Raising healthy animals with less usage of antibiotics is the future challenge for animal husbandry in Europe. Consumers, retailers and authorities are clearly giving this message. In some countries measures are already implemented; in other countries the discussions are just starting up.
Overall the picture is clear that in Europe sustainable animal husbandry with controlled low usage of antibiotics will be the future demand.
What steps can be taken to reach this objective? It is clear that it will not be simply replacing antibiotics by one single alternative. To reach the goal farmers have to work on a multi-factorial approach, like farm management, climate and hygiene.
Nutrition can be an important part in this approach. Several steps can be taken from a nutritional point of view to increase the health of the animals. In order to reach this, three important steps are described.
1. Reduce undigested protein
Protein is normally digested in the small intestine and provides amino acids to the animal. Amino acids are the building blocks for protein deposition (growth) and are important for a great amount of functions in the body.
Unfortunately the protein that we supply via the diet is not 100% digestible. If protein is not digested in the small intestine, it will reach the large intestine and forms a substrate for pathogens (like E. coli) to develop. Too much undigested protein can give an imbalance of the microflora and may lead to digestive disorders like diarrhoea.
On the one hand we want to provide high amounts of protein to the animal for optimal performance, on the other hand we want a low amount of protein to reduce the risk of digestive disorders.
This seems a paradox, but with the correct tools, nutritionists are able to manage this very well. To face this issue it is key to know the exact requirement of the animal for each essential amino acid, the so called ideal amino acid profile. This profile varies between species (pigs are different to poultry) and also varies per stage of life (piglets are different to fattening pigs). Over the last few years a lot of new research has become available that reveals this ideal amino acid profile.
Once we know the requirement of each amino acid we can supply a diet that meets this ideal amino acid profile as close as possible. The amino acids in the diet are supplied via protein feedstuffs and feed grade amino acids. Today we have the first five limiting amino acids (lysine, threonine, methionine, tryptophan and valine) available in free feed grade form. These feed grade amino acids are 100% digestible, so they do not contribute to undigested protein. The next limiting amino acids (isoleucine, leucine, histidine, etc) should be added via protein rich feedstuffs.
Most preferably the feedstuffs chosen have a high digestibility. It is important to formulate a diet which covers the requirement for each amino acid, but without oversupplying the animals’ requirements, so no lack and no excess. With the current knowledge on the requirement of all these amino acids we can formulate a diet with a lower crude protein level (lower level of undigested protein), keeping the same or even better animal performance.
2. Optimise microbiota
The microbiota in the gut consists of billions of microbes that live in close relationship with the host animal. Three different types of host-microbiota relationship can be described, being symbiotic, commensal or pathogenic (see Table 1).