Effect of prepartum dietary-cation anion difference on performance, blood mineral and metabolite concentrations in Holstein dairy cows

Dietary cation-anion difference (DCAD) initiates a compensatory metabolic acidosis, which improves calcium (Ca) absorption and mobilization before calving and minimizes clinical and subclinical hypocalcaemia after calving. The goal of this study was to evaluate how mineral concentrations, blood metabolites, parathyroid hormone (PTH), and productive performance were affected by prepartum dietary cation-anion difference (DCAD mEq [(Na + K – Cl + S)]/kg of dry matter (DM)) in postpartum dairy cows. Forty-eight multiparous Holstein cows ranging from 2 to 5 lactations with an average body weight of 685 ± 10 kg (mean ± SD) were allocated in a randomized block design with three prepartum diets differing in DCAD (0, –100, and –180 mEq/ kg DM). All cows were fed the same postpartum diet and kept on trial for 66 days. Cows fed –180 and –100 mEq DCAD had greater prepartum non-esterified fatty acid (NEFA) concentrations than cows fed 0 mEq DCAD. Cows fed –180 mEq DCAD had greater serum Ca concentrations than cows fed –100 and 0 mEq DCAD. PTH concentrations were greater in cows fed 0 mEq DCAD than in cows fed –100 or –180 mEq DCAD. Cows fed 0 mEq DCAD had higher milk protein and solid-not-fat (SNF) levels than cows fed –100 or –180 mEq DCAD. Treatment and interaction had no effect on milk yield, 3.5% fat-corrected milk (FCM), energy-corrected milk (ECM), milk fat, total solids (TS), lactose, milk urea nitrogen (MUN), magnesium (Mg), sodium (Na), chloride (Cl), potassium (K), beta hydroxybutyric acid (BHBA), and liver or kidney functions. We concluded that adding anionic salts to dairy cows’ diets (–100 and –180 mEq DCAD) improved postpartum Ca availability and reduced clinical and subclinical hypocalcaemia while having no effect on milk yield or fat-corrected milk.