Voluntary waiting period (VWP) is more than just an arbitrary time frame. Even under the most ideal of circumstances, parturition is undeniably among the most strenuous actives an animal can undergo.
Dairy cows find themselves in a unique situation post-calving: Not only do they need to undergo the usual recovery of parturition, but they must be metabolically and physically prepared to undergo the next lactation cycle.
The internal healing of the cow’s reproductive tract is essential, not only for a successful rebreeding but also for her longevity and welfare. That said, a good VWP is essential for the sake of management and reproductive efficiency.
While there has been much discussion and variety on VWP within the industry, research has provided us with some general guidelines.
Definition of and importance of VWP
To stay within a 12-month calving interval, a cow must be rebred within 90 days after calving. Biologically, it typically takes 40 to 50 days for a reproductive tract to return to normal.
“There is an optimal window of time to initiate the breeding program considering the reproductive performance, culling and milk yield of cows,” says Gustavo Schuenemann, DVM, of Ohio State University’s Department of Veterinary Preventive Medicine. “Getting cows pregnant too early or too late could negatively affect the lactation curve by either dropping peak milk yield and increasing the risk for pregnancy or extending the lactation and creating an increased risk for culling.”
Both scenarios – due to breeding back too late or too soon – can reduce the entire herd’s overall reproductive performance over time.
As with many other post-fresh period activities, VWP has a relationship with many other variables surrounding management and nutrition. Jonathan Holewinski, premier account manager for Alta Genetics, says these details matter for herds determining an optimal VWP as opposed to a “cookie-cutter” approach. He points to poor nutrition and low body condition scores (BCS) as a typical example of where VWP can make a positive or negative difference.
“This can lead to very low conception rates, costing more money in the long run on, plus added reproduction and labor costs,” he explains. “Pushing VWP longer would be beneficial to save costs, (but) if VWP gets pushed too long then cows could develop a BCS too high and struggle with transition in her following lactation.”
The ‘best practice’
Under normal conditions, the process of uterine involution – that is, the uterus returning to its pre-pregnancy anatomy and function – is completed within the first 30 days after calving. Schuenemann says in the case of high-producing dairy cows this should fall between 60 all the way to 80 days for them to reach potential peak milk yield prior to the next conception.
“The VWP is often adjusted by parity,” he says, “in which the insemination of cows starts at 70 to 80 days after calving for first-lactation cows and 60 to 70 days after calving for multiparous cows.”
A specific universal standard is a topic Holewinski finds often brought up. While an ideal world would allow for each cow to have a customized VWP program, he says the most realistic for a herd or group should be between 50 and 80 days in milk.
“It should be tailored to the individual herd on what the herd can effectively execute,” he says, adding that consistency is key. “The most common shortfall I see is programs that are not making sure the team follows the protocol in place and compliance is not 100 percent.”
There also is an economic side to be considered. For example, Holewinski notes an aggressive approach breeding back 50 days in milk can result in fewer hormone costs and less labor when used in an intensive timed-A.I. program if done consistently and reliably. In these cases, it can balance out higher semen costs and lower conception rates.
Contrarily, longer VWPs need to have an enhanced conception rate to capitalize on peak lactation performance. Any program, Holewinski says, has its economic pros and cons.
“My recommendation is to analyze what can be executed effectively and tailor to the goals that are in place,” he says. “Often I see the best-performance herds, in terms of looking at strictly reproductive performance, are herds that are greater than 70 days in milk for their VWP and have a timed A.I. in place for first service.”
Holewinski also recommends having a reference manual for the standard operating procedures on hand to decrease the likelihood of error. This can include any notes about how to identify animals that are eligible either with chalk or in the herd software system.
Make it your own
The team, management and tools available on a specific farm should also account for all VWP decisions.
In recent times, the industry has increased confidence in getting more cows pregnant quickly and effectively, according to Don Niles, a veterinarian, co-owner and manager of Dairy Dreams LLC in Casco, Wisconsin.
In some cases, this has led to drying cows off while they are still at a high level of production. This is what has led more farms to a more widespread re-evaluation of VWP. Timed A.I., done properly, has been a big contributor to this.
“The next thing that’s come along are the activity monitor systems – and they’re getting better and better,” says Niles. “And our ability to manage them is getting better and better.”
Now herds using these monitors have found themselves able to replace either wholly or partly their timed-A.I. programs as they can use custom identification better than a typical tail chalker.
“A lot of the more progressive herds are using a combination of timed A.I., activity meters, some use all one and some all the other programs,” he observes, “but the combination of the two seems to really be as like rocket fuel for breeding programs.”
He notes that this can lead back to the problem of drying cows still milking heavily. Due to the confidence of being able to breed cows back, some herds are looking at increasing or decreasing their dry periods accordingly.
