That's according to research from Aarhus University in Denmark that was reported in the January Journal of Dairy Science. The study attempted to develop an algorithm to detect and characterize behavioral estrus from activity data recorded hourly and then apply the algorithm to activity data from an experimental herd. The algorithm was based on deviations from hourly activity counts and was used to identify estrus onset, length and intensity.
The experiment herd was made up of Holsteins, Jerseys and Red Danes, totaling 3,674 activity episodes. The researchers found:
- An activity episode lasted 9.25 hours in heifers and 8.12 hours in cows.
- Red Danes had significantly fewer days to first estrus compared to Holsteins and Jerseys at 29.4, 33.1 and 33.9 days, respectively.
- Jerseys had significantly shorter duration and less strength of estrus than Red Danes and Holsteins.
- Days from calving to first episode of high activity was negatively correlated with body condition scores in early lactation.
Researchers say that the activity monitor data and the algorithmic baseline could supply valuable information about fertility traits, and be helpful in managing herd fertility.