Abstract:
African Giant Land Snails (AGLS) (Archachatina marginata) are a good source of protein
with low-fat content but with slow growth rate which may be due to genetic or nutritional
factors. Conventional high fibre feed resources fed to AGLS have a marginal nutrient
profile. Growth enhancers such as enzymes, prebiotics, probiotics, and organic acids have
been used to optimise productivity in other animals but reports on their use in AGLS
nutrition is scanty. Therefore, effects of diets supplemented with enzyme, prebiotics and
probiotics on performance of AGLS were investigated.
Grower AGLS (n=240), weighing 92.03±1.55 g, procured from Ikire market, Osun State
and certified at the Department of zoology, University of Ibadan. They were allotted to diets
containing 0.00 (T1, Control), 0.10 (T2), 0.15(T3) and 0.20 g/kg (T4) β-D-mannanase
in five replicates for 98 days. Grower AGLS (n=350), weighing 100.08±1.73 g were allott
ed to another seven compounded diets containing 0.00 (M1, Control), 0.1 mg/kg oxytetrac
ycline (M2), 0.50(M3), 1.00(M4), 1.50(M5), 2.00(M6) and 2.50 g/kg(M7) mannanoligosacch
aride plus organic acids blend in five replicates for 98 days. Another batch of grower AGLS
(n=400) weighing 94.12±1.77 g were allotted to eight different diets containing 0.00
probiotics (D1, Control), 0.1 mg oxytetracycline/ kg (D2), 1x108 (D3), 2x108 (D4) and 3x108
CFU Lactobacillus plantarum (Lacp)/ kg (D5), 1x108 (D6), 2x108 (D7), and 3x108
Saccharomyces cerevisiae (Sac)/ kg (D8) in five replicates for 98 days. Using standard
procedures, Feed Intake (FI, g/snail/day), Body Weight Gain (BWG, g/snail), Feed
Conversion Ratio (FCR), Live Weight (LW, g/snail), Dressing Percentage (DP), Protein
Digestibility-PD (%) and Fibre Digestibility-FD were assessed. Haemolymph (5 mL) was
sampled to determine Total Protein (TP) and Packed Cell Volume (PCV) using standard
procedures. Data were subjected to descriptive statistics, polynomial regression and
ANOVA at 𝛼0.05.
The FI of AGLS was similar for all treatments, however, BWG and PD were significantly
higher in T4 (295.0±6.6 and 69.4±2.0) than T1 (276.1±10.3 and 65.1±0.6) and T2 (280.0±5.8
and 66.4±1.1), but similar to T3 (290.0±10.3 and 68.9±1.5), respectively with β-Dmannanase supplementation. Increased β-D-mannanase inclusion in the diet of AGLS
significantly enhanced FD (R2=0.9), DP (R2=0.8) and LW (R2=0.7) of AGLS. Grower
AGLS on M7 had the highest BWG and LW of 178.6±1.07, and 181.7±2.1 respectively.
The LW of Grower AGLS on M7 (181.7±2.1) was similar to M6 (181.7±2.1) but higher than
M5 (167.4±1.71), M4 (166.1±1.52), M3 (164.5±2.1), M2 (171.8±1.11) and 161.8±1.55 (M1).
The AGLS fed M7 had higher serum TP (8.8±0.52 g/L) and PCV (54.1±2.98%) compared
to other treatments. The FI significantly increased linearly (R2=1) with dietary inclusion of
Lacp and Sac. The BWG of AGLS for D6 (142.5±13.6) and D7 (143.9±12.3) were similar.
Optimum BWG of AGLS (R2 = 1.0) on Lacp diets was obtained at 2.0×108 CFU (D4,
142.9±18.4).
Sole dietary supplement of African giant land snail with any of β-D-mannanase at 0.5 g/kg,
mannanoligosaccharides plus organic acid blend (2.5 g/kg), Lactobacillus plantarum
(2.0×108 CFU/ kg) and Saccharomyces cerevisiae (3.0×108 CFU/ kg) enhanced growth
performance and nutrient digestibility.
