GROWTH PERFORMANCE OF AFRICAN GIANT LAND SNAILS ( Archachatina marginata ) FED WITH FEED FORMULATED WITH DIFFERENT CALCIUM SOURCES

The study was conducted to examine the performance of growing snails (Archachatina marginata) fed with formulated feed supplemented with calcium from four sources (Agricultural Limestone, Bone meal, Egg shell and Snail shell) in the domestication unit of Department of Forest Resources and Wildlife Management, Faculty of Agriculture, University of Benin, Benin City. A total of sixty (60) juvenile snails with average weight of 97.85±2.06g were randomly allotted to five treatment groups (T1, T2, T3, T4 and T5), replicated three times with four snails per replicate in a completely randomized design. The treatment was Agricultural limestone (T1), Bone Meal (T2), Egg shell (T3), Snail shell (T4) and control: natural feed (T5). The feeding trials lasted for 16 weeks. The results showed no significant differences (P>0.05) in weight gain (12.50a ± 3.15), shell length (0.35a ± 0.06) and shell width increment (0.163 ± 0.03) of the snails under the various diet. Increases in body weight, shell length, shell width was recorded in all the treatments with the highest recorded in snails (Archachatina marginata) under feed formulated with the snail shells. The result showed significant differences (P<0.05) in edible tissue weight (112.57a ± 0.91), shell weight (58.5a ± 0.3) and visceral weight (31.90a ± 0.2) of the snails. Snails fed with feed formulated with snail shell, had a significant (P<0.05) higher value than the snail fed with other diets. It was concluded that the snails fed with snail shell meal performed better in terms of growth performances in the snails compared to other snails fed with other sources of calcium. Formulated feed with adequate quality of calcium source should be fed to snails, for growth and development of the snails.


INTRODUCTION
Snails refer to rather wild variety of shell bearing invertebrate animal nonsegmented bodied cold-blooded mollusk with hard and slippery skin.They could be terrestrial, and aquatic of both African and European origin used by man as food [1].Snail belongs to the class Gastropod a classification that includes fresh water, sea and slugs.The snail ancestor is one of the earliest known types of animal in the world; there is fossil evidence of primitive gastropods dating back to the late Cambrian period this means they lived nearly 500 million years ago.
Several factors can greatly influence the growth of snail including population density, stress (snails are sensitive to light, noise, vibration, unsanitary conditions and irregular feeding) temperature influence the activities of snail performance temperature above 20 o c will cause the snail to aestivate and when the environment is too dry the snail will hibernate in order to regulate their body fluid continually .snailthrive well under ambient temperature of 20 o c with considerable growth rate all year round with zero chance of aestivation [1].Within the same snail population and under the same conditions, some snail will grow faster than others.Some will take twice as long to mature.This may help the species survive bad weather in the wild.Snails are highly appreciated in many countries for its nutritive and medical values, the richness of snail meat in terms of nutrients has caused the demand for snail to increase over the years [2].They are known to be rich in important minerals including potassium, phosphorus, iron, and low in cholesterol and fats [3].Algae plant that are decaying are often a good meal for them, they seek for calcium to get a thicker shell by eating dirt and other source of calcium in the wild this necessary to keep their shell hard and protective.The aim of this study is to investigate the effect of varied calcium sources on the growth and performance of African giant land snail (Archachatina marginata)

Study Site
The experiment was conducted in the wildlife domestication unit of the Department of Forest Resources and Wildlife Management, Faculty of Agriculture, University of Benin, Benin City, Edo State, Nigeria.The site lies between latitude 6.1 0 and 6.8 0 N of the equator and longitude 5.4 0 and 6.0 0 E of the Greenwich Meridian.The attitude is 74.5m above sea level.University of Benin is located in the rainforest zone of southern Nigeria.Rainfall is usually light with a peak of 2000mm.annually and in some places exceeding 8000mm.The University of Benin has an annual rainfall of 1500mm the relative humidity is about 75% at noon and about 95% at 6a.m while the minimum and maximum temperature are between 27 0 C and 32 0 C respectively.

Experimental Animals and Duration of Study
Juvenile African giant land snails (Archachatina marginata) were used in the experiment.Juvenile snails were purchased from Eki-uwa, Benin City.A total of 60 snails were used for the study, which lasted for four months (120 days).

Experimental Diets
The protein and carbohydrate sources were used to compound feed containing 20% crude protein.The feed was divided into four (T1, T2, T3, and T4) with T1, T2, T3, T4, containing agricultural limestone, bone meal, egg shell, and snail shell meal as sources of calcium respectively.

