The nutritional management of barramundi, Lates calcarifer– a review

Barramundi nutrition research has been undertaken since the 1980s. From that time to the present, the requirements for most nutrients, energy demand, ingredient utilization and the effects of nutrition on flesh quality aspects have all been examined to varying extents. Optimal protein content of diets has been shown to vary with diet energy density and also the size of fish that are being fed. Most studies have suggested a protein requirement from 450 to 550 g kg^?1. For small fish, a protein to energy ratio of 25 to 30 g MJ^?1 is suggested. Limited work has been carried out on fish larger than 500 g. The 10 essential amino acids for other fish are also considered to be required by barramundi. Proportional requirements have been identified for methionine, lysine and arginine. Protein utilization efficiency by barramundi has been estimated at 46% efficiency. Iteratively determined protein and amino acid requirements suggest that the requirement for protein and amino acids will decrease with increasing fish size and are largely consistent with empirically determined requirements. Lipid requirements for energy and essential fatty acids (EFAs) show that smaller fish performed the best with a dietary lipid level of 140–160 g kg^?1, while growth of larger fish continued to improve with lipid levels up to 190 g kg^?1, although no higher levels were examined. EFA requirements have been identified for long‐chain n‐3 fatty acids and minimum levels of 10 g kg^?1 have been indicated. An optimal ratio of n‐3 to n‐6 fatty acids of 1.5 to 1.8:1 was also suggested. Barramundi have shown limited capacity to utilize dietary carbohydrates for energy, with starch digestibilities below 30% at even low inclusion levels. Barramundi also exhibit limited glycaemic control, being unable to rapidly reduce blood glucose levels. Requirements have been demonstrated for several key vitamins and quantitative requirements determined for varying forms of ascorbic acid (vitamin C). Quantitative requirements have also been established for pyridoxine and pantothenic acid but only qualitative assessments for other key vitamins. Few mineral requirements have been identified. Phosphorus is the only mineral to be studied and a requirement between 5.5 and 6.5 g kg^?1 is suggested. Energy demands of barramundi have been shown to be largely driven by thermodynamic demands on metabolic requirements and the demand for somatic energy deposition. Energy utilization by barramundi has been estimated as 68% efficient. Energy demands for maintenance are shown to be related to liveweight by an exponent of about 0.8. Variations in temperature are shown to vary the maintenance energy requirement but do not affect the efficiency of energy utilization. Feed management through feed specification selection has been shown to be possible through selection of feed protein and energy content based on the fish's change in somatic energy density. Typically, this leads to the use of lower protein and higher energy density feeds with larger fish. Ration allocation based on changes in fish size and temperatures has been studied from both iterative and empirical perspectives, and tables were developed based on these findings. Several key feed ingredients have been evaluated for their digestibility, palatability and energy and nutrient utilization. Among those ingredients were meat meals, lupin kernel meals, soybean meals and some plant oils. Limited effects of feed ingredients on flesh quality have been noted, although some effects of diet nutrient and energy specifications have been noted.