Aquaculture view
Part of the IAF editorial panel, Dom has a PhD in Nutritional Sciences from the University of Guelph, Canada.
Today he teaches various undergraduate and graduate courses on animal nutrition and agriculture at the University of Guelph. Between 2007 and 2009, he coordinated the “Paris Semester”, a study abroad program for undergraduate students at the University of Guelph.
He serves on a number of international committees, including the US National Research Council Committee on Nutrient Requirements of Fish and Shrimp.
See all of the Aquaculture view columns here.
January - February 2013
Increasing the emphasis on quality assurance for raw materials used in aquaculture feed production
The high price and relative volatility in the supply of some feedstuffs are forcing aquaculture feed manufacturers to play with an increasingly diverse portfolio of ‘economical’ raw materials. Larger manufacturers often need to source the required high volumes of certain raw materials from multiple suppliers. Small manufacturers due to their lesser needs may be able to source from single suppliers but, at the same time, may be even more at the mercy of capriciousness of the markets. To maintain their competitiveness, formulators must formulate feeds to lower or narrower essential nutrient specifications to minimize costs but they must ensure that the feeds can sustain high growth, feed efficiency, health, and product quality of the animals at the farm. The production of highly nutritious and cost effective feeds with an increasingly wide array of feed ingredients obtained from different suppliers is clearly not an easy task. This is certainly keeping some feed formulators awake at night.Sourcing of raw materials from different countries, manufacturers or brokers arguably results in greater probability for significant variations in the quality of the raw materials purchased. The high price of certain feedstuffs (for example fishmeal) may also incite (unscrupulous) suppliers to adopt deceptive practices, such as product adulteration (for example blending less expensive raw materials with more expensive raw materials). Some recent experiences I had in the field and as well as recent discussion with experts indicated that variability in the nutritive quality and adulteration of feedstuffs are not a thing of the past. In this very complex context, quality assurance (QA) plays an extremely important role.
QA usually involves the definitions of specifications for the purchasing of the raw materials and for the inspection and analysis of these raw materials as they are received at the feed mill. Most, if not all, aquaculture feed manufacturers have adopted some sort of QA process and invest very significant financial and staff resources in this. The main emphasis of QA systems in place is on chemical composition, mainly on proximate analysis (crude protein, crude lipids, crude fibre, etc.), of the raw materials. Relatively little emphasis is placed on direct measurements of individual nutrient or contaminant levels due to the often prohibitive cost of this type of analysis. Near Infrared Reflectance Spectroscopy (NIRS) is widely used by most aquaculture feed manufacturers around the world to obtain rapid and generally accurate estimation of the proximate and individual nutrient levels of batches of raw materials.
Relatively little emphasis is placed on assessment of the nutritive value of different batches of raw materials. There is some experimental evidence that significant variability exists in the digestibility and bio-availability of the individual nutrients of different batches common aquaculture feed ingredients. Fishmeals, feather meals, meat and bone meals and DDGS often come to mind as ingredients that can vary quite significantly in terms of digestibility and nutritional quality. However, variability in digestibility and nutritive value is not only limited to these ingredients.
I find it unfortunate that so few research efforts are invested by aquaculture nutrition researchers on these issues that are so important to the aquaculture feed industry. Better research and more data would really help guide QA efforts of aquaculture feed manufacturers. For example, NIRS is highly dependent on the availability of high quality raw data on the composition and nutritive value (for example amino acid digestibility) of different raw materials so that reliable calibration of the instruments can be done. This is one area where academic research groups could play a very important role and yet are virtually absent.
Other rapid but more direct ways of assessing the nutritive value of different batches of raw materials are also required. Pepsin digestibility is probably one of the most widely used tests to estimate digestibility of protein. However, there is some controversy as to the proper concentration of pepsin to be used and the applicability of this type of tests to different aquatic animal species and different raw materials. There is very limited published experimental (animal) studies examining the reliability of pepsin digestibility assays and defining their limitations. Other in vitro tests, such as pH-stat protein digestion assays have been developed but they also suffer from a lack of standardisation and lack of validation. Right now, efforts are really disparate and different groups are proposing very different approaches. There should be systematic and concerted efforts on this topic.
Turning away raw material shipments is not always feasible in the current climate. It is perhaps more important for feed manufacturers to learn how to better identify and determine the consequence of variability in composition and learn how to safely and appropriately use raw materials that differ from the established specifications. This is another important role in which academic research laboratories could play a role.
I am sometime feeling that too much reliance on ‘laboratory tests’ to assess quality of raw materials may result in a certain ‘lost of touch’ with reality. It is my experience that frontline QA personnel and general feed production staffs are not always highly aware of how different raw materials should look, smell and feel like. These are primary indicators that something may not be ‘right’ with the quality of raw material received. Clearly, more training of front line staff is needed.
Finally, how unfortunate is the fact that the techniques commonly used by feed manufacturers for QA are not currently taught in most academic institutions? I wonder how many aquaculture nutritionists have been properly trained in the use of NIRS equipment or have received basic training in feed microscopy? How can we expect to progress as an industry if the new blood does not have the proper academic background and training?
Am I so far in left field? Any feedback? Let me know by email: dbureau@uoguelph.ca, or leave a comment below
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