Effects of supplementing different feed additives to high-concentrate diets containing potassium carbonate on dairy cow performance.

Meeting the buffer requirements of concentrate-fed dairy cows is a challenging task. We evaluated the effect of supplementing different feed additives to diets containing KCO on feed intake, nutrient digestion and milk production of dairy cows. Eight peak lactation high yielding Holstein cows were used in a replicated 4 × 4 Latin square design with 4 periods of 21 d (14 d for diet adaptation and 7 d for sampling and data collection). Treatments comprised control (a diet containing a rumen buffer with the active component of KCO at 6% of dietary dry matter (DDM) and containing 10% K); yeast, the control diet supplemented with live yeast (0.06% of DDM); essential oils (EO), the control diet supplemented with essential oils (0.02% of DDM) and; peptides, the control diet supplemented with biogenic peptides (0.16% of DDM). Feed intake was greater ( < 0.001) in the yeast treatment (33.2 kg/d) compared to the others (30.9 to 32.1 kg/d). Dry matter and starch digestibilities were similar across the treatments. Cows that were supplemented with EO had a greater energy-corrected milk yield than control, and those supplemented with yeast and peptides were intermediate. Milk protein production was greater ( < 0.01) in EO and peptide treatments than in the control, with yeast treatment intermediate. In high-concentrate diets containing KCO supplementing with yeast increased feed intake while supplementing wth essential oils increased energy-corrected milk yield, with small effects on milk protein yield.