Bulls need to be monitored throughout the breeding season.
By: Kris Ringwall, Beef Specialist, NDSU Extension Service
For most, June is bull turnout time. Some lingering cows still may need to calve, but the focus is on cropping and haying because the plans for next year’s feed supply are well under way.
Producers wanting March-April calves already have turned out the bulls. A June 1 turnout has a projected March 12 start of calving. A July 1 turnout has a projected April 11 start of calving.
But do not get too focused on other activities. Bulls need to be monitored throughout the breeding season. And if the bulls are not turned out yet, keep an eye on them in their pens. A dull, droopy bull may very well mean a poor day in the breeding pen.
If your bull was turned out on June 6, 62 percent or more of the cows exposed should be bred by June 27 (one heat cycle). By July 18 (two heat cycles), 87 percent of the cows should be pregnant.
Remember, I am using an average bull with a bull turnout date of June 6. Goals reflective of an individual producer’s management calendar need to be established for bulls turned out from mid-May to mid-July or later.
An achievable goal for producers turning out bulls for natural service on May 15 would be 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 bred by July 10, July 24 and Aug. 7, respectively.
Unfortunately, the evaluation of bulls while in the breeding pasture is difficult, but the bulls still need to be monitored. Excessive cows in heat past the second cycle should be a huge warning of potential bull problems.
Only 10 percent of the cows are expected to be in heat after two breeding cycles, so if 100 cows are exposed to the bulls, only 10 cows should be cycling after 42 days of breeding. On average, that would mean only one cow in heat every couple of days.
However, the obvious is not always obvious because bulls will tend to seem content and may even be somewhat distant with the cows and still have conceived calves with all the cows that were in heat.
Every breeding season, someone will call and ask, “I just do not think the bull is breeding. What should I do?” The response to the first question is, “Was the bull’s fertility checked?” If the answer is “yes,” the producer has some reassurance. Bull fertility may change, but if the bull was healthy at the breeding soundness exam and remains active with no obvious health issues, the bull’s fertility should not change.
Bulls mate at their own pace. Ask yourself, “Was the bull in good physical condition to meet the rigors of an active reproductive life as the bull was turned out to the cows? Was the bull allowed some pre-breeding exercise prior to bull turnout?”
Re-evaluate the bull’s physical condition, body condition, feet and legs, eyes and any other indication of illness. At this point of the breeding season, internal rectal examinations are only available with a lot of work, but a producer certainly can do a visual external examination of the testes, scrotum, penis and prepuce to note changes.
Bulls can get hurt, particularly the penis while mating, and if hurt, the bull will not breed. But even given all the precautions and evaluations, some bulls still will not mate, regardless of their excellent physical condition and having passed the breeding soundness exam. So keep an eye on the bull, but more importantly, keep an eye on the cows and monitor heat-cycling activity.
For some producers, multiple sires with cows provide backup bull power; however, multiple sires also means the establishment of a pecking order. In some cases, bulls may fight aggressively while mating, or the more timid bull simply may chose not to mate.
Two bulls in a breeding pen seldom sire half the calves each. One bull will tend to sire more calves. Thus, the single-mated groups have fewer dynamics of bull management but more impact if the bull fails to breed.
The number of cows a bull can breed annually can be quite high. Three to four mature bulls per 100 cows are the most common quoted numbers, but some producers run two mature bulls per 100 cows if the physical ability of the bulls to breed is evident. Producers must take managerial care to assure bulls are in breeding shape prior to bull turnout.
In closing, a cow is expected to start cycling following birth and prior to the bull arriving, and then settle with next year’s calf. Therefore, the cow is expected to maintain an average calving interval of 365 days. When a cow fails to meet those expectations, the cull pen gate is opened and off she goes.
That’s a sad point, so let’s make sure the problem was not the bull. As a producer, one could ask why all the cows don’t conceive on the first 21 days of the breeding season. Is it the bull or is it the cows? Keep an eye on both.
May you find all your ear tags.