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Published July 24, 2010, 12:00 AM

Time for bulls to come home

It seems like yesterday that the cattle were sorted and sent to grass. The summer has been good because of reasonable rain showers, moderate temperatures and good grass growth.

By: By Kris Ringwall, The Dickinson Press

It seems like yesterday that the cattle were sorted and sent to grass. The summer has been good because of reasonable rain showers, moderate temperatures and good grass growth.

Because of this, pulling cattle out of summer pasture is not real popular. At the Dickinson Research Extension Center, we are starting to pull the bulls. Pulling bulls is a management choice. Many producers allow bulls to run the summer with the cows, maybe even into fall and, for a few, well into winter.

The logic is there. One less group of cattle to worry about and no one wants to be hauling feed when there is ample grass.

For the last few years, the center was geared to pulling bulls in the fall because of the out-of-sight, out-of-mind idea. That choice led to stretched-out calving and more shuffling of cows in the spring.

What is the true value of late-bred cows? Well, one would know if a package of bred cows was properly marketed and sold in the fall.

If a cow is pregnant, she stays. The question comes down to the calving distribution for a herd. In the cow herd appraisal program software database (CHAPS), 63.1 percent of the cows calved in the first 21 days and 85.8 percent calved by 42 days of the calving season.

The start date is based on when the bulls were turned out or at least when the first bull went to summer pasture, plus 285 days, which is a typical gestation length. If the 21-day periods do not line up very well, the CHAPS program will default to making the day the third mature cow (not first-calf heifers) calves as the official start date to the calving season.

Either way, the cows are allotted to reasonable 21-day increments. The next assumption is that cows that calved within the first 21 days bred in the first 21 days and those that calved in the second 21 days conceived during the second 21 days of the breeding cycle.

Variable gestation lengths may not always allow for an exact statement, but for managerial decision making, the numbers work.

What is the value of keeping a bull out for another cycle? At the end of calving, typically, 92.9 percent of the cows have calved.

Regardless of how long the bull was left in with the cows, seven cows out of every 100 still did not breed. So, the extra month of a calving season only will increase the percentage of total cows calving an additional 7.1 percent, or seven calves for every 100 cows. To many, the economic impact of seven light calves is significant, so producers continue to go for some light calves.

The cost of calving is significant and time-consuming. Watching 100 head for the first 21 days, 37 head for the next 21 days and seven head for the next 21 days creates an ever-increasing cost scenario in terms of each pregnant cow. In addition to time, late-calving cows tie up pens. This puts other ranch operations on hold. Significant labor and resources are dedicated to processing and hauling partially filled trailer loads of cows to pastures.

In addition, it is easy to get tired of calving. So, everyone needs to make up his or her own mind, but the center started pulling bulls last week.

Another point that often is forgotten is that late-calving cows have the same gestation length as those that calve early. Once a cow is late, (during the third 21 days of the calving season), the odds that she will calve during the first 21 days of the calving season next year are very low.

Generally, late cows are late cows, and pulling bulls in a timely manner simply opens the door for late cows to be open cows that are more likely to find a new home at the end of the grazing season.

Back to pulling bulls.

May you find all your ear tags.

— Ringwall is the North Dakota State University Extension Service

beef specialist. Comments are welcome at http://www.BeefTalk.com.

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