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European Journal of Applied Sciences – Vol. 11, No. 3
Publication Date: June 25, 2023
DOI:10.14738/aivp.113.14887
Sika, N. A., Amani, N. S. C., & N’dri, K. J. (2023). Effect of Diet and Crude Dietary Protein Content on Reproductive Performance of
The Snail Achatina fulica (Bowdich, 1720). European Journal of Applied Sciences, Vol - 11(3). 569-576.
Services for Science and Education – United Kingdom
Effect of Diet and Crude Dietary Protein Content on Reproductive
Performance of The Snail Achatina fulica (Bowdich, 1720)
Sika, Nygblé A.
Laboratory of Animal Biology and Cytology, UFR Natural Sciences
Nangui Abrogoua University of Abidjan, Côte d’Ivoire
Amani, N’dri S. C.
Departement Animal Biology, UFR Biological Sciences,
Péléféro Gon Coulibaly Universiy of Korogho, Côte d’Ivoire
N’dri, Kouassi J.
Laboratory of Animal Biology and Cytology, UFR Natural Sciences
Nangui Abrogoua University of Abidjan, Côte d’Ivoire
ABSTRACT
The effect of diet and protein content on reproductive parameters was studied of
225 juveniles of Achatina fulica. For this, these snails were subjected to two green
fodders (R1 and R2) and three concentrated flours diets (R3, R4 and R5) with
different protein contents (10.5%; 14% and 17.5%), for two years in the
experimental farm of Nangui Abrougoua University. The R1 diet includes Lactuca
sativa (Asteraceae), Carica papaya (Caricaceae), Brassica oleracea (Brassicaceae),
Cecropia peltata (Moraceae), Laportea aestuans (Urticaceae), and Phaulopsis
falcisepala (Acanthaceae). The R2 diet, in addition to the leaves used for the R1 diet,
is supplemented with leaves of Leucena leucocephala (Fabaceae-Mimosoideae), a
relatively protein-rich plant. The animals submitted to the diets consisting of green
fodder began to lay from the seventh month, whereas with the concentrated diets
(R3, R4 and R5) the snails laid eggs from three months, i.e. with a reduction in the
age of first lay by four months. Concentrated diets provide higher average monthly
laying numbers (between 0.41 and 0.57) as well as a higher number of eggs per
laying (between 215 and 233 eggs) compared to R1 and R2. The highest protein R5
diet is the one that provides the best reproductive performance. Additionally, the
strong positive correlation (r=0.99) between diet protein content and laying and
egg number per laying indicates that the protein content of the diet significantly
improves the reproductive performance of A. fulica.
Keywords: Achatina fulica, diet, protein content, reproduction
INTRODUCTION
In most countries of sub-Saharan Africa, an important proportion of animal protein for human
consumption has so far come from wild animals. Several animals, among which snails feature
prominently, are threatened with extinction due to poaching. In Côte d'Ivoire for example, a
study by Kouassi et al. 2008 on the markets of the economic capital (Abidjan) revealed that for
the only year 2008, more than 1700 tons of snails were marketed. Indeed, snails have been
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widely consumed and have even been part of dietary habits since prehistoric times (Murphy,
2001). If the meat of these animals is so much appreciated and increasingly consumed by the
Ivorian populations, it is partly thanks to its scent and flavor (Kouassi et al., 2007). In addition,
this meat contains important nutritional qualities. Indeed, it is an important source of protein,
amino acids (lysine, phenylalanine and leucine), energy and mineral matter (Fagbuaro et al.,
2006; Diomandé et al., 2008; Otchoumou et al., 2010) and very poor in lipids. It is rightly
recommended in dietetics in low-fat diets (Engmann et al., 2013). The species Achatina
achatina and Archachatina ventricosa, which were once the most consumed species, are
becoming increasingly rare, forcing populations to introduce new species such as Achatina
fulica into their eating habits. In order to have snail meat continuously available, several works
have been initiated for the development of breeding of these animals. In this sense, various food
formulations have been tested to substitute plant foods. These concentrated feeds must contain
optimal proportions of certain elements such as proteins to improve zootechnical performance.
