Effects of Saccharomyces cerevisiae Supplementation and Anhydrous Ammonia Treatment of Wheat Straw on In-situ Degradability and, Rumen Fermentation and Growth Performance of Yearling Lambs

The effects of Saccharomyces cerevisiae supplementation ($6.6{\times}10^8cfu$) and anhydrous ammonia treatment (3%) of wheat straw (WS) were investigated on in-situ dry matter (DM) degradability, and on rumen fermentation and growth performance of lambs. Rumen-fistulated Menemen sheep fed a diet with and without live yeast were used to assess the DM degradability characteristics of WS and ammonia-treated wheat straw ($WS_{NH3}$). Twenty-six yearling Menemen male lambs were fed in four groups. Lambs of control group (WS) received untreated WS without supplemental yeast, whereas other three groups were fed WS treated with anhydrous ammonia ($WS_{NH3}$ group), untreated WS and yeast (WS+YEAST group) or WS treated with anhydrous ammonia and yeast ($WS_{NH3}$+YEAST group). Supplemented live yeast (4 g/d) was added in the diet. Lambs were offered untreated or ammonia treated WS ad-libitum and concentrate was fed at 1% of live body weight. The degradability of the water-insoluble (fraction B) was significantly increased by all of the treatment groups. Potential degradability (A+B), effective DM degradability's (pe2, pe5, and pe8) and average daily weight gain increased only in $WS_{NH3}$+YEAST group (p<0.05). Voluntary DM intake was not increased by the treatments (p>0.05), but voluntary metabolizable energy and crude protein intake were increased by $WS_{NH3}$ and by $WS_{NH3}$+YEAST (p<0.05). Average daily rumen pH was not affected by any of the treatments, but average daily $NH_3$-N was significantly higher in the $WS_{NH3}$ and $WS_{NH3}$+YEAST groups, and total volatile fatty acids were significantly higher in the WS+YEAST and $WS_{NH3}$+YEAST groups. In conclusion, the improvement of feed value of WS was better by the combination of ammonia-treatment and yeast supplementation compared to either treatment alone.