The Importance of Treating Subclinical Hypocalcemia

Ken Zanzalari_cropped

Ken Zanzalari, Animate Product Manager, Prince Agri-Products

Today’s DairyLine topic focuses on the importance of treating subclinical hypocalcemia with Ken Zanzalari, Animate Product Manager with Prince Agri-Products. Here’s a transcript of Ken’s interview:

Q: Dairy producers are familiar with milk fever, but transition cows can also be at risk from subclinical hypocalcemia.  Ken, would you please explain that term and how it affects dairy cow health and milk production?

A: Subclinical hypocalcemia is a blood calcium level in fresh cows that is below normal.  Like a lot of diseases, there is always a clinical form of a disease and a subclinical. And subclinical hypocalcemia is where blood calcium levels are below normal, but not low enough to where cattle are severely affected by that low blood concentration. Most dairymen are familiar with clinical milk fever because in those situations, typically cows are down and need to take immediate calcium therapy. But subclinical cows track under the radar, so to speak.  They’re out in the herd, suffering from subclinical hypocalcemia, but unless you have a really good herdsman, they’re not going to be able to detect it, unless you take some measures to measure it. 

And the negative impact it has on cow health is a much greater risk of DA’s, significantly less dry matter intake and much greater risk for retained placentas, metritis and infertility.

Q. Recent research has indicated that the threshold for subclinical hypocalcemia should be higher than the traditional definition.  Tell us about that.

A: That’s correct Bill. Subclinical hypocalcemia has been known for many years in the industry. In fact, you dig into the research, the first case of clinical milk fever, I think, was documented in the literature in the 1700’s. And there was some really good work at USDA in Ames, Iowa, where in the 70’s, they looked into this disease and disorder and determined that based off their numbers, and numbers they saw in the field, that a normal blood  calcium level should be somewhere between  8 and 11 milligrams per deciliter.

But recently, some newer research at several different universities has looked into that a little bit further, and their suggestion is that the threshold should not be 8 milligrams per deciliter, but 8 ½ or above. And what they were able to do that was a little bit different than the earlier work was to track these animals a little further out into lactation to look at milk yield, reproductive inefficiencies and things like that. And so, they have baseline blood calcium levels that almost pre- determine what kind of production that cow will have, and what her risk is for some of these other health disorders, whereas the earlier work kind of lumped cows together and came up with, what I would call, a best guess estimate of at what threshold level should we start considering adjusting diets, giving calcium therapy to help these cows through that transition period.   

Q. Your team of dairy technical specialists work with producers to conduct blood sampling to monitor for subclinical hypocalcemia. How is that a useful tool?

As I mentioned, cows that are subclinical hypocalcaemic can appear normal. They get up to the feed bunk, they get up when prodded to go to the milk parlor, but they’re sluggish. Sometimes it is very noticeable, but a lot of times these cows appear healthy. But in reality, if you were to really closely examine these animals and follow their habits, you notice that they spend less time eating at the feed bunk. They have less ruminal contractions and a host of other things.

And so, what we have designed is a way, through the use of Michigan State University, a blood calcium testing program. You can go to a farm and explain all these things and what you’re after, but it’s always easy to measure something and then go back and substantiate those numbers with facts.

We have a program where we’ll work with the producer, their veterinarian, their nutritional consultant, and pull blood, establish a baseline of where their herd is and the incident rate of the subclinical hypocalcaemia on their farm.
And then, if things are fine, great. But what we have found out  is that there is a large population of cows that are subclinical hypocalcemic, by any standard, whether you use the old 8 milligram per deciliter, or the new 8 ½ milligram per deciliter threshold.

And by some simple adjustment in how they feed and what they feed, we can have dramatic effects. So it’s a program, it’s a tool that we make available to dairymen to really fine tune their nutrition cow program.

Q. More producers are adopting a negative DCAD diet to maintain proper blood calcium levels in close-up dairy cows. Can you provide more information about that and how Animate from Prince Agri Products can help achieve a successful DCAD diet?

A lot of great work was done in this whole area, and there are several ways to try and reduce not only clinical milk fever but also subclinical milk fever, or subclinical hypocalcemia. But in the four or five ways that we know we can try to control that, the most effective by far, and the most practical by far in today’s dairy industry, is the use of a negative DCAD diet. In other words, we feed mineral salts to acidify the animal and by doing so, we trigger calcium metabolism in that cow. That helps her get through that period where we know, with the onset of lactation, she’s going to struggle to maintain normal blood calcium levels. 

 And so negative DCAD diets are very effective. They’re very cost effective. And of all the methods that have been found to reduce clinical milk fever or subclinical hypocalcemia, it’s the most effective way.

More and more producers are using a more properly balanced negative DCAD diet, and Animate, which is a unique patented  anionic mineral supplement, delivers the appropriate level and combinations of minerals, and it’s highly palatable. Because it’s highly palatable it can help attain a negative DCAD diet while also maintaining high dry matter intakes.

Q. What are your recommendations for successfully managing a properly balanced DCAD diet?

It sounds difficult but it’s not. A couple things are very important. One, with negative DCAD diets, we know that we have to fully acidify the animal. In other words, we have to make her system acidic. And the way we do that is feeding her those mineral salts. And how we know we are feeding her the proper amount of those salts is by regularly testing urine pH , because urine pH will tell us along the scale of acidification where she’s at. And one of the problems in the industry, and again going back to some of the earlier work, the target level of acidification in a lot of different research trials were all over the board.

What we have found from doing probably over 3,500 blood samples on 150 farms throughout North America is that fully acidified diets, where urine pHs are between 5 ½ and 6, is the most beneficial. So that’s the number one thing you need to do when you start feeding that program.

We know that there is a minimum of about 21 days that the animal needs to be on that diet to be fully effective.  The other thing that is really critical is having proper levels of calcium, phosphorous, magnesium in the diet.  And when you get those three levels right, along with those other key points I just mentioned, a successful negative DCAD program is easy to obtain. And the payback is well over 4-1 in what it will cost you – approximately $20 for a 21 day close up period. And what that cow will return to you is not only in milk volume, subsequent lactation, but the health benefits as well.

Q- If somebody wanted to find out more, maybe talk to your team of dairy technical specialists?

The easiest way, because we have about 20 sales people now in the U.S., is to visit our website, at Through that link, you are able to contact our office in Quincy, Illinois. By leaving just some contact information, the correct sales representative from our organization would be able to follow up with that person.  


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