The use of poultry by-product meals in pelleted feed for humpback grouper

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 (Tacon et al., 2006).

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 (Williams et al. 2004). 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 (Bureau et al., 1999). 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% (Nengas et al., 1999; Takagi et al., 2000; Gaylord and Rawles, 2005). The improved performance of PBM was mainly due to the improved quality of the product through the use of more advanced processing technology.

We recently conducted a feeding trial using PBM of two origins (local vs. imported) and grades (feed vs. pet food) in the diets of humpback grouper at graded levels and compared with a fish meal-based diet (control diet) for the effects on growth, feed efficiency, body composition and nutrient digestibility.

The full results of this project were published in:
Shapawi, R., Ng, W.K., & Mustafa, S., 2007. Replacement of fish meal with poultry by-product meal in diets formulated for the humpback grouper, Cromileptes altivelis. Aquaculture 273, 118-126