Dietary cation-anion difference (DCAD) for close-up dry cows doesn’t have to be hard. For many dairy producers looking to try DCAD for the first time, implementing a brand new nutritional practice on-farm can often seem like a daunting task. But it doesn’t have to be. With partial DCAD, producers new to DCAD can take an easier approach to starting the journey safely.
The impact of good transition cow nutrition on the health of your herd is undeniable. A successful DCAD program will ward off expensive treatments by preventing problems before they ever begin. But a fear of implementation, of not being able to “make it work,” seems to keep too many away from something that can take their operation to the next level. Many producers have been taught to believe a ‘successful’ DCAD program requires committing 100 percent to a full approach that will produce maximum results. But that’s just not true. DCAD success is not one-size-fits-all, and your success should not be measured by the severity of your program.
Feeding a chloride source to create a negative DCAD diet helps to slightly acidify the pre-fresh cow’s blood, which in turn improves her calcium status at calving. By improving her calcium status, you improve the health of the animal, helping prevent milk fever as well as detrimental diseases related to subclinical hypocalcemia, such as retained placenta, metritis, early lactation mastitis, displaced abomasum and ketosis.
DCAD is a tried and true practice; its benefits have been proven time and time again by research and on-farm success. But trying to take off at top speed to capture the maximum benefits presents unnecessary challenges that can steepen the learning curve and complicate the practice.
While it is certainly possible to find DCAD success within a more extreme range, which is characterized by pH levels between 5.5 and 6, this makes the practice more difficult to manage. The lower the pH goes, the more closely it needs to be monitored to ensure cows’ levels don’t dip below 5.5 and become over-acidified.
Partial DCAD is one way to ease into the positive change for your pre-fresh transition cows without taking on all the additional risk and responsibility that can come from the more extreme full DCAD. Partial DCAD allows producers to reap the majority of benefits of a DCAD program without facing the steeper learning curve.
Partial DCAD is a bit more of a phased-in approach to adjusting the dietary ratios of sodium, potassium, chloride and sulfate in pre-fresh dairy diets. With partial DCAD, you feed less anionic supplement than with full DCAD. And even if clinical milk fever is not a problem in your herd, cows still respond to partial DCAD with a noticeable reduction in other problems associated with hypocalcemia.
The management requirements for achieving success are much less stringent with partial DCAD, and there is less risk of overfeeding the anionic supplement since the DCAD is calculated at a more moderate level. Also, there is less need to go full bore with the urine pH testing, even though testing of urine pH is still a good practice. This will make it even easier for your on-farm team to learn the simple process of pH testing and manage it for themselves without an issue.
For producers looking to try out a partial DCAD program, start by working with your nutritionist to select a quality, consistent, palatable anionic supplement. Remember traditional anionic salts can result in lower feed intake due to its taste, so look for a palatable commercial option instead.
As you get started, monitor urine pH to determine how much anionic supplement to feed. The more you feed, the lower the pH will go. The ideal partial DCAD range to aim for is between 6 and 7. If you feed enough anions to keep the cows in this range, you don’t have to worry about over-acidification. As time goes on, you can monitor much less frequently than someone taking the full DCAD approach.
Because you are easing into DCAD management gradually with partial DCAD, your on-farm employees have time to learn the ropes and develop the skills needed to take ownership of this practice. If you decide you want to ramp up the management and transition to full DCAD later, that’s no problem. Starting small doesn’t prevent you from expanding.
Pre-fresh DCAD success may look different for you than it does your neighbor. What works for one producer may not be the right fit for another. Success is possible and easily achievable with a partial approach. If a fear of failure has prevented you from taking on the highly beneficial practice of pre-fresh DCAD, consider partial DCAD an option for you. This simplified approach will help you reach your own version of DCAD success, without the fear of failing. 
PHOTO: Partial DCAD allows producers to reap most benefits of a DCAD program without facing a steep learning curve. Photo by Mike Dixon.
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Tim Brown
- Director of Technical Support
- SoyChlor
- Email Tim Brown
