The Nutrient Digestibility of Commercial and Farm-Prepared Feeds for Onchorynchus mykiss, Dicentrarchus labrax, and Salmo trutta labrax

We compared the digestion rate of commercial, and farm-prepared feeds, in three species (Onchorynchus mykiss, Dicentrarchus labrax, and Salmo trutta labrax) reared at two temperatures (12 degrees C and 17 degrees C). Rearing conditions, except for hydrodynamic conditions of the offshore farms, were simulated in the experiment. There were significant differences in overall digestibility between the diets; overall protein digestibility of the farm-prepared feed was much higher than that of the commercial feed (P<0.01). Lipid digestibility of farm-prepared diets was competitive but not significant compared to commercial feeds. The results may be attributed to poorly digestible ingredients of commercial feeds while farm-prepared feeds include mainly fresh anchovy and other ingredients such as hardtack meal, corn meal, wheat flour, and soybean meal. Consequently, farm-prepared diets seem to be much more competitive in respect to both digestibility, and cost, compared to commercial diets. In addition, the nutrient digestion rate of farm-prepared feeds was more balanced and stable.