The importance of this study lies in the fact that it provides an answer on the effect of diet and
the influence of protein content on the reproductive performance of the snail Achatina fulica.
METHOD
Biological Material
The animals used for this study are Achatinidae molluscs belonging to Achatina fulica (Bowdich,
1720) species with light brown pigmented flesh. These snails are, with Achatina achatina and
Archachatina ventricosa, the most consumed snails in Côte d'Ivoire. The snails chosen for this
study were born at the Nangui Abrogoua University's experimental farm from parents
themselves born at the said farm. The choice of this species is justified by the fact that Achatina
fulica is the most prolific species of the Achatina genus (Kouassi et al., 2010; Otchoumou et al.,
2003). In addition, A. fulica, formerly little consumed in Côte d'Ivoire, is increasingly consumed
today. Regarding biological performance, A. fulica can reach 250 g at the adult stage. It is a
species with a short reproductive cycle. Its duration of sexual maturity in rearing environments
can be reduced up to 3 months of age (Otchoumou et al., 2003).
Experimental Site
This study was carried out at the experimental farm of Nangui Abrogoua University (Abidjan,
Côte d’Ivoire). This center includes a building where breeding takes place under shelter and an
open-air experimentation area. The mean monthly temperature and relative humidity in the
barn were 26.7 ± 1.4°C and 82.6 ± 1.4%, respectively. The photoperiod was 12 hours light and
12 hours dark. The snails were reared in plastic tanks 0.66 m long, 0.6 m wide and 0.2 m high,
giving a base area of about 0.4 m2 and a volume of 0. 08 m3. These enclosures are equipped
with a mosquito net type cover constituting an anti-leakage device. Their bottom is covered
with soil to a height of 4 cm thick.
Experimentation
Two hundred and twenty-five (225) approximately 3-day-old Achatina fulica snails were
randomly allocated after five (5) diets, including two green fodder compounds (R1 and R2) and
three flour concentrates (R3; R4 and R5). These animals were distributed at a rate of 15
individuals per rearing tank and therefore three times for each diet. The experiment therefore
required the use of 15 breeding chambers, i.e., 45 snails tested per type of food. The R1 green
fodders plant diet consists of leaves of Lactuca sativa (Asteraceae), Carica papaya (Caricacea),
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Sika, N. A., Amani, N. S. C., & N’dri, K. J. (2023). Effect of Diet and Crude Dietary Protein Content on Reproductive Performance of The Snail Achatina
fulica (Bowdich, 1720). European Journal of Applied Sciences, Vol - 11(3). 569-576.
URL: http://dx.doi.org/10.14738/aivp.113.14887
Brassica oleracea (Brassicaceae), Cecropia peltata (Moracae), Laportea aestuans (Urticaceae)
and Phaulopsis falcisepala (Acanthaceae). The R2 diet, in addition to the leaves used for the R1
diet, is supplemented with leaves of Leucena leucocephala (Fabaceae-Mimosoideae), a plant
relatively rich in protein (Table 1).
Table 1 : Composition of diets based on green fodder
Components (g) R1 R2
Carica papaya 16,68 14,28
Lactuca sativa 16,68 14,28
Brassica oleracea 16,68 14,28
Cecropia peltata 16,68 14,28
Phaulopsis falcisepala 16,68 14,28
Laportea aestuans 16,68 14,28
leucena leucocephala 00 14,28
Total (g) 100 100
As for diets based on concentrated flours, they are formulated by varying their content of soy
flour, a source of protein (Table 2).
