Tannins
Tannins are traditionally divided to 2 groups: hydrolyseable (HT) and condensed (KT).The most important are condensed tannins because of their antinutritive effect.
Biologic effects
Tannins have possitive and neggative effects on nutritive value. High levels decrease feed intake, protein and sacharides digestibility and performance. Low and medium levels protect against tympania and increase nonamoniacal nitrogen and flow essential amino acids flow from the rumen, whereby increase feed efficiency.
Condensed tannins content in freezy-dried forage samples in % of dra matter (KALAČ a MÍKA, 1997):
- sorghum low tannin level - 0.14 %
- sorghum high tannin level - 1.18 %
- barley - 0.11 %
- triticale - 0.09 %
- cotton seed - 1.60 %
- řepkové semeno - 0,48 %
- soya bean - 0.10 %
Effect restrict possibility
Most effective technique for seeds, mainly faba bean, peas and sorghum is breeding. Low tannin line in faba bean always has wite flowers, so that's easy to recognise them. Condensed tannins are treated as the most important of present antinutritive factors. Low tannins line cultivation can be complicated by higher affinity to illnesses and lower yields.