Current research suggests that by managing the length of the dry period according to the cow's parity, dairy producers can increase lifetime productivity of their cows, an SDSU expert says.
South Dakota State University Extension Dairy Specialist Alvaro Garcia says the length of the dry period as it affects cow performance in current and subsequent lactations has been the focus of recent attention.
"Every management aspect of the dairy that can improve net returns matters, particularly when facing low milk prices. Managing lactation periods in relation to parity may benefit lifetime productivity in spite of slightly lower average daily milk yields," Garcia says.
When cows are dried while still producing decent amounts of milk, the yield lost in the current lactation may offset what would be gained with a longer dry period in the subsequent lactation. Furthermore, cows with longer dry periods still eat while not generating income from milk and are thus being "subsidized" by their lactating herd-mates, Garcia says.
A recent research trial conducted by the Agricultural Research Service showed that the minimum of days dry to maximize production across adjacent lactations depends on parity. With 40 to 45 days dry there was little loss in production across first and second lactation. Dry periods of 55 to 65 days were required after second and third lactations. Lifetime production was maximized by 40 to 50 days dry after first lactation and 30 to 40 days dry after second and later lactations.
"The authors of this study concluded that although dry periods of 30 to 40 days can be used after second and later lactations without cost in lifetime yield, their benefit to lifetime production is minimal. They also recommended avoiding dry periods shorter than 30 days or longer than 70 days, as they were costly to lifetime yield," Garcia says.
"In order to maximize lifetime production (in contrast to yield across adjacent lactations), first lactation cows can be dried for 41 to 50 days, while cows can be dried only 31 to 40 days after second and later lactations," Garcia says. "As a result of the shorter dry periods, lifetime production is maximized as cows have more days in milk during their entire productive life."
After quantifying the effects of days dry on lifetime yield, the authors found that cows that were dried for more than 90 days produced over 8,800 pounds less lifetime milk yield than cows with dry periods of 40 to 60 days. Even dry periods of 70 to 80 days resulted in a reduction of about 5,500 pounds in lifetime milk yield.