Table 2 : Composition of diets based on concentrated flours
Components (g) R3 R4 R5
Maize 15,3 15,3 15,3
Soybean meal 16 16 16
Soybeans 5 10 20
Soft wheat 15 15 15
Di-calcium phosphate 4 4 4
Vitamin complex 0,5 0,5 0,5
Calcium carbonate 28,7 28,7 28,7
Salt 0,4 0,4 0,4
Trace elements 0,1 0,1 0,1
Agar agar 15 10 0
Total (g) 100 100 100
To avoid the simultaneous variation of the rate of other nutrients following the decrease in the
rate of the protein source in the R3 and R4 diets, powdered agar-agar is incorporated into them.
Thus, to diets R3 and R4, 15% and 10% of this compound are added respectively in order to
adjust their percentage composition to 100%. Thus, the proportions of seed soy flour in the R3,
R4 and R5 diets are 5%, 10% and 20% respectively. This made it possible to obtain diets with
variable protein contents (10.5% for R3; 14% for R4 and 17.5% for R5). Food is weighed before
being served to them every two days. At the end of the two days, the food refusals are weighed
and the feeders are properly washed before being reused. For each food served, a control of
100 g is placed under the same experimental conditions in tanks containing no animals.
Weighing these control foods at the same time as the food refusals makes it possible to make
weight corrections due to desiccation for plant diets of green fodder and to hydration for
concentrated flour diets. The breeding substrates are watered daily morning and evening with
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tap water at the rate of 0.30 litre/substrate/watering, in order to maintain a relatively constant
humidity. The substrates are regularly cleared of food refusals, dead animals and faeces to
avoid the development of possible pathogens. The dead animals are inventoried by diet and
replaced by animals of the same age and substantially the same weight, reared under the same
experimental conditions in order to maintain the initial densities. The snails are weighed every
two weeks.
Snails are fed the same diets until sexual maturity. During laying periods, the substrates are
regularly inspected to detect possible eggs. The prospection of the substrates is practiced
manually to avoid breaking the eggs. Eggs found simultaneously in the same location (buried
or on the surface of rearing litter) are considered to constitute a clutch. They are removed with
a plastic spoon, brood counted and weighed. The large and small diameters of these eggs are
measured to the nearest millimeter. The eggs of each clutch are incubated separately, protected
from light. The incubation substrates are lightly watered once a week in order to maintain a
relatively constant humidity. After 9 days, the setter trays are regularly inspected to detect
hatchlings and remove them from the trays to prevent them from attacking unhatched eggs.
The average of the egg incubation times for each clutch is considered the incubation period for
that laying. Hatchlings are counted and hatch rates determined. Thus, the reproductive
performances of the animals, by diet, are estimated from the age of first laying, the number of
broods per snail, the frequency of the broods, the number of eggs per brood, the weight, the
large and small egg diameters and their incubation times. The data collected allowed to
estimate the total number of layind per snail and the hatching rate according.
Datas Analysis
A correlation analysis was performed to estimate the degree of relationship between
reproductive parameters and protein content of the diet. The correlation coefficient measures
the level of joint variation of two variable measures. Also, the mean values of the reproduction
parameters were compared by an analysis of variance (ANOVA) respectively according to
Tukey's HSD test. These various statistical treatments were carried out using the software
STATISTICA version 7.1
RESULTS
Egg-Laying Characteristics
The number of broods per snail is higher during rainy seasons and lower during dry periods,
regardless of the protein content of the diet (Figure 1). During reproduction periods, egg-laying
peaks are recorded during June’s month. In addition, the average number of broods per snail
increases with age. Thus, the numbers of laying recorded during the first year are lower than
those obtained during the second year. The first laying of snails submitted to plant diets R1 and
R2 takes place at the age of 7 months (Table 3). On the other hand, those subjected to the R3
concentrated diet lay eggs at 5 months when, those subjected to the R4 and R5 diets lay eggs at
4 months. Thus, the age at first laying of A. fulica can be reduced with the crude protein content
of their diet. Animals fed concentrated diets have better reproductive performance than those
fed vegetable diets. Both, fodder plant diets show the same effects on snail egg-laying
characteristics. Statistical analysis reveals no significant difference in Tukey's HSD test at P <
0.05, between the incubation period and the hatching rate of eggs collected from snails
subjected to vegetable diets of green forage (R1 and R2). The average monthly number of
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Sika, N. A., Amani, N. S. C., & N’dri, K. J. (2023). Effect of Diet and Crude Dietary Protein Content on Reproductive Performance of The Snail Achatina
fulica (Bowdich, 1720). European Journal of Applied Sciences, Vol - 11(3). 569-576.
