Palatability and intake of silage in dairy cows, in relation to hygienic quality

in two groups of 20-28 dairy cows the influence of the hygienic quality of silages on roughage intake was tested. A Calan gate system was used to register the intake of roughage and the frequency of visits tc the gates electronically. Loa hygienic quality was produced mainly by secondary fermentation of silage by storage exposed to air. Single-choice experiments a ere carried out as follows: a control period with fresh silage quality was followed by a period with silage of low hygienic quality. The silage of poor hygienic quality led to a decrease in roughage intake of about 10-20%. In two-choice experiments a control period was followed by a period a with two alternatives in quality, distributed equally on the Calan gates. The cows clearly preferred the fresh silage quality. The daily intake of silage and the meal frequency a;ere higher at the gates containing the better silage quality. The hygienic quality of the silages was judged by macroscopic examination, pH-determination, dry matter content and microbial examination. After secondary fermentation of silage the results of microbial examinations corresponded well with the sensorial tests. However, the differences in microbial count were too small to judge the hygienic quality by microbial examination alone.