Experimental Design
The experiment was laid out in a complete randomized design with five treatments and three replications per treatment each replicate contained four juvenile's snails.The experimental model is as follows.

GROWTH PERFORMANCE OF AFRICAN GIANT LAND SNAILS (Archachatina marginata) FED WITH FEED FORMULATED WITH DIFFERENT CALCIUM SOURCES
Where: Tij= the effect of the j th observation in the i th treatment µ i = general mean of the population ti= the effect of the i th treatment on the snails eij = random error associated with the j th observation in the i th treatment

Proximate Analysis
The experiential diets and the carcass were analysed for their proximate components according to Association of official analytical chemists [4].

Data Analysis
The data collected were analyzed with descriptive statistics of frequency and percentage summarized in table and inferential statistics using analysis of variance (ANOVA).Means of variables that were significant were separated using Duncan's New Multiple Range Test.

Proximate Composition
Table 1 below shows that proximate composition of the experimental diets.The results revealed a variation in the chemical composition of the experimental diets.The gross energy of the diet ranged from 1,649 to 2284 kcal/kg with the highest recorded in the bone meal diet, why the least was observed in the control diet.The % crude protein had comparable values for the formulated feed but differ significantly with the control feed (natural feed).The percentage crude fibre decrease with increase in protein, it ranged from 12.11% to 26.38% with the highest (26.38%) value recorded in the control meal while the least (12.11%) was observed in the feed formulated with the bone meal.The % fat increases with an increase in the crude protein content of the feed.The highest (19.84%) fat was observed in feed formulated with bone meal while the least (5.94%) was recorded in the control feed.The % ash content of the feed varies, with the feed formulated with limestone (32.49%), had the highest and the lowest (20.62%) was observed in the control feed.The Nitrogen free extract ranged from 28.25 to 42.14.The control diet recorded the highest (42.14) while the least (28.25 was observed in the feed formulated with limestone.NFE-Nitrogen Free Extract

Weight Gain of The Snails
The results showed that there was no significant difference (P>0.05) in weight gain of the snails among the various sources of calcium in the feed.(Table 2), the mean weight gain of the snails, varied among the feed.The highest (12.50±3.15)mean weight gain was recorded in feed formulated with snail shell, while others are 12.41±3.21,12.27±3.14,12.23±2.87and 8.06±2.51for feed formulated with bone meal, agricultural limestone, egg shell and natural feed respectively (Table 2).Means with same letters are not significantly different (P>0.05)

Shell Length Increment of The Snails
As indicated in Table 3, there was no significant different (p>0.05) in shell length increment of the snails among the various sources of calcium under review, the feed formulated with snail shell had the highest (0.35±0.06) mean shell increment while the least (0.26±0.05) was recorded in the control.Means with same letters are not significantly different (P>0.05)

Shell Width Increment of Snails
The results showed that there was no significant difference (p>0.05) in mean shell width increment of the snails among the sources of calcium fed to the snail (Table 4) the mean shell width increment varied with the highest (0.163±0.03), recorded in the snails fed with feed formulated with snail shell while others are (0.161±0.02) 0.151±0.03,0.0150±0.02and 0.133±0.02for feed formulated with bone meal, agricultural limestone, egg shell and control respectively.Means with same letters are not significantly different (P>0.05)

Eggs of Snails Recorded
Table 5 shows the number of eggs recorded in each calcium sources.The highest number of eggs was found in snails fed with feed formulated with snail shell (8.0±1.00) while the least was recorded in agriculture limestone (3.3±1.97)

Feed Conversion Ratio (Fcr) And Feed Conversion Efficiency (Fce)
The results of the feed intake, feed conversion ratio (FCR) and feed conversion efficiency (FCE) are given in Table 7.The results revealed no significant difference (P>0.05) in feed intake and feed conversion ratios of the snails among the diets under review.The Table showed significant difference (P<0.05) in feed conversion efficiency of the snails in the diets under consideration.Means with same letters along the row are not significantly different (P>0.05)

Proximate Carcass Composition of Snail
Table 9 shows the feed nutrient utilization indices.The results showed variation in the chemical composition of the snail tissue in the feed with the calcium sources.The moisture content of the snails in each treatment varied from 70.43 to 84.10% with the highest (84.90%) recorded in the snails fed with the control diet.The snails under bone meal diet had the highest % crude protein (7.94), % fat (7.12), while the lowest % crude protein (4.81) and % fat (3.62) were recorded in the snails under the control diets.The snails under the control diet had the highest (7.14) crude fibre while the lowest (4.85) was observed in the snail's carder bone meal diet.

