by Mélanie Guédon, Market & Product Manager Aquaculture, Prossential, France

For 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 are not the same. Producers jealously guard their manufacturing secrets and it is sometimes complicated to have precise information on the parameters of hydrolysis and drying.


So, how to choose?

As a last resort, there is price, which is often related to the quality of the product, and which reflects the level of technology employed in the process and the care of the raw material. There are some feather meals which are half the price of fishmeal. A price that must be justified by performance, and which remains very much lower than the price of fishmeal.

That being said, aquafeed manufacturers need guarantees. In vitro analyses can give a certain amount of information (proximate composition and pepsic digestibility for example). But they do not provide sufficiently precise indications of the actual nutritional performance of the products in fish or shrimp, which can only be attested by in vivo tests.

If you plan to replace part of the fishmeal used in your fish or shrimp diet formulas with feather meals, in vivo performances of the product must be taken into account. Only few manufacturers today have embarked on such tests and the communication of their results.

Nevertheless, these tests will be an utmost important element for the choice of the quality of the feather meal and its incorporation rate in your pellets.

In view of these objective criteria, feather meals within the Prossential range offer a number of concrete benefits. When presented at the Aquaculture 2018 trade show in Montpellier at the end of August in France, they aroused interest.

We have launched - and patented - a vacuum drying process that allows a reduction of the drying temperature and thus improves preservation of the nutritional qualities of the product. Since we control the full process from raw feather collection to transformation and production of the finished product in our plants in France, we can ensure a stable, high quality product all year round.

In vivo trials on sea bream confirm interesting results for a high-rate substitution of this LT feather meal (low temperature) and inclusion rate of up to 15 percent.

This feather meal drying process was not the only novelty presented in Montpellier. For 2020, a technological leap is announced. Its goal is to offer a 'next generation' feather meal with even better nutritional qualities, but also enhanced organoleptic and physical properties.

 

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