by Kevin Scallon
Director of Technical Services

Dairy producers and nutritionists have been working diligently for years to better manage transition cows. Countless combinations of low potassium forages, low calcium, high calcium, anionic salts, high energy diets, low energy diets, palatability enhancers and numerous additives of every variety have been tried, with varying degrees of success, in an attempt to prevent or manage the problems associated with freshening dairy cows.

As we look for answers to questions it is often times apparent that the most difficult part of the process is coming up with the right question. Recently several researchers have taken a different look at the question of transition management. Rather than questioning how to manage the cow’s changes through the transition process maybe we should consider questioning the transition process itself!

Midwest Dairy Business ran a series of articles in their September 2003 issue discussing research on the dry and transition periods and reported some very interesting findings as a result. This article will attempt to summarize that series. If you would like copies of the complete series let us know and we can forward those to you.

The 60 day dry period originated in Great Britain during World War II in an attempt to increase food production. It was quickly adopted in the US and has been standard practice ever since. Research since that time has focused more on rationalizing and building support for the 60 day dry period than questioning if there was a better way.

Recently several researchers looked at evaluating response to shortening the dry period from approximately 60 days to 30 or even 0 days. Eliminating the dry period completely poses many questions and considerable research is still needed to evaluate the impact. However, shortening the dry period from 60 to 30 or 40 days has shown no negative effects on dry matter intake, body weight, body condition score or postpartum health. In several studies, health and reproduction were improved following a shortened dry period.

Relating to effects on udder health , the dry period is split into three physiological phases: 1) involution, in which secretion of milk stops and the nutrients are reabsorbed into circulation; 2) a steady state or rest phase; and 3) the proliferation phase, in which both the number and secretory activity of cells increase. Capuca, a USDA researcher, claims a 25 day period is necessary to achieve complete involution. The proliferation phase begins a few days before calving and extends to peak milk production. It’s the rest phase in the middle that has never been proven to be necessary. Elimination of this rest phase would allow dry periods to be shortened, presumably with little or no impact on involution or proliferation.

Shortening the dry period increases herd productivity by keeping a larger percentage of the herd in milk, and for each cow, a larger percentage of her lifetime in production. Shortening the dry period could also eliminate the need for a far-off dry group. In theory, this would mean fewer group and ration changes, minimizing both social and nutritional stresses common in typical dry and transition cow programs commonly used today.

It is too early to say we have all the answers on the appropriate length of the dry period. Research to date would suggest there are both risks and benefits to a shortened dry period. The benefits in health and reproductive performance need to be balanced with the potential to reduce milk production in the lactation following the shortened dry period. This is a decision that should be made on a cow by cow and farm by farm basis.

We at ANC feel that a dry period of between 40 - 60 days may be appropriate for cows producing enough milk to exceed their feed cost. For cows producing less than that, and heifers entering their second lactation, a 60 day dry period is still appropriate. This recommendation is, of course, based on the availability of adequate labor and facilities to accommodate the change.

Dr. Wayne Weiland, Technical Service Specialist with Monsanto Dairy Business, put together a series of questions that need to be addressed when considering a shortened dry period strategy.

· Is there an ability to house and feed more cows? Remember that overcrowding often has costs in both production and health.
· Is there capacity to milk more cows?
· Do facilities allow for more cows in the pre-fresh group?
· How wide is the variation around the current desired dry period length? How many cows are currently too long or too short relative to what is desired?
· Are accurate breeding dates, and thus due dates, maintained?

It is also important to consider the implications of a shorter dry period on treatment protocols, vaccination and foot health programs, ration changes and feed inventories, and normal variation in gestation due to season and multiple birth pregnancies. A full copy of Dr. Weiland’s paper entitled “Considerations for Modifying Dry Period Length” can be obtained by contacting your ANC consultant or the ANC office at 608-846-2727.