One of the biggest challenges facing animal production in recent years is the availability of protein sources for diet formulation. Protein is one of the most expensive nutrients in the feed formula and it should be borne in mind that the raw protein requirements in poultry and pigs ranges between 16-23% depending on the breeding phase.

Animal production continues to grow worldwide, which means that the demand for traditional protein sources has also increased, increasing their price and reducing their availability.

Likewise, the recent logistics crisis worldwide has shown that, depending on traditional protein sources such as soybeans, which are produced by a small number of countries and exported around the world, leaves producers unprotected in this type of situations and therefore it is necessary to look for alternative protein sources that can be produced locally.

These protein sources must meet certain requirements to be used in animal feed: percentage of crude protein, digestibility, presence of anti-nutritional factors, the protein cost…

A wide variety of new sources of protein for animal feed have been evaluated, the most promising ones are described below:

1. Oilseeds

Rapeseed meal or canola flour are well-known and widely used as a replacement for soybean meal. The crude protein content of these oilseed meals varies from 30 to 40% depending on the method of oil extraction. The main limitation of these flours is the presence of anti-nutritional factors, mainly glucosinolates, which have negative effects on the productivity of poultry and pigs.

Another oilseed with a high content of crude protein is cottonseed flour, whose percentage of protein is between 30 to 50%, however, it also contains anti-nutritional factors, in this case gossypol.

2. Legume seeds

Some seeds of legumes such as lupins or peas can also be considered an alternative protein source of great interest for animal feed, since they have a high percentage of crude protein, 32–42% in the case of lupin and 21–25% in the case of peas, in addition to being species whose cultivation in Europe is frequent, so they are available in the market.

The problem when using these species, as with oilseeds, lies in the presence of anti-nutritional factors such as alkaloids or trypsin inhibitors. It is necessary to develop physico-chemical methods that reduce or eliminate these components.

Another problem to highlight is the amino acid composition of these protein sources, for example, lupine is poor in methionine and requires the supplementation of this amino acid when used in diets for birds.

1. Macroalgae and microalgae

In recent years, the cultivation of macroalgae and microalgae has gained weight worldwide due to the different applications they have, although macroalgae have been cultivated and consumed for many years in Asia.

It has been observed that microalgae such as Chlorella or Spirulina contain a high percentage of protein, which can reach 50%, and several trials have shown positive results with the use of these microalgae as sources of protein for animal feed.

However, the cultivation of this type of microalgae is not completely defined at a commercial level, so that it allows to obtain a constant volume of microalgae with a specific and stable percentage of protein at a competitive price for animal feed.

2. Insect flours

The use of insects for animal feed has been developing in recent years. These are a really interesting alternative, taking into account that they allow to transform organic matter into quality protein for animal feed. Also, insects were part of the natural diet of birds, so their composition fits their nutritional requirements.

The European Union (EU) has already taken the first steps to promote the development of insects as an alternative protein source, approving the use of insect meal for feeding poultry and pigs.