DISCUSSION
The findings revealed appreciable increment in live body weight, shell length and width of the snails.The growth performances of the snails fed with the formulated feed with calcium sources were better than the snails fed with natural feed.This revealed that calcium plays a significant role in growth performances of African giant land snails, (Archachatina marginata).The findings agree with the report made by Eruvbetine et al. (1996) that fast growth rate of snail feed with adequate quantity of calcium source promote shell growth and tissue development of snails [5].However, the snails fed with feed formulated with snail shell performed better in weight gain, shell length and width increment (Tables 2, 3 and 4) compared to other sources of calcium considered for this study.
This result could be attributed to snail shell as source of calcium with high quality calcium.Ireland, noted that snails need a lot of high quality calcium intake for growth and shell formation [6].Snails fed with a good source of calcium may attain proper development and growth under normal environment condition [2].The quality of calcium source utilized by snails play an important role in egg production.The findings showed that more eggs were produced by snail shell (Table 5) than the snails fed with other diets under review.A researcher reported that snails deprived of calcium view under eypivie development have stunted growth with low eggs production and shell deformity [7].
It was observed from the findings that the mortality rate was highest (Table 6) in the snails fed with the natural feed (control), followed by those subjected to Agricultural limestone.No mortality was recorded in snails fed with snail shell.This could be attributed with the nature and quality of calcium sources consumed by the snails among other factors.The findings revealed that the lower the feed conversion ratio, the better the feed conversion efficiency.The lower feed conversion ratio recorded by the snails on the formulated feed over the snails on the control feed indicates that African giant land snail utilized the nutrients available in the formulated feed more efficiently.The snails in the formulated feed were efficient user of the feed.Though not significant (P>0.05), the feed formulated with the bone meal recorded the highest FCE (Table 7) as compared with other sources of calcium considered in this study.The results is in line with the report by some researcher state that snails fed with formulated diet of 20% crude protein are more efficient users of the diet over the snails fed with the natural feed [8].The reason why snails on formulated feed perform better than the ones on natural feed might be due to the fact that available nutrients of the diets originate from different feedstuffs there by making them more balance.Observation from the findings showed that the feed formulated with the different calcium sources had appreciable effect on the edible tissue of the snails (Table 8) the snails fed with the feed formulated with snail shells had the highest edible weight as well as the shell weight compared with the snails raised under other calcium sources.
The nutrient utilization of the snails under the formulated feed was highly influenced by the dietary crude protein content of the diets.The nutrient composition (Table 9) is higher in the snails under the formulated feed, compared to the snails under natural feed.The variability that exist among the tissue composition of the snails under formulated feed might be due to the sources of calcium in the feed.The best was observed in the snail feed with the bone meal in terms of the % crude protein and % crude fat contents of the snails.The results is in agreement with Ejidike (2010) who reported that snail fed with formulated feed with high crude protein perform best in terms of edible tissue quality of the snails.

CONCLUSION
It could be generally concluded that the results from the study showed that the feed formulated with different calcium sources played a significant role in growth performance of African giant land snails (Archachatina marginata).The study revealed that fast growth rate and high increase in weight, shell length and shell diameter of A. marginata can be achieved by feed formulation with graded quality of snail shell (SS) Calcium sources.
This study further proved that snail shell meal in graded quantity added to supplement snail diet is palatable for snail consumption if properly prepared to attract snails.Normal amounts of snail shell added to snail diet improved the growth rate and tissue development of snail.This study shows that there is an indication that large scale commercial production of snails can be achieved when snails are placed on the consumption and utilization of snail shell diet as snails get to maturity fast due to fast growth rate.

Table 1 :
Proximate Analysis of the Experimental Diets

Table 2 :
Mean Weight Gain of the Snail (g)

Table 3 :
Mean shell length increment of the snails (cm)

Table 4 :
Mean shell width increment of the snail (cm)

Table 5 :
Numbers of eggs recorded The mortality rate of the snails was revealed in table 6. Snails fed with natural feed (control) have the highest (41.79), and then followed by snails fed with agriculture limestone.No mortality rate was recorded in the snail's shell.

Table 6 :
Mortality rate of the snails (%)

Table 7 :
Feed intake, Feed conversion ratio (FCR) and Feed conversion efficiency (FCE) of the snails

Table 8
shows the edible tissue, shell and viscera weight of the snail.The results revealed significant differences (P<0.05) in edible tissue, shell and visceral weight of the snails fed with the experimental diet.Snails fed with feed formulated with snail shell dominated other feed in edible tissue and shell weight while snail fed with bone meal dominated other feed in the visceral weight of the snails.

Table 8 :
Mean Carcass weight of the snails

Table 9 :
Proximate Carcass composition of A. marginata fed with different calcium sources