Bureau had the following messages with regard to reducing environmental impacts: Formulation for fish of different sizes: If the same formulation is used for fish of different sizes, there can be tremendous impact on the environment, such as phosphorus output. Feeds should be reformulated for fish size, while respecting certain risk margins. Further reduction of environmental impact is by selecting raw materials or supplementing with enzymes. Ingredient selection: Understand ingredients and not just simply fat/protein etc and develop solutions. Fibre and faecal cohesiveness: To target lower waste output, the focus should be on dietary fibre. For example, feeds with soybean meal and enzyme cocktail are less cohesive, more easily breakable with higher faecal material waste.
Improving feed quality
Feeding management
How can we minimize waste output? “Simply by making high density feed, we can improve on feed conversion ratios and reduce the waste output. We can reduce solid waste by 50%; in the mid-1980s, the solid waste output was 0.28kg/kg rainbow trout produced but in 2000s, it declined to about 0.17kg. The first step is to get rid of indigestible matter. In a farm in China, run by farmer cum professor Wang Yan, the transition from feeding raw fish to pelleted feeds to a marine fish species reduced total nitogen wastes/tonne of fish produced from 91kg to 45kg.
How feed is used is as important as the formulation and processing. “At the farm level, there are factors affecting feed utilization such as health issues, water pollution etc. Feed millers will need to tease out what impacts feed utilization. They need to develop tools and training programs to make farmers more efficient. Identify the conditions impacting FCR and start making adaptations,” said Bureau.
“A major issue here in Asia is formulating feeds for different species, culture systems and market demand (economy feeds etc). But formulators need to think more in terms of waste output which is an emerging issue. They should no longer focus on specification only but move to digestible nutrient basis; FCR is higher with low density feeds and lower (better) with higher digestible nutrient density feeds. ” Marketing different feed grades based on feed quality and feed costs is common in Asia. “Actually, on a cost basis (feed cost per kg of fish), these feeds are equal as the FCR is higher with lower quality feed. However, in terms of waste output, they are not equal. The higher quality/higher cost feed will have a much lower waste output. We can easily formulate tilapia feeds to optimize the reduction of waste output, as has been done with the trout.”
The recommendation is to use models to make sense of data collected. “These are available and we can run simulation of situations. Adaptable and scientifically developed feeding charts will also help. In the industry, many are using different feeding charts. We developed Wittaya Aqua (Wit in Aquaculture Production and Feeding Management) for easy access to farm and feed manufacturer and as more information is added, we can increase its robustness. The aim is to help improve efficiency, sustainability and long-term profitability of aquaculture operations. As we gather more information, it will improve the answers for ‘what if’ situations.” Models could be valuable for improving productive efficiency of aquaculture operations. Information from the laboratory and field can be used to construct models which can help to identify areas of improvement for production. However, Bureau warned not to blindly believe output from models or field data.
NEXT ISSUE March/April 2018 Issue focus: Health Management Industry review: Marine Fish Feed/Production Technology: Feed Additives, Omega 3 oils Deadlines: Articles – January 19, Adverts - January 26
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January/February 2018 AQUA Culture Asia Pacific Magazine
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