Effects of dietary calcium on growth and oviposition of the African land snail Limicolaria flammea (Pulmonata: Achatinidae)

Abstract

In an attempt to elucidate the role of calcium in the life of the edible Achatinid snail, Limicolaria flammea (Müller) I investigated short and long term effects of calcium added to the food. The short term experiments lasted for 18, 30 and 32 weeks respectively, while the long term experiment to determine life time utilization of calcium carbonate lasted for 15 months. In the short term experiments, hatchlings were divided into densities of one, ten and 50 snails. In the 10 snail group, there was a positive correlation between calcium provision, body weight (t test, p < 0.01; r = 0.96, p < 0.0001) and shell length (t test, p < 0.01; r = 0.96, p < 0.00001). There was also a positive correlation between increase in shell length and availability of calcium in the 1 snail group (t test, p< 0.01; r = 0.99, p < 0.00001). In the 50-snail group, the correlation was positive for shell length of the snails (t test, p < 0.05; r = 0.99, p < 0.0001) and body weight (t-test, p < 0.05; r = 99, p < 0.00001). Mortality was very high in the snails deprived of calcium and they did not produce eggs. In the long term experiment, there were three feeding peaks in L. flammea. In the first feeding peak, amount of food and calcium ingested by the snails increased in the first three months of life. The second feeding peak occurred at six months of age, while the last occurred at 10 months of age. The amount of calcium ingested during the second peak decreased gradually in the 4th and 5 th month. The amount of calcium ingested was lowest during the 3rd feeding peak. The period of highest weight gained by the snails was between the 1st and 6th month and then dropped at between six and 12 months of age which corresponds to the period of egg production. There were also three peaks of egg production; the first was between six and eight months (535 eggs), the second at between 10 and 11 months (350 eggs) and the third at 13 to 14 months (310 eggs) respectively. Rev. Biol. Trop. 56 (1): 333-343. Epub 2008 March 31.

Factors controlling shell carbon isotopic composition of land snail &lt;i&gt;Acusta despecta sieboldiana&lt;/i&gt; estimated from lab culturing experiment

“…Therefore, these snails show higher mortality. Figures Egonmwan (2008) reported a positive correlation between calcium provision, snail body weight and shell length. High mortality was observed for snails that were deprived of a calcium source.…”

“…This fact is explainable by the larger proportion of lime- stone ingested during the early period of land snails to enhance their growth rates. Egonmwan (2008) reported that the amount of food ingestion increases gradually, although calcium ingestion first increases (1-3 months, but increase rate is lower than diet consumption) and then decreases (4-6 months) during the first 6 months, suggesting that the contribution of ingested carbonate can be expected to decrease along with the snail growth. Our estimated contributions of ingested carbonate (Fig.…”

Factors controlling shell carbon isotopic composition of land snail &lt;i&gt;Acusta despecta sieboldiana&lt;/i&gt; estimated from laboratory culturing experiment

“…Therefore, these snails show higher mortality. Egonmwan (2008) reported a positive correlation between calcium provision, snail body weight, and shell length. High mortality was observed for snails that were deprived of a calcium source.…”

“…The solid line of Fig. 3 shows a model of diet-controlled snail shell carbonate δ 13 C (Francey, 1983;Stott, 2002), whereas the dashed line shows a flux balance model based on CO 2 diffusion when the input flux of CO 2 is equal to respired flux of CO 2 in the body fluid of land snails (Balakrishnan and Yapp, 2004). However, additional enrichments were observed in the published results and in this study (e.g., snails cultured at 20 and 25 • C with carbonate), suggesting a contribution a "−" means those fed Ca 3 (PO 4 ) 2 , which is probably hard and rarely ingested by snails; b snails regarded as a control group, cultured under an air-free exchange system with a small amount of soil; c mixture of four individuals cultured in the same condition (sizes are similar); d average value of snails of S34-S41; * x, calculated proportion of metabolic CO 2 ; y, proportion of atmospheric CO 2 ; z, proportion of CO 2 produced from ingested carbonate from ingested carbonate.…”

Utilización tradicional y composición bioquímica de seis conchas de moluscos en Nigeria

“…Similarly, Finkelstein et al (1993) added clam shells to lactating cow feed as a calcium supplement because snail shell is known to have high concentration of calcium. Egonmwan (2008) reported that a positive relationship existed between snail (Limicolaria flammea) shell and calcium concentration. The presence of these vital minerals needed for strong teeth in snail shells warranted their inclusion in formula for washing teeth in rural areas of Ondo state.…”