NDSU Extension - Ramsey County


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April 12, 2010 Ag Column


I am going to overshoot my column size with the information provided below but I do need to add a couple of comments.  First off it is hard to imagine we came so close to possibly being in the field this weekend, for some.  I say this with tongue in cheek, but this rain sure smells good.  I checked the NDawn station this morning and bare soil temperatures east of Crary is 41 degrees and turf soil is 38 degrees, so we are still too cold for germination but it would be good to get some nutrients applied.  I might also encourage any of you cattle producers to seriously think about selling any late calving cows or good cows that may have lost a calf as this cow market is absolutely tremendous.  It seems to not a make a difference on quality, although some cows do fit in a lower kill category but even so markets are too good to pass up.  The same also holds true for bulls.  Markets that are in the upper 60’s to lower 70’s makes this a great time to improve herd genetics for not much money by selling off the old and buying new.

In the midst of calving, some attention needs to be given to the bull because bull fertility is not guaranteed and not something that can be turned off and on.

What we forget in the management of bulls is that the expectation is for the bulls to breed cows through a very defined breeding that ultimately produces a tight calving season.

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.

Typically, at least for the those cows enrolled in the North Dakota Beef Cattle Improvement Association's CHAPS program, just more than 63 percent of the cows exposed to bulls settle with a calf the first cycle (CHAPS five-year rolling average). Cows that settle with a calf during the second cycle amount to 25 percent, with the remaining cows getting bred the third or later cycles during the breeding season.

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? Well, both could be at fault. However, once a cow calves, her annual calving date is very hard to change. If she starts her productive life conceiving during the first 21 days of the breeding season, pending no calving difficulty and proper nutrition, she should continue to maintain a 365-day calving interval (give or take a couple of
days) if there is a fertile bull available.

Again, looking at the CHAPS rolling five-year average for heifers that start their productive life calving before or during the first 21 days of the calving season based on mature cows, approximately 71 percent meet the criteria. Another 14 percent calf during the second 21 days of the calving season, essentially making it very difficult, even with exposure to very fertile bulls, to ever calve in the first 21 days of the calving season.

The point is that the bull only can settle cows that are cycling, but there is a gradual drop from the 71 percent of heifers that start calving early to the 63 percent that calve the first 21 days as a mature cow. That 8 percent drop could be blamed on the cows. However, the infertile or simply poor-libido bulls also could be a factor.

After all the time spent selecting fertile cows and keeping them in good breeding condition, one should not take a chance and expose them to infertile bulls. Each year takes a toll on the bulls in the bull pen. Some obviously are incapable of a vigorous breeding schedule. The obvious includes structural problems and injuries created by the day-to-day jostling in the bull pen.

The opposite also is true when the typical coach-potato bull that is overpampered and overfed is turned out with a group of cycling cows. A lot of effort is wasted on good cow management if good bull management is lacking or nonexistent.

The bottom line: Bulls need to be in physical condition to meet the rigors of an active reproductive life. A little exercise doesn't hurt, but the old digital exam still is required even in the healthiest appearing male, so a complete breeding soundness exam is a must. It should include a physical evaluation of its body condition, feet and legs, eyes and any other indication of illness. A rectal examination for evaluation of the prostate and other internal reproductive organs, plus an external examination of the testes, scrotum, penis and prepuce, is required.

A semen evaluation based on volume, color, motility and morphology should conclude the breeding soundness exam. All these evaluations need to be done now, one to two months prior to bull turn out, to acquire the needed replacements and correct needed deficiencies in the existing bull pen.


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