The successful delivery and survival of a newborn calf is the goal of every dairy pregnancy, but unfortunately it doesn’t always work out that way.
Researchers at Ohio State University may have uncovered one way to improve those outcomes – increase the time and consistency that close-up cows are able to lie down and rest.
The Ohio State team, whose results were published in the Journal of Dairy Science, evaluated 1,044 cows from three Ohio dairies. Using electronic data loggers, they assess lying time and frequency starting 14 days before expected calving dates.
In addition to total lying time, they evaluated the consistency of lying session length from day to day. This was called the “coefficient of variation” (CV).
They also drew blood on days 14 and 7 before anticipated calving to check serum nonesterified fatty acid (NEFA) concentration, and again 48 hours after calving to measure total blood calcium. Higher serum NEFA concentration near calving has been associated with higher levels of several transition-cow diseases.
Both first-calf heifers and multiparous cows were included in the study.
Stillbirths were defined as calves that were born dead, or died within 24 hours of birth. A total of 50 stillbirths — or 4.8% of the data set — occurred. Comparing cows that delivered live calves to those with stillbirths, the researchers observed:
– Dams with live calves had more lying time in the 7 days leading up to calving than those with stillbirths. First-calf heifers with live calves rested an average of 55 minutes longer per day; multiparous cows with live calves rested an average of 46 minutes longer per day.
– Difficult calvings contributed to higher levels of stillbirth, but herd, parity, and season did not.
– Multiparous cows with a stillborn calf had higher prepartum serum NEFA concentration compared to their multiparous herdmates with a live calf. This difference did not occur among first-calf heifers.
– Regardless of parity, the incidence of postpartum milk fever was higher for dams with a stillborn calf versus those that delivered live calves.
– The CV ratio for all dams with stillbirths varied significantly more in the 7 days leading up to calving compared to dams with live births, regardless of parity.
The researchers concluded that dams that had stillbirths rested less, and less consistently, in the week leading up to calving. Multiparous stillbirth dams also had higher serum NEFA concentrations during that period, and all stillbirth dams had higher incidence of milk fever in the 48 hours after calving.
Thus, improving the factors that encourage close-up cows and heifers to lie down and rest could result in more live births, and dry-cow resting environments should be investigated if a herd is experiencing a high incidence of stillbirths.
