In India, the freshwater fish is generally being cultured in earthen ponds under the provision of fertilization and supplementary feeding. At present, the average freshwater fish production is 2.9 t/ha and to achieve the fish production of 8.0 MMT in next five years, the present fish production level is to be enhanced to 4-5 t/ha. This increase in fish production from the existing level of 2.9 t/ha to 4-5 t/ha is possible only through the provision of supplementary feeding. Feed is the highest recurring cost in modern day aquaculture constituting about 50-60% of the total production cost. By 2050, the targeted freshwater fish production in India is 17.0 MMT and to achieve this target, about 23 MMT of feed is required. The availability of fish feed ingredients would be the major challenge for the aquaculturists in the coming years. Therefore, the much valued available feed resources must be used judiciously through proper feed and feeding management practices.
In the present paper, we have discussed in brief about the present status of fed fish culture,ensuring the availability of feed ingredients and formulated feed, importance of plant feed resources, need of feed based aquaculture, optimizing the feed management strategies and feed processing technologies for the benefit of fish growers, feed manufacturers, researchers, financial institutions and policy makers.
Status of fed fish culture
On a global basis, the fed freshwater fish production is 21.34 MMT, valued at US$27.36 billion. More than 85.5% of fed fish and crustacean aquaculture production was produced on the Asian continent in 2008 (26.9 MMT). However, the fed fish production in India is 3.08 MMT which accounts 9.8% of the total global fish production (FAO, 2010). At present, only 43.85 MMT of concentrated feeds are available in the country, where as the demand for the concentrated feed by the different animal husbandry sector is 142.68
MMT, with a deficit of about 70%. Farm-made aquafeed feed plays an important role in the production of low-valued freshwater fish species. More than 97% of the carp feeds used by Indian farmers are farm-made aquafeeds and they are the mainstay of feed inputs. At present, about 7.0 MMT of ingredients are being used for farm-made fish production. The total volume of manufactured feed sold in the country in 2010 was 60,000 t of pelleted fish feed and 3,72,000 t of extruded floating feed (Giri, 2013).
Ensuring availability of feed ingredients and formulated feed
The fish feed resources are mainly comprised of the by-products of the agro-processing industries and the availability of these by-products depends on the production of the main crops like oilseeds, cereals and pulses, which in turn largely influenced by the success/failure of monsoon. There is a very remote possibilityof significant increase in production of these agricultural by-products in near future as there is a marginal increase in agricultural production (oilseeds,
cereals and pulses) in the country. However, during the last decade, the price of the most of the fish feed ingredients had increased significantly to the tune of 3-4 times in India. Therefore, identification of alternate feed ingredients and their use in the fish feed would be one of the major challenges in the future. So far the freshwater fish farming in India has been relying on the use of conventional feed mixture comprising of mainly the oil cakes and brans with an approximate FCR of 3.0-4.0. With the growing aquaculture production in the country, it is necessary to use the limited feed resources more judiciously by improving the feed efficiency. The fish feed ingredients are finite resources and many of these ingredients are having multiple users from other animal production systems such as dairy and poultry and therefore, it is envisaged that there will be an acute shortage of ingredients in the days to come. In order to better utilize and also to save the scarce and much valued fish feed resources, proper feed and feeding strategies are also required. The use of sinking/floating pellets must be encouraged rather than relying on use
of conventional feed mixture for better feed consumption, low wastage and efficient nutrient utilization and gain. Therefore, to save the scarce and costly feed resources, emphasis must be given for the establishment of more number feed mills to produce therequired quantities of floating feeds. In this regard, ICAR-CIFA had made a thorough survey on available fish feed resources in the country and a fish feed resource inventory in the form of a book entitled “Fish Feed Resources and Farm Made Feeds” was published which provides information about the quantity available feed ingredients, place of availability, chemical compositions, different antinutritional factors present in feed ingredients and their amelioration measures, processing and use of these ingredients in formulating different fish feeds, fish feed production processes and storage of prepared feed.
Use of plant based feed: need of the hour
Fish meal is still considered the most desirable protein source in aquaculture diets for carnivorous and omnivorous fish, because of its high protein content, balanced amino acid profiles, high digestibility and palatability, and rich essential n-3 polyenoic fatty acid levels. The global aquaculture demand for fish meal was 32% of the world supply by 1999 (New and Wijkstom, 2002), 37% in 2000 (Chamberlain, 2000), and might reach 65% by 2010 (Chamberlain, 2000) and nearly 70% by 2015 (New and Wijkstom, 2002). The volume of fish meal and oil used in aquaculture, particularly for carnivorous fish, is so huge that aquaculture of these species is still perceived as net consumers rather than producers, and this practice has raised concern about the sustainability of these industries. The high cost of fish meal and concerns regarding its future availability have made it imperative for the nutritionists to reduce or eliminate the fish meal from fish and crustacean diets as a strategy to avoid any risk on the future of aquaculture industry. Substantial efforts have been made around the globe in evaluating the wide range of potential ingredients of plant origin (Glencrosset al., 2007; Glencrosset al., 2011; Oujifardet al., 2012).
