Laboratory rearing conditions for improved growth of juvenile Helix aspersa Müller snails (original) (raw)
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International Journal of Agriculture and Forestry
This study provides information on the growth and correlations between body traits of juveniles of two ectotypes of snail[Archachatina marginata var. saturalis (P)]. Three hundred juveniles, one hundred and fifty each of the black-skinned (BS) and white-skinned (WS) ectotypes selected from a pool on the basis of active appearance and absence of injury, blister or lesion on the foot and/or shell were used for the study. The selected juveniles were grouped into two on the basis of skin (foot) colour. Each group was replicated five times with ten juveniles per group in a completely randomized design. The results of this study showed that during the juvenile phase of growth, there was progressive weight increment with significant differences (P<0.05) between the juveniles of the two snail ectotypes (BS and WS) at hatch through to week two after hatch. The significant difference seized to exist after week two as growth was at par among the ectotypes. The absence of significant difference (P>0.05) after week two could mean that irrespective of their pigmentation and weight at hatch, juveniles of a particular breed always grow to catch up with others within the same environment. The results also showed that growth in terms of weight gain was generally low/slow during the first few weeks of life after hatch. The reason for this could be that the juveniles eat little or no feed (concentrate and/or forage) during this stage of life. The results of estimates of association between traits showed that all evaluated traits had strong positive correlations in the two snail ectotypes studied. The correlations between these traits were highly significant (P<0.001). The positive correlation values recorded among these traits could mean that the traits are influenced by the same genes in the same direction, and that there are direct relationships between the traits. Besides, it could be that weight increment in snails is as a result of increase in the size of corresponding traits. The high degree of correlation among traits indicates that selection for one trait will lead to improvement in the other trait. The results of this study could guide breeders in the development of stocks, and thus increase the availability of animal protein for the teeming Nigerian populace.
International Journal of Agriculture and Forestry, 2012
This study provides information on the growth and correlations between body traits of juveniles of two ectotypes of snail[Archachatina marginata var. saturalis (P)]. Three hundred juveniles, one hundred and fifty each of the black-skinned (BS) and white-skinned (WS) ectotypes selected from a pool on the basis of active appearance and absence of injury, blister or lesion on the foot and/or shell were used for the study. The selected juveniles were grouped into two on the basis of skin (foot) colour. Each group was replicated five times with ten juveniles per group in a completely randomized design. The results of this study showed that during the juvenile phase of growth, there was progressive weight increment with significant differences (P<0.05) between the juveniles of the two snail ectotypes (BS and WS) at hatch through to week two after hatch. The significant difference seized to exist after week two as growth was at par among the ectotypes. The absence of significant difference (P>0.05) after week two could mean that irrespective of their pigmentation and weight at hatch, juveniles of a particular breed always grow to catch up with others within the same environment. The results also showed that growth in terms of weight gain was generally low/slow during the first few weeks of life after hatch. The reason for this could be that the juveniles eat little or no feed (concentrate and/or forage) during this stage of life. The results of estimates of association between traits showed that all evaluated traits had strong positive correlations in the two snail ectotypes studied. The correlations between these traits were highly significant (P<0.001). The positive correlation values recorded among these traits could mean that the traits are influenced by the same genes in the same direction, and that there are direct relationships between the traits. Besides, it could be that weight increment in snails is as a result of increase in the size of corresponding traits. The high degree of correlation among traits indicates that selection for one trait will lead to improvement in the other trait. The results of this study could guide breeders in the development of stocks, and thus increase the availability of animal protein for the teeming Nigerian populace.
Effect of Population Density on Growth of Land Snail Helix aspersa maxima
Journal of Applied Animal Research, 1992
The first few weeks of life are of great importance f i r the growth of snails. Breeders have to carefully handle this delicate and costly phase. The impact of population density increased with the number of animals and the duration of nursery. The highest tested densities did not have a negative effect on growth up to two weeks, after which a strong negative influence was observed. Elod, here given ad libitum, was not the main limiting factor and cherriical interactions between snails via mucus trucks are envisaged
Aacl Bioflux, 2015
In this research, the growth and survival rate of juvenile Helix lucorum was determined during the eight weeks. Coefficient variation (CV) in assessing variability of shell height and live weigth was investigated. One week old juvenile snails with a mean shell height of 6.73±0.03 mm and a mean weight of 0.10±0.01 g were stocked to the three rearing boxes with a density of 13 snails per group at the start of the experiment. At the beginning of the study, the variability of shell height and live weight showed relatively little difference as 9.71% and 28.16% but this gradually increased towards the end of the study. The final variation of shell height and live weight was calculated 20.32% and 59.84%, respectively. At the end of the study, cumulative survival rate was found 97.74%. In conclusion, snails showed high survival rate with high size variation in the study. Initial stocking density is optimal for rearing juvenile H. lucorum but after four weeks, stocking density should be decr...
