Dairy management decisions such as the ideal voluntary waiting period and days dry are the topics of productivity conversations across the globe. Suggestions to shorten dry periods and extend voluntary waits to as many as 120 days in milk have left the industry questioning conventional management approaches.
Improvements in reproductive success might be expected with a shorter dry period, but cumulative milk production and early lactation survivability within the following lactation also need to be assessed. Unintended consequences of management decisions must be considered to fully capitalize on the major genetic progress the national herd has made within the last two decades.
A data set from 60 progressive herds nationwide from 2019 to 2024 helped the authors identify trends on over 109,000 animals. The results of their study were discussed recently on the “Dairy Science Digest” podcast by guests veterinarians Mike Overton and Steve Eicker.
With currently high replacement heifer costs, many producers try to promote longer productive lives by extending the voluntary waiting period, or by shortening days dry. However, management manipulations aimed solely at keeping cows longer is not the most profitable approach. More lifetime milk may appear attractive if the metric is at the cow level, but optimizing productivity per slot at the herd level should be the main focus. Mastitis, metabolic disease, and reproductive failure are all challenges that could compromise productivity and longevity.
This retrospective analysis revealed that longer days open and either short or long days dry were associated with greater risk of early lactation removals in the subsequent lactation. Cows diagnosed with mastitis were also at an elevated risk of premature replacement. One case of mastitis boosted those odds by 20%, but two or more cases raised the risk of replacement up to 50%, making it a strong predictor of premature removal risk in the next lactation.
According to the Council of Dairy Cattle Breeding, the annual rates of genetic improvement have doubled since 2012, when genomic selection became available. This technology has cultivated the opportunity for selective pressure in both the male and female before the phenotype is expressed in the mature animal.
Dairy producers can see the change happening before their eyes. Genetic advisers agree that you can’t just focus on one trait. When deciding what sires to put in the tank, some breeders look to indices, including the Net Merit Index (NM$), the Total Performance Index (TPI), and the Dairy Wellness Profit Index (DWP$).
“Investing in selection indices is kind of like buying mutual funds rather than putting all your money into one particular stock — it helps to diversify your risk and ensure continual forward progress across a variety of traits,” Overton explained. “As DWP$ index increased, cows were more likely to get pregnant by 90 days, have more milk by 90 days, and were less likely to leave by 90 days.”
However, as a more productive animal evolves, does she need to be managed differently? Is there a carry-over effect for longer or shorter days dry or open? Can we measure associations in the next lactation for management decisions such as voluntary waiting period (VWP)?
“There’s a lot of buzz coming over from Europe for extreme extension of the voluntary waiting period, suggesting 120 to 150 days before service,” said Overton, “but the data simply doesn’t support that practice."
Optimal voluntary waits for most herds are likely still in the 60 to 70 day range. This recommendation is across the herd, regardless of lactation number. “Just because you can, doesn’t mean you should,” Overton cautioned in regard to a delayed VWP for first lactation animals.
Management decisions can make or break an operation. Keeping close track of your data will ensure you are able to recognize trends in your data. Identify your major management opportunities by improved recording and monitoring of key leading indicators of future performance and important outcomes.
These findings were summarized in a peer-reviewed open access Journal of Dairy Science at article found at: www.journalofdairyscience.org. To learn more, listen to the monthly podcast, “Dairy Science Digest.”
