Legend session: Forage secondary compounds; past, present and future

Forages contain plant secondary compounds. These are primarily produced to protect the plant from attack by micro-organism, insects and herbivores. Research during the last 40 years has produced an insight into the biochemistry, metabolism and interaction of these compounds, specifically the unique amino acid S-methyl cysteine sulphoxide (SMCO) and condensed tannins (CT). Both occur within forage consumed by farmed livestock. SCMO induces anaemia in herbivores. Through plant breeding and effective management brassica crops can now be fed to livestock as a supplement without restricting growth rate. A wide range of plants contain CT. CT have been shown to have the capacity to bind to soluble proteins in the rumen enabling increased absorption of essential amino acids from the small intestine. This benefits body growth, milk production, wool growth and ovulation rate. CT have also been shown to have a direct effect on gastrointestinal parasites inhibiting their growth and fecundity, particularly in sheep. As a result of this detailed research we are now able to exploit the unique attributes of some plant secondary compounds and use them to our advantage to benefit animal production and the performance of our farmed livestock. Ways in which we able to do this are discussed.