You could go as little as 45 days after calving if cows were in good health.
We start breeding after 50 days postcalving. This strategy aims to keep the herd average number of days open a lower number than industry averages.
The end result is shorter lactations. This could be good or bad depending on how you view things. A 12 to 15 month lactation will produce higher milk production records per lactation. But you will get 2 calves in 3 years if you wait longer before breeding cows back. A 9 to 11 month lactation may produce smaller milk production records per lactation, but the goal is to produce 3 calves and 3 lactations in 3 years.
Brings you full circle to comparing per lactation production to lifetime production.