Aquafeeds
Animal and plant raw materials each require a unique assessment of their compositional and nutritional variability
Like all intensive animal production industries, aquaculture is heavily reliant on feed inputs to sustain its production. Traditionally, there has been much reliance on the use of wild‐caught fishery products, like fishmeal and fish oil, in feeds for aquaculture species and because of this, some sectors of aquaculture have been perceived as a net fish user rather than a producer (10.1073/pnas.0905235106 ). However, in addition to alleviating concerns about the reliability of aquaculture as a food provider, and the long‐term sustainability of aquaculture as an industry, the use of alternative raw materials to fishmeals and oils also empowers the formulator with additional options.
Alternative protein meals and oils can generally be divided into those of plant or animal origin (although there are also various emerging bacterial and fungal products), and many have considerable potential to supply the required dietary nutrients for aquaculture species. The optimization of the use of these resources in aquaculture diets depends on a detailed understanding of the chemical composition of these products, the consequences of feeding these products and their influence on each specific species being fed.
However, like the use of any raw materials, the use of alternative proteins and oils to those from fishery products also introduces a suite of risks that needs to be considered to enable the production of safe, sustainable and functional feeds. But there is some disparity internationally among the raw materials that are used and the associated perceptions surrounding the risk with their use. Some of this international disparity can be linked to the incidence of food scandals that have historically arisen because of contamination of human food either via the feed or other points in the production chain.
Therefore, the feed provided to production animals that are consumed by humans is a critically important control point for overall food safety, and consequently, regulations have evolved in different regions of the world that set certain standards to regulate what raw materials are permitted in feeds for certain species. In addition to these statutory regulations, some regions/markets have also instigated “voluntary” regulation of the use of some raw materials, based on risks to market perceptions and ideologies.
This article – adapted and summarized from the original publication [Glencross, B.D. et al. 2020. Reviews in Aquaculture (2020) 12, 703–758. doi: 10.1111/raq.12347] – is an assessment of these risks.
Updating nutritional research strategies for the optimal evaluation of aquafeed ingredients, part 1
Alternative raw materials
In assessing the potential of alternative raw materials, it is a fallacy that there needs to be a search for a single ideal replacement, as this simply transfers risk from one raw material to another. A more appropriate strategy is to enable the use of a broad suite of raw materials that enables formulators’ substantial flexibility to adapt to changes in supply, price and quality risks as they arise. This is only achieved by developing an improved understanding of a broad range of raw materials, understanding their limitations and then applying the knowledge of those constraints against the specific nutrient demands of each of the species when diets are formulated.
Among raw materials, there has been considerable research on the use of plant protein resources in the diets of aquaculture species. Soybean products are the most widely produced and used plant protein source in aquaculture diet formulations, and they have been applied with considerable success in diets for a wide range of species. However, there is a range of other plant protein concentrates produced from corn, faba beans, lupins, peas and rapeseed that have value as potential aquaculture feed ingredients.
Rendered animal meals, also called land‐animal proteins (LAPs), are another protein resource stream that have been widely used in aquaculture diet formulations, with considerable success. Additionally, there is substantial production of animal‐derived oils from some sectors and these too have potential as a feed resource, but similarly to other ingredients, there is a disparity in the use of these resources throughout the world as well.
Risk management
Many formulators place “confidence constraints” around the use of certain raw materials and these constraints are largely placed due to confidence issues in a range of topics such as nutritional variability, concerns with potential contaminants and impact on feed processing, among others. Much of the setting of these constraints derives from issues associated with elements of the risk assessment for use of each raw material.
The process of risk management consists of the systematic application of a series of policies, procedures and practices applied to the tasks of communicating, establishing the context, followed by the identification, analysis, evaluation, treatment, monitoring and review of a given risk, based on a series of considered assumptions and uncertainties (Codex Alimentarius Commission, 2017; Fig. 1). Risk assessment is a scientific‐based process that is considered to consist of four stages: (i) hazard identification, (ii) hazard characterization, (iii) exposure assessment and (iv) risk characterization.
In terms of the aquaculture feed sector, there are different elements to the risk associated with feed production that need to be considered. First is the risk associated with producing a product (or failing to) to the specifications required for a particular species. In the process of attempting to meet these specifications, risk is encountered in combining raw materials together and the potential for those raw materials to bring in contaminants and pathogens. These contaminants and pathogens can have implications not only for the animal being fed, but also the consumer of that animal.
Two critical elements to the viable commercial use of raw materials are their reliable supply and the price for which they are charged. Each of these elements’ presents critical risks for feed production.