Quantitative Measurements of Two Breeds of Snail
2014
Snail farming requires little experience, and the animals are usually found in cool environment. In this study ninety animals comprising of fifty Archachatina marginata and forty Achatina achatina were used. Data collected include Shell Length (SL), Shell Width (SW), Height of Snail (HS) Snail Live Weight (SLW), Aperture Length (AL), Aperture Width (AW) Visceral and Foot Weight(VFW), Visceral Weight (VW), Foot Weight (FW), Foot thickness (FT). The mean snail length (SL) was 8.29 + 0.31cm in A. marginata and 7.84 + 0.20cm is A. achatina. The A. marginata had a longer length than the A. chatina. The aperture length was longer in A. marginata 5.08 + 0.19cm than A. achatina 4.69 + 0.11cm. The mean foot weight is higher in A. marginata (34.21 + 3.20g) than A. achatina (26.98 + 2.26g). The mean shell weight of A. marginata (24.24 + 2.01g) is higher than A. achatina (14.46 + 1.48g). The mean shell length of A. marginata was not significantly different (P<0.01) from A. achatina. The SLW of A. marginata is significantly different (P<0.01) from A. achatina. The prediction power is more with shell width (20.013) in A. marginata and shell weight (0.771) in A. achatina. These findings should be considered in improvement programme to increase the meat yield of snail.
Journal of Molluscan Studies, 2008
A photogrammetric methodology is proposed to measure the diameter of snail shells on digital pictures. Digital photographs were taken of juvenile Cantereus aspersus snails. AutoCAD image analysis software was used for the measurements and the results were contrasted with data obtained using a digital caliper in the same snails to compare the accuracy of both methods. The snails were individually weighed and the shell diameter was measured once a week, for a total of 7 weeks. After the third week, there were no significant differences between both methods, whereas in the first 2 weeks the measurements obtained with a digital caliper scored larger diameters than the photogrammetric measurements. This is probably due to the difficulty to define the end of the shell with the caliper, whereas the photogrammetric analysis does not involve any risk for the snail. To test the reproducibility and repeatability of both methodologies seven snails were measured five times by three different examiners. Using the variance components analysis, the repeatability was 4.8% of the total variation for the photogrammetric methodology and 6.9% for the conventional methodology, while the reproducibility was 0.0% and 2.7% for the photogrammetric and conventional methodology, respectively. These findings indicate that the photogrammetric methodology can be used with confidence to measure the diameter of snail shells. The great advantage of this method is the ability to magnify the images to make more precise measurements from snails of any size, which is especially useful in the early stages of development. The growth data were used to construct a model for live weight (LW) estimation based on shell diameter. The snails showed high growth rates both in terms of shell diameter and LW. The shell diameters showed a low individual variation (16.2% CV) and were normally distributed, whereas the LWs showed greater variability (36.8% CV) and were not normally distributed. The best model for estimating LW from shell diameter in juvenile snails is the multiplicative model, with a high determination coefficient (96%).
American Malacological Bulletin, 2007
With the aim of integrating the physiology and evolutionary ecology of Lymnaea stagnalis (Linnaeus, 1758), we studied the effects of day length and food availability on the energy budget. Snails were assigned to two different photoperiods and three levels of food availability. The snails were kept individually, and food consumption, growth, and egg production were measured for about 2 months. Snails could nearly compensate for a one-day starvation period by increasing the rate of food-intake. However, food-intake rates did not increase further after a starvation period of 2 days. Growth was well described by the Von Bertalanffy growth equation. The ultimate size of snails kept under medium-day conditions (MD; light:dark = 12:12 h) was not affected by food availability. By contrast, the ultimate size of snails kept under long-day conditions (LD; light:dark = 16:8 h) depended on food availability; those fed the lowest quantities grow the least. Dry-weight densities (dry weight/wet weight) of MD snails were considerably above those of LD snails. In MD snails, food availability did not appreciably affect dry-weight density. By contrast, in LD snails, dry-weight density decreased with decreasing food availability. The reproductive output of LD snails declined with declining food availability, but was 2 to 4 times that of MD snails. The difference in reproductive output was largely accounted for by the difference in stored energy, i.e. dry-weight density. To gauge the extent to which the conclusions from our laboratory work applied to free-living snails, a field study was conducted. The wild-caught snails' dry-weight density was also lowest in long-day conditions when most eggs were laid. However, the dry-weight densities during medium and short days were lower than the dry-weight densities of laboratory animals under LD conditions. Thus, in the field, snails stored less energy than in the laboratory.