| Autor: |
Moraes MA; Centro de Pesquisa e Desenvolvimento Especializado em Recursos Hídricos, Instituto de Pesca - IP, Avenida Francisco Matarazzo, 455, Parque da Água Branca, CP 61070, CEP 05001-900, São Paulo, SP, Brazil., Carmo CF; Centro de Pesquisa e Desenvolvimento Especializado em Recursos Hídricos, Instituto de Pesca - IP, Avenida Francisco Matarazzo, 455, Parque da Água Branca, CP 61070, CEP 05001-900, São Paulo, SP, Brazil., Tabata YA; Estação Experimental de Salmonicultura, Agência Paulista de Tecnologia dos Agronegócios - APTA, Parque Estadual de Campos do Jordão, CP 361, CEP 12460-000, Campos do Jordão, SP, Brazil., Vaz-Dos-Santos AM; Laboratório de Esclerocronologia, Universidade Federal do Paraná - UFPR, Rua Pioneiro, 2153, CEP 85950-000, Palotina, PR, Brazil., Mercante CT; Centro de Pesquisa e Desenvolvimento Especializado em Recursos Hídricos, Instituto de Pesca - IP, Avenida Francisco Matarazzo, 455, Parque da Água Branca, CP 61070, CEP 05001-900, São Paulo, SP, Brazil. |
| Abstrakt: |
The phosphorus and nitrogen discharge via effluent of intensive trout farming system was quantified through the use of environmental indicators. The nutrient loads, the mass balance, the estimated amount of nutrients in feed and the amount of nutrients converted in fish biomass were calculated based on the concentrations of phosphorus (P) and nitrogen (N) in the feed and in the water. Of the offered feed, 24.75 kg were available as P and 99.00 kg as N, of these, 9.32 kg P (38%) and 29.12 kg N (25%) were converted into fish biomass and 15.43 kg P (62%) and 69.88 kg N (75%) were exported via effluent. The loads and the mass balance show the excessive discharge of nutrients via effluent, corroborated by the feed conversion ratio (2.12:1) due to the low efficiency of feed utilization, therefore, it is proposed the use of this zootechnical parameter as environmental indicator. In addition, feed management practices are not adequate, highlighting the low frequency of feeding during the day, excessive amount and low quality of feed offered. These results demonstrate the need for adequate feed management and the need for careful monitoring of effluent. |