URL: http://dx.doi.org/10.14738/aivp.113.14887
broods per broodstock in animals subjected to concentrated diets varies between 0.41 and 0.57
with an average number of eggs per brood varying between 215 and 233. The number of broods
observed per snail subjected to R5 is higher than that recorded among those subject to R3.
Statistical analysis indicates that the R4 diet has an intermediate effect compared to these two
concentrated diets on laying performance of snails. There was no significant difference in
Tukey's HSD test at P < 0.05 between the concentrated diets for the mean number of eggs per
snail, which varied between 215 and 233.
Figure 1 : Evolution of laying according to regimes and seasons, SDS: small dry season ; LDS :
long dry season ; SRS : small rainy season ; LRS : long rainy season
Table 3 : Reproductive parameters according to diets
Variables R1 R2 R3 R4 R5
Age of first laying (months) 07 ±2,02a 07±1,50a 05±2,30b 04±1,52c 04±1,15c
Average monthly number of
laying/snail
0,30 ±0,12c 0,33±0,14c 0,41±0,15b 0,48±0,22ab 0,57±0,19a
Average number of eggs/
laying
200±52,00b 202±44b 215±63a 221±71,00a 233±55a
Average egg weight (g) 0,17±0,02d 0,18±0,03d 0,19±0,05c 0,21±0,08b 0,23±0,06a
Large diameter of an egg
(mm)
04,29±0,07d 04,27±0,04d 05,37±0,17c 05,43±0,13b 05,64±0,16a
Small diameter of an egg
(mm)
03,35±0,54d 03,41±0,36d 04,31±0,10c 04,35±0,08b 04,45±0,11a
Mean incubation time (d) 16,59±1,97b 16,26±1,52b 14,47±2,09a 15,19±1,78a 14,79±1,92a
Average hatching rate (%) 66,00±1,47b 68,12±2,1b 85,38±2,09a 85,67±3,50a 85,84±2,16a
Characteristics of Eggs
The statistical analysis shows that the eggs laid by the animals subjected R5 (17.5% protein)
have a higher average weight, which is 0.23 g. The large diameters and the small diameters of
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the eggs laid by R5 are the largest. They measure 5.64 mm and 4.45 mm respectively. Also, the
eggs laid by the animals subjected to the R3 diet are smaller (5.37 mm for the large diameter
and 4.31 mm for the small diameter) and of less weight (0.19 g) than those laid by the animals
subjected to the R4 concentrated diet, with a large diameter of 5.43 mm; a small diameter of
4.35 mm and an average weight of 0.21 g. No significant difference in Tukey's HSD test at P <
0.05, is observed between the concentrated diets on the one hand and on the other hand,
between the vegetable diets concerning the incubation times and the hatching rates.
Hatchability is higher with concentrate diets than with green fodder diets. The correlation
analysis between the protein and mineral content of the diet and the reproductive parameters
(age at first laying, number of laying and eggs per laying) is summarized in Table 4. The first
laying is negatively correlated with the crude protein content of the diet. This explains a
reduction in the time of appearance of sexual maturity in snails depending on the protein
content of the diet. Moreover, a very strong positive correlation was recorded between the
protein content of the diet and the number of laying and eggs per laying (r = 0.99). Also, these
parameters (number of laying and eggs per laying) are very strongly and positively correlated
with mineral content (r = 0.89 and 0.90). This reflects an improvement in snail egg-laying
performance with the mineral content of the diet.
