OZONATED COTTON STALKS AS A SILAGE ADDITIVE - DIGESTION OF TOTAL AND CELL-WALL MONOSACCHARIDE CONSTITUENTS OF LUCERNE BASED DAIRY-COWS RATIONS

Lucerne was ensiled either by the conventional wilting process (WL) or as a mixture of 80% fresh lucerne + 20% ozonated cotton stalks (L+OCS ), and the effect of feeding these silages to dairy cows on performanc e and on the digestibility of ration carbohydrate constituents was exa mined. Ten cows in mid-lactation were divided into two equal groups wi th similar performance data at the onset of the experiment, and fed ad libitum for 28 days total mixed rations composed of 70% concentrate, 15% lucerne hay and 15% of either WL silage or L+OCS silage. Average d aily milk yields during the experimental period were 27.1 and 27.6 kg in the WL and L+OCS groups, respectively, and the L+OCS cows gained hi gher body weight. Milk composition was similar in both treatments. The WL silage had a lower content of neutral detergent soluble (NDS) gluc ose, neutral detergent fibre (NDF) glucose and NDF xylose, and a highe r content of arabinose, galactose and mannose than L+OCS silage. Carbo hydrate digestibility was 83 and 85% in the WL and L+OCS rations, resp ectively. NDF digestibility was similar (45.0%) in both rations; howev er, digestion of NDF glucose, xylose and total polysaccharides was sli ghtly higher in the L+OCS group than in the WL ration. In both rations , NDF glucose was more digestible than NDF xylose and NDF uronic acid and less digestible than NDF arabinose, galactose and mannose. Digesti bility of total NDS carbohydrate was 89% in WL ration and 91% in L+OCS ration, and in both groups, digestion of NDS mannose and galactose wa s lower than that of NDS glucose, arabinose and pectin. Data of this s tudy indicate that a direct-cut and ensiled lucerne silage made of L+O CS is equivalent to lucerne haylage as a component in lactating cow ra tions.