Growing global needs for food call for substantial increases in protein production in coming years, and for diligent conservation efforts. Manures from farm animals have been viewed both as a resource and as a waste p...Growing global needs for food call for substantial increases in protein production in coming years, and for diligent conservation efforts. Manures from farm animals have been viewed both as a resource and as a waste product, but they are critically important sources of nutrients for organic and integrated farming and for traditional Asian aquaculture. Given constraints on livestock production and capture fisheries, careful development of the aquaculture industry is a necessity. The production volume and market share of tilapia are advancing extremely rapidly, and so too is the proliferation of misinformation and controversy. Culture and feeding practices differ widely, but feeding is usually recognized as the single largest cost to producers. Traditional Asian integrated farming practices involve the use of manures and other farm wastes to promote algae and zoo-plankton production, serving as a sole or supplemental nutrient source to the food chain that supports tilapia growout. Tilapia also ingest manures. The efficient use of nutrients from manures can have multiple benefits to integrated terrestrial agriculture and aquaculture, as long as product safety and quality are not compromised. With efficient use, handling of manures is simplified, fish production costs are reduced, fish nutrition can be improved, and potentially polluting materials are cycled constructively on integrated farms. Consumer and press reactions to the use of farm manures in food production can be highly polarized. Published responses cover a range of extremes, from enthusiastic endorsement to volatile reactions and outright rejection;in some areas this practice is considered to be more of a “PR (Public Relations) problem” than a health hazard. The perception in online public media that tilapia coming from ponds fertilized with manure are heavily contaminated with pathogens has not been supported by evidence. The perspectives of farmers in two major tilapia production areas (China and the Philippines) are included.展开更多
Aquaponics is a fish-plant recirculating system where nutrients received from the fish culture are absorbed by the plants for growth.The technology is relatively new for fish culture in Kenya,and the principles and op...Aquaponics is a fish-plant recirculating system where nutrients received from the fish culture are absorbed by the plants for growth.The technology is relatively new for fish culture in Kenya,and the principles and operations remain largely untested for many fish species.This study determined how stocking density affects the growth performance and water quality in a Nile tilapia-lettuce(Lactuca sativa)aquaponics system.The experimental design included five replicates for each of the aquaponic systems stocked at densities of 150,300,and 450 fish/m^(3) for a rearing period of 56 days.Each treatment had a planting density of 16 lettuce/m2.The water quality parameters ranges during the rearing period were 3.83-5.35 mg/L for dissolved oxygen,7.44 to 7.6 for pH,0.014 mg/L to 0.032 mg/L for total ammonium nitrate(TAN),1.11-1.34 mg/L for nitrate,and 0.01-0.08 mg/L for nitrite,and all decreased with increasing stocking density.The final weight of fingerlings was 25.2±4.2 g,32.0±3.8 g and 42.6±3.1 g for 450,300,and 150 fish/m^(3) respectively.Specific growth rate(SGR)was reduced with increasing stocking density whereas food conversion ratio(FCR)increased with stocking density.Aquaponic systems with the lowest stocking densities performed better than 300 and 450 fish/m^(3) respectively.展开更多
文摘Growing global needs for food call for substantial increases in protein production in coming years, and for diligent conservation efforts. Manures from farm animals have been viewed both as a resource and as a waste product, but they are critically important sources of nutrients for organic and integrated farming and for traditional Asian aquaculture. Given constraints on livestock production and capture fisheries, careful development of the aquaculture industry is a necessity. The production volume and market share of tilapia are advancing extremely rapidly, and so too is the proliferation of misinformation and controversy. Culture and feeding practices differ widely, but feeding is usually recognized as the single largest cost to producers. Traditional Asian integrated farming practices involve the use of manures and other farm wastes to promote algae and zoo-plankton production, serving as a sole or supplemental nutrient source to the food chain that supports tilapia growout. Tilapia also ingest manures. The efficient use of nutrients from manures can have multiple benefits to integrated terrestrial agriculture and aquaculture, as long as product safety and quality are not compromised. With efficient use, handling of manures is simplified, fish production costs are reduced, fish nutrition can be improved, and potentially polluting materials are cycled constructively on integrated farms. Consumer and press reactions to the use of farm manures in food production can be highly polarized. Published responses cover a range of extremes, from enthusiastic endorsement to volatile reactions and outright rejection;in some areas this practice is considered to be more of a “PR (Public Relations) problem” than a health hazard. The perception in online public media that tilapia coming from ponds fertilized with manure are heavily contaminated with pathogens has not been supported by evidence. The perspectives of farmers in two major tilapia production areas (China and the Philippines) are included.
基金Special thanks go to AquaFish Innovation Lab under the United States Agency for International Development(USAID)Cooperative Agreement Number EPP-A-00-06-00012-00 and the National Research funds(NRF)formerly known as the National Commission for Science Technology and Innovation(NACOSTI)for funding this project.
文摘Aquaponics is a fish-plant recirculating system where nutrients received from the fish culture are absorbed by the plants for growth.The technology is relatively new for fish culture in Kenya,and the principles and operations remain largely untested for many fish species.This study determined how stocking density affects the growth performance and water quality in a Nile tilapia-lettuce(Lactuca sativa)aquaponics system.The experimental design included five replicates for each of the aquaponic systems stocked at densities of 150,300,and 450 fish/m^(3) for a rearing period of 56 days.Each treatment had a planting density of 16 lettuce/m2.The water quality parameters ranges during the rearing period were 3.83-5.35 mg/L for dissolved oxygen,7.44 to 7.6 for pH,0.014 mg/L to 0.032 mg/L for total ammonium nitrate(TAN),1.11-1.34 mg/L for nitrate,and 0.01-0.08 mg/L for nitrite,and all decreased with increasing stocking density.The final weight of fingerlings was 25.2±4.2 g,32.0±3.8 g and 42.6±3.1 g for 450,300,and 150 fish/m^(3) respectively.Specific growth rate(SGR)was reduced with increasing stocking density whereas food conversion ratio(FCR)increased with stocking density.Aquaponic systems with the lowest stocking densities performed better than 300 and 450 fish/m^(3) respectively.
