Abstract #M280

# M280
The effect of feeding zeolite A during the prepartum period on serum mineral concentrations in multiparous Holstein cows.
Allison L. Kerwin*1, Charlene M. Ryan1, Brittany M. Leno1, Morten Jakobsen2, Per Theilgaard3, Thomas R. Overton1, 1Department of Animal Science, Cornell University, Ithaca, NY, 2Protekta Inc, Lucknow, ON, Canada, 3Vitfoss, Graasten, Denmarke.

The objective was to determine the effect of feeding zeolite A during the prepartum period on peripartum serum mineral status. Holstein cows (n = 55) entering second or greater lactation were assigned randomly to one of 2 dietary treatments starting 21 d before expected calving; control (CON): 40% corn silage, 33% wheat straw, and 27% concentrate or experimental (EXP): CON plus zeolite A (X-Zelit, Protekta Inc./Vitfoss) at 3.3% of DM, targeting 500 g/d as-fed. Blood was collected 1×/wk from enrollment until 7 d before expected calving, daily through 7 DIM with 2 samples within the 24 h of calving, and 3x/wk from wk 2 to 4. Data were analyzed in SAS v. 9.4 with repeated-measures ANOVA using the MIXED procedure. The difference in prevalence of subclinical hypocalcemia (SCH; serum Ca <8.5 mg/dL) between treatments by day and chronic SCH (cSCH; all serum samples between 0 and 3 DIM with Ca <8.5 mg/dL) was tested with Fisher’s exact test. There was a treatment by day effect on serum Ca (prepartum: P = 0.06, postpartum: P < 0.001), P (prepartum: P = 0.04, postpartum: < 0.001) and Mg (prepartum: P < 0.01, postpartum: P < 0.001). Cows fed EXP had higher prepartum serum Ca (9.88 ± 0.10 vs. 9.26 ± 0.10 mg/dL, P < 0.001), lower P (3.20 ± 0.13 vs 6.30 ± 0.12 mg/dL, P < 0.001) and lower Mg (1.70 ± 0.03 vs. 1.84 ± 0.03 mEq/L, P < 0.01). Cows fed EXP had higher postpartum serum Ca (9.33 ± 0.09 vs. 8.60 ± 0.09 mg/dL, P < 0.001) and lower P (3.70 ± 0.13 vs 4.32 ± 0.12 mg/dL, P < 0.001). The prevalence of hypocalcemia was higher in cows fed CON at −3, −1, 0.25, 0.75, 2, 3, and 15 DIM and tended to be higher at 6 DIM. The largest difference in hypocalcemia prevalence was at 0.75 DIM; 90% of cows fed CON vs. 31% of cows fed EXP. No cows fed EXP had cSCH vs. 35% of CON cows and half of the EXP fed cows had no SCH through 3 DIM compared with 3% of CON cows (P < 0.001). Cows fed EXP had higher serum Ca and lower serum P and Mg with differences being most pronounced during the immediate peripartum period. Feeding zeolite A during the prepartum period resulted in markedly improved Ca status during the periparturient period.

Key Words: hypocalcemia, zeolite A, mineral status