Development of a water recirculating system for bullfrog production: technological innovation for small farmers

Sílvia Conceição Reis Pereira Mello,Marcelo Maia Pereira,Willian Nascimento Silva,Eliane Rodrigues,Roberto Rodrigues De Oliveira,José Teixeira De Seixas Filho

doi:10.1590/s1413-70542016000100006

Abstract

ABSTRACT Despite the technological progress in frog farming, issues related to the environment, biosafety, and the use of technologies that minimise environmental impacts are frequently neglected by farmers. With the goal of developing a low-cost technology for reuse and preservation of water quality, an anaerobic filtering system combined with an aerobic filtering system was implemented in the grow-out sector in the Frog Culture Research Unit at Fundação Instituto de Pesca do Estado do Rio de Janeiro (FIPERJ). The filtering system received the effluent from six pens of frogs that were populated with 362 frogs in different development phases. The efficiency of the filtering system was evaluated by an analysis of the water before and after passing through the filters. In addition to the standards of water quality, the animals' performance was also observed through monitoring rates of survival, weight gain and feed conversion ratio. The results showed the effectiveness of the filtering system by removing organic matter, on average 87%. The values of total ammonia and non-ionisable reached 1.04 and 0.004 mg/L, respectively. Also, frogs subjected to the system presented satisfactory rates of weight gain and a high survival rate (97%).

Highlights

The bullfrog (Lithobates catesbeianus) is the most reared species worldwide and has adapted very well to Brazilian climatic conditions
This study was developed at the Frog Culture Research Unit of FIPERJ in Guaratiba, geographic coordinates S 22o 59’ 57.2’’and W 043o 35’22.4’’, in the city of Rio de Janeiro from July to September 2011
The weight gain reached was the expected for Lithobates castebeianus, with different ranges of live weight, considering the mean temperature observed in the water, once animals were submitted to the wet rearing system, remaining in the water

Summary

Introduction

The bullfrog (Lithobates catesbeianus) is the most reared species worldwide and has adapted very well to Brazilian climatic conditions. Other species are studied in Brazil for commercial purposes, but did not show good production performance (Carraro, 2008). Frog culture is an activity in expansion, with technological consolidation in several countries, in Brazil, China, Ecuador, Indonesia, Mexico, Taiwan and Thailand. The wet or inundated system was first employed in Asia, mostly in Taiwan and Thailand, and later adapted in Latin America in Argentina, Uruguay, Ecuador, Guatemala, and Mexico. Culture pens of the wet type, as opposed to those in semi-dry systems, can be employed for either of the frog culture phases (i.e., tadpole rearing nursery or grow-out sector). Each pen has its own water inlet and drainpipe, and a constant flow of water is kept throughout the culture period (Flores-Nava, 2000)

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Results