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 with increasing levels (0, 200, 400 and 600 g day(-1)) of meadow grass hay (H), rolled barley (B) or pelleted sugar-beet pulp (P) on ruminal characteristics and straw degradation was studied using eight adult ewes, divided in two groups, receiving either untreated (US) or ammonia treated (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 showed higher ammonia-N (NH3-N) concentration than those fed TS, either as the only feed (17.5 and 12.3 mg per 100 ml) or supplemented (15.0 and 12.7 mg per 100 ml). There was no effect of ammoniation over rumen pH or total volatile fatty acid (VFA) concentration. Supplementation with B or P depressed pH and enhanced VFA concentration, whereas H did not have any great effect. Extent of straw rumen degradation was enhanced by ammoniation (maximum degradation of 593 and 741 g kg(-1) for US and TS), but rate of degradation and lag time remained unaffected. Both rate and extent of straw degradation were decreased to a similar extent when supplemented with B or P, while with H this effect was only noticeable when it was included in the diet at 600 g day(-1).