USE OF ARTIFICIAL GRAZING SUBSTRATES IN BULLFROG TADPOLE CULTURE

A 45-day experiment was conducted to compare the effects of vertical a nd horizontal artificial grazing surfaces on Rana catesbeiana tadpole growth and metamorphosis. Groups of Stage 26 tadpoles were stocked at 1 individual 1(-1) in 10(-1) plastic containers. Powdered, moistened f eed mixed with gelatine, was adhered to acrylic plates as feeding subs trates in T-1 (vertical, parallel to the side walls) and T-2 (horizont al, at mid-depth). As a control (C), the same feed was spread homogene ously on the bottom of a third set of containers. I;our replicates wer e used for each treatment. Growth of tadpoles in T, was significantly higher (P<0.05) than that in T, or C, with an individual mean weight a t metamorphic climax of 3.2 g (+/-0.04 s.e.), as opposed to 2.3 g (+/- 0.05 s.e.) and 2.1 g (+/-0.07 s.e.), respectively. The percentage of m etamorphosed individuals was also significantly higher(P<0.05) in T-2 (81%), than in T-1 (73%) and C (55%). Respective food conversion ratio s for T-2, T-1 and C were 2.40, 2.82 and 2.65. (C) 1997 Elsevier Scien ce B,V.