Effect of added chestnut tannin on nitrogen retention and digestiblity in ruminants fed with grass forage

The use of chestnut tannin (CT) (hydrolysable tannins), added at a low concentration (4 g CT/100 g of total nitrogen (TN) = 0,8 g cT/kg of DM distribute) to a grass forage for growing sheep, improves the N retention (P0,01). The improvement of N retention is explained by the decrease of nitrogen in the urine, indicating a better use of absorbed nitrogen. Moreover, the addition at these low concentrations of CT to fresh grass does not alter neither the digestibility of its constituents (OM, TN, ADF) nor the rate of ingestion