Sixty days of rest - that's the rule for dry-cow management, and has been for ages.

The dictum says that you must do everything you can to give a cow 60 days of rest or production will suffer in the next lactation. However, new research shows that with today's cows and technologies used in dairy production, 60 days of rest may no longer be necessary. You may be able to get by with a much shorter dry period - 40 days or less.

A couple of caveats exist. To succeed you must maintain accurate pregnancy information and have instituted a good transition cow program. If you have these tools in place, then you are a prime candidate to try this revolutionary new idea. Here's why you should consider shortening your cows' dry period.
Research yields surprises
While some producers and scholars argue that a 40-day dry period doesn't allow enough time for cows to gear up for the next lactation, new information says otherwise.

Researchers at the University of Florida found that when they reduced dry periods to less than 40 days, cows maintained milk production in the subsequent lactation - a feat previously thought to be impossible. And, the researchers go on to say in an April 2002 Journal of Dairy Science article that the animals actually had higher production than herdmates with longer dry periods.

Data from recent University of Florida on-farm experiments show that cows with a 32-day dry period produced 13 percent more milk than herdmates dry for 61 days. The 32-day dry cows didn't receive special treatment or health protocols, either.

A similar University of Florida study found cows with a 31-day dry period produced 2 percent more milk than cows with a 61-day dry period. These figures correspond to research conducted at Cornell University in the early 1970s and a Danish experiment from 1991.

"We have a total of five actual animal trials and, obviously, we need more numbers," says Kermit Bachman, dairy management specialist, University of Florida. "But, the data so far suggest that a 40-day dry period may be more profitable than standard 60-day recommendations." That's because you get an extra 20 or more days of milk production out of a lactation without sacrificing production in the following lactation.

Worth a second look
The 60-day standard has not been challenged in decades. So, the new hypothesis poses a significant shake-up of conventional thinking. The traditional 60-day rule is based largely on an analysis of accumulated production records and not on planned animal experiments.

Therefore, a shorter dry period may be worth a second look. Any data supporting dry off at 60 days before calving' recommendations are old and apply to cows that differ from today's cows.

Today's cows may never lose the mammary alveolar cells in late lactation and, therefore, may not need as much of a rest to be a profitable milk- maker.

Bachman reports that animals in the Florida experiments came through the transition period well. This may be due to the shorter dry period positively affecting rumen microbe populations and rumen papillae development. And this may translate into better health during the transition period.

After all, with a shorter dry period, you aren't introducing cows to as many changes and ration adaptations. You are essentially eliminating the far-off group and feeding cows a more energy-dense ration throughout the dry period that more closely resembles a fresh- cow diet.

Bachman postulates these factors aid in rumen function. However, this significantly changes dry cow management, and calls for greater attention to dry cow nutrition than may have been previously required. A shorter dry period also eliminates a ration, which can save time and money.

"Physiologically, there is no reason not to try a 40-day dry period," says Tony Capuco, research physiologist at the USDA-Agricultural Research Service station in Beltsville, Md. "Dry period length really becomes a function of producer economics."

Long-term effects
The biggest question mark surrounding shifting dry period length centers on its long-term effects. Current data suggest it can work well for the lactation immediately following the shorter rest period. However, implications for a third or fourth lactation are currently unknown. It may not put future production at risk, but no definitive answer yet exists.

It should be noted that the University of Florida data relate to the dry periods between second and third lactations and higher. "We have not re-searched adequately the dry period between first and second lactations," Bachman admits.

Also, keep in mind that heat stress tends to shorten gestation length, which also shortens dry period length. This becomes a factor if a planned short dry period is further shortened due to heat stress.

In the meantime, you may want to explore the concept with a few cows that were milking hard at dry-off to see if a shorter dry period works for your management style.

Economic evaluation

When does reducing dry period length pay? According to the latest research, most of the time, even if you factor in the old premise that a decreased dry period will cost you production in the ensuing lactation. So, let's put some numbers to that theory. If it pencils out when production dips, it will also pencil out with a more favorable production level.

1. Conservatively, let's assume that cutting 20 days from your dry period will negatively affect milk production by 4 percent the second lactation, or 880 pounds of milk for cows averaging 22,000 pounds annually.

2. Cows will maintain the total 22,000-pound annual production level - that is, make up for that estimated 880-pound decrease - over two lactations if they milk 44 pounds a day for those 20 extra days. This is a realistic expectation for modern dairy cows. Therefore, you haven't lost any production after all.

3. If cows exceed this 44-pound daily level for the extra 20 days, or do not drop in production in the second lactation, as occurred in the Florida experiments, you'll see a positive return to your bottom-line.

4. Just keep in mind that you also need to factor in whether this late lactation level of production covers a cow's variable cost as part of the milking herd. Or if it is cheaper to manage her variable cost as a member of the dry-cow pen. Note that parlor pressure dictates that the most profitable cow be milked.