Bulls have a job for only 9 weeks of the year. We turned out the bulls for the breeding season in late July and picked them up yesterday after three cycles (63 days).
Bulls can be difficult to handle and therefore are rarely in the corral. The one time of year that the bulls are in the corral is for semen testing.
Semen testing is performed to identify bulls with reduced fertility not just to find those which are sterile. Very few bulls are sterile, but a significant percent have reduced fertility. Semen testing provides a “snapshot” in time of the reproductive status of the bull. Even a bull classed as “Satisfactory” does NOT mean he will always be an acceptable breeder. Semen production takes about two months, so the semen used on the first day of the breeding season was started into production about 60 days prior. Hence, our bulls are semen tested every year.
The Breeding Season
We want bulls in peak physical condition for the breeding season. During the heat of summer when they are working they will walk many miles. They have been together in a pasture so they have established their pecking order. But as bulls are put into the breeding field they will establish a new pecking order.
Throughout the breeding season, the bulls will be monitored for soundness in feet, legs and eyes anything that would decrease the ability of a bull to travel and breed cows. It also includes monitoring breeding performance in the field – that is a bulls ability to breed, breeding behaviour, and libido to determine success rates. If a bull becomes unsound during the breeding season, he will be pulled from the field and replaced with a fresh bull.
Cow to Bull Ratio
A common cow to bull ratio is 25 to 1. This will vary with the size of breeding field, terrain, number of cows in each field and age of bulls being used (as yearling bulls will have a lower cow to bull ratio than mature bulls). While smaller fields, with limited vertical requirements could probably comfortably support a ratio of 30 to 1 the fields we use are decently large with multiple water holes and rolling hills. Hence, we stick with the 25 to 1 recommendation.
One thing we explored when we went to Artificial Insemination (AI) was if it would reduce or increase the demand for bulls. While AI would be expected to reduce the demand for bulls, by using timed synchronization it meant that all of the cows that were open would be in heat over a very short period of time (~3 days), actually increasing the demand for bulls.
Now that the breeding season is over the bulls will have time to regain condition before winter.