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Influence of feed and feeding strategy on fish production and product quality of organic fishery products (ÖkoFuProQua)
Project
Project code: 2808OE157
Contract period: 01.11.2008
- 30.11.2011
Budget: 15,802 Euro
Purpose of research: Applied research
In this project the influence of feed composition and feeding strategy on organic fish production and fish quality was assessed. The project was financed by the “German Federal Ministry of Food, Agriculture and Consumer Protection (BMELV)” and supervised by the “German Federal Office for Agriculture and Food (BLE)”. Two fish species, Brown trout (Salmo trutta fario L.) and Arctic charr (Salvelinus alpinus L.), were raised to market size according to the organic guidelines of “Naturland”, a German founded association for organic agriculture. As part of the organic production, the production in earthen ponds, a strict stocking density (max 10 kg/m3) and the use of certified organic feeds is required. Three certified organic trout feeds of different suppliers were tested against each other in a growth trial. A control group was fed a standard trout diet. Additionally the effect of the feeding strategy, hand feeding (2 times/day) compared to automated feeding (continuous), was investigated. The feeding levels were adjusted throughout the experiment according to the growth performance of the animals. Also, standard water quality parameters and fish health were regularly recorded. Upon reaching average standard market size, the growth performance and product quality of the fish was analysed and compared. The brown trout groups showed comparable and acceptable growth performances throughout the trial for all used feed stuffs. The fish reached market size in 9.5 months. Size differences during harvest were explained by feed composition with high energy feeds (fat content up to 25 %) performing better in the early stages of the trial. Growth in the last months of the experiment was retarded due to the high level of maturity in the fish. As expected, the high level of maturity directly affected filet quality and weight. The feed conversion ratio (FCR) was ranging between 1.0 and 2.5, from acceptable to economically unfeasible. It was seen, that costs of organic feed stuffs are higher compared to standard diets due to more expensive certified raw products. The costs for feed/kg fish growth ranged from 1.61 €/kg for the standard diet compared to 2.30 €/kg for the organic feeds. Arctic charr had a worse overall performance in the experiment than Brown trout. The fish reached harvest size after 10.5 months. Slower growth rates, early maturation and a lower overall disease resistance added up to an economically sub-optimal cost/growth ratio. The costs for the standard diet were 3.10 €/kg compared to the organic 6.22 €/kg growth. The required stocking density of < 10 kg/m3 appears to be too low for Arctic charr, leading to a reduced and varying feed intake. The right feeding strategy can be used to counteract this discontinuous feed uptake. It was seen, that adaptable hand feeding with direct observation of fish behaviour during feeding yields better growth results, less food spillage and associated better water quality in the ponds. In an automated feeding regime depending on calculated feeding tables, daily feed corrections are more difficult and feed loss is inevitable. The analysis of the fish end-product quality showed no differences between the different feeds or the feeding strategy. No significant differences were found for the chemical, physical, instrumental or sensory parameters analysed during the quality testing. Overall the product quality was good and within the accepted range for food quality. The body composition of the filets was in line with average market quality. In Arctic charr this study was the first to investigate filet body composition and will be used as a baseline for further studies. Both fish species and all groups had high amounts of taurine and omega-3 and omega-6 fatty acids, highlighting the healthy and important role of fish in human diets. The tested modern organic feed stuffs yielded similar production values compared to standard diets. High value raw materials in modern organic feeds guarantee a comparable growth to standard, conventional feed stuffs. The product quality of the organic end product was comparable to established conventional fish product. The overall costs for organic fish production is higher, due to higher feed and production prizes, because of strict maximum production limits requested by organic certifiers. Feed costs alone cause a 40-50% price increase in the end product. It was shown that organic Brown trout production is economically feasible, whereas the organic production of Arctic charr is difficult and production guidelines need to be revised.
Section overview
Subjects
- Pond fisheries
Framework programme
Federal Organic Farming Scheme and other forms of sustainable agriculture (BÖLN)
Funding programme
Excutive institution
MRI - Department of Safety and Quality of Milk and Fish Products (MRI-MF)
