Effects of feeding level and body size on food utilization of the freshwater snail Pila globosa

Food supply caused an increase in the overall energy budget of all size groups of Pila globosa. Feeding rate increased from 3.4 to 28.7, 2.0 to 19.1 and 0.2 to 7.2 mg/g/day in young, intermediate and old snails respectively. The corresponding increase in body weight (growth rate) ranged from 1.3 to 2.7, 0.5 to 1.5 and 0.4 to 0.5 mg/g/day. When compared with the other two groups, maximum values were recorded for young P. globosa, i.e. an increase in size (ageing) caused a decrease in the energy budget. Data obtained for the maintenance, optimum and maximum feeding rates for the young P. globosa were 12.0, 22.0 and 28.8 mg/g/day. The corresponding values for the intermediate and old snails were 7.4, 14.0 and 19.0 mg/g/day and 4.1, 5.6 and 7.2 mg/g/day. With the increase in body weight, a progressive reduction in the slope of the regression lines was noticed in the body weight-conversion rate relationship.Paper presented in the first Indian Conference on Ecology and Environmental Sciences, University of Rajasthan, Jaipur (1980).