Now is the time to check the bulls. Are the bulls actually working or are they quietly passing the day lying in the shade? It's not easy to keep up with bull breeding activity, but a keen eye by a producer can detect the difference between inactive and active bulls.
The North Dakota Beef Cattle Improvement Association processes beef records for many producers. Typically, these producers turned out their bulls in late spring to early summer. If one reviews the records since 1998, 32 percent of the producers turned their bulls out in May and 58 percent turned bulls out in June.
In recent years, the typical bull turnout date from 2002 through 2008 was June 7, 6, 9, 4, 2, 9 and 5, respectively. For the purpose of discussion, let's assume a typical bull turnout date of June 6. By June 27, the bulls will have been exposed to the cows for one heat cycle. These producers should have 63 percent or more of their cows bred by the end of June.
By July 18, bulls will have been exposed to the cows for 42 days, or have had the opportunity to be exposed to each cow for two heat cycles. For mature cows,
86 percent of the cows should be pregnant at this point. Of course, keep in mind that I am using an average bull turnout date of June 6.
Since most bulls are turned out from mid-May to late June, a set of goals can be established to monitor breeding performance. For example, a goal for those producers turning out bulls for natural service on May 15 should have 90 percent of the cows bred by June 26. Likewise, producers with bull turnout dates of May 29, June 12 and June 26 should expect 90 percent of their cows to have conceived and be with calf by July 10, July 24 and Aug. 7.
So, one can assume all is well when having turnout fertility-checked bulls that are sound and aggressive breeders. However, one also can assume that even though a bull tested good prior to bull turnout, not all bulls breed cows.
Fall surprises can be avoided by simply monitoring the cows. A quick check of the cow cycling activity can be made by remembering that the average estrous cycle of the cow is 21 days. If all the cows are cycling, about 5 percent should be expressing "heat" each day (one day divided by 21 days).
Let's assume one has 100 cows. An average of five cows should be in heat or estrus on any given day. Realizing that not all the cows calve the first 21 days of the calving season, this number can be adjusted. In fact, typically, only 63 percent of the cows calve the first 21 days of the calving season. For typical producers who expose mature bulls to 100 cows, at least three to four cows should be in heat every day early in the breeding season.