Thirty multiparous lactating Friesian cows were used to study the effect of partial or complete replacement of corn silage with lactic acid bacteria (LAB), molasses and calcium carbonate ensiled sugar beet tops for 3 months in a complete randomized experimental design with repeated measures. A week after parturition, cows were grouped into three treatments of 10 cows each and fed a control treatment containing corn silage at 300 g/kg DM. In the other treated diets, 50% or 100% of the control corn silage was substituted with beet tops silage treated with LAB included at 150 g or 300 g per kg diet. Ensiling of beet tops with LAB decreased its contents of oxalic acid and neutral detergent and acid detergent fibers but increased its contents of non-structural carbohydrate and calcium. Without affecting daily milk production and feed efficiency, beet tops silage treated with LAB diets decreased (p < 0.05) feed intake, total ruminal volatile fatty acids, acetate and propionate concentrations, energy-corrected milk yield and concentrations of milk total solids, fat, protein and energy. In conclusion, beet tops silage treated with LAB can replace corn silage in diets of lactating cows. An inclusion rate of 15% of beet tops silage treated with LAB (replacing 50% of corn silage) in the diet was the most suitable level for lactating cows under the current experimental conditions.
Keywords: Beet tops silage; cattle; lactic acid bacteria; milk; oxalic acid; rumen parameters.