental diets was carried out according to the method of AOAC.(1990). The data were subjected to analysis of variance (SAS 1995). Sources of variation were treatments and error.
The choice of pawpaw leaf as the control diet was based on earlier observations (Awesu 1980; Imevbore 1990; Akinnusi 1998) that snails preferred the leaf and the fruit of pawpaw to other feeds. The peels of the different fruits had similar composition (Table 1) but were considerable lower in DM, crude protein and ash content compared with the control diet of pawpaw leaves.
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Table 1. Proximate composition of the fruit peels and the Pawpaw leaves |
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|
% |
Ripe Mango |
Ripe Pawpaw |
Cocoyam (CP) |
Plantain |
Pawpaw Leaf |
| % fresh basis | |||||
|
Dry matter |
9.42 |
9.26 |
10.2 |
10.1 |
21.3 |
| % in DM | |||||
|
Crude Protein |
9.12 |
8.96 |
9.31 |
7.82 |
23.9 |
|
Crude Fibre |
5.24 |
6.87 |
9.34 |
5.81 |
10.5 |
|
Ether Extract |
0.42 |
0.49 |
1.56 |
1.24 |
0.38 |
|
Ash |
2.34 |
4.61 |
4.10 |
5.62 |
7.61 |
|
Nitrogen Free Extract |
64.2 |
57.4 |
49.5 |
65.4 |
36.7 |
The snail teeth (Radula) are tiny and delicate and not as strong as other livestock teeth hence snails prefer succulent, low fibre feeds to others (Omole 1998). This preference can be observed in the performance data (Table 2) which indicated that ripe pawpaw peels supported better growth than the other fruit peels, and was comparable to what was observed on the control diet of pawpaw leaves.
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Table 2. Mean values of performance of growing snails fed peels of different fruits or the control diet of pawpaw leaves |
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|
|
Ripe Mango |
Ripe Pawpaw |
Cocoyam (CP) |
Plantain |
Pawpaw Leaf |
SEM |
|
Feed intake, g/mth |
122d |
149a |
140 b |
124c |
147 a |
2.28 |
|
Initial weight, g |
64.6 |
64.0 |
63.9 |
64.1 |
64.2 |
0.39 |
|
Final weight, g |
141 d |
169 a |
150 c |
140d |
163b |
3.21 |
|
Weight gain, g/mth |
12.7c |
17.6a |
14.4 b |
12.8 c |
16.4 ab |
2.41 |
|
Shell length increment, mm/mth |
8.77 c |
11.4 a |
9.83 ab |
8.80 b |
10.9 a |
1.98 |
|
Shell width increment, mm/mth |
3.67 c |
6.60 a |
3.80 b |
3.73 bc |
5.21 a |
1.06 |
|
DM feed conversion |
9.56 a |
8.49 b |
9.69 a |
9.73 a |
8.94 b |
1.10 |
|
Means with different superscripts along the same row are significantly different (P < 0.05). |
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There were no differences between treatments for the carcass analysis (Table 3).
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Table 3. Carcass analysis of snails fed peels of different fruits or the control diet of pawpaw leaves |
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|
|
Ripe Mango |
Ripe Pawpaw |
Cocoyam (CP) |
Plantain |
Pawpaw Leaf |
SEM |
|
Live weight, g |
102 |
110 |
106 |
101 |
108 |
2.94 |
|
Foot Weight, g |
38.8 |
44.2 |
42.5 |
40.2 |
41.1 |
0.94 |
|
Shell Weight, g |
33.7 |
35.3 |
33.7 |
33.1 |
34.1 |
1.23 |
|
Viscera Weight, g |
16.2 |
18.1 |
17.9 |
16.9 |
17.5 |
1.14 |
|
Dressing Percent |
44.9 |
45.2 |
45.2 |
45.0 |
45.0 |
0.89 |
|
Viscera % of Live weight |
21.1 |
21.4 |
21.0 |
20.9 |
21.0 |
0.99 |
|
Shell, % of Live weight |
24.7 |
24.9 |
24.8 |
24.7 |
24.7 |
0.47 |
|
|
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It is concluded that all the fruit peels used in this experiment (Mango, pawpaw, cocoyam and plantain) could be used successfully for snail production without adverse effects.
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Received 8 July 2004; Accepted 13 September 2004