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Differing nutritional responses to dietary soybean meal in rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar)
- Refstie, S., Korsoen, O.J., Storebakken, T., Baeverfjord, G., Lein, I., Roem, A.J.
- Aquaculture 2000 no.1/2 pp. 49-63
- Salmo salar, interspecific variation, dietary fat, soybean meal, nitrogen, digestible energy, feed conversion, Oncorhynchus mykiss, fish meal, liveweight gain, digestibility, fish feeding
- This study was carried out to compare the responses of rainbow trout and Atlantic salmon to being fed defatted soybean meal. Two extruded experimental diets containing either low-temperature (LT)-fish meal as the sole protein ingredient or 32% fish meal and 30% soybean meal, were each fed to triplicate groups of 0.1 kg trout or 0.2 kg salmon maintained in 7 degrees C freshwater. The experiment lasted 84 days, divided into three periods. Weight gain of the trout was similar with both diets, whereas the salmon gained 44% more weight with the fish meal diet than with the soybean meal diet. The apparent digestibilities were 6% higher for nitrogen, 8% higher for fat, and 11% higher for energy in the trout than in the salmon. The feed conversion ratio (FCR) was 24% lower, the nitrogen retention 34% higher, and the energy-retention 28% higher in the salmon than in the trout. Within each species, the digestibility of nitrogen was similar for both diets. In trout, the digestibilities of fat and energy were 4% higher, the nitrogen retention 8% higher, and the energy retention 9% higher with the fish meal than with the soybean meal diet. Similarly, but more severe within the salmon, the respective digestibilities of fat and energy were 16% and 9% higher, the nitrogen retention 19% higher, and the energy retention 23% higher with the fish meal than with the soybean meal diet. Both species developed enteritis in the distal intestine when fed the soybean meal diet.