Supply risk
Most feed manufacturing sites have a finite number of raw material storage options. Because of this constraint, feed manufacturers prefer to allocate those storage options to raw materials that they can routinely and consistently source as it avoids issues associated with mixing and contamination of different raw materials and reduces issues associated with shortfalls in supply of any raw material during the manufacturing process. Therefore, raw materials that are available in large volume are preferential for clear reasons. While small volume raw materials may be options, they are less attractive to manufacturers due to the need to constantly adapt to changing constraints imposed with each new raw material.
Consistent changing of raw materials also increases the risks of mistakes being made during the manufacturing process and represents an additional reason why raw materials with large volumes of supply are preferred. However, what constitutes a large (or small) volume supply raw material is a matter of conjecture.
Price risk
There is a range of economic factors that affect profitability, but key among them is the price volatility of various raw materials. There is substantial variability in price among raw materials. Notably, the price charged for any specific raw material is generally closely linked to their protein and/or profit (protein + fat) content. However, this relationship is not a linear one, with decreasing competition among higher protein content raw materials, there is an increasing price value on these products. In many cases, high protein products are also substantially processed to achieve this degree of protein concentration and this processing comes at a cost.
There is also substantial variability in raw material prices across both spatial and temporal ranges (Fig. 2). In most cases, this is largely influenced by supply and demand economics. But there are other key factors influencing this variation in the price of specific raw materials, and not all of them respond to the same drivers. It has been suggested that there is growing volatility in global commodity markets due to a shortening of life cycles and economic and competitive forces creating additional uncertainly, and there is a range of measures to assess volatility in markets.
Commodities (raw materials) have more volatility in their price than manufactured products, presumably due to the ability of manufacturers to defray price volatility through varying their raw material use. However, there are contrasting views that have argued that commodity volatility has not increased over time and that globalization has reduced volatility and market (economic) isolation has a higher association with commodity price volatility.
Perhaps, the most obvious link to the cost of production of many of the raw materials used in feeds is the close link to the cost of the energy input into their production processes, generally gauged as the crude oil price, whether that being the cost of operating boats to go to sea to catch fish for fishmeal or the cost of operating farm machinery to grow and harvest crops (Fig. 3). The influence of energy prices on the prices/costs for raw materials can also be seen via the impact of biodiesel and bioethanol on the prices for cereal grains.
However, since 2006, it has become clear that there has been somewhat of a decoupling of fishmeal and fish oil prices from the crude oil price driver. This has been most likely due to increasing constraints associated with global supplies of these commodities – hence supply and demand economics coming to the fore again.
Finally, another important factor influencing the volatility of raw material prices is that of the added variable of currency exchange rates. In global trade, most transactions take place in U.S. dollars. Therefore, the price paid for internationally sourced raw materials by any manufacturer will be heavily influenced by the rate of currency exchange with whatever the local currency might be. As such, acute changes in foreign exchange rates can also result in acute changes in raw material prices.
Managing supply and price risk
To manage these vagaries in both supply and price risk, there is a suite of strategies that the feed sector traditionally employs. These can generally be grouped as either input-related (i.e., linked to raw material acquisition) or process-related (i.e., optimizing the use of those raw materials). In terms of process-related controls, the most common is to use linear least-cost formulation, which considers all the different raw materials available against the target product specifications and then optimizes the combination based on meeting those specifications at the lowest cost.
A more advanced practice along these lines is to use multi-mix formulation, which is an extension of the linear least-cost programming approach, that considers many different products at once to optimize the use of raw materials across an entire site or even across an entire business. A variant on this is the use of a multiperiod production plan, which blocks the production of products by variation in supply of raw materials according to the most optimal use of those raw materials in the inventory.
A broader approach to reduce the raw material risk is to improve the overall efficiency of the feed production system. In a modern context, two approaches to reduce the risk in manufacturing systems have been considered: “lean” and/or “agile” manufacturing practices. In these practices, the focus has centered more on controlling those internal factors that can be influenced directly by a business to streamline them and as such make the process as lean as possible.
The lean strategy is simply a method for the elimination of inefficiencies within a manufacturing system, including imbalances in workloads. Agile manufacturing, on the other hand, is a term used to describe an organization that has instigated the processes, tools and training that allows them to respond quickly to changing customer needs and market opportunities, while still maintaining some control over costs and quality.
In terms of raw material input risk management, there are also a series of strategies that can be used. Forward contracting of supplies is one such option, in which a forward contract between a supplier and purchaser is agreed to buy a parcel of a raw material at a specified future time at a pre-agreed price. In such a situation, both parties assume some of the risk by agreeing to the transaction in the future. As the purchaser has to assume a long position (i.e., that the price is likely to go up), the supplier assumes a short position (i.e., that the price is likely to go down).
