Comparison of a Negative DCAD and X-Zelit Prefresh Strategy

OVERVIEW

A recent field trial was conducted by Kansas State University on a 5000-cow commercial dairy herd comparing a negative DCAD and a X-Zelit prepartum feeding strategy in a side-by-side study.  Second lactation and older cows (n=1,102) were randomly assigned to be supplemented with either BioChlor (DCAD -106 meq/kg) or X-Zelit (500 grams per head daily) in the 21-day prepartum period. In a subgroup of cows (n=30 per treatment), blood samples were collected at 0, 48 and 72 hours relative to calving to determine calcium, phosphorus and magnesium status.

Both treatment diets contained the same prefresh ingredients except for the inclusion of either BioChlor or X-Zelit and there was a difference in dietary calcium concentration (2.53%: DCAD versus .57%: X-Zelit).  Cows in both treatments were similarly managed and KSU research staff were present daily to assist the farm crew in mixing the prefresh diets.

RESULTS

Blood calcium levels were significantly higher for the X-Zelit fed cows at both calving and 48 hours post-calving (Figure 1).  Not only did the X-Zelit treatment have much higher blood calcium levels, but there was less variability for the X-Zelit cows compared to the negative DCAD cows.  Higher and tighter blood calcium levels are critically important to maintain optimal health and production during the first 48-72 hours post-calving.

                                                                                 Figure 1. 

Both blood phosphorus and magnesium were lower at calving for the X-Zelit group (Figures 2 & 3).  Even though the blood magnesium was lower, it was still within the normal range. However, at 48-72 hours, both the blood phosphorus and magnesium levels were equal and/or higher in the X-Zelit cows compared to the negative DCAD cows.

Figure 2.                                                                                           Figure 3. 

IMPLICATIONS

This field trial data strongly agrees with the Cornell research trial (Kerwin et al., 2019) showing significantly higher blood calcium levels through the first 48-72 hours post-calving. The postpartum blood phosphorus and magnesium levels were also similar between this field study and the Kerwin data. In addition, chronic subclinical hypocalcemia (cSCH) cows are defined as cows that remain below the optimal blood calcium (8.5 mg/dl) level for the first 72 hours post-calving. There continues to more evidence emerging that cSCH cows are very high risk for reproductive failure, lower milk production and removal from the herd. The X-Zelit strategy provides the best opportunity for minimizing chronic subclinical hypocalcemia at the farm level.

BOTTOM LINE

Achieving transition cow success is challenging for both the cows and the producers. A seamless transition into lactation is essential to maintain health and achieve expected production and financial goals. In contrast to the negative DCAD approach, the X-Zelit strategy allows producers to achieve optimal fresh cow blood calcium status with the convenience of feeding more home-grown forages instead of sourcing low potassium forages and routinely monitoring urine pH. Furthermore, higher blood calcium levels will reduce the need for supplemental calcium boluses, minimizing fresh cow touches. Overall, the X-Zelit strategy will simplify the implementation and management of your pre-fresh feeding program while achieving transition success.

ROD MARTIN, M.S., PAS

DAIRY NUTRITIONIST & BUSINESS DEVELOPMENT-USA

rma@protekta.com