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Effect of a low-DCAD, high-calcium acidogenic ration on hypocalcemia and health outcomes in New Zealand farms.

M. Gorocica

W125
Effect of a low-DCAD, high-calcium acidogenic ration on hypocalcemia and health outcomes in New Zealand farms.
B. J. McKay1, N. Chrystal2, K. Zanzalari3, M. Gorocica*3. 1Dairy Production Systems LTD Hamilton, New Zealand, 2Complete Feed Solutions LTD Auckland, New Zealand, 3Phibro Animal Health Corporation Teaneck, NJ.

An observational study was conducted to assess the effectiveness of a low DCAD, high calcium ration in reducing hypocalcemia (HC) and HC-associated disorders under New Zealand feeding conditions. Four farms with high incidence rates of clinical milk fever (5.5% over the last 3 y) were selected. Results from the current (CUR) vs the previous (PREV) calving seasons were contrasted using β-regression with marginal means comparison. In both CUR and PREV seasons, a concentrate mix was formulated to complement estimated forage intake to meet or exceed NRC (2001) requirements. DCAD and Ca levels were the main differences between concentrate offered in CUR vs PREV seasons. For PREV, the total ration DCAD ranged from −47 to +92 vs −100 to −150 mEq/kg DM in the CUR season. Total Ca supplied was estimated at 85 g vs 180 g/d in PREV and CUR, respectively. The concentrate mix was offered during the last 21–28 d of gestation. Urine pH was measured weekly. Target range for urine pH was 5.5 – 6.0. If urine pH was off target, the amount of concentrate mix offered was adjusted accordingly. A 69% reduction (P < 0.01) in the incidence rate of clinical HC was observed (5.4% vs. 1.9% for PREV and CUR, respectively). Calving assists (5.1 vs 2.8%), retained placenta (4.0 vs 2.0%) and total peri-calving disorders (18.4 vs 7.4%), were all numerically reduced in the CUR vs PREV seasons but variation across farms and the relatively small number of farms enrolled in the study prevented reaching statistical significance (all P > 0.10). In conclusion, health outcomes during the CUR season suggest a low DCAD, high calcium ration may be an effective tool to manage hypocalcemia and other related issues under grazing conditions in New Zealand

Keywords: hypocalcemia, DCAD, New Zealand.