Typically, such forward purchasing is not widely used in the aquaculture feed industry, with most companies preferring shorter terms-of-trade for purchasing raw materials (e.g., 90-day terms). Another commonly used strategy is to diversify sourcing options to ensure that for any key raw material used, that it is preferably obtained from two or more suppliers. This then allows active competition between the suppliers by keeping the prices down and quality high.
Compositional and nutritional variability
Determining the nutritional value of any raw material is a critical aspect of being able to attribute an economic value to the product. However, variability in the nutritional value of any of these products can also impact their perceived value, with reduced levels of variability being favored, in that this allows for greater confidence in formulating diets closer to the animal’s requirements.
The assessment of variability in the chemical composition of raw materials is one aspect of assessing this nutritional value. This can be readily obtained using standard analytical techniques, although the application of near-infrared (NIR) spectroscopy [a method that makes use of the near-infrared region of the electromagnetic spectrum from about 700 to 2500 nanometers] has led to the development of some rapid (<1 minute) assessment systems that allow the cost-effective analysis of large numbers of samples.
However, a more comprehensive determination of nutritional values and the assessment of their variability have been comparatively more difficult and slower parameters to assess, as it requires information on the extent to which the nutrients from an ingredient are absorbed (digested) and made available for growth. However, a lack of standardized data on the digestible value of raw materials remains one of the constraints to the broader adoption of many alternative raw materials.
Additionally, there is a general paucity of knowledge on the level of intrinsic nutritional variability within many raw materials, with only limited studies providing any focus on either rendered animal meals or feed grains. Furthermore, the effective characterization of this variability and, just as important, the characterization of the origins of the raw materials being assessed (e.g., where it was produced, how it was processed, etc.) are key issues that need addressing to enable firstly an understanding of the extent of the problem and then secondly to empower research to provide solutions.
Causes of variability
Variability exists in all raw materials. For feed grains, there are numerous causes of this variability. Protein, carbohydrate and lipid levels in all feed grains can vary considerably depending on growing season attributes, cultivar, farm management practices and soil conditions. In addition to these primary production points of control, subsequent management of feed grains can also impart significant variability to their nutritional value. Differences in segregation, storage and processing have also all been implicated in affecting the feed grain composition. Importantly, such variability in composition has also been noted to extend to the digestible value of feed grains and other raw materials and occurs across species.
Similarly, rendered animal products can also be quite variable and this variability has been implicated as one of the key reasons limiting their application in aquaculture feeds. Points of influence in rendered products include the animal species used, what components are included (e.g., whole animal, deboned, bone-in, blood, etc.), age of the components since slaughter, the temperature of storage of the components (e.g., chilled or ambient), cooking temperature during wet rendering and the drying method employed. There is evidence to support that each of these control points in the rendering process can affect the nutrient composition and nutrient digestibility of rendered animal products.
The variability in the nutritional value of raw material depends on both the total nutrient content and the biological availability of the specific nutrients it contains. This biological availability has two aspects to it: the ability of an animal to absorb nutrients (digestibility) from the raw material and the ability of the animal to convert those nutrients into growth (utilization).
Implications of variability
The nutritional value of most feed grains is usually a direct reflection of their digestible nutrient (and energy) content. Accordingly, any variability in the digestible value of these raw materials should translate to variability in their economic value. Arguably, the combination of compositional variability with digestible variability means that the true economic value of raw materials is actually much wider than given credit for. Furthermore, the combination of variability in crude composition and that of the digestible value is compounded, with the resultant impact of substantially greater variability being observed in the actual levels of digestible nutrients.
In addition to the variability in composition and digestibility of raw materials, the consequences of not effectively managing this has been demonstrated in terms of a direct and measurable impact on their nutritional value. In a series of studies where the diets were formulated on their gross compositional values, it was possible to demonstrate the direct impact associated with variability in the digestibility of protein and energy from a single component raw material in those diets.
The ability to chemically identify those factors within raw materials that affect their own nutrient and energy digestible values lends itself to the development of further raw material assessment methods, such as the use of NIR to measure digestibility of both individual raw material and compound diets.
Strategies to manage variability
There are a range of strategies that can be used to manage raw material variability. Typically, this variability is managed, to an extent, through increasing the diet formulation specifications to allow for an over-specification of key nutrients. Although this formulation strategy reduces performance risk, it does increase the cost of the diet manufacturing process. The capacity to better manage this variability depends on an improved ability to rapidly measure the nutritional value of raw materials prior to the formulation process and an ability to capture and respond to the information in near real-time.
There are several options that can be considered for managing such raw material variability, but ultimately it is probably the adaptation of the use of near-infrared (NIR) spectroscopy that is one of the more viable options to pursue for such near real-time adaptation.
The second and final part of this article will discuss genetically modified organisms, changes to product qualities, and an overall perspective of all the risks discussed and their management.
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