Role of branched‐chain amino acids on growth, physiology and metabolism of different fish species: A review

Branched-chain amino acids (BCAAs), leucine, isoleucine and valine have an enormous functional significance because of their involvement in fish physiology. Branched-chain amino acids are not limited to act as substrates of protein synthesis but are also part of the protein synthesis regulation. BCAAs regulate various key signalling pathways. Leucine has a pivotal role in mTOR activation, while isoleucine and valine have a predominant energy and glucose metabolism action. Research over the years has highlighted the importance of dietary BCAAs levels on the growth and development of fish. The available data suggest that fish require slightly higher amounts of BCAAs at the initial stage than at the latter stages of life. BCAAs requirements of different fish species have indicated wide variations: 11.5 to 91.0 g leucine/kg dietary protein, 15.4 to 42.3 g isoleucine/kg dietary protein and 17.7 to 46.91 g valine/kg dietary protein. This review paper covers the dietary BCAA requirements of various fish species and the modulation action of BCAAs on vital functions, as protein synthesis, metabolic pathway, glucose transportation and immune response.