One dry cow group or two?

One dry cow group or two?

by Mary Beth de Ondarza
The author has a dairy nutrition consulting business, Paradox Nutrition, LLC, in West Chazy, N.Y.

At one time, I was a big advocate of two dry cow groups: a far-off group (60 to 21 days before calving) and a close-up group (21 days to calving). But over the last several years, some excellent producers have proved me wrong and had great results with just one dry cow group. The main advantage to having only one dry cow group is that cow moves are reduced.

Every time you move a cow, she will be stressed, especially over her new penmates. This stress can reduce intake, cause more metabolic problems and elevate fat mobilization. Another advantage of having only one dry cow group is that it eliminates the problem of early calving cows being moved and put on a close-up diet only a week before calving.

At the same time, I still see many two dry-group systems in place on farms that work well. So, what is the best answer? It depends on a number of factors.

First, consider that dry cows with high intakes will have fewer problems. Researchers at the University of British Columbia found that, in the week before calving, a 2.2-pound reduction in dry matter intake doubled the risk of subclinical ketosis, and cows were three times more likely to have metritis.

How much dry matter are your dry cows eating during the last four weeks before calving? How can you get intakes higher?
Researchers have found Holstein dry cow intakes ranging from 23.5 pounds per day to 36 pounds per day. That is a huge range! Consider cow comfort and its effect on intake. Researchers at the University of Wisconsin recommend that stocking density relative to headlocks be greater than 80 percent (a pen with 16 cows should have 20 headlocks).

Close-up cows should have at least 30 inches of bunk space per cow. Freestalls should be 54 inches wide. Bedded packs should have a minimum of 100 square feet per cow and be cleaned every few days. Overcrowding dry cows will reduce intakes and elevate the incidence of displaced abomasums.

Penn State University researchers have suggested that including more digestible fiber both from forages and by-products may help to boost dry matter intake. Higher levels of digestible fiber will also help to reduce dietary starch, improving rumen health prior to calving.

Given your facilities, how can you group so that the close-up cows are most comfortable?
If space is at a premium in your facility, having two dry cow groups may allow you to at least give more space and comfort to the close-up cows while leaving the far-off cows slightly more crowded. On the other hand, if you are currently bringing close-up cows into a tie stall barn so that you can give them extra grain, maybe it would actually be better to leave them in one dry cow group where they are more comfortable and eat better.

What is the body condition of your cows at dry-off? And what is the typical dry period length in your herd?
A body condition score of 3.5 (sacral ligament visible; tailhead ligament barely visible) is best for dry cows. Fat cows will eat less before calving and mobilize more fat. With one group of dry cows, dietary energy is typically slightly higher (0.63 to 0.65 Mcal/lb) than in a far-off dry group (0.58 to 0.60 Mcal/lb). So, it can be difficult to keep cows that are already a little heavy from gaining more weight with one dry cow group, especially if they also have long dry periods.

High-producing herds with good reproductive programs and shorter dry periods (40 to 50 days) tend to have the most success with one dry group. They have very few fat cows in the herd. It is best to work on fat cow problems during the last two months of lactation. The solution likely requires addressing reproductive issues as well as reducing dietary energy.

How easy is it for you to make two dry cow rations?
Obviously, it should be easier to make one dry cow TMR rather than two. Dry cows should always have a fresh, palatable, well-mixed TMR. If you are trying to save time by feeding refusals, hay separately or topdressing grain to your close-up cows because you can’t make a TMR for them, you may be surprised with the positive response that you get when you have one dry cow group receiving a well-balanced, consistent TMR every day.

Do you have a fresh cow ration?
Ration changes should never be drastic. Since a one-group dry ration should have a lower energy density than a close-up ration, it is more important to have a fresh cow ration when you have only one dry group. The fresh cow ration (0 to 14 or 21 days in milk or DIM) should have a slightly lower energy density than the high-cow ration. Without a fresh ration, it may be better to have a close-up ration.

If you have the facilities for two groups of dry cows, would it be better to have a heifer dry group and a mature cow group rather than prefresh and far-off dry groups?
According to Rick Grant, Miner Institute, Chazy, N.Y., lactating heifers that are in a separate group will eat 10 to 15 percent more, rest 20 percent more and make 10 percent more milk than lactating heifers that are mixed with older cows. Also, first-calf heifers grouped with older cows will spend 16 percent less time ruminating.

Many producers have seen the benefits of separating first-calf lactating heifers. It seems likely that these animals would also benefit from separate grouping prior to calving, especially if overcrowding is an issue.

Should anionic products be fed for the entire dry period?
I have had success controlling milk fever with dry cow diets containing corn silage (13 to 15 pounds dry matter or DM), low-potassium hay or straw (4 to 6 pounds DM) and a small amount of grain (6 to 7 pounds). These diets contain less than 1.2 percent potassium with diet magnesium at 0.4 to 0.45 percent.

But, if subclinical milk fever issues still persist, it can help to add a chloride source that doesn’t depress intake to bring dietary chloride (Cl) to within 0.5 percentage point of dietary potassium (K) (if 1.3 percent K, then 0.8 percent Cl). This achieves a diet DCAD of 0 mEq/kg and urinary pH of 6.2 to 6.8. The main issue with feeding an anionic product for the entire dry period is cost.

After three or four weeks on an anionic product, urine pH will rise because the cow adapts by using bone to buffer the acid. Positive responses to the anionic product should still be seen. However, monitor urine pH only in cows on the diet for less than three weeks for ration adjustment purposes.

Consider your operation carefully, and work with your nutritionist to determine the best dry cow strategy for your dairy. What may be right for your neighbor may not be right for you.

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