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PD/A CRSP Aquanews-Summer 2003

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Changes in Types of Feeds for Pangasius Catfish Culture Improve Production in the Mekong Delta

by Truong Quoc Phu and Tran Thi Thanh Hien, College of Aquaculture and Fisheries, Can Tho University

ulture of the Pangasius catfish has developed rapidly in recent years along the Mekong River, especially in four provinces: Angiang, Dongthap, Can Tho, and Vinhlong. The two main culture systems are cage culture and earthen pond culture. In 2002, it was estimated that 6,809 cages and 2,917 ha of pond were engaged in Pangasius catfish culture. This is a two-fold increase over figures for 1995. To foster the development of Pangasius catfish culture, many kinds of artificial feeds, notably commercially manufactured pellets were produced, but the use of pellets in catfish culture is still limited.

Fish pond and feeding hut.

Photo by: Pham Thanh Liem

Feed cost for Pangasius catfish culture is one important parameter affecting profit of production, as it usually occupies a high proportion (65 to 70%) of total operating costs. Therefore, selection of appropriate feeds is of primary concern to farmers. A survey conducted as part of the Aquaculture CRSP project and provincial reports in 2002 showed that most farmers used homemade feeds for their production.

Feeding machine.

Photo by: Truong Quoc Phu

For cage culture systems, 95 to 97% of cages used homemade feeds (Angiang, Dongthap, and Vinhlong provinces). The proportion of cages in which fish were fed pellets only was very low, typically 3 to 5%. In Hongngu district, no cages used pellets only (Aquaculture CRSP project survey). However, among the cages that used homemade feeds, pellets were supplemented in almost all cages at the beginning of crop when fishes were of small size. In Can Tho province, the percentage of cage culture systems that used pellets only was rather high at 32%.

As with cage culture systems, in earthen pond systems homemade feeds were mainly used. The percentage of pellet use is relatively higher than in cage culture. Can Tho province again has a high percentage of pellet use, 46%, whereas in the other three provinces only 5 to 10% of ponds used pellets.

There are interesting reasons to explain why artificial feeds have not been accepted by farmers:

• Materials for making feeds are locally available and cheap. Thus, the cost of pellets is higher than homemade feeds. Interview data from the Department of Agriculture and Rural Development (2002) showed the average feed conversion ratio (FCR) for homemade feed ranges from 2.7 to 3.0 and for pellets ranges from 1.4 to 1.5. The price of homemade feed is about US$0.12 to 0.13 and for pellets US$0.27 to 0.30 per kilogram. Hence the feed cost for producing one kilogram of fish ranges from US$0.31 to 0.39 for homemade feed and US$0.38 to 0.45 for pellet feed. Thus, farmers reduce feed cost if they make feeds themselves. This is the main reason why farmers have not been using artificial feeds for production.

Feed pellets, 18 to 32% protein.

Photo by: Duong Nhut Long

• Payment for materials for making feeds can be delayed, while pellets have to be paid for in cash. Because of limitation on investment, farmers have to select homemade feed for their production.

• Farmers can change the ingredients of homemade feed according to necessity. Feeding is divided into two

Trash Fish

Photo by: Truong Quoc Phu

stages. The first stage uses feed containing a high level of protein and minerals to help fishes gain maximum length. In the second stage (last three months), farmers usually increase the carbohydrate concentration of homemade feed for fattening fishes before harvest. They expect their fishes to grow heavier (contain more fat) and thus result in higher production.

The difference between Can Tho and other provinces in feed use is due to many cages and ponds in Can Tho belonging to pellet-producing companies.

Some of the companies involved in pellet producing, fish culture, and even fish processing are also engaged in Pangasius culture. Hence, pellets that those companies have produced are also used in their cages and ponds. Many of the same companies have widely promoted their culture techniques to farmers in the area in recent years. Thus, the marketing and extension programs of pellet-producing companies have contributed to promoting pellet use among farmers.

Although the ratio of artificial feed use to homemade feed use remains low, it seems to have changed compared with a few years before. The survey in 1993 showed all farmers used homemade feeds (Tuan and Binh, 1994). Then some farmers added 13% commercial feed concentrates to improve protein content of homemade feeds (Phuong, 1998). Today, many farmers supplement with pellets at the first stage of the crop while some farmers use pellets for the whole crop.

Homemade feed, 15 to 25% protein.

Photo by: Truong Quoc Phu

The ingredients for processing homemade feeds were also improved in comparison with former practice. According to the 1993 survey, feeds for Pangasius catfish were made from agricultural byproducts (rice bran and broken rice), vegetables (water spinach, squash, carrots, etc.), and trash fish in the proportions 40, 45, and 15%, respectively. All farmers used vegetables for making feed (Tuan and Binh, 1994). Recently, the main ingredients of homemade feeds are trash fish, marine fish (30 to 40%), and rice bran (60 to 70%) depending on the size of fishes and investment capacity of farmers. Homemade feeds are also supplemented with vitamins, minerals, and vegetables. However, only 2% of farmers add vegetables to homemade feeds.

Improvements in feeds used by farmers have significantly contributed to increases in growth rate, survival of fishes, and shortening of the culture cycle. This demonstrates that today most farmers realize the nutritional role of feed, but they still use homemade feeds because of economic aspects.

Still, despite its greater affordability, homemade feed can have low and sometimes imbalanced nutritional value, which causes low quality of marketable fishes due to high fat accumulation in the fish abdomen. This in turn reduces the proportion of fillet meat in the processed fish and fails to meet the international market’s increasing requirement for quality low fat products.

Fish feeding.

Photo by: Duong Nhut Long

In the future, pellets are expected to gradually replace homemade feeds as Pangasius catfish culture expands and more attention is paid to product quality.

Literature Cited

Phuong, N.T., 1998. Pangasius catfish cage aquaculture in the Mekong delta, Vietnam: Current situation analysis and studies for feed improvement. Ph.D. thesis, Institute Polytechnique of Toulouse, France.

Tuan, N.A. and C.T. Binh, 1994. Some economical and social aspects of cage culture in the Mekong River in Vietnam. TML Conference Proceedings, 4:275-280.

Department of Agriculture and Rural Development, 2002. Annual reports from Angiang, Dongthap, Can Tho, and Vinhlong provinces (in Vietnamese).

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