Carp is the mainstay in Indian aquaculture. Carp being an omnivorous fish (preferably herbivorous), can use very efficiently the plant feed resources. Research carried out at ICAR-CIFA revealed that the carp can grow very well with feeding of fish meal and fish oil free diets. Several nutrient-rich plant products have assumed great importance for aquaculture. Proper combinations of different plant ingredients and incorporation/fortification of deficient amino acids and vitamins and minerals not only balance the nutrients but also act upon their deficiency-compensation mechanism. The important plant ingredients include wide range of oil seed residues, cereals, millets, etc. These are available to a tune of 48.85 MMT (2009-10) as feed concentrates in India. There are nine major oil seeds produced in India. These are groundnut, soybean, rapeseed/mustard, sesame, castor, sunflower, linseed, safflower and niger. In addition, cotton seed, oil palm seed and copra contributes to the edible oil pool of the country. Other plant by-products such as sal seed, neem seed, mahua seed, karanj seed, rubber seed, physic nut, Indian doomba etc., are also some potential feed resources which could be used in fish feed. The total oilseed and oil production in the country is 33.6 and 8.4 MMT, respectively (2011-12). Madhya Pradesh, Rajasthan and Gujarat produce more than half of the total oil seed production in India. The oil cakes residues that are produced after the extraction of oil which constitutes around 65% of the oil seeds and are extensively used as protein sources in formulating the fish feeds. The estimated oil cake production in India is 22.68 MMT (2011-12). Cereal by-products/cereals such as rice bran, wheat bran, maize, sorghum, bajra and millets, etc. are the major sources of carbohydrate and energy in fish feed and their quantum of availability in the country is about 6.20, 8.0, 12, 9.0, 10.37 and 2.6 MMT, respectively.
Promoting feed-based aquaculture
Globally the fed aquaculture constitutes about 75% of the current production from aquaculture. In China, more than 90% of the aquaculture production comes through feed based aquaculture, but in India, the fed fish culture is less than 20%. As compared to India, the per cent of fed fish culture is higher even in less developed neighboring countries like Bangladesh and Sri Lanka. In India, the commercial aquaculture feed production is only 247283 t (2006-07). In semi-intensive fish farming, provision of supplementary feeding is essential to realize the maximum growth potential of fish and also to enhance the fish production in the stipulated culture period. To achieve the production target of 16-20 MMT by 2050, the fed fish culture in India has to be raised to 3-4 times from the present levels of 20% to at least 70-80%, which would be a major challenges for the researchers, extension functionaries, fish feed producers and the administrators in the future. It is also necessary to convert 10-15% of the aquafarms of the country to intensive aquaculture systems such as raceway culture, running water culture, recirculatory aquaculture, etc., which are the complete feed based aquaculture.
Optimizing the feed management strategies
The profitability of a commercial farming operation is of paramount importance to the farmer. Adopting appropriate feed management strategies is instrumental in ensuring that feed use is optimized and that the highest economic returns are available to the farmer (FAO, 2010). The maximum growth rate of fish isattained by feeding it to satiation and the over- or under-feeding results feed inefficiencies (Kaushik, 2000). In case of over-feeding, in addition to nutrient loss, there is increased levels of farm effluents. Underfeeding results lowered growth rates and increases size heterogeneity in fish population as hierarchies develop. Optimization of feeding strategies involves the provision of appropriate ration sizes and feeding rates, feeding frequencies, and feeding times that take into consideration the endogenous feeding rhythms of the farmed species (FAO, 2013). To utilize the feed and nutrient more efficiently, the fish are to be fed with standard feeding chart/table that are developed through the intensive research efforts.
Feed manufacturing technologies
Irrespective of feed ingredients used and the formulations applied, the manufacturing processes and type of feed produced can significantly affect feed performance. Generally the farmers are more concerned about the quality feed ingredients, but very often they are unaware that feed processing has a significant effect on feed quality and utilization. Presenting feeds as simple dry or moist mixtures or as moist mixed feeds leads to much of the feed being dispersed in the water column, resulting in low ingestion rates and high economic feed conversion ratios (eFCR). Feed efficiencies can be improved by encouraging farmers to use simple extruders and compressing their feed ingredients into dry pellets. Likewise, improving milling and the binding characteristics of the pellets reduces the amount of fines, improves pellet hardness and water stability, improves eFCR, and results in cost savings to the farmer. Focusing on improving efficiencies in the farm-made and small-scale feed manufacturing sectors is likely to bring significant gains to on-farm feed efficiencies. The potential to develop public-private partnerships with farmer groups and associations to share resources and improve access to improved feed manufacturing capacity should be considered to promote feed based aquaculture (FAO, 2013).
ICAR-CIFA has state of art feed mill facility with a production capacity of about 300 kg/hour for conducting research on feed technology development and demonstrating the students/researchers/farmers/entrepreneurs about the production of extruded floating pellets.
The importance of supplementary feed has been greatly realized in India during mid-seventies when the composite fish culture was undertaken at Pond Culture Division of CIFRI at Cuttack, Odisha. During the last three decades, there is a paradigm shift in fish feed sector. The traditional use of rice bran-oil cake mixture as fish feed has now been gradually replaced with nutritionally balanced extruded feeds. At present, species specific diets are being developed for the different life stages of fish. In India, still only about 15-20% of the fish farmers use fish feed. Therefore, there is a tremendous scope for feed based aquaculture to enhance the fish production in the country and also to meet the nutritional security of the growing population. Generally, small and marginal fish farmers that constitute the backbone of Indian aquaculture use mash feed for carp culture and use about 3 kg feed for 1 kg of fish produced. It is now well established that nutritionally balanced pelleted diet (floating/sinking form) prepared by using different feed ingredients with fortification of desired feed additives like functional food aids, binders, growth promoters, immunostimulants, prebiotics, probiotics and digestive and cellulolytic enzymes can improve the feed:gain ratio to 1.1-1.5:1. It is the combined responsibility of all stakeholders of aquaculture to save and better utilize the much valued feed resources of the country through proper feed and feeding management practices.
Dr P. Jayasankar and Dr K.N. Mohanta, ICAR-Central Institute of Freshwater Aquaculture