EFFECT OF AMMONIA TREATMENT AND CARBOHYDRATE SUPPLEMENTATION OF BARLEY STRAW ON RUMEN LIQUID CHARACTERISTICS AND SUBSTRATE DEGRADATION BY SHEEP

The effect of ammonia treatment and supplementation of barley straw wi th increasing levels (0, 200, 400 and 600 g day(-1)) of meadow grass h ay (H), rolled barley (B) or pelleted sugar-beet pulp (P) on ruminal c haracteristics and straw degradation was studied using eight adult ewe s, divided in two groups, receiving either untreated (US) or ammonia t reated (TS) straw, supplemented with H, B or P consecutively. Urea (30 g kg(-1) straw) was added to US 24 h before feeding. Sheep fed US sho wed higher ammonia-N (NH3-N) concentration than those fed TS, either a s the only feed (17.5 and 12.3 mg per 100 ml) or supplemented (15.0 an d 12.7 mg per 100 ml). There was no effect of ammoniation over rumen p H or total volatile fatty acid (VFA) concentration. Supplementation wi th B or P depressed pH and enhanced VFA concentration, whereas H did n ot have any great effect. Extent of straw rumen degradation was enhanc ed by ammoniation (maximum degradation of 593 and 741 g kg(-1) for US and TS), but rate of degradation and lag time remained unaffected. Bot h rate and extent of straw degradation were decreased to a similar ext ent when supplemented with B or P, while with H this effect was only n oticeable when it was included in the diet at 600 g day(-1).