Table 4 : Correlation between egg-laying performance and protein and mineral content
of the diet
% protein % mineral
materials
Age of first
laying
Nomber
of laying
Number of
eggs/laying
% protein 1
% mineral materials 0,94 1
Age of first laying -0,97 -0,99 1
Nomber of laying 0,99 0,89 -0,94 1
Number of eggs/laying 0,99 0,90 -0,94 0,99 1
DISCUSSION
Analysis of the results of this study showed that the reproductive performance of A. fulica are
influenced by diet. Indeed, the reproductive performance of animals subjected to concentrated
diets remains much better compared to those of animals subjected to green fodder. Thus, the
age of first laying with the R1 vegetable diet without Leucaena is 7 months, that with the R5
concentrated diet is 4 months, ie a difference of 3 months. Also, the number of monthly layings
made by a snail subjected to the R1 diet is 0.3 while that of a snail subjected to the R5 diet is
0.57. This corresponds to a monthly egg laying difference of 0.27. This means that after one
year, the R5 diet makes it possible to gain about 4 broods more per individual than with the R1
vegetable diet. This difference between the reproductive performance of snails subjected to
green fodders and those subjected to concentrated diets could be explained, according to
Otchoumou et al. (2005) by the level of dietary calcium present in the diet. Indeed, the snail
uses dietary calcium for the calcification of these eggs (Bonnet et al., 1990). On the other hand,
the results of this study showed that calcium, although necessary, is not the only element
responsible for the reproductive performance observed in animals subjected to concentrated
diets. Increasing the protein content of concentrated diets resulted in improved reproductive
performance in animals. Thus, with a 7% difference in protein between the R3 concentrated
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Sika, N. A., Amani, N. S. C., & N’dri, K. J. (2023). Effect of Diet and Crude Dietary Protein Content on Reproductive Performance of The Snail Achatina
fulica (Bowdich, 1720). European Journal of Applied Sciences, Vol - 11(3). 569-576.
URL: http://dx.doi.org/10.14738/aivp.113.14887
diet and the R5 diet, the age at first lay was reduced by approximately one month. This also
allowed a monthly gain of 0.16 laying per individual.
Concerning the average age at the first laying, the results showed that it is 7 ± 2.02 months for
R1 and 7 ± 1.5 months for R2 in animals fed green fodders diets. This age falls within the age
range of sexual maturity presented by Waitkuwait (1987); Upatham et al. (1988) and Zongo et
al. (1990). The R5 concentrated diet containing 17.5% protein reduces sexual maturity time
limit until 4 months. Also, the ages of first laying of the animals subjected to the different diets
concentrated in this study are late in relation to the period of sexual maturity. This may be due
to the high dietary protein content of the diet. However, Otchoumou et al. (2005) showed by
observation of histological sections of ovotestis from snails of the same species fed with
concentrated diets that this time until sexual maturity obtained is 2.5 months.
CONCLUSION
Dietary protein content influences reproductive parameters of Achatina fulica. With the diets
made up of green fodder (R1 and R2), the age of first laying is late (7 months) whereas with the
concentrated diets (R3, R4 and R5) the age of first laying is reduced at three months. Thus, the
age at first laying of snails is reduced with the crude protein content of their diet. Animals fed
concentrated diets have better reproductive performance than those fed vegetable diets of
green fodders. In addition, concentrated diets result in higher average monthly laying’s
numbers (between 0.41 and 0.57) as well as a higher number of eggs per laying (between 215
and 233 eggs). Moreover, concentrated diets give eggs better characteristics than diets with
green fodder. However, the R5 diet with the highest protein content results in heavier and
larger eggs than all other diets. It should also be noted that the nature of the feed (green fodder
or concentrate) has no effect on the incubation period and the hatching rate.
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