Wood molasses as a preservative for high moisture barley: 2. Ration digestibility and rumen fermentation in sheep

Abstract

The effect of wood molasses ensiled barley on ration digestibility and nitrogen utilization (Exp. 1 and Exp. 2) and on rumen fermentation and degradation rate in sacco (Exp.2) was investigated in two experiments. The ration contained 0.9 kg of DM. The proportion of hay was 30 % in Exp. 1 and 40 % in Exp. 2. In Exp. I the experimental diets were dried barley (DB) and barley ensiled with a level of 8 (WMB8) or 16 % (WMB16) wood molasses of barley DM. In Exp. 2 the diets were dried barley (DB), propionic acid-treated barley (PAB) and barleys ensiled with 0.3 % v/w % of AIV II solution (AIVB) or with wood molasses at a level of 12 % of barley DM (WMB12). The ration digestibility decreased with increasing levels of wood molasses. The difference in DM and organic matter(OM) digestibility was significant (P < 0.05) between DB and WMB16. Wood molasses tended to decrease the apparent digestibility of crude protein and crude fibre and to increase nitrogen retention. The percentages of nitrogen retained of ingested were in Exp. 1 on DB, WMB8 and WMB16 diets 13.1, 17.8 and 15.8 % and in Exp. 2 on DB, PAB, AIV Band WMB12 diets 13.8, 13.2, 10.3and 14.5%, respectively. After feeding, the concentration of total VFA in the rumen was higher when ensiled barleys were fed. The proportion of propionic acid in the total VFA was greater with DB and PAB than with AIVB and WMB12 diets (P < 0.01), and butyric acid was correspondingly lower (P < 0.01 and P > 0.05). The proportion of isovaleric and valeric acids was highest on AIVB diet. On DB and PAB diets the ammonia concentration in the rumen decreased after feeding, but on AIVB and WMB12 diets the highest value was reached 1.5 hours after feeding. The degradation rate of DM and CP as determined by nylon bag method was faster on AIVB and WMB12 than on DB and PAB diets.