A Healthier Herd Through the Perfect Dry Cow Program
Transition Period: A Vulnerable Stage
The dry period is one of the most important stages in a cow’s life cycle. It's also a period where their immune system is at its weakest, leaving them vulnerable to a host of diseases.
Research has indicated that immune responsiveness decreases for many cows during the transition period. Jesse Goff (Iowa State University) reported a 25-40% decrease in both innate and acquired immunity during the transition period.
This decrease in immune function has been linked to inflammation which is in turn associated with diseases such as mastitis and metritis.
Other transition cow diseases such as retained placenta (a failure of the cow’s immune system to reject the placenta as foreign material after calving) and metritis (failure of the immune system to clean up the inevitable contamination that occurs during calving) are likely a result of this suppressed immune system.
DMI: The "Holy Grail" of the Dry Cow Program
We know that dry matter intake (DMI) influences cow performance but DMI also has a significant impact on health and immune function. Reduced DMI directly predisposes the cow to increased metabolic disease through decreased nutrient intake, which increases the mobilization of fat and decreases calcium supply contributing to ketosis and milk fever.
The underlying driver behind most of the “non-nutritional” factors that affect cow health is their contribution to a decrease in dry matter intake. A rapid and precipitous decrease in dry matter intake before calving will lead to ketosis or sub-clinical ketosis. The onset of this disease may in turn be followed by a cascade of other metabolic disorders in the fresh cow. Therefore, minimizing the decline in dry matter intake prior to calving is very important in controlling fresh cow disorders.
Combatting Decline in DMI Through Farm Management
Pen moves, overcrowding, and inadequate bunk space have an indirect impact on immunity via decreased dry matter intake. Let's take a look at how to combat this with some smart farm management protocols to put in place for the transition period.
Bunk Space and Number of Headlocks
As dairy herds have moved from tie stall barns to free stall and bedding pack facilities, inadequate bunk space has become more of an issue. Inadequate bunk space or inadequate numbers of headlocks is especially serious for “at-risk” dry cows:
- Subordinate cows
- Lame cows
- Recently moved animals
- Overly conditioned cows
Stocking density plays a major role in the amount of bunk space available for a dry cow, especially in light of the dry cow’s eating behaviour. Research at the University of Wisconsin (Mentink and Cook, 2006) demonstrated that at peak bunk use in the lactating group only 80% of the headlocks were filled. This is primarily due to the size of the cow and the width of the headlock. Cows are not 61 cm (24") wide! The increased girth of the dry cow increases the risk of decreased dry matter intake due to available bunk space.
Recommendation to ensure all dry cows eat at the same time:
- Maintain an 80% stocking density for close-up dry cows
- with 61 cm (24") headlocks.
- Install 76 cm (30") headlocks.
- Provide 76 cm (30") of bunk space as the minimum
- requirement for a dry cow facility.
Available Bunk Space vs. Number of Cows
If the recommendation of 76 cm (30") of bunk space/cow is to become a standard, then it is difficult to make a 3 - row pen work versus a 2 - row pen. New dry facilities will likely move to 2 - row pens rather than 3 - row pens to keep stocking density at a reasonable rate.
Size of Stalls
Increasing the stall dimensions and bedding pack space from traditional measurements will improve comfort for all of the dry cows. Undersized free stalls (< 114 cm (45")) effectively reduce stall usage due to large cows “over-lapping” stalls with their feet and rumen. The recommendation for stall width (centre to centre) for mature dry cows and heifers is 135 - 137 cm (52" - 54") and 122 cm (48") respectively for free stalls and up to 152 cm (60") for tie stall facilities.
Bedding pack barns are becoming increasingly popular, especially for close-up cows. In many situations, the close-up cow is successfully calving in the bedding pack facility rather than a traditional calving pen. The University of Wisconsin has determined that a minimum pack size (excluding feed alley) of 11.15 m2 (120 sq. ft.)/dry cow will provide adequate space for movement and lying and reduce the moisture/contamination of the bedding pack.
Cow Management: Reducing Stress and "Social Turmoil"
Cortisol (often referred to as the “stress” hormone) is a powerful immune suppressant. Since it is also responsible for the onset of parturition, it spikes at the start of parturition. This spike, along with other hormonal changes associated with the calving process, is what causes most of the immune suppression associated with calving.
Introducing new cows to a pen will inevitably cause stress and “social turmoil” with the newcomers. This is primarily displayed by both antagonistic physical and posturing behaviour that will last 2 - 3 days.
What are some of the steps that can be taken to minimize this behaviour?
- Move cows weekly rather than daily.
- Move cows into the close-up group based on 14 - 28 days
- Avoid moving animals into a maternity pen 2 - 3 days pre-calving.
Time Spent in Maternity Pen
One of the great debates on many dairy operations is when to move the dry cow to the calving/maternity pen.
Dr. Gary Oetzel, from the University of Wisconsin School of Veterinary Medicine, worked with two commercial herds and demonstrated the effect of moving the cow to the maternity pen too early.
The “short stay” cows in both operations had a reduced culling rate (2.6 X and 3.1 X) during this time period. “Short stay” cows in Herd #1 had increased mature equivalent production while Herd #2 had reduced metabolic disorders (ketosis, displaced abomasum).
Here are the recommendations on when to move dry cows to the maternity pen:
- Move cows at < than 2 days before expected calving.
- Move “6 - legged” cows (calf is presented).
- Do not move cows between 2 -10 days prior to expected calving date.
In many tie stall operations, the calving pens have become the close-up pens for the dry cows. The cows either move from a group housing situation or an individual tie stall to the individual calving pen. The same premise would apply in this scenario – avoid moving dry cows in this high risk period of 2 -10 days prior to the expected calving date. In many tie stall operations, the calving pen isolates the dry cow from herdmates, leading to reduced dry matter intake