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Abstract. The objective of this study is to determine the optimal protein level for best growth and development of Rana perezi Seoane larvae. Performance of four diets containing 28%, 33·5%, 39% and 45·5% protein was compared. Tadpoles provided diets with 39% and 45·5% gross protein achieved the best results with regard to growth (weight gain, growth rate, feed conversion, etc.) and development (length of larval period, percentage of metamorphosis, etc.). Considering that protein is the most expensive diet component, it is estimated that the optimum quantity of protein for R. perezi larvae is about 39%.

Skeletal malformations at metamorphosis in Rana perezi tadpoles reared in culture have been studied. Tadpoles were fed ten artificially compounded and fresh diets and kept at two different temperatures. Animals were maintained in fiberglass tanks. Bone damages are related to the nourishment with compound diets. Tadpoles fed such diets showed variable percentages of scoliosis, kyphosis, luxations, and subluxations in the hind limbs, aplasia in phalanges, and wide failures of ossification. The data suggest the origin of the lesions is a deficiency in some compounded diets that could alter collagen metabolism during skeletal adjustments at metamorphosis.