The political demands on the agricultural industry to reduce nitrogen emissions in swine husbandry are ever increasing. The envisaged drastic reduction in ammonia emissions will not be possible if feeding remains the same without reducing the number of animals or increasing the number of exhaust air purification systems. Optimized feeding with the aim of increasing the efficacy of feedstuffs containing protein is an effective way of lowering nitrogen emissions.
By supplementing essential amino acids opportunities arise to further reduce the crude protein content in feed mixtures. It is decisive to find the right balance between the amino acids in feed protein to avoid any drop in performance, poorer feed conversion and unnecessary environmental burden. In addition to crude protein, also the amino acids lysine, methionine, cysteine, threonine and tryptophan are currently taken into account when optimizing feed for fattening pigs.
Determining a lower limit for crude protein does not fully exploit the potential for maximum reduction of crude protein. Feed optimization with lower limits for every essential amino acid in accordance with ideal protein without limitation of crude protein is much more effective.
Trials have shown that supplementation with L-tryptophan enable a considerable reduction in crude protein content to 15% and 13% in the beginning and final fattening phase respectively. These trials were also able to refute the concern that meat quality suffers as a result of reducing the crude protein content too much. Even a reduction in crude protein content to 11.5% (45-70 kg LW) and 9% (88-110 kg LW) is possible in fattening pig feed without any drop in performance provided that additional supplementation with L-isoleucin and L-valine took place. Without supplementation with L-valine, however, the fattening performance dropped significantly.
The crude protein content in fattening pig feed can be reduced by 4 to 5% points with the amino acids currently approved in accordance with feed law and nitrogen emissions thus reduced by 50%.