Graduate Exit Seminar

 

Most farmed fish species are limited in the use of plant-based ingredients (PBI) in their diet because of anti-nutritional factors and limiting amino acids especially lysine and methionine which are the first limiting indispensable amino acids (IDAA) in the plant sources. As one of the strategies to increase the limited use of PBI, we hypothesize that the "interchangeable imbalanced-balanced feeding strategy" of IDAA with limited and complementary diets would increase the utilization efficiency of limiting amino acids. This feeding strategy of nutrients intake may in fact be similar to the situation in nature, i.e. animals may acquire food from different sources containing complementary nutrients and the diversity of all food sources may satisfy the nutritional requirement in that animal. This study addressed the effect of dietary level of limiting IDAA in relation to alternative feed sources and feeding strategies in Atlantic salmon juveniles. Four sub-objectives were addressed to accept or reject the hypothesis: l) the essentiality and interaction of dietary lysine and methionine supplements in Atlantic salmon alevins, 2) the effect of dietary methionine concentrations, and evaluation of feeding strategies alternating methionine delivery with the imbalanced IDAA (insufficient or enriched in methionine) and complete IDAA diet, 3) investigation of the efficiency of methionine under alternative feeding strategy for practical diet and to determine the maximum use of soybean meals in Atlantic salmon starter diet, and 4) examination of the effect of dietary methionine deficiency on the activity of digestive enzymes that are critical in early life stages of fish.