The little Bacillus subtilis is particularly welcome in pig feed because it has the attractive quality that it is expected to be able to help farmers reduce the impact of nitrogen from agriculture on the environment. Scientists are now aiming at developing new strains of Bacillus subtilis that are tailor-made for this job.
In order to ensure optimum growth development, pigs are fed feed that fulfils all their nutritional requirements. With regard to protein, pigs are actually fed more than they need. This is done to ensure that their requirements for the individual amino acids are met. Amino acids are the building blocks that make up protein.
Protein a burden to the environment
An excess of protein in the feed is a burden on the pig and the environment. The pig’s metabolism has to work overtime to break down the excess protein and the resulting excess nitrogen goes straight into the environment via the pig’s urine and manure.
Best case scenario would be if the farmer could reduce the protein content in the feed without risking an amino acid deficit in the pigs. The first limiting amino acids – typically lysine and methionine – can be added to the feed as artificial amino acids so that the protein content can be reduced. This is, however, not possible for all amino acids when the price of feed needs to be kept within reasonable limits.
Tailor made bacteria
It appears that specially developed Bacillus subtilis strains can lend a helping hand. Various strains of the bacteria produce a surplus of some of the pig’s essential amino acids.
“If we can get supplements of the individual amino acids via bacteria, then we can reduce the protein content in the feed and protect the environment against excess nitrogen,” says head of research unit Hanne Damgaard Poulsen from the Department of Animal Health and Bioscience at Aarhus University and chairman of the steering committee for the new research project.
The bioscience company Chr. Hansen A/S is leading the project and already has a collection of different strains of Bacillus subtilis developed under laboratory conditions. The intention now is to let promising samples of the bacteria try some country living and demonstrate how they perform.
At Aarhus University the scientists will add the individual strains of Bacillus subtilis to regular pig feed and follow what happens. They will investigate how the bacteria manage in the feed and in the digestive tract of the pig in competition with the pig’s other bacterial flora. The scientists will study the bacteria’s amino acid production and what happens to these amino acids.
“The bacteria will experience an environmental shift from laboratory conditions to farm conditions. They can produce amino acids for the use of the pig but perhaps other bacteria in the intestine will consume the amino acids that Bacillus subtilis produce. We do not know anything about that yet but there are far-reaching environmental perspectives in finding specific bacteria that can be added to the feed under practical conditions,” says Hanne Damgaard Poulsen.
“The use of Bacillus is not unknown in pig production. It is already renowned for having other beneficial effects on pig growth so perhaps we can kill two birds with one stone.”
The three and a half-year project, which has a budget of 15.6 million kr., has received funding from the Danish National Advanced Technology Foundation. The Ministry of Food, Agriculture and Fisheries has also contributed to financing that part of the project that is being carried out at Aarhus University and the company Chr. Hansen A/S is also a sponsor of the project. The project is called AminoBac and has recently held its kick-off meeting.
Text: Janne Hansen