It is well documented that animals have a requirement for individual amino acids, and not for protein as a whole. In addition, determination of protein requirements is highly dependent on the use of a balanced digestible amino acid profile and is thus easily confounded by raw material choice and variation inherent with formulation to varying total or digestible protein in dose response studies.
Senior Researcher
Skretting AI
Principal Researcher
Skretting AI
Precision nutrition has received a great deal of recent attention in the aquaculture nutrition field, and for very good reason. The rapid expansion of the aquaculture industry has created pressures in a number of areas in which feed formulation and production play a key role, including a greater focus on reducing the environmental impact of these operations. This is particularly true for the growing recirculating/closed aquaculture system (RAS/CAS) sector, where release of nutrients to the environment is strictly monitored. Reduction of nutrient release from these systems can be achieved by optimisation of biological and mechanical filtration systems or through improved efficiency of removal of solid waste to sludge collection systems. Expansion of filtration system capacity, however, is energy and space intensive. Improvements in removal of undigested nutrients bound in faecal waste in salmonid CAS has been achieved in recent years through the use of faecal binders, such as in Skretting’s CAS-specific product lines. Reduction of dissolved nutrients in the system can also be accomplished via nutritional intervention, through improvement of the efficiency of retention of ingested nutrients. It is this approach which forms the basis of Skretting’s new feed formulation concept AmiNova.
It is well documented that animals have a requirement for individual amino acids, and not for protein as a whole. In addition, determination of protein requirements is highly dependent on the use of a balanced digestible amino acid profile and is thus easily confounded by raw material choice and variation inherent with formulation to varying total or digestible protein in dose response studies. As a result, estimates of protein requirements may be prone to overestimation where protein content is inflated by specific amino acids being provided in excess in order for minimum requirements of limiting amino acids to be met with available raw materials. In addition, the “protein” content of diets and raw materials, and any requirement estimates based on these analysed contents, are in reality measurements of the nitrogen (N) content (multiplied by varying conversion factors). A certain proportion of this N comes from N-containing compounds not directly used for protein deposition (“non-protein N”, which can constitute up to 20% of total N). This N can be in the form of nucleic acids (not directly used for growth or health maintenance when coming from an exogenous source) or phospholipids and non-proteinaceous amino acids (which are required in varying quantities at different stages of the animal’s lifecycle). By establishing requirements for all individual N-containing compounds, rather than protein as a whole, it is possible to safely reduce oversupply of unnecessary N in feed formulations.
Skretting Aquaculture Innovation (Skretting AI) has worked for many years on establishing and re-establishing digestible amino acid requirements for many cultured aquatic species, with changing raw material baskets, and improved understanding of the factors contributing to variations in these requirements. The Skretting AminoBalance concept, launched in 1996, was the first step in optimising dietary N supply through formulation to a defined balance of amino acids modelled across fish size, and based on targeted studies. Through further research and re-establishment and validation of these requirements in numerous controlled studies and field trials, Skretting AI has been able to refine this concept further and launch its latest innovation: AmiNova, a new feed formulation concept that brings an even greater level of precision to fish nutrition.
AmiNova is a concept whereby supply of nitrogenous compounds is optimised, reducing the artificial inflation of non-essential N, thereby reducing the excretion and eventual release to the environment of excess N. In developing this concept, Skretting AI Principal Researcher Ramón Fontanillas investigated the interactive effect of varying supply of total digestible N and the supply of amino acids at optimal inclusions, derived from numerous internal Skretting trials over the past 30 years, on Atlantic salmon and rainbow trout (Oncorhynchus mykiss) performance at varying fish size. Adequate supply of the essential amino acids (EAAs, those which cannot be synthesised by the animal) is most often the primary consideration when balancing N in aquatic feed formulations (with some exceptions for non-essential amino acids – NEAAs – with important non-protein functions). NEAAs may, however, become important when EAA supply is limited. When formulating to both protein and amino acid targets, it is assumed that supply of NEAAs, which are also required in a certain ratio for optimal protein deposition, is sufficient. At the same time, many EAAs are artificially boosted above requirement in this situation, allowing excess EAAs to be used for limiting NEAA synthesis, where required. Where this inflation of amino acid levels is not present, such as when formulating with lower or no total N targets, however, utilisation of EAAs could conceivably be influenced by the NEAA content of the diet. As such, the interaction between amino N source and the response to varying total N supply was also investigated in the concept development stage.
Results of the concept development trials have shown that reductions in total digestible N were possible in Atlantic salmon diets, without significantly impacting growth or feed utilisation (Figure 1), when all essential nitrogenous micronutrient requirements were met. In addition, dissolved N discharge by Atlantic salmon was observed to be reduced by up to 25% at the lowest level of digestible dietary N (Figure 2), primarily related to reductions in branchial ammonia excretion. This shows that use of the AmiNova concept in aquatic feed formulations promotes higher N retention and optimises the proportion of N used for protein deposition and growth. Similar results were seen in growth and dissolved N excretion in response to lowering total digestible N in diets for rainbow trout. Reduction or elimination of the target for total digestible N will allow for greater formulation flexibility, and support customers in reducing their environmental footprint and ability to meet stringent regulatory requirements. These results have since been validated in several controlled and field trials, demonstrating the value of the use of this formulation concept, and the amino acid requirements underpinning it.
The use of AmiNova, having been developed and validated initially using Atlantic salmon and rainbow trout as model species, can now be assessed for extension to other species where nitrogenous compound requirements are well documented.
About David Poppi
David Poppi is a Senior Researcher in the Salmonid Nutrition team of Skretting Aquaculture Innovation (Skretting AI) with a PhD in amino acid metabolism in fish, and 19 years of experience in aquaculture industrial and research roles. His main areas of expertise and research at Skretting AI are protein and amino acid utilisation, feed intake regulation, and application of protein raw materials in salmonid diets. Skretting AI is the innovation and product development arm of Skretting, a global leader in aquatic animal nutrition and feed production.About Ramón Fontanillas
Ramón Fontanillas is a veterinarian with a PhD in animal nutrition, working as the Principal Researcher in Shrimp and Warmwater Species in Skretting Aquaculture Innovation. Dr. Fontanillas worked in several animal feed industry positions before landing at Skretting in 2004. During his 20-year career in Skretting, he has conducted research on a wide range of topics with several species, but currently focusses on protein, amino acid, energy and mineral requirements of European sea bass, Sea bream, Atlantic salmon, rainbow trout, and warmwater fish species.
