Abstract #T280

# T280
Effects of varying prepartum DCAD and calcium concentrations on pre- and postpartum body weight, intake, milk yield and milk composition.
A. L. Diehl*1, J. K. Bernard1, S. Tao1, T. N. Smith1, D. J. Kirk2, D. J. McClean2, J. D. Chapman2, 1University of Georgia, Tifton, GA, 2Phibro Animal Health, Corp, Teaneck, NJ.

Eighty-two multiparous Holstein cows were enrolled 28 d before calving through 63 DIM between January and October, 2016 and assigned to 1 of 4 dietary treatments in a randomized block design experiment with a 2 × 2 factorial arrangement of treatments. Dietary treatments provided 2 dietary cation-anion concentrations (DCAD): −22 mEq/100 g DM (NEG) or −3 mEq/100 g DM (NEU); and 2 dietary Ca concentrations: 1.0% or 1.5% of DM. Cows were individually fed and DMI recorded daily. After calving, cows were milked 3 times daily, yield recorded at each milking and samples collected once weekly for analysis of components. Body weight and BCS were recorded 21 d before calving, and 0, 21, and 63 DIM. No interactions were observed between DCAD and Ca for any variables measured. No significant differences (P > 0.10) were observed in BW or BCS due to DCAD or Ca. Prepartum intake was 15.1, 13.0, 17.3, and 14.8 kg/d for 1.0%-NEG, 1.5%- NEG, 1.0%-NEU, and 1.5%-NEU, respectively. Prepartum DMI was lower (P = 0.0096) for NEG compared with NEU (16.0 and 14.2 kg/d, respectively) and lower (P = 0.0038) for 1.5 compared with 1.0% Ca (14.0 and 16.2 kg/d, respectively). Postpartum daily DMI was not different (P > 0.10) among treatments and averaged 24.0, 23.0, 22.5, and 23.0 kg/d for 1.0%-NEG, 1.5%- NEG, 1.0%-NEU, and 1.5%-NEU, respectively. Daily milk yield was not different among treatments (P > 0.10) but an interaction (P = 0.0125) was observed for DCAD and DIM (P = 0.0125) due to higher milk yield after 45 DIM for NEG compared with NEU. No differences (P > 0.10) were observed in milk component percentage or yield among treatments. In this trial, feeding −22 mEq/100 g DM compared with −3 mEq/100 g DM, or 1.5% Ca compared with 1.0% Ca reduced DMI prepartum. Feeding −22 mEq/100 g DM prepartum supported increased milk yield after 45 to 55 DIM.

Key Words: DCAD, calcium, dry matter intake