Aquaculture for all

Study: Poultry By-product Meals in Farmed Grouper

GENERAL - The Network of Aquaculture Centres in Asia-Pacific (NACA) recently conducted a feeding trial using PBM of two origins in the diets of farmed humpback grouper. The results showed valuable benefits.

Grouper farming, especially in Southeast Asia, is still heavily dependent on feeding with trash fish. The demand for trash fish is increasing steadily despite decreasing prey fish stocks in the world’s oceans and competing use for human consumption.

According to NACA, in order to sustain the rapidly expanding marine fish farming industry in Southeast Asia, more farmers are using commercial formulated feeds in the aquaculture of captive groupers. Currently available commercial feeds for tropical marine carnivorous fish are based on fish meal as the main dietary protein source. Total global fish meal production has remained relatively static over the past quarter century.

This limited supply coupled with increasing demand for fish meal has greatly inflated the cost of this commodity. Therefore, finding suitable protein sources as alternatives to fish meal is critical in the commercial culture of carnivorous fish species, especially for fish such as the humpback grouper, Cromileptes altivelis, which require high protein (about 50%) in their diets.

Groupers, especially slower growing species such as the humpback grouper, are highly valued fish, priced for their excellent meat quality and taste in the regional live fish trade.

One potential fish meal alternative is poultry by-product meals (PBM) which are rendered by-products from the poultry processing industry.

PBM are produced in many parts of the world, including the Southeast Asia region which accounts for approximately one-quarter of the global poultry trade (FAO, 2004). It has high potential to be incorporated in the diet of carnivorous fish species such as groupers due to its high protein content and lower price compared to fish meal.

In addition, studies on the apparent digestibility of PBM revealed that this product is well-digested by several fish species. Back in 1980s -1990s, PBM was only able to replace fish meal in fish diets at a level not exceeding 50%.

Tremendous improvement has been achieved in recent years when PBM was reported to be able to replace fish meal at higher levels of up to 100%.

The improved performance of PBM was mainly due to the improved quality of the product through the use of more advanced processing technology.

The study concluded that, in view of the high protein requirement of humpback groupers, the use of PBM will contribute significantly to cost-savings. In addition, humpback groupers are slow-growing species, which takes a longer time to reach marketable size compared with other grouper species.

This longer culture period implies a higher requirement for feed input and cost of maintenance. Therefore, feed costs can be substantially reduced with the inclusion of greater quantities of PBM in the diets of humpback grouper and possibly in the diets of other tropical marine carnivorous cultured fish species.

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