The search for alternatives to soya protein in pig feed is not new - the original driver “GMO-free” has now been joined by the issues of “climate protection” and “regionality”. Rapeseed meal can be regarded as an established alternative. Other alternatives to soya meal that are currently being discussed are both plant-based (grain legumes, algae, sunflower meal, etc.) and animal-based (processed animal proteins, insect protein).
Grain legumes
The cultivation of grain legumes (including lupins, field beans and peas) has increased in Germany in recent years. However, the quantities available for livestock feed are still far below the utilisation possibilities (only 1 % share in compound feed in 2022/23) because cultivation is often not profitable. Not least because the payout price for growers is closely aligned with the grain price. Grain legumes are considered sustainable: they reduce nitrogen fertiliser use, loosen up the crop rotation and reduce the need to buy in soya.
Fattening trials with grain legumes show that peas, for example, have a clear added value in feed because they not only partially replace soya, but also lead to better feed conversion (2.63 compared to 2.73). In combination with rapeseed meal, the deficit of sulphur-containing amino acids can also be reduced. Feeding field beans resulted in almost the same feed costs per kg gain as the use of soya extraction meal in the control group, while the costs were higher for lupins.
Grain legumes also contain antinutritive substances such as tannins and trypsin inhibitors (field beans, peas), which potentially reduce protein digestibility and feed intake. However, this does not play a significant role in pig feeding. In the case of sweet lupins, the focus is currently shifting to white lupins, as higher alkaloid contents have been analysed. New trials show that the feed intake of fattening pigs decreases from a white lupin content of 10 %. It remains to be seen whether the recommendations for the use of white lupin need to be adjusted. Further studies are necessary.
Animal proteins
With the re-authorisation of processed animal proteins (PAP) in 2021, a high-quality protein source has been added. This includes slaughter by-products, for example. The source material corresponds to risk category 3 and is therefore of food quality, but is not used as such. Pigs may be fed poultry PAP, but not pig PAP. In trials, the use of processed animal protein in piglet rearing led to fewer diarrhoea problems and calmer animal behaviour in undocked piglets. The use of PAP is only practicable to a limited extent due to strict requirements in compound feed production (only non-species-specific material - zero tolerance in feed for the same animal species).
Insect protein
Since September 2021, insect protein may be fed to pigs or poultry, for example. If self-mixing farmers want to use insect protein, they require registration or authorisation. Eight insect species are currently authorised in the EU. The Black Soldier Fly (BSF) is the most important species in terms of protein production. It can also be used live as a feed for suckling piglets in the farrowing pen.
Why feed insect protein? In terms of sustainability, it is hoped that insect protein will replace soya imports from South America. Feeding insects with by-products from food production is also intended to save land for growing fodder crops. Currently, however, the problem with this idea is that insects are categorised as farm animals. Therefore, the same requirements are placed on feed for insects as on feed for farm animals that are used to produce food. Feeding waste is therefore not permitted, although insects are naturally able to utilise organic waste and therefore also excrement. If only safe feed is allowed to be fed to insects, there is direct competition with other farm animals for by-products from the food industry, for example. If these feedstuffs are first fed to insects and then the insect protein is used in livestock, double transformation losses occur - there is no efficiency gain. With regard to pig feeding, insect protein can certainly be viewed favourably, as pigs are omnivores and animal protein is particularly beneficial when feeding piglets.
To date, insect protein has mainly been used in pet food. In the livestock sector, protein feed has hardly been of any significance to date. The production of insect protein is increasing and the first farms are planning to start fattening larvae. However, the total quantities available are still negligible. The protein quality depends on the insect species and the feed basis. In addition to the amino acid content, data on the digestible amino acids in insect protein is also required for targeted use in pig feed.
Feeding trial with insect protein
High performance, but ... The Lower Saxony Chamber of Agriculture has fed insect protein to fattening pigs in a trial. As a result, the use of 4 % insect protein from the black soldier fly was possible without any loss of performance. The protein quality of the product used was roughly comparable to HP soya meal. However, the lysine concentration of HP soya is not quite achieved. On the other hand, the fat content (high proportion of lauric acid) is higher.
It was possible to save 10 kg of soya meal per animal. However, the feed costs per 100 kg gain increased by 44 € (+ 54 %). This means that the goal of saving soya meal is completely uneconomical at the current price level of insect protein, even if only small quantities are used. Possible effects on animal health and behaviour in young animals, which could be of particular interest from the point of view of avoiding docking, are currently being investigated at the Bingen University of Applied Sciences.
In the draft of the new Animal Protection Act, the word ‘vertebrate’ has been replaced by ‘animal’ in some places. It remains to be seen whether this will have consequences for the so-called ‘harvesting’ and processing of larvae in the future.
Algae & Co.
A total of four types of algae are included in the positive list for straight feedingstuffs. Some of them are very rich in fat and provide high-quality proteins that are suitable for human and animal nutrition. However, toxin and heavy metal contents must be taken into account. The importance of algae protein in pig feeding is currently very limited.
This also applies to other protein sources such as sunflower extraction meal, fishmeal or stillage. However, due to its high crude fibre content, sunflower extraction meal is a very common component in compound feed for sows. Fishmeal is currently still used to a certain extent in piglet feed, but its importance is declining - not least due to high prices. Stillage feed is established as a by-product of bioethanol production in the ruminant sector. The rather low protein quality often speaks against the use of the liquid or dried product in pigs. The feed value depends heavily on the source product (e.g. wheat, rye).
Living larvae in the barn?
Insects produce antimicrobial peptides (AMP) to ward off germs. Using them in feed could have a positive effect on intestinal health, tail biting or ear necrosis. Research is currently being carried out into whether feeding live larvae in piglet rearing promotes exploratory behaviour, is suitable as an activity material or as a transition feed in the weaning phase. Initial results show: Piglets love larvae and prefer them to prestarter. As live larvae must remain alive until they are eaten, there are still questions regarding delivery and storage. And: The black soldier fly, for example, is considered potentially invasive and must not be released into the environment.
The outlook
There are many protein feedstuffs that could be an alternative to South American soya extraction meal, but only a few are actually relevant in pig feeding at present. The decisive factors for widespread use are protein quality, stable and high yields, good market availability and, of course, price. Possible problems with undesirable ingredients (e.g. tannins) are negligible. Deficits in the amino acid pattern can be solved by using free amino acids.
One property of protein alternatives that will certainly be valued even more highly in the future is their GMO-free status. The attribute ‘domestic protein feed’ could also gain in importance in the future if the market honours the sustainable and climate-friendly production of animal protein.