CHEMICAL ANALYSES OF THE SHELLS OF BLACK-SKINNED AND ALBINO GIANT AFRICAN LAND SNAILS (Archachatina marginata)

CHEMICAL ANALYSES OF THE SHELLS OF BLACK-SKINNED AND ALBINO GIANT AFRICAN LAND SNAILS (Archachatina marginata) Akinnusi, F.A.O1.; Oropo,A²; Oladepo,O.A¹; Akanni, K.T³., Ademolu,K.O²* 1Centre for Entrepreneurship and Leadership Studies, Christland University, Abeokuta, Nigeria, 2 Department of Pure and Applied Zoology, Federal University of Agriculture, Abeokuta, Nigeria, 3School of Early Childhood and Primary Education, Federal College of Education, Abeokuta.
*Corresponding author’s email: kennyademolu@yahoo.com

ABSTRACT

This study was conducted to compare biochemical analyses of the shells of black-skinned and albino giant African land snails. A total of forty snails (20 albino and 20 black-skinned snails) were used for this experiment. The minerals (Ca2+, Fe2+, Mg2+, Na+, Zn+, K+) and proximate (crude protein, ash, fibre, crude fat and carbohydrate) composition of shells of the two ectotypes were evaluated by standard methods. The shell of albino snails had significantly higher (p˂0.05) carbohydrate content than black skinned shell (8.55 % and 1.12 % respectively). However, black-skinned snail shells have higher concentrations for all the minerals.

INTRODUCTION

Archachatina marginata (Swainson, 1821).is one of the species of African land snails known as Giant African Land Snails (Okon, Ibom 2012., Akinnusi 2004). It could be black or white skinned (Okon, Ibom, 2012). The black skinned A. marginata snail is popular and appreciated (Akinnusi, 2004). Although the white skinned A.marginata snail has the same nutritional attributes as the black skinned one, they are being discriminated against by some people because of taboos and superstitious beliefs in some communities, others associate them with certain gods or deities; hence its domestication has been discouraged by some snail farmers (Okon, Ibom, 2012). Albinism is a hereditary deficiency of pigmentation which may involve the entire body or parts of the body. It is believed to be caused by an enzyme deficiency involving the metabolism of melanin during prenatal development (Allegretti et al.,2009). The shell is a typical calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the Phylum Mollusca, which includes snails, clams, tusk shells, periwinkle shell and several other classes (Yoloye 1994). When the snail grows, its shell (and body) expands only at the aperture margin while the shell thickness and the degree of mineralization increase all the time (Barker, 2001).

Shells are disposed as wastes where they constitute environmental nuisance
due to unpleasant odor and unsightly appearance (Adewuyi and Ola, 2005). Apart from the high nutrient value of snail flesh, the shell also plays a role in folk medicine (Akinnusi, 2004). Calcium improves blood clotting, to store medicinal concoctions, as material to produce tooth powder, or as a component of feed for farm animals, particularly layer hens (Ademolu et al. 2015). Agbelusi and Ejidike (1992) reported that snail shells were used not only as calcium source to farm animals but as an important ingredient in traditional medicine. A lot of works have been reported on black skinned A. marginata snail, but not much is documented on white skinned A. marginata. Therefore the aim of this study is to evaluate the shell chemical composition of black and white skinned A. marginata.

MATERIALS AND METHODS
Experimental animals and management

Forty (40) snails (20 black and 20 albino snails) were purchased from Kuto market, Abeokuta, Ogun State, Nigeria. They were brought to the Snailery Unit of Department of Pure and Applied Zoology, federal University of Agriculture, Abeokuta, Nigeria, in plastic baskets. These baskets were filled with moist loamy soil up to a depth of 2cm. The snails were fed ad-libitum with fresh pawpaw leaves for two weeks (acclimatization) at 7.00pm daily as described by Ademolu et al., (2010). Water was also made available to snails in water troughs present in each
compartment. All the snails were deshelled, the shell and flesh were weighed using sensitive electronic scale (MettlerPM 11K), and the shell thickness was measured using a micrometer screw gauge.

Chemical analysis
The proximate composition (ash, fibre, protein, fat and carbohydrate) of the snails shells was determined by A.O.A.C (1990) methods. Also, the mineral analyses of the shells (Fe2+, Na+, Ca2+, Mg2+, Cl-, K+) were carried out using spectrophotometry method.

Statistical Analysis
Data collected from the experiment were analyzed using T-test.

RESULTS
Table 1 shows the proximate composition of the shells of two snail ectotypes. There was no significant difference in the dry matter content between the two snail ectotypes. The shells had low fat and protein content. However, the shell of albino snails had higher carbohydrate content than black-skinned snail (8.55 % and 1.12 % respectively).

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