ABSTRACT
A 16-week study was conducted
to investigate the effect of dietary protein and energy levels on the growth
performance of African giant land snail (Achatina
achatina). Two hundred and forty eight weeks
old African giant land snails were used
for the study. The snails were randomly divided into 16 groups of 15 snails
each. The groups were randomly assigned to 16 diets in a 4 x 4 factorial
arrangement involving four levels ((18%, 20%, 22%, and 24%) of protein and four
energy levels (2.6, 2.8, 3.0 and 3.2Mcal/kg ME). Each treatment was replicated
3 times with 5 snails per replicate. Results showed that while body weight
gain, feed intake, protein efficiency ratio and carcass yield were
significantly (P < 0.05) increased at the 24%CP and 3.2Mcal/Kg ME levels,
FCR and cost of feed per kg weight gain were decreased(P < 0.05). There were
significant (P < 0.05) interactions between protein and energy levels on final
body weight, average daily weight gain, average daily feed intake, feed
conversion ratio, protein efficiency ratio, shell length, shell width, feed
cost per kg weight gain and carcass yield. Feed intake was significantly (P
< 0.05) decreased at the 3.0 Mcal/kg ME and 18%CP levels, and at the 3.2
Mcal/kg ME and 18% CP levels; FCR values were decreased(P < 0.05) at the 3.0
Mcal/kg ME and 24 %CP levels, and at the 3.2 Mcal/kg ME and 24% CP levels; PER
was enhanced (P < 0.05) at the 24 %CP level and at the 2.80 Mcal/kg, 3.0
Mcal/kg and 3.2 Mcal/kg energy levels; shell length was enhanced (P < 0.05)
at the 3.0 Mcal/kg ME and 22% CP levels, and at the 24% CP and 3.2 Mcal/kg ME
levels; shell width was enhanced (P < 0.05) at the 3.0 Mcal/kg ME and 24% CP
levels, and at the 24% CP and 3.2 Mcal/kg ME levels. Feed cost per kg weight
gain was significantly (P < 0.05) reduced at the 24% CP and 3.2 Mcal/kg ME
levels. The results obtained in the present study show that the dietary protein
and energy levels of 24% and 3.2Mcal/kg ME are adequate for the growth of
African giant land snails (Achatina achatina)
in the humid tropics.
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND
The importance of protein in
the diet of man cannot be over-emphasized. Protein is required for normal
growth and repair of the body tissues. It is the principal constituent of the
organs of the animals’ body. Protein can be of plant or animal origin. Most
plant protein is deficient in one amino acid or the other and may be associated
with one anti- nutritional factor or another. Soyabean for instance is a
vegetable protein source that contains trypsin inhibitor and is deficient in
methionine.
Animal protein is of high
biological value and possesses all the essential amino acids in desirable
quantities. The sources of animal protein include macro and micro livestock.
The macro livestock are the conventional big animals such as sheep, goat,
cattle, etc. However, the cost of production of macro livestock in term of
housing, feeding, space and disease control is high. Micro livestock are
excellent and cheaper sources of animal proteins (Akinnusi, 1998; NRC, 1991).
The term micro livestock refers to a group of livestock associated with small
body size, moderate nutrition and management (Oji, 2000). It includes snails,
rabbits and cane rat, among others.
Snails are invertebrate, shell
bearing animals that are passive or inactive during the day, but very active in
the night, at dusk or when it rains. They are usually found in cool environment
(Segun 1975; FAO, 1986).
Snail meat tastes good and it
is also consumer friendly. When eaten, it serves as a special delicacy in the
diet. Snail meat is particularly rich in protein (Ajayi et
al., 1978). According to Imevbore and Ademosun (1988)
indicated that snail meat has a protein
content of 88.37 (dry weight, basis) low total fat content (1.64 percent),
saturated fatty acids (28.71 percent) and cholesterol content (20.28mg/100g
fresh sample). The analysis also showed that snail meat is a rich
In West Africa, the common
breeds of snail reared are the African giant land snail: Archachatina
Marginata, Achatina achatina and Achatina
fulica (Awesu, 1980; FAO, 1986 and Akinnusi, 1997). These breeds
vary in their adaptability to environment, size at day old, size at maturity,
egg size, and growth rate (Amusan and Omidiji, 1999).
The two giant land snails
common in Nigeria are Achatina achatina
and Archachatina marginata. Achatina achatina has
a brown shell with conspicuous zigzag
streaks and a narrow apex. The foot (the fleshy part) is grey in colour. Archachatina
marginata has a wide bulbous apex and the foot is usually dark brown
to black in colour.
According to Amusan and Omidiji
(1999) Archatina achatina species has been found to be
more difficult to breed in Nigeria they do not eat well and the growth rate is
very slow compared to Archachatina marginata
species.
1.2 STATEMENT
OF PROBLEM
According to Nisbet (1974),
Hodasi (1979), Awesu (1980), FAO (1986), Akinnusi (1998), Amusan et al
(1998) and Ayodele and Asimalowo (1999), the conventional feeds of snail
comprises bread fruit, water leaf, pawpaw leaf, sweet orange, mango fruits,
ripe fruits of plantain and banana, pineapple. These feedstuffs are mainly of
plant origin, seasonal, perishable, and relatively scarce during the dry season
and cannot supply all the nutrients needed for the optimum performance of
snail. In commercial production of snail especially in the urban area, it is
very difficult to source for these feeds. However, the major causes of slow
growth and mortality in snail production may be as a result of improper stocking
rate and poor nutrition. To ameliorate the problem of feed shortage, it is
It has been reported that feed
particle size has significant effects on consumption, weight gain and nutrients
digestibility (Ohn et al., 1983; Reece et al.,
1986). Due to the fact that the teeth of snails (radula) are very tiny and
delicate, there is need to determine the feed particle size effects on
performance of snails.
1.3 OBJECTIVES
The
specific objectives of the study are as follows:
1.
To investigate the effects of varying
dietary energy and protein levels on growth performance of giant land snails.
2.
To determine the optimum protein and
energy levels that will support optimum/normal growth in giant land snails.
3.
To determine the effects of varying
dietary protein and energy levels on
carcass
yield and organ characteristics of the
giant land snails
4. To determine the cost of feeding African giant land
snail with diets containing varying protein and energy levels.....
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Item Type: Postgraduate Material | Attribute: 61 pages | Chapters: 1-5
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