Studying a Shorter Dry Period
The University of Laval in Canada recently compared the effects of two different dry period lengths on health and reproduction.The study, published in the July Journal
of Dairy Science, featured 850 Holstein cows from 13 commercial
dairy herds that were assigned to a 35-day (short)
or a 60-day (conventional) dry period, based on milk yield,
number of calves and estimated calving interval.
Cows enrolled in the conventional dry period group were
fed a dry cow ration from dry-off until 21 days pre-partum,
at which time they were switched to a pre-calving ration.
A pre-calving ration was fed to cows of the short dry
period group throughout the entire shortened dry period.
Results showed:
Dry period management did not affect the culling rate for
second-lactation cows, but a significantly higher culling
rate occurred in multiparous cows with conventional dry
periods, compared with those with short dry periods.
A lower incidence of metabolic disorders occurred for
second-lactation cows, compared with third or later
lactation cows in both groups.
Cases of mild ketosis were lower for cows in the
shortened dry period group.
The occurrence of retained placenta was higher for
second- and later-lactation cows in the short dry period.
However, this did not lead to increased cases of metritis.
Researchers concluded that a short dry
period can transition cows back to the
milking herd sooner without major effects
on health and reproduction parameters.