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 K₂CO₃ 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 K₂CO₃ at 6% of dietary dry matter (DDM) and containing 10% K); yeast, the control diet supplemented with live Saccharomyces cerevisiae 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 (P < 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 (P < 0.01) in EO and peptide treatments than in the control, with yeast treatment intermediate. In high-concentrate diets containing K₂CO_3, supplementing with yeast increased feed intake while supplementing wth essential oils increased energy-corrected milk yield, with small effects on milk protein yield.