Feather meal for aqua feed: How to make the best choices
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by Mélanie Guédon, Market & Product Manager Aquaculture, Prossential, France
or some years, feather meal has enjoyed growing interest from aquafeed producers. As a protein source, it has indisputable advantages for replacing fishmeal in aquaculture feed: nutritional advantages in terms of protein content and digestibility, but also economic benefits. However, not all feather meals are equal and their quality is closely related to the manufacturing process. Let’s see how to choose the feather meal you need. We’ll start with the process. Feathers are mainly made of keratin, so they are extremely rich in protein. But as such, they are not bio-available after a simple grinding. There is only one way to obtain a digestible feather meal: hydrolysis, which is literally defined as “a chemical reaction in which water is used to break down a compound”. Thermal hydrolysis, which is the conventional process, is simple in its principle: it consists in cooking poultry feathers in a quantity of water, at a given temperature and pressure, during a certain time, so as to break down the keratin chains in order to obtain, after drying, a digestible protein powder. From that point on, it is clear that all feather meals are necessarily hydrolysed, whether they are called “hydrolysed feather meals” or simply “feather meals”. It is also useful to know that the name “hydrolysed” does not constitute a distinctive sign of quality between the different feather meals offered in the aquafeed market, since hydrolysis is the only way to produce them. There are different products on the market in terms of protein levels and digestibility. Why? Which parameters affect the final quality of the products throughout the chain? And how to be certain to make the right choice?
Raw materials matter
To begin with, there is the raw material quality. Feather meal
will not be the same depending on whether the manufacturer uses 100 percent poultry feather materials or that its original blend is more heterogeneous and contains, even in small amounts, blood, necks, feet, or other undesirable parts of the animal. To collect pure poultry feathers, it is crucial to master the sourcing and to have engaged with poultry slaughterhouses— strict quality approaches to eliminate these undesirables. Another important element affecting feather meal quality is freshness and therefore the collection-to-process timing. The shorter it is, the less likely the raw materials will have time to degrade and the best chance to preserve all nutritional qualities.
The heart of the process
Hydrolysis: Hydrolysis, it has been said, is the heart of the process to obtain feather meal. It aims to break the keratin chain and destroy the potential pathogens present in the raw material. At this point, four parameters are important: the temperature, the duration, the pressure and the amount of water. The best optimisation of these four parameters is the guarantee of a good quality product, on both nutritional and sanitary sides. This is the heart of the manufacturers’ know-how. Drying step: The drying step for evaporation of moisture from the wet hydrolysed feathers resulting from the hydrolysis is the last step before grinding and sieving. Nutritional quality of feather meal is greatly affected by the drying step, meaning by temperature and residence time. Indeed, the higher the heat, the more the nutritional characteristics are degraded. The main challenge is to employ efficient drying (that is to say to obtain a moisture content lower than 8% which allows the stabilisation of the shelf life of the product), while preserving the nutritional qualities. It will, therefore, be necessary to limit the temperature and/or the residence time to the strict minimum. On this point, obviously, all processes are not equal. As we said, there are several qualities of feather meals. Although they may have the same name, their characteristics
18 | May 2019 